Effects of Different Nitrogen Fertilizer Levels on Fe, Mn, Cu and Zn Concentrations in Shoot and Grain Quality in Rice (Oryza sativa)

In a pot experiment, effects of N fertilizer application on the concentrations of Fe, Mn, Cu and Zn in shoot of rice and the quality of brown rice were studied. In the treatments with N fertilizer application, the concentrations of Fe, Mn, Cu and Zn in most parts of rice shoot increased compared with control (no N fertilizer application). This indicated that the transportation ability of microelements from root to shoot in rice was improved with N fertilizer application. Effect of N fertilizer on IR68144 was similar to that of on IR64, but the concentrations of the microelements in plant differed, suggesting that the characteristic expression of the two rice genotypes was not controlled by the amount of N fertilizer supplied. The concentrations of those microelements in brown rice increased at first and then decreased with increasing N fertilizer application, reaching the highest at 160 kg/ha, at which the Fe, Mn, Cu and Zn concentrations in brown rice increased by 28.96%, 41.34%, 58.31% and 16.0% for IR64, and by 22.16%, 13.75%, 8.75% and 20.21% for IR68144 compared with control, respectively. Moreover, N fertilizer promoted the accumulation of protein, decreased the accumulation of amylose in grain, and enhanced gel consistency of brown rice. These results indicate that appropriate N fertilizer management could increase micronutrient contents in grain and improve nutrition quality of rice.