Effect of Water Deficit on Sporogenesis in Wheat (Triticum aestivum L.)

Plants of Triticum aestivum L., cv. Gabo, were grown in a glasshouse for 4 weeks and then transferred to a controlled environment with 20±1 °C temperature and 16 h photoperiod. They were subjected to water deficit by withholding the water supply during various stages of floral development, including those immediately before meiosis and all stages until just after anthesis. The proportion of apparently normal florets which produced grain was reduced when water deficit occurred during and immediately after meiosis in the generative tissues. The effect of this reduced grain set on total grain yield was partially compensated by an increase in the weight of the remaining grains. Cross-pollination between stressed and well-watered plants showed that grain set was reduced as a direct consequence of the induction of male sterility by water stress, whereas female fertility was unaffected. A large proportion of the anthers on water-stressed plants were small and shrivelled, did not dehisce normally and contained pollen which was devoid of normal cytoplasmic constituents and showed no staining reaction with triphenyl tetrazolium chloride. This effect on male fertility was not a result of desiccation of the sporogenous tissue, but an indirect outcome of the decrease in water potential elsewhere in the plant.