|Title||Seed quality in informal seed systems|
|Source||University. Promotor(en): Paul Struik, co-promotor(en): Tjeerd-Jan Stomph. - S.l. : s.n. - ISBN 9789461736420 - 120|
Crop and Weed Ecology
Centre for Crop Systems Analysis
|Publication type||Dissertation, internally prepared|
|Keyword(s)||zaadkwaliteit - zaadfysiologie - vigna unguiculata - vignabonen - zaadkieming - zaadpathologie - mycotoxinen - zea mays - nigeria - seed quality - seed physiology - cowpeas - seed germination - seed pathology - mycotoxins|
|Categories||Seed Production / Plant Physiology|
Keywords: informal seed systems, seed recycling, seed quality, germination, seed pathology, seed health, seed-borne diseases, mycotoxigenic fungi, Fusarium verticillioides, mycotoxins, Vigna unguiculata, Zea mays, Nigeria.
Seed is a crucial input for agricultural production. Approximately 80% of the smallholder farmers in Africa depend for their seed on the informal seed system, consisting of farmers involved in selection, production and dissemination of seed. The lack of overhead, distribution and seed testing costs enables seed-producing farmers to offer seed for low prices, but seed quality is not always good. Seed-producing farmers multiply their seed on-farm without frequent seed renewal, referred to as seed recycling, which may lead to low seed quality. This research analysed the effect of seed recycling on physiological quality and seed health of cowpea and maize, and compared seed quality of the formal and informal seed system.
We tested the physical and physiological quality of cowpea seeds produced by the formal and informal seed system. Five out of six foundation seed samples, 79 out of 81 samples of farmers’ seed, and six out of six seed company samples failed to meet standards for foundation and certified seeds of the National Agriculture Seed Council (NASC), the seed industry regulatory agency in Nigeria. No evidence was found for a negative effect of seed recycling on physiological quality of cowpea seeds. We analysed 45,500 cowpea seeds for seed-borne bacteria and fungi to compare the performance of formal and informal seed systems. All samples were heavily infected with seed-borne pathogens, including Fusarium oxysporum (69% of the samples) and Macrophomina phaseolina (76%). No evidence was found that seed recycling in the informal seed system did lead to increased levels of seed-borne pathogens. We also analysed seed quality of farmer-produced maize seed to compare it with the formal seed system. The seed company samples had significantly higher germination (99.3%) than farmer-produced seed (97.7%), but not a single sample passed the requirements for certified seed of the NASC. Twelve seed-borne pathogens were identified including Bipolaris maydis (found in 45% of the farmer-produced samples), Botryodiplodia theobromae (97%) and Fusarium verticillioides (100%). Seed recycling had no negative effect on the physiological quality or seed health of maize seed. We analysed formal and informal seed systems to assess the opportunities to prevent mycotoxigenic fungi infection in maize seeds. A range of control methods to avoid fungal infection and mycotoxin production is discussed in relation to three criteria for sustainable implementation in developing countries. An integrated approach is recommended, with special attention towards the local seed system. As an overall conclusion of the work it can be stated that the informal seed system did not underperform compared to the formal seed system for cowpea, but did underperform in relation to seed company samples of maize. There was no evidence that seed recycling reduces seed quality of cowpea and maize seed samples, so frequent seed renewal will not improve seed quality of the informal seed system. We recommend a new quality assurance system for the informal seed system based on seed quality testing by farmers themselves, without interference by government or external laboratories. Farmers publish their seed testing results on the bag, while buyers can retest the seed to verify the quality. Further research is required to develop and implement this system in different countries, agro-ecologies and crops, and to develop methods that enable farmers to test seed health quality themselves.