Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Making interventions work on the farm : Unravelling the gap between technology-oriented potato interventions and livelihood building in Southern Ethiopia
Tadesse, Yenenesh - \ 2017
University. Promotor(en): Paul Struik, co-promotor(en): Conny Almekinders; Rogier Schulte. - Wageningen : Wageningen University - ISBN 9789463436847 - 120
potatoes - crop production - crop physiology - technology - intervention - livelihood strategies - livelihoods - ethiopia - east africa - aardappelen - gewasproductie - gewasfysiologie - technologie - interventie - strategieën voor levensonderhoud - middelen van bestaan - ethiopië - oost-afrika

Poor adoption of modern technologies in sub-Saharan Africa is one of the major factors that limit food production and thereby threaten food security of smallholder farmers. This is despite the potential and emerging success stories of new technologies in increasing productivity of smallholder agriculture. Explanations for low uptake of technologies are diverse. Some studies associated it with characteristics of the farmers and their farm; others attributed it to poor access to information about a particular technology, while some others recognize the importance of technology attributes. Farmers’ adoption decision is shaped socially and the farming practices are changing, not only because of the technical changes introduced, but also because of changes in social circumstances among smallholders. All these possible reasons did, however, miss largely important insights on how local complexities influence adoption. The research presented in this thesis analyses the social dynamics of technology-oriented interventions. More specifically, the study assessed the influence of technology introduction strategies, social networks and social differentiation on the adoption, dissemination and effects of potato technologies. As a case, it used interventions introducing improved potato technologies in Chencha, Southern Ethiopia. The field work combined individual and group in-depth interviews, household surveys and field observation for data collection.

Results show that the efforts to introduce technologies for improved potato production to progressive farmers with the assumption that farmers will eventually adopt, once they become familiar with the technology is a distant prospect. Some of the production practices - agronomic field and storage practices - failed to spread to poor farmers as expected, while the majority of agronomic practices fitted well with wealthy farmers. This resulted in diverse outcomes and strategies for livelihood improvement at household level. Access to the technologies and the necessary resources and diverse needs for technology were important factors in explaining variation in adoption and effects of technology across wealth categories. Tracing the seed diffusion through farmers’ networks showed that not all households had equal access to improved seed potatoes, mainly because of social barriers formed by differences in wealth, gender and religion, and because the type of personal relationship (relatives, neighbours, friends and acquaintance) between seed providers and seed recipients affected farmer to farmer seed sharing. In addition, the set-up of farmer-group based seed production demands resources and faces contextual challenges, which could be addressed through a long-term approach that engages continually in diagnosis and responding to the emerging social as well as material challenges. Development practitioners, however, took organizing group initiatives as a one-time process of design and start-up activity. Thus, clean seed potato production and dissemination through farmers’ organizations could not be sustainable. In conclusion, the present study has indicated that through providing special attention to the social dynamics researchers can arrive at better understanding of constraints affecting technology adoption. This implies effective interventions for a range of farm contexts involve not only finding technical solutions but also integrated understanding of farmers’ production conditions and existing social dynamics.

Understanding relations between pastoralism and its changing natural environment
Tamou, Charles - \ 2017
University. Promotor(en): Imke de Boer, co-promotor(en): Simon Oosting; Raimon Ripoll Bosch; I. Youssao Aboudou Karim. - Wageningen : Wageningen University - ISBN 9789463431552 - 154
pastoralism - livestock - grazing - crop production - nature conservation - cattle breeds - environment - nature reserves - benin - pastoralisme - vee - begrazing - gewasproductie - natuurbescherming - rundveerassen - milieu - natuurreservaten

The competition for land has become an issue of major concern and cause of conflict, especially between pastoralists and crop farmers, but also between pastoralists and nature conservation institutions. The Biosphere Reserve of W in Benin Republic (WBR) and its surrounding lands are located in the agro-pastoral contact zone in West Africa, enabling competition for land, and affecting the relations between pastoralism and its environment. The general aim of this thesis, therefore, was to understand the relations between pastoralism and its changing natural environment. In terms of land use change, cropland area around WBR expanded, whereas grazing area reduced. Population growth and rising demand for food crops and cash crops were the indirect causes of this loss of grazing lands. Competing claims over land existed between crop farmers and pastoralists, among crop farmers, and among crop farmers, pastoralists, and the WBR authority due to past expropriation, unfair and incomplete implementation of the WBR regulations and the increasing shift of pastoral lifestyle to crop farming. In terms of effects of grazing on plant communities, highly grazed sites had more species diversity than lowly grazed sites. This suggests that the current level of grazing was not damaging plant communities’ diversity. Annual species dominated the surveyed vegetation, suggesting that restoration of grazing lands with perennials requires human intervention. Herding involves taking decisions and moving of livestock in search for feed. Herding decisions are based on traditional ecological knowledge (TEK) of soil, forage and livestock. Pastoralists identified five different soils, which they selected for herding at different times of the year. Perennial grasses were perceived of high nutritional quality, whereas annuals were of low nutritional quality. Afzelia africana had high perceived quality for milk production, whereas Khaya senegalensis had the highest perceived quality for meat production, health and strength. In decision making for herding, pastoralists used a holistic approach, combining TEK about soil, vegetation and livestock, in a structured and prioritised reasoning. Changes in the pastoral system can lead to changes in desired livestock traits, which may lead to loss of indigenous breeds. Keteeji was valued for its endurance and tolerance to trypanosomiasis, Bodeeji was highly valued for endurance and Gudali was perceived of high value for meat and milk production, but of low value for endurance. To deal with the changing and unfavourable conditions of their environment, pastoralists preferred cattle breeds performing well on adaptive traits i.e. withstanding hunger, intelligence, and withstanding disease. Our results suggest that pastoralism is under pressure and that its survival depends on policies. In the pessimistic scenario, i.e. without any change, pastoralists will use, likely, the stepping-out strategy in the future. In the optimistic scenario, two possible institutional interventions could help maintaining pastoralism in the region: payments for ecosystem services provided by pastoralism, and association of pastoralism with nature conservation. In practice, however, the implementation of these two interventions is very challenging, which implies an increasing vulnerability of pastoralists and pastoral lifestyle.

