Effect of Green Manures and Levels of Nitrogen on Some Growth Attributes of Transplant Aman Rice
An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, during the period from May to November 1998 to investigate the effect of green manures and different levels of nitrogen on the growth performance of transplant aman rice (cv. BRRI dhan 32). The experiment consisted of 3 green manuring crops viz. Sesbania rostrata, Sesbania aculeata and Crotalaria juncea and 5 levels of nitrogen viz. 0, 20, 40, 60 and 80 kg ha-1. Growth attributes such as leaf area index, crop growth rate and net assimilation rate increased up to 67 DAT irrespective of green manure crops and different levels of nitrogen and thereafter declined. On the other hand, plant height and leaf area duration increased with the increasing levels of nitrogen in combination with green manuring crops. Application of 40 kg N ha-1 along with Sesbania rostrata green manuring showed the best performance in respect of grain yield and net assimilation rate of transplant aman rice. S. aculeata exhibited similar behaviour as that of S. rostrata but Crotalaria juncea showed relatively poor performance in respect of growth attributes of rice due to less amount of biomass added during incorporation.
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