Effect of Irradiance on Soybean Utilization of Nitrate During Pod Fill

Motoki Ikeda, Noriyuki Ikeda, Kouichi Shimizu, Junji Ishizuka
1994 Journal of the Faculty of Agriculture Kyushu University  
Pot experiments were conducted in sand culture to evaluate the effect of irradiance on the utilization of nitrate by soybean (Glycine mM: (L.) Merr. cv Orihime) during the podfilling period. Different irradiant conditions were obtained by shading the plant stands with a cheesecloth. At 55%ambient light the dry matter, the seed yield, and the nitrogen utilization were reduced in a nitrate nutrition but those were only slightly affected in an ammonium nutrition. When 0 and 2 milimolar nitrate
more » ... limolar nitrate were applied, the reduction in carbon exchange rates, leaf nitrate reductase activity and leaf nitrogen concentration took place earlier in high irradiance than in low irradiance, but the irradiant conditions did not affect the final dry matter production, the seed yield and the nitrate utilization. An increase in irradiance was required for a greater dry matter and seed production and higher nitrate utilization when 10 milimolar nitrate was applied. A decrease in irradiance lowered the nitrate uptake rather than its assimilation, which ultimately led to a lower utilization of a high level of nitrate applied.
doi:10.5109/24063 fatcat:pbkjygqdnfanjczpi3jc7aefwy