Optimization of productivity and quality of irrigated tomato (Solanum lycopersicum L.) by smallholder farmers in the Central Rift Valley area of Oromia, Ethiopia
Gemechis, Ambecha O. - \ 2017
University. Promotor(en): Paul Struik, co-promotor(en): B. Emana. - Wageningen : Wageningen University - ISBN 9789463431576 - 262
solanum lycopersicum - irrigation - crop production - optimization - photosynthesis - chlorophyll - gas exchange - water use efficiency - crop yield - ethiopia - irrigatie - gewasproductie - optimalisatie - fotosynthese - chlorofyl - gasuitwisseling - watergebruiksrendement - gewasopbrengst - ethiopië

Tomato (Solanum lycopersicum L.) is a vegetable crop with high potential to contribute to poverty reduction via increased income and food security. It is widely grown by smallholders, has high productivity and its demand is increasing. Ethiopia produced about 30,700 Mg of tomatoes on 5,027 ha annually in 2014/2015. Average yields are only 6.1 Mg ha-1, below the world average yields. There is both a need and a potential to increase tomato production per unit area.

The aim of this thesis is to analyze the irrigated tomato production systems of smallholder farmers in Ethiopia, to survey and characterize the tomato in selected ecoregions and seasons, and to identify yield-limiting or yield-reducing factors and opportunities to enhance yield by using a combination of surveys and field experiments. Field experiments on optimization of yield and quality of field-grown tomato were carried out at Ziway, Ethiopia, for two seasons to study the impact of different irrigation practices applied, based on local empirical practices, deficit irrigation, or crop water requirement.

This thesis begins with a survey of tomato production systems. The survey details the area and production in various zones and for each of these zones yield- determining, yield-limiting, and yield-reducing factors and opportunities for improving yield and quality are indicated. It also avails area, production and yield data for each growing season and typifies the production systems in these zones. Low temperature (cold) from October-January and shortage of improved seeds are recognized as yield-determining factors, whereas insufficient water and nutrient (fertilizer) supply proved to be yield-limiting factors across zones. Late blight (Phytophthora infestans), Fusarium wilt (Fusarium oxysporum) and different pests and weeds are identified as yield-reducing factors in the zones. Experienced growers who have access to extension service recorded significant yield increment. Farmers Research Groups improved actual average yield with the use of improved technology (improved varieties and quality seed), and better efficiencies of water and fertilizer use. This study quantified influences of irrigation systems and strategies on growth-determining tomato features. Variation in irrigation systems and strategies accounted for variation in growth and dry matter accumulation. Greater performance for yield-related traits was obtained with drip irrigation based on crop water requirement for tomato varieties. Examination of plants showed also that local empirical irrigation is responsible for the occurrence of Phytophthora root rot, whereas deficit irrigation proved cause for occurrence of Fusarium wilt (Fusarium oxysporum), blossom end rot and broome rape (Orobanche ramosa) on roots or leaves, stems or fruits.

The experiments on irrigation scheduling with different irrigation systems and strategies gave useful indications on the possibility to improve commercial yield (CY) and water use efficiency. Promising results on CY and agronomical water use efficiency of tomato were achieved with drip irrigation based on crop water requirement, while for the biological water use efficiency higher value was obtained with deficit drip irrigation in both seasons. The findings indicate that the CY was decreased significantly for deficit by 50% in drip irrigation and deficit by 50% in furrow irrigation in both seasons. Mean CY for drip irrigation according to crop water requirement increased by 51% and 56% compared with deficit drip irrigation, whereas furrow irrigation based on crop water requirement increased by 52% and 54% compared with deficit furrow in Experiments 1 and 2, respectively. However, water use efficiency decreased with the increasing water volume.

Simultaneous measurements of rate of photosynthesis based on gas exchange measurements and the thylakoid electron flux based on chlorophyll fluorescence were used to investigate physiological limitations to photosynthesis in leaves of deficit irrigated tomato plants under open field situations. Combined leaf gas exchange/chlorophyll fluorescence measurements differentiated the treatments effectively. Reduction in rate of photosynthesis, stomatal conductance and the maximum quantum efficiency of photosystem II varied across seasons of all varieties, whereas leaf temperature was increased by deficit irrigation in all varieties. Among varieties studied, Miya was found relatively tolerant to deficit irrigation. Stomatal limitation of rate of photosynthesis increased significantly as a result of water stress suggesting a strong influence of the stomatal behaviour.

We also determined the influence of irrigation systems and strategies on water saving and tomato fruit quality. Using deficit drip irrigation was the best management strategy to optimize water use and tomato quality. Fruit dry matter content, acid content and total soluble solids were significantly higher with deficit drip irrigation than with other treatments.

From this thesis it appeared that agro-climatic conditions, access to resources and culture all contribute to the relatively low yields of tomato in the Central Rift Valley of Ethiopia. The thesis also proved that significant advances can be made in yield, quality and resource use efficiency.

Crop growth and development in closed and semi-closed greenhouses
Qian, Tian - \ 2017
University. Promotor(en): Leo Marcelis, co-promotor(en): Anja Dieleman; Anne Elings. - Wageningen : Wageningen University - ISBN 9789463430708 - 112
crops - crop production - growth - greenhouse crops - greenhouse horticulture - climate - semi-closed greenhouses - photosynthesis - temperature - gewassen - gewasproductie - groei - kasgewassen - glastuinbouw - klimaat - semi-gesloten kassen - fotosynthese - temperatuur

(Semi-)closed greenhouses have been developed over the last decades to conserve energy. In a closed greenhouse, window ventilation is fully replaced by mechanical cooling while solar heat is temporarily stored in an aquifer. A semi-closed greenhouse has a smaller cooling capacity than a closed greenhouse and, in which mechanical cooling is combined with window ventilation. (Semi-)closed greenhouses create new climate conditions: high CO2 concentrations irrespective of the outdoor climate, and vertical gradients in temperature and vapour pressure deficit throughout the canopy. This thesis focuses on the crop physiology in (semi-)closed greenhouses, and investigates the effects of the new climate conditions on crop growth, development and underlying processes.

Cumulative production in (semi) closed greenhouses increased by 6-14% compared to the open greenhouse, depending on the cooling capacity. The production increase in the (semi-)closed greenhouses was explained by the higher CO2 concentrations. In many species, feedback inhibition of photosynthesis occurs when plants are grown at high CO2. The results, however, suggest that high CO2 concentrations do not cause feedback inhibition in high producing crops, because the plants have sufficient sink organs (fruits) to utilise all assimilates. Pruning experiments showed that photosynthetic acclimation to elevated CO2 concentration only occurred when the number of fruits was considerably reduced.

