Effects of boron on pollen viability in wheat

Abstract

Grain set failure in wheat, caused by boron (B) deficiency, is associated with poorly developed pollen and anthers. This paper presents results of a study of the effect of B on pollen viability when it was supplied "internally" through the roots and externally in an agar medium for in vitro germination. There was no major effect of B supply to wheat plants on the number of pollen anther-1 or the percentage of pollen with positive reaction to iodine. Pollen germination in the medium was, however, responsive to both internal and external B supply. When B was not added to the medium, germination was poor, regardless of the level of B supplied to the plant, in both a B deficiency sensitive (SW41) and a B deficiency tolerant (Sonora 64) genotypes. The percentage of germinated pollen and length of the pollen tube increased with increasing medium B. With 20-100 mg H3BO3 L-1 in the medium, the percentage of germinated pollen and length of the pollen tube responded positively to increasing B supply to the plant. No difference was found between sensitive and tolerant genotypes in the effect of B on their pollen viability. On the other hand, without added B in the nutrient solution applied to the plant, grain set was depressed in the B deficiency sensitive SW41 and not in the B deficiency tolerant Sonora 64. A difference in B supply to the germinating pollen in the stigma and style is one possible explanation for this variation in the response to B among wheat genotypes. © 1993 Kluwer Academic Publishers.