effect of green manure crops and nitrogen fertilizer levels on dry matter remobilization efficiency in wheat (triticum aestivum l.) internodes

in order to evaluate the effect of nitrogen rates and green manure crops on dry matter mobilization and mobilization efficiency indices of wheat (triticum aestivum l.) a field experiment was conducted in agricultural faculty of shahid chamran university, ahvaz during growing season of 2010-2011. the experimental design was split-plot based on randomized complete block with three replications. main plot included four nitrogen rates (i.e. 0, 50, 100 and 150 kgn.ha-1) and sub-plot included six green manure crops containing millet (pennisetum sp.), amaranth (amaranthus sp.), sesbania (sesbania sp.), cowpea (vigna unguiculata l.), mung bean (vigna radiata l.) and fallow. this experiment was done at two stages. first, planting and turn down of green manure crops and then planting of wheat. the results showed that the maximum weight and specific weight of all stem internodes obtained from 0 to 20 days after wheat anthesis. then, this trend decreased from 20 to 50 days after wheat anthesis due to remobilization of dry matter to grain. mobilized dry matter was more in control (0 kg.n.h-1) than in high n application for peduncle (219 vs. 181 mg) and penultimate (203 vs. 165 mg), while, was less in the lower internodes (403 vs. 407 mg). generally, with increasing of nitrogen levels, dry matter mobilization efficiency was decreased by. so, the effect of green manure crops not limited only by soil properties, while influences the relationship between physiological sources and sink.