Cooling below the canopy induced vertical temperature and vapour pressure deficit gradients. These gradients correlated with outside radiation and outside temperature. Despite the occurrence of vertical temperature gradients, plant growth and fruit yield were mostly unaffected. Leaf and truss initiation rates did not differ in the presence or absence of a vertical temperature gradients, since air temperatures at the top of the canopy were kept comparable. The only observed response of plants to the vertical temperature gradient was the reduced rate of fruit development in the lower part of the canopy. This resulted in a longer period between anthesis and fruit harvest and an increase in the average fruit weight in summer. However, total fruit production over the whole season was not affected.

The effects of the climate factors light, CO2 concentration, temperature, and humidity on leaf photosynthesis were investigated. The photosynthesis model of Farquhar, von Caemmerer and Berry (FvCB) was modified by adding a sub-model for Ribulose-1,5-bisphosphate carboxylase (Rubisco) activation. The photosynthetic parameters: the maximum carboxylation capacity (Vcmax) and the maximum electron transport rate (Jmax), α (the efficiency of light energy conversion), θ (the curvature of light response of electron transport), and Rd (the non-photorespiratory CO2 release) were estimated based on measurements under a wide range of environmental conditions in the semi-closed greenhouse. The simultaneous estimation method and the nonlinear mixed effects model were applied to ensure the accuracy of the parameter estimation. Observations and predictions matched well (R2=0.94).

The yield increase in a closed greenhouse, compared to that in an open greenhouse was analyzed based on physiological and developmental processes. The yield increase in the (semi-)closed greenhouses was the result of an increase of net leaf photosynthesis. The (semi-)closed greenhouses have been applied commercially first in the Netherlands, and later in other countries. The knowledge obtained from (semi-)closed greenhouses is applied in conventional open greenhouse as well, which is called the next generation greenhouse cultivation. A number of innovations are being developed for greenhouse industry to reduce energy consumption while improving production and quality.

Microcredit to women and its contribution to production and household food security
Namayengo, Mayanja Muyonga Faith - \ 2017
University. Promotor(en): Gerrit Antonides, co-promotor(en): Johan van Ophem. - Wageningen : Wageningen University - ISBN 9789463431101 - 235
credit - women - agricultural production - food security - crop production - animal production - household income - household budgets - food supply - uganda - krediet - vrouwen - landbouwproductie - voedselzekerheid - gewasproductie - dierlijke productie - gezinsinkomen - huishoudbudgetten - voedselvoorziening

The contents of this dissertation are based on a quantitative and qualitative survey that was conducted to assess the contribution of microcredit access of women to production and household food security status, and the factors associated with enterprise performance and food security outcomes. In order to do so four main issues were addressed: (a) assessment of the borrowing context and the match or mismatch between lender and borrower goals and objectives; (b) the extent to which taking microcredit affected business input expenditures and performance of non-farm MEs; (c) the extent to which taking microcredit affected production input expenditures and outputs from farming activities; (d) the changes in household food security associated with microcredit.

The study was conducted among female microcredit clients of BRAC, one of the largest micro lenders in Uganda. The overall study design was a panel approach, involving two waves of data collection. In one analytical approach, baseline data for a group of existing borrowers (Old borrowers=OB) and incoming borrowers (New borrowers=NB) before they received their first loan, was used in a quasi-experimental cross-sectional design to assess the effect of borrowing as the difference between the two groups using propensity score matching (PSM).

In an alternative approach, two waves of data for the NB and a control group (CG) of women who never borrowed from BRAC or other MFI, was subjected to difference-in-difference analysis (DID), with Kernel matching, to assess differences between borrowers and non-borrowers.

We found that BRAC reaches poor, less educated subsistence farmers who also run diverse non-farm microenterprises (MEs). The group-lending model BRAC uses is effective in ensuring loan repayment. However, much as BRAC gives out production loans, many women borrow to meet lump-sum monetary needs, in addition to investment in non-farm MEs. High costs of borrowing, limited loan amounts, the stress caused by weekly loan repayment and resolution of lump-sum cash needs were identified as reasons for women to stop borrowing. The diversion of loans to non-production activities, the size and types of businesses, and loan terms and processes were identified and factors that could diminish the contribution of microcredit to ME expansion and income increase.

Assessment of the effect of borrowing on non-farm ME performance revealed that much as borrowers invested reasonable fractions of received loans into non-farm MEs leading to improvement in monetary worth, the borrowing context, loan repayment terms, type and size of microenterprises did favour higher profits.

In regard to farm production, borrowing did not lead to extra recurrent crop and animal production expenditures. The prevailing subsistence nature of crop and animal production did not seem to favour extra investment. As such, borrowing did not improve household food availability, through own production.

Assessment of the effect of borrowing on household food security revealed a decline in food security following the uptake of microcredit. The analysis reveals robustly lower dietary diversity among long-time borrowers than among new borrowers, and larger reductions in dietary diversity scores among new borrowers, after one year, compared to controls. The reduction in dietary diversity was traced to a reduction in animal-source food, fruit and sugar intake. This was partly explained by observation of an apparent shift from own production to reliance on food purchase by households, which is not accompanied by substantial increase in income.

Overall, we found that taking microcredit did not lead to improved farm and non-farm production or food security among the rural women borrowers studied. This was mainly attributed to nature of activities the women engage in, the loan terms and processes, and the local context the women operate under.

