Effects of boron deficiency on anther development and floret fertility in wheat (Triticum aestivum L-'Wilgoyne')

Boron (B) deficiency limits reproductive growth more than vegetative growth in cereals such as wheat. The purpose bf the present study was to identify the critical stages of anther development of wheat ('Wilgoyne') during which B deficiency causes a significant and irreversible decrease of floret fertility in order to formulate timely measures for correcting or preventing this problem. Withdrawing B from the rooting medium for 3 d between premeiotic interphase through meiosis to late tetrad, limited anther elongation and resulted in the loss of pollen viability. The negative effects of B withdrawal on anther length suggest that the role of B in reproductive cell walls is similar to that in vegetative ones. The results indicated that as more florets reached meiosis within the period of B withdrawal, the lower was floret fertility and the number of grains set in a whole ear. For the whole ear, the critical period during which B deficiency causes maximal and irreversible damage to floret fertility was about 7 d, extending from the early emergence of the flag leaf to 2-3 d after its full emergence. The results suggest that there are two phases of pollen development sensitive to boron deficiency: the period from premeiotic interphase through meiosis to late tetrad was the most sensitive stage of microsporogenesis in wheat while the period from mitosis-I to II during which starch accumulation occurred in pollen grains was less sensitive. (C) 2000 Annals of Botany Company.