study of dry matter and nitrogen accumulation, remobilization and harvest index in bread and durum wheat cultivars

the aim of this experiment was the study of dry matter and nitrogen (n) accumulation, remobilization and harvest index in different wheat cultivars. five bread wheat cultivars (darya, kuhdasht, shiroudi, tajan and zagros) and two durum wheat cultivars (arya and dena) were studied under optimum growth conditions during 2008-2009 at research field of gorgan university of agricultural sciences and natural resources, gorgan, iran. experimental design was a randomized complete block design with four replications. results indicated that average total dry matter remobilization was 23.8%,which was affected by cultivar. furthermore, results indicated that 57% of n remobilization from vegetative organs before anthesis and 11% from n uptake and/or n remobilization after anthesis contributed for grain growth. therefore, majority of grain n supplied by remobilization of n from vegetative organs during seed filling period. among organs, the leaves had the highest n remobilization (nearly 72%). results indicated that leaves and stems n concentration decreased 57 and 54%, respectively, at the time of physiological maturity as compared with anthesis. n harvest index was 72.2% which it was not affected by cultivar. meanwhile, n concentration in senesced leaves and stems along with grains were 1.04, 0.43 and 2.13%, respectively. the amount of harvest index was 44.1%, and it was not affected by the cultivar. there was a positive and significant correlation between the amount of n uptake by vegetative tissues, especially in leaves, with grain n and grain yield. the parameters obtained in this study can be used in wheat n modeling.