Exploring opportunities for rural livelihoods and food security in Central Mozambique
Leonardo, Wilson José - \ 2017
University. Promotor(en): Ken Giller, co-promotor(en): Gerrie van de Ven; Henk Udo. - Wageningen : Wageningen University - ISBN 9789463431651 - 183
agricultural production systems - food security - crop production - livelihoods - small farms - biofuels - farming systems - models - intensification - mozambique - agrarische productiesystemen - voedselzekerheid - gewasproductie - middelen van bestaan - kleine landbouwbedrijven - biobrandstoffen - bedrijfssystemen - modellen - intensivering

Growing awareness of widespread hunger and poverty in many countries in the SSA is spurring a focus on productivity increase in smallholder farming systems. The rationale is that with current production systems many SSA countries are not keeping pace with population growth and changing of peoples’ lifestyles. To respond to this challenge the Government of Mozambique developed its Strategic Plan for Agricultural Development (PEDSA) aiming to improve agricultural productivity of the majority of smallholder farmers who depend on agriculture for their livelihoods. Smallholder farmers are diverse in terms of resources and aspirations. The main objectives of this study are first to understand the diversity among maize-based smallholder farms and their current constraints in improving agricultural productivity in the Manica Plateau, Central Mozambique, and second, building on that understanding to explore options for biomass production either for food, cash or biofuel at farm level and contributions to maize availability in the region. The study was conducted in the Dombe and Zembe Administrative Posts. Farmers in the two posts cultivate both food and cash crops using the same resources, however, distances to the urban market differ, with Zembe close and Dombe far away from the markets. In addition, the agroecological conditions for crop production are more favourable in Dombe compared with Zembe. Using farm surveys, direct observations and on-farm measurements, followed by Principal Components Analysis (PCA) I identified land and labour as the variables that can best explain the variability found among smallholder farms (Chapter 2). Based on these variables I categorised farms into four Farm Types (FT): FT1. Large farms (4.4 ha in Dombe and 2.2 ha in Zembe), hiring in labour; FT2. Intermediate sized farms (1.9-1.2 ha), hiring in and out labour; FT3a. Small farms (1.1-0.9 ha), sharing labour; and FT3b. Small farms (1.0-0.7 ha), hiring out labour. The maize yield and maize labour productivities were higher on large farms (2.3 t ha-1 in Dombe and 2.0 t ha-1 in Zembe; 2.5×10-3 t h-1 in Dombe and 2.6 ×10-3 t h-1 in Zembe) compared with small farms (1.5 t ha-1 in Dombe and 1.1 t ha-1 in Zembe; 1.4×10-3 t h-1 in Dombe and 0.9×10-3 t h-1 in Zembe). The hiring in labour from small farms allowed large farms to timely weed their fields. Small farms were resource constrained and hired out labour (mutrakita) for cash or food to the detriment of weeding their own fields, resulting in poor crop yields. Excessive alcohol consumption by small farms also raised concerns on labour quality. Chapter 3 explored options aiming at addressing farmers’ objectives of being maize self-sufficient and increased gross margin and the contribution to national objective of producing food. A bio-economic farm model was used to investigate two pathways to increase agricultural production: (i) extensification, expanding the current cultivated area; and (ii) intensification, increasing input use and output per unit of land.

In the extensification pathway I considered the use of animal traction, herbicides and cultivators to save labour, whereas in the intensification pathway I explored the use improved varieties of maize, sesame, sunflower, pigeonpea and fertilizers. I focused on the large farms and the small farms hiring out labour as they represent both sides of the spectrum. The simulated results showed that combining labour and labour saving technologies substantially increased both gross margin and maize yields of large and small farms in both posts. Minor trade-offs is observed on large farms between the two goals whereas for small farms we see synergies between the goals. We concluded that prospects for increasing gross margin and food production are much better for large farms in Dombe compared with other farms. In Dombe, the maximum gross margin of large farms was 7530 $ y-1 per farm and maximum maize sales of 30.4 t y-1 per farm. In Zembe, the maximum gross margin of large farms (2410 $ y-1 per farm) and maximum maize sales (9.5 t y-1 per farm) were comparable to small farms in Dombe. I further assessed the impact of two biofuel investments (jatropha plantation and sunflower outgrower schemes) on farm level food security (food availability, access to food, stability of food, utilization of food). The results showed positive impact on small farms from employment on a jatropha plantation by increasing access to food and no impacts on intermediate and large farms. Impacts on food security from the sunflower outgrower scheme were minor which may be explained by the poor yields.

The need to link smallholder farmers to markets has been increasingly recognized as important strategy to promote rural development and poverty reduction. I developed an analytical framework, the Windmill Approach that looked at decision making at farm level to grow certain crops and at transaction strategies (Chapter 5). Through this framework I showed that a farmer decision to participate in a particular (new) value chain is determined by (a) the suitability of the new crop in the farm system (including the adaptability of the current farm system), and (b) the farmer’s experience with selling in various value chains. This has major policy implications as it highlights that to support smallholder farmers access to markets a holistic approach is needed that combines farming systems analysis and transaction cost theory.

In order to explore the opportunities for smallholder development there is need to understand the diversity of farms and farmers’ social and economic context. For large farms, in Central Mozambique farms with on average 2-4 ha of land, opportunities to improve their livelihoods through crop production can follow two pathways: intensification and extensification. Smallholders continue to produce staple food crops even when working on a plantation or participating in outgrower schemes. For small farms, off-farm opportunities such as those in a biofuel plantation are the best options to improve their livelihoods.

A generic method to analyse yield gaps in feed-crop livestock systems
Linden, Aart van der - \ 2017
University. Promotor(en): Imke de Boer; Martin van Ittersum, co-promotor(en): Simon Oosting; Gerrie van de Ven. - Wageningen : Wageningen University - ISBN 9789463430746 - 214
animal production - fodder crops - livestock feeding - crop production - crop yield - crop ecology - quantitative analysis - beef production - farming systems - dierlijke productie - voedergewassen - veevoeding - gewasproductie - gewasopbrengst - gewasecologie - kwantitatieve analyse - rundvleesproductie - bedrijfssystemen

Global livestock production is expected to increase in future decades, and expansion of the agricultural area for feed production is not desired. Hence, increasing livestock production per unit agricultural area is essential. The bio-physical scope to increase production of livestock systems with the corresponding feed crop production (feed-crop livestock systems) could not be assessed generically at the start of this research. In crop production, however, crop models based on concepts of production ecology are widely applied to assess the bio-physical scope to increase actual production. The difference between the biophysical scope and actual production is referred to as the yield gap. The objectives of this thesis were 1) to develop a generic framework to assess the scope to increase production in feed crop-livestock systems based on concepts of production ecology, 2) to develop a generic livestock model simulating potential (i.e. maximum theoretical) and feed-limited livestock production, and 3) to apply this framework and model to feed-crop livestock systems, and conduct yield gap analyses.

