Soluble Carbohydrates and Floret Fertility in Wheat in Relation to Population Density Stress

Wheat, variety Sonalika, was grown at different densities in both field and pots during the winter seasons 1983–84 and 1984–85. Grain yield pattern of the spikelets of the main shoot inflorescence was similar in both the field and pots, the spikelets in the middle part of the ear contributed most and yield per spikelet decreased progressively towards the apex and the base. Increased population density decreased yield of grain, primarily by decreasing spikelet number and the fertility of florets. High population density accelerated growth of the spike for some time during the pre-anthesis period and the soluble carbohydrate concentration was also higher under these conditions. During both anthesis and post-anthesis, the soluble carbohydrate concentration and the growth of the spike declined much faster in the high-density population. High density also decreased the floret fertility and growth in dry weight in all the spikelets, but it was more severe on the basal spikelets, resulting in complete sterility of the florets at these nodes. The soluble carbohydrate concentration of these slow-growing, sterile, basal spikelets was found to be higher in comparison to that of fertile spikelets in the middle and top positions within the ear.