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 whi ch B deficiency causes a significant and irreversible decrease of floret fe rtility in order to formulate timely measures for correcting or preventing this problem. Withdrawing B from the rooting medium for 3 d between premeio tic interphase through meiosis to late tetrad, limited anther elongation an d resulted in the loss of pollen viability. The negative effects of B withd rawal on anther length suggest that the role of B in reproductive cell wall s 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 f loret 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 irrev ersible 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 s uggest that there are two phases of pollen development sensitive to boron d eficiency: the period from premeiotic interphase through meiosis to late te trad was the most sensitive stage of microsporogenesis in wheat while the p eriod from mitosis-I to II during which starch accumulation occurred in pol len grains was less sensitive. (C) 2000 Annals of Botany Company.