Concepts of production ecology for livestock were specified in more detail. Feed efficiency at herd level was a suited benchmark for livestock production only, and production of animal-source food per hectare for feed-crop livestock systems. Application of the framework showed that the yield gap was 79% of the potential beef production of a cow-calf system, and 72% of a cow-calf-fattener system in the Charolais region of France. The model LiGAPS-Beef (Livestock simulator for Generic analysis of Animal Production Systems – Beef cattle) was developed to simulate potential and feed-limited production of beef cattle using input data about animals’ genotype, climate, and feed quality and availability. The model consists of sub-models describing thermoregulation, feed intake and digestion, and energy and protein utilisation. Model evaluation under different agro-ecological conditions indicated live weight gain was estimated fairly well (15.4% deviation from measured values). LiGAPS-Beef was coupled with crop growth models to simulate potential and resource-limited production of twelve grass-based beef production systems in the Charolais region. Resource-limited production combines feed-limited production of cattle and water-limited production of feed crops. Yield gaps were on average 85% of potential live weight production per hectare, and 47% of resource-limited production. Yield gaps were attributed to feed quality and quantity limitation (41% of potential production), water-limitation in feed crops (31%), the combination of sub-optimal selling or slaughter weights, culling rates, calving dates, age at first calving, and stocking densities (9%), and the combination of prolonged calving intervals and calf mortality (2%). Improved grassland management and an earlier start of the grazing season may increase live weight production per hectare. Furthermore, the resource-limited production of bulls was simulated to increase by 6-14% from 1999-2006 up to 2050 due to climate change.

From the results of this thesis, it can be concluded that 1) a generic framework using concepts of production ecology is available now to assess the bio-physical scope to increase production in feed-crop livestock systems per unit area; 2) the mechanistic model LiGAPS-Beef simulates potential and feed-limited production of beef cattle fairly well; 3) combining LiGAPS-Beef with crop growth models allows to quantify yield gaps in feed-crop livestock systems, and to analyse these yield gaps. The method described in this thesis can be used subsequently to identify options to mitigate yield gaps, and to increase livestock production per unit area, which may contribute to sustainable intensification of agriculture.

Understanding the productivity of cassava in West Africa
Ezui, Kodjovi Senam - \ 2017
University. Promotor(en): Ken Giller, co-promotor(en): Linus Franke; A. Mando. - Wageningen : Wageningen University - ISBN 9789463430470 - 183
manihot esculenta - cassava - crop production - rainfed agriculture - drought - crop yield - water use efficiency - radiation use efficiency - fertilizers - togo - ghana - west africa - cassave - gewasproductie - regenafhankelijke landbouw - droogte - gewasopbrengst - watergebruiksrendement - stralingsbenuttigingsefficiëntie - kunstmeststoffen - west-afrika

Drought stress and sub-optimal soil fertility management are major constraints to crop production in general and to cassava (Manihot esculenta Crantz) in particular in the rain-fed cropping systems in West Africa. Cassava is an important source of calories for millions of smallholder households in sub-Sahara Africa. The prime aim of this research was to understand cassava productivity in order to contribute to improving yields, food security and farm incomes in rain-fed cassava production systems in West Africa. A long-term goal was to contribute to a decision support tool for site-specific crop and nutrient management recommendations. Firstly, we studied farmers’ perception of cassava production constraints, assessed drivers of diversity among households and analysed the suitability of farmers’ resource endowment groups to the intensification of cassava production. The results indicate that farmers perceived erratic rainfall and poor soil fertility to be prime constraints to cassava production. The agricultural potential of the area and the proximity to regional markets were major drivers for the adoption of crop intensification options including the use of mineral and organic fertilizers. While the use of mineral and organic fertilizers was common in the Maritime zone that had a low agricultural potential, storage roots yields were below the national average of 2.2 Mg dry matter per hectare, and average incomes of 0.62, 0.46 and 0.46 US$ per capita per day for the high, medium and low farmer resource groups (REGs – HRE, MRE and LRE, respectively) were below the poverty line requirement of 1.25 US$. In the high agricultural potential Plateaux zone, HRE and MRE households passed this poverty line by earning 2.58 and 2.59 US$ per capita per day, respectively, unlike the LRE households with 0.89 US$ per capita per day. Secondly, we investigated the effects of mineral fertilizer on nutrient uptake, nutrient physiological use efficiency and storage roots yields of cassava since soil fertility was a major issue across the zones. We used an approach based on the model for the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS). This model was successfully adapted for cassava and it appropriately assessed the response of cassava to N, P and K applications, especially in years with good rainfall. Under high drought stress, the model overestimated cassava yields. Thirdly, we investigated the impact of balanced nutrition on nutrient use efficiency, yield and return on investment compared to blanket fertilizer use as commonly practiced in cassava production systems in Southern Togo, and in Southern and Northern Ghana. The balanced nutrition approach of the QUEFTS model aimed to maximize simultaneously nutrient use efficiency of N, P and K in accordance with the plant’s needs. Larger nutrient use efficiencies of 20.5 to 23.9 kg storage root dry matter (DM) per kilo crop nutrient equivalent (1kCNE of a nutrient is the quantity of that nutrient that has the same effect on yield as 1 kg of N under balanced nutrition conditions) were achieved at balanced nutrition at harvest index (HI) of 0.50 compared to 20.0 to 20.5 kg storage root DM per kilo CNE for the blanket rates recommended by national research services for cassava production. Lower benefit:cost ratios of 2.4±0.9 were obtained for the blanket fertilizer rates versus 3.8±1.1 for the balanced fertilizer rates. Our study revealed that potassium (K) was a major yield limiting factor for cassava production, especially on the Ferralsols in Southern Togo. Hence, we fourthly studied the effect of K and its interaction with nitrogen (N), phosphorus (P), and the timing of harvest on the productivity of cassava in relation to the effects of K on radiation use efficiency (RUE), light interception, water use efficiency (WUE) and water transpiration. The results suggest that K plays a leading role in RUE and WUE, while N is the leading nutrient for light interception and water transpiration. Potassium effects on RUE and WUE depended on the availability of N and harvest time. Values of RUE and WUE declined with harvest at 4, 8 and 11 months after planting. Thus, enhanced K management with sufficient supply of N during the early stage of development of cassava is needed to maximize RUE and WUE, and consequently attain larger storage root yields. Given that erratic rainfall was another major constraint to cassava production according to the results of the farm survey, and due to the inability of QUEFTS modelling to assess drought effects on cassava yield successfully, another modelling approach based on light interception and utilization (LINTUL) was used. We quantified drought impacts on yields and explored strategies to improve yields through evaluation of planting dates in Southern Togo. The evaluation of the model indicated good agreement between simulated and observed leaf area index (Normalised Root Mean Square Error - NRMSE - 17% of the average observed LAI), storage roots yields (NRMSE 5.8% of the average observed yield) and total biomass yield (NRMSE 5.8% of the average observed). Simulated yield losses due to drought ranged from 9-60% of the water-limited yields. The evaluation of planting dates from mid-January to mid-July indicated that the best planting window is around mid-February. Higher amount of cropping season rainfall was also achieved with early planting. These results contradict current practices of starting planting around mid-March to mid-April. However, the results indicate the possibility to increase cassava yields with early planting, which led to less yield losses due to drought. By contrast, late planting around June-July gave larger potential yields, and suggested these periods to be the best planting window for cassava under irrigated conditions in Southern Togo. This shows that appropriate water control and planting periods can contribute to attaining larger yields in Southern Togo. Further improvement of the LINTUL model is required towards using it to assess water-limited yield, which can be used as boundary constraint in QUEFTS to derive site-specific fertilizer requirements for enhanced cassava yield and returns on investments in West Africa.

