Effect of nitrogen on dry matter and nutrient-accumulation pattern in wheat (Triticum aestivum) under different dates of sowing

The field experiment was conducted during 1992-93 and 1993-94 to study the effect of nitrogen on dry matter and nutrient-accumulation pattem in wheat (Triticum aestivum L. emend. Fiori & Paol.). The crop accumulated 9% dry ma tter, 14% N, 11% P and 16% K during first 40 days after sowing (DAS), 31% d ry matter, 38% N, 30% P and 28%K between 40 and 60 DAS, 49% dry matter, 37% N, 47%P and 38%K between 60 and 80 DAS and 11% dry matter, 1% N, 11% P and 17% K from 80 DAS to maturity. The pattern of dry matter and P accumulatio n was similar and 89% of their total accumulation was completed by 80 DAS; the peak period of their accumulation (47-49%) being from 60 to 80 DAS. The rate of N and K accumulation was faster than that of dry-matter accumulati on up to 60 DAS, thereafter the rate of N accumulation matched the rate of dry-matter accumulation, whereas the rate of K accumulation decreased but c ontinued till maturity. The peak period of N and K accumulation was from 40 to 80 DAS; 74% N and 67% K was accumulated during this period. Delay in sowing resulted in the reduction in total dry matter, N, P and K a ccumulation, but the rate of their accumulation was faster in late-sown cro p. Nitrogen application significantly increased the accumulation of dry mat ter, N, P, and K, particularly in late-sown crop. The late-sown crop requir ed more N to accumulate dry matter and nutrients similar to that accumulate d in early-sown crop and thus higher rate of N can mitigate the adverse eff ect of delay in sowing.