Effect of Temperature on Attributes of the Main Shoot Ear in Wheat Gultivars

The main shoot ear length and number of spikelets of cultivars of durum, aestivum and Triticale sown in the first week of November, December and January, under high fertility conditions, showed little variation in the three sowings, but the number of grains, grain yield and kernel weight decreased markedly with delay in sowing. Number of grains and grain yield in the basal, lower middle, middle, upper middle and basal increased from basal to middle zone of the ear but tended to decrease in upper middle and upper zones. Higher temperature decreased the grain number, grain yield and kernel weight in all the zones, but the relative responses of the different zones and different species varied.

The mean relative contributions of the first (A), second (B), third (C), fourth (D) and other distal florets of spikelets at the different positions in the ear of two bread wheat varieties, differing in grain number per ear, grown under normal sowing were also assessed. The mean number of grains from the different florets of the ear varied as A>B>C>D, while the grain yield and kernel weight were of the order B>A>C>D. The probable advantage of increasing the number of spikelets and the fertile florets of an ear, in augmenting grain yield per ear, is discussed.