On yield gains and yield gaps in wheat-maize intercropping : opportunities for sustainable increases in grain production
Gou, Fang - \ 2017
University. Promotor(en): Martin van Ittersum, co-promotor(en): Wopke van der Werf. - Wageningen : Wageningen University - ISBN 9789462579811 - 202
zea mays - triticum - intercropping - crop yield - grain crops - crop production - models - photosynthesis - tussenteelt - gewasopbrengst - graangewassen - gewasproductie - modellen - fotosynthese

Intercropping is the cultivation of two or more crop species simultaneously in the same field, while relay intercropping means that the growing periods of the crop species are only partially overlapping. Intercropping has advantages with respect to productivity, resource capture, build-up of soil organic matter, and pest and disease suppression. This thesis aims to quantify and explain the yield advantages in wheat-maize relay intercropping and to assess the importance of intercropping for food production and land use efficiency.

Wheat-maize intercropping had land equivalent ratios around or above one in two experiments in the Netherlands. Wheat in border rows showed major yield increases, and this yield increase was due to increases in the number of tillers per plant and the number of kernels per ear. The yield advantage of intercropped wheat was associated with a high radiation interception and radiation use efficiency (RUE). Under Dutch growing conditions, maize performance in the intercrop was constrained. Intercropping had a negative effect on the yield per plant and radiation use efficiency of maize. A strip intercrop model was developed, parameterized and tested with data on wheat-maize intercropping in the Netherlands. The model simulates radiation interception and growth in relay-strip intercrops with two species in different planting configurations. The model also allows simulating the consequences of border row effects for total system productivity. Bayesian analysis was applied to calibrate radiation use efficiency of wheat and maize in sole crops and intercrop. Intercropped wheat had higher a RUE than sole wheat, while intercropped maize had a lower RUE than sole maize. Intercropped maize had less favourable leaf traits (e.g. nitrogen content) during the flowering stage than sole maize in 2014, but the leaves in the intercrop had a higher photosynthetic rate than those in the sole crop. Possible explanations for this finding include differences between sole and mixed crops in water acquisition from soil, light distribution in the canopy, nitrogen distribution within the leaf and the contribution of the ear leaf to the growth of the cob. The low radiation use efficiency in intercropped maize may relate to nitrogen deficiency during grain filling. New concepts for potential yield, yield gain and yield gap in intercropping were developed in this thesis. Using crop model simulations and farm survey data, those concepts were operationalized in the context of wheat and maize production in an oasis area (Zhangye city) in northwest China. Wheat-maize intercropping resulted in substantial yield gains under potential and actual growing conditions. A comparison of potential and actual yields indicated a yield gap of 33% for sole wheat, 49% for sole maize, 15% for intercropped wheat, and 51% for intercropped maize. The land use analysis showed that discontinuing the use of intercropping in this region will decrease grain production substantially.

Overall, this thesis studied the growth and productivity of wheat-maize intercropping at organ, plant and cropping system level, and also assessed its contribution to grain production at a regional level. The findings suggest that intercropping of food crops provides opportunities to meet increasing food demands. New technologies are needed to make strip intercropping efficient in terms of labour use and breeding should pay attention to cultivars that are suitable for intercropping.

