Dry matter accumulation and associated changes in biochemical parameters during wheat grain development

Field experiments were conducted in Rajkot, Gujarat, India comparing three cultivars of wheat, viz. Raj-1555, Lok-1 and Sonera, all differing in their grain yield. Apical grain of the seventh spikelet from the main spike was selected as a representative grain in each cultivar and analyzed at 4-day i ntervals from anthesis to maturity for dry matter, starch, sugars and prote in content. The data for dry matter accumulation and starch content were fi tted to a quadratic polynomial exponential which revealed a close correspon dence between these two parameters. The absolute rates of starch and dry ma tter accumulation were highest in Lok-1 followed by Sonera and Raj-1555, re spectively; however, the duration of the grain-filling observed from these curves was highest in Raj-1555. The maximum weight of the grain at harvest was in Lok-1 (80 mg) followed by Raj-1555 (71 mg) and Sonera (50 mg), respe ctively. Increase in the starch content coincided well with dry matter accu mulation. Reducing and nonreducing sugars were high during early stage but declined with advances in growth up to almost middle of the grain growth; h igh levels were even found at later stages. Although protein increased with increasing grain growth in Raj-1555 and Sonera, no clear trend was observe d in Lok-1 in relation to dry matter accumulation. The results are discusse d in relation to the use of polynomial functions and the contribution of ph otosynthate supply from various plant parts in relation to grain growth and yield in wheat.