Sorghum can compensate for chilling-induced grain loss

Chilling during male gametophyte development in sorghum (Sorghum bicolor L. Moench) inhibits development of microspores, causing male sterility. The aim of this study was to assess the effects of night chilling on yield components in sorghum. This study identified and employed collar distance as a morphological marker of anther development following chilling. Two cultivars Buster and Bonus, were subjected to three temperature regimes (25/20 degrees C, 25/12 degrees C and 25/8 degrees C) for five consecutive nights at 0 cm collar distance, which corresponds to the meiotic stage of anther development. Pollen viability, grain number and harvest index were reduced in both cultivars at 12 and 8 degrees C night temperatures. Total grain weight of cultivar Bonus was not reduced as much as Buster at 12 degrees C because of the ability of Bonus to increase individual grain weight when grain number was low. This work further elucidates the mechanism and genetic potential of chilling-induced yield compensation for developing sorghum cultivars that are better adapted to low night temperatures.