Transition to more water efficient agriculture production in Thailand : Fact finding
Blom-Zandstra, M. ; Kempenaar, C. ; Rothuis, A.J. - \ 2016
Wageningen : Wageningen Plant Research (Report / Wageningen Plant Research 663) - 22 p.
crops - water use efficiency - water deficit - crop production - thailand - gewassen - watergebruiksrendement - watertekort - gewasproductie
Thailand will face major water scarcity problems. The question is how Thailand can remain an important producer of agriculture crops (such as rice) while facing severe water shortages in the near future. To generate “more crop per drop” a sequence of innovations need to be introduced.
Less at the top, more gain at the bottom : better light penetration leads to higher production
Heuvelink, E. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)4. - ISSN 2215-0633 - p. 18 - 19.
greenhouse horticulture - greenhouses - light penetration - crop production - farm management - diffused glass - glastuinbouw - kassen - lichtpenetratie - gewasproductie - agrarische bedrijfsvoering - diffuus glas
If light penetrates the crop better, it results in higher production. This is because the leaves that are deeper in the crop are a long way from their light saturation point. Diffuse glass or coatings and the distribution of the crop are the most applicable ways to achieve better light penetration. Other methods are usually beyond the reach of the grower
Potassium, the major organiser in numerous plant processes : involved in almost everything the plant turns into plant
Heuvelink, E. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)4. - ISSN 2215-0633 - p. 46 - 47.
greenhouse horticulture - crop production - crop quality - potassium - plant development - nutrient requirements - glastuinbouw - gewasproductie - gewaskwaliteit - kalium - plantenontwikkeling - voedingsstoffenbehoeften
No potassium no plant: A huge number of processes are dependent on this element. Luckily, hardly any problems occur because the plant is good at looking after itself in this respect.
Filmpje: Paprika, schermen bij tropisch weer, geen binnenrot
Gelder, A. de - \ 2016
Kasalsenergiebron.nl
paprika's - gewasproductie - energiebesparing - energiegebruik - gewaskwaliteit - glastuinbouw - teeltsystemen - sweet peppers - crop production - energy saving - energy consumption - crop quality - greenhouse horticulture - cropping systems
Het weglaten van de minimumbuis en het gebruik van twee energieschermen elke nacht, ook tijdens de warmste dagen in augustus, waren de opvallendste aspecten tijdens het onderzoek ‘Paprika energiezuinig met een goede kwaliteit’. Aat Dijkshoorn (LTO Glaskracht Nederland), Jeroen Zwinkels (Delphy), Arie de Gelder (Wageningen University & Research) en telers Danny van der Spek (Paprikakwekerij Van der Spek) en Maikel van den Berg (Quality Peppers) vertellen in dit filmpje over deze opvallende resultaten van het onderzoek.
Crop intensification options and trade-offs with the water balance in the Central Rift Valley of Ethiopia
Debas, Mezegebu - \ 2016
University. Promotor(en): Martin van Ittersum, co-promotor(en): Huib Hengsdijk; Katrien Descheemaeker. - Wageningen : Wageningen University - ISBN 9789462578616 - 178
cropping systems - intensification - water balance - crop production - land use - climatic change - crop yield - water use - irrigation - ethiopia - teeltsystemen - intensivering - waterbalans - gewasproductie - landgebruik - klimaatverandering - gewasopbrengst - watergebruik - irrigatie - ethiopië

The Central Rift Valley (CRV) of Ethiopia is a closed basin for which claims on land and water have strongly increased over the past decade resulting in over-exploitation of the resources. A clear symptom is the declining trend in the water level of the terminal Lake Abyata. The actual productivity of most cereals in the CRV is less than 2 t ha-1 associated with low input use and poor crop management. Consequently, there are two major development objectives in the CRV, i.e. producing sufficient food for the increasing population, while at the same time ensuring efficient use of limited water and land resources under variable and changing climate conditions. The low productive cereal systems and a declining resource base call for options to increase crop productivity and improve resource use efficiency in order to meet the growing demand for food.

In this thesis, the recent impacts were quantified of climate change, land use change and irrigation water abstraction on water availability of Lake Abyata of the CRV. The trends in lake levels, river discharges, basin rainfall, temperature and irrigation development (ca. 1975-2008) were analysed and the additional evapotranspiration loss resulting from temperature change and irrigated land were computed. We also analysed land use change (1990-2007) and the associated changes in runoff. Results showed that temperature has increased over 34 years (p<0.001) whereas annual rainfall has not changed significantly. Consequently, increased evapotranspiration consumed 62 and 145 Mm3 of additional water from lakes and land surface, respectively, during 1990-2007. Furthermore, an estimated 285 Mm3yr-1 of water was abstracted for irrigation in 2009 of which approximately 170 Mm3yr-1 is irrecoverable evapotranspiration loss. In addition, surface runoff has increased in the upper, and decreased in lower sub-basins of the CRV associated with extensive land use change (1990-2007).

We analysed a large number of data from farmers’ fields (>10,000) and experimental data across the CRV from 2004-2009 to quantify the gaps (Yg) between actual (farm) and experimental (water-limited potential - Yw) yields of maize and wheat in homogenous farming zones. We found that the average (2004-2009) yield gap of maize and wheat ranged between 4.2-9.2 t ha-1, and 2.5-4.7 t ha-1, respectively, across farming zones. The actual N and P application in farmers’ fields was low, as about 46% of maize and 27% of wheat fields did not receive fertilisers. We calibrated, validated and used the Agricultural Production System Simulator (APSIM) model to explore intensification options and their trade-offs with water losses through evapotranspiration. Variety selection and N fertilization were more important for yield gap closure than crop residue management and planting density, and the magnitude of their effect depended on soil type and climate. There was a trade-off between intensification and water use through evapotranspiration, as increasing yield comes at the cost of increased transpiration. However, this trade-off can be minimized by choosing location-specific N levels at which both water use efficiency (WUE) and gross margin are maximised. These application rates varied between 75 and 250 kg N ha-1 across locations and soils, and allowed producing 80% of Yw of maize and wheat. Climate change was projected to lower Yw of maize and wheat by ca. 15-25% and 2-30%, respectively, compared to current climate conditions.

An automated gridded simulation framework was developed to scale up the promising intensification options from field scale to basin scale. We then aggregated basin scale production and identified trade-offs between production and water use for different land use scenarios. This procedure allowed designing land use scenarios based on a spatially explicit optimization of WUE and gross margin per grid cell. Consequences of land use scenarios for food production and water use at basin level were evaluated. Results of the different land use scenarios demonstrated that crop intensification options for which WUE and gross margin are maximised can meet the projected food demand (year 2050) of the growing population in the CRV while at the same time saving large areas of the currently cultivated land. In the intensification scenarios total water loss through evapotranspiration from agricultural land is reduced compared with water loss from current cultivated land and low crop productivity levels.

It is concluded that the current land use together with climate change and water abstraction for irrigation negatively affected the basin level water balance in CRV over the past decade. Furthermore, the scope for further expansion of farmland to increase food production is very limited. The focus should, therefore, be towards intensification also because the existing yield gaps are huge and hence the scope for intensification is large. Model-based exploration of intensification options can be used to prioritize promising options, to close the yield gap and for quantifying trade-offs. Scaling up of promising options allows to assess whether the food demand of the growing population can be met while at the same time saving the less productive land and water per unit agricultural product.

