Union Catalogue of Agricultural Libraries in the Netherlands
The WUR Library Catalogue contains bibliographic data on books and periodicals held by the libraries of Wageningen University and Research Centre and some 15 associated libraries. Holding data are added to each record.
Subjects covered include Agrotechnology, Food and Food Production, Plant and Animal Sciences, Soil Science, Geo-information, Landscape and Spatial Planning, Water and Climate, Ecosystem Studies, Economics and Society.
The joint collections of the participating libraries cover a substantial part of the internationally available scientific literature in these disciplines.
As far as Dutch scientific literature in these fields is concerned, coverage can be considered near 100%, including much of the so-called "grey literature".
All titles are entered in their original language. Keywords are added to facilitate subject searching.
The database is updated every day and now contains over 830.000 records.
Germination of pear pollen markedly improved when boric acid was added to the medium. The pollen was more sensitive to boron in water than in 10 % sugar solution. Supplying weak solutions of boron to pear branches before flowering resulted in a good germination of the pollen in sugar solution without boron. Spraying apple-trees and pear-trees with boron solutions had no significant effect on fruit set, despite the pollen sensitivity to boron in vitro.The amount of boric acid in the medium determined percentage germination (saturation curve) and length of pollen tubes. Boron was not required until the tubes protruded. Temperature and sugar concentration both showed optimum values for germination. The effect of boron on germination rate was positively correlated with temperature and negatively with sugar concentration. An increase of 10°C roughly doubled this influence on germination rate. Germination was positively correlated with pollen grain number per drop, whether or not boron was present. So the mutual stimulation of the pollen was more effective with boron or with pollen from rather boron-rich branches. Pollen extracts in 10 % sugar solution with or without boron stimulated germination (also of other species).Both apple and pear pollen (and those of many other species) remained viable longest at both low humidity and temperature. In deep-freeze longevity was more than 2 years at -180°. Viability remained unchanged. Longevity would probably have been indefinite.
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