Young fruits pull so hard, flowers above abort : developing fruits function too strongly as sink
Heuvelink, E. ; Marcelis, L.F.M. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)2. - ISSN 2215-0633 - p. 16 - 17.
horticulture - greenhouse horticulture - capsicum - crop growth stage - maturity stage - auxins - crop production - parthenocarpy - tuinbouw - glastuinbouw - gewassen, groeifasen - groeifasen, rijp - auxinen - gewasproductie - parthenocarpie
Sweet peppers arrive in waves. New fruits lure so many assimilates towards them that the flowers above them abort. This article provides various suggestions about how to flatten out the peaks and troughs. In the long term, breeding can also play an important role.
Iron is essential for photosynthesis and respiration : iron deficiency : the most common deficiency disorder
Heuvelink, E. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)1. - ISSN 2215-0633 - p. 48 - 49.
horticulture - greenhouse horticulture - rosaceae - chelates - ph - iron - deficiency - plant disorders - crop production - tuinbouw - glastuinbouw - chelaten - ijzer - deficiëntie - afwijkingen, planten - gewasproductie

Iron plays a major role in photosynthesis. That’s why a shortage directly affects the production capacity of the plant. The application of chelates has made iron much more easy to absorb. Nevertheless it’s an element that we have to keep an eye on.
MonQi: Toolbox for monitoring and evaluating the management and performance of smallholder farms
Duivenbooden, N. van; Beek, C.L. van - \ 2015
Alterra - 6 p.
small farms - management - farm management - crop production - fertilizer application - nutrient accounting system - pesticides - teaching materials - kleine landbouwbedrijven - bedrijfsvoering - agrarische bedrijfsvoering - gewasproductie - bemesting - mineralenboekhouding - pesticiden - lesmaterialen
Although Integrated Soil Fertility is on the map for decades, the real implementation at farm level does not take off, with associated consequences of soil nutrient mining and insecure agricultural production. A different approach is therefore needed to monitor and evaluate current land use at farm level. We present here the M&E-tool MonQI that can provide insights in the various determining processes.
Exploring options for improving water and nitrogen use efficiency in crop production systems
Qin, W. - \ 2015
University. Promotor(en): Oene Oenema, co-promotor(en): C. Hu; Marius Heinen. - Wageningen : Wageningen University - ISBN 9789462575035 - 188
gewasproductie - agrarische productiesystemen - watergebruiksrendement - stikstof - nutriëntengebruiksefficiëntie - mulchen - fertigatie - crop production - agricultural production systems - water use efficiency - nitrogen - nutrient use efficiency - mulching - fertigation

Water and nitrogen (N) are two key limiting factors in global crop production. However, the optimization of water and N use is often studied separately, and the interactions between water and N use in crop production are often neglected. Lack of systematic and quantitative understanding of the interactions between water and N use may lead to misleading and/or biased recommendations. The main objective of this thesis research was ‘to increase the understanding of interactions between water and N use in crop production’. The specific objectives were (i) to analyse water and N use and their interactions in crop yields and in water and N use efficiencies (WUE and NUE), and (ii) to explore options for increasing crop yields and water and N use efficiencies simultaneously.

In this thesis, I combined the use of literature review and meta-analysis, long-term field experiments and soil-crop modelling to quantify relationships between water and N use and their interactions in crop yields, WUE and NUE, and to explore options for improving the productivity and sustainability of two important and contrasting crop systems (i.e., annual cereal and perennial orange systems).

In arid and semi-arid regions, such as the Loess Plateau, I found that the water loss via soil evaporation was large as much as 60 to 70% of total rainfall and thereby significantly limited wheat yields. Soil mulching can effectively reduce soil evaporation thereby increasing crop yields by up to 60%. In sub-humid regions, the productivity and sustainability of rainfed wheat-soybean rotation systems can be constrained by soil fertility and other factors besides water and nutrient management. Fertilization and soil organic amendments greatly increased wheat yield and WUE, but decreased NUE.

In advanced fertigated orange production systems, a main challenge is to optimize water and N use for optimal yield while minimizing environmental pollution. Fertigation provides opportunities to simultaneously optimize water and N use in orange production systems. Optimization of water and N supply is, however, complicated in practice due to erratic and uncontrollable rainfall, which may lead to large incidental losses. Improving water and N input can significantly and simultaneously increase orange yield, WUE and NUE (by 20, 30 and 40% respectively). Importantly, even with optimal water and N input levels, fractionation (split) strategies can significantly increase orange yield and reduce N losses.

In conclusion, rainfed cereal crop yields, WUE and NUE in dryland agriculture can be increased by up to 60%, with currently available knowledge and soil mulching techniques. In many regions in the world, there is still a large gap between observed farm yield and attainable yield by best management. Given large potentials in low-performing agricultural systems, investments in knowledge and education, infrastructures and subsidies should also be prioritized for these regions. Potentially, this will significantly contribute to local and global food security at large.

Simple systems abroad coupled to hight-tech solutions : MexiCultura: cooperation between Holland and Mexico
Velden, P. van; Elings, A. - \ 2015
In Greenhouses : the international magazine for greenhouse growers 4 (2015)2. - ISSN 2215-0633 - p. 26 - 27.
glastuinbouw - kastechniek - kassen - bouwtechnologie - bouwconstructie - innovaties - gewasproductie - kennisoverdracht - samenwerking - mexico - nederland - greenhouse horticulture - greenhouse technology - greenhouses - construction technology - building construction - innovations - crop production - knowledge transfer - cooperation - netherlands
Doing business with Mexican entrepreneurs is high on the wish list of Dutch companies. That’s not so simple when you’re used to building high-tech greenhouses. Yet the local growers want to improve their current methods of production. The Dutch can be of service by offering knowledge about simple heating systems and ways to save water.
Stuurlicht in de Glastuinbouw : 1. Kansen voor energiebesparing?
Dueck, T.A. ; Hogewoning, S. ; Pot, S. ; Meinen, E. ; Trouwborst, G. ; Kempkes, F.L.K. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1349) - 56
teelt onder bescherming - gewasproductie - gewasopbrengst - gewaskwaliteit - gewasfysiologie - kunstlicht - kunstmatige verlichting - plantenfysiologie - aanvullend licht - blauw licht - verrood licht - rood licht - phalaenopsis - kalanchoe - chrysanten - protected cultivation - crop production - crop yield - crop quality - crop physiology - artificial light - artificial lighting - plant physiology - supplementary light - blue light - far red light - red light - chrysanthemums
This report focusses on energy efficient steering light applications by energy efficient lighting systems, but especially with new possibilities to influence crop growth and production with the light spectrum. After an introduction of the physiological background and application of steering light, new applications for steering light in the future are described with respect to energy saving opportunities. Possible scenario’s for steering light are presented for phalaenopsis, chrysanthemum and kalanchoë.
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