Biochar Application Enhanced Post-Heading Radiation Use Efficiency in Field-Grown Rice (Oryza sativa L.)

It has been shown that adding biochar to soil can improve nitrogen (N) uptake and utilization in rice (Oryza sativa L.). However, there is a lack of research on the physiological alterations of rice as a result of the changes in nitrogen uptake due to the addition of biochar. This study conducted field experiments in 2015 and 2016 with the goal of testing the hypothesis that the application of biochar would enhance radiation use efficiency (RUE) of rice by improving the plant's ability to take in and utilize nitrogen. Our results demonstrated that the application of biochar (20 t ha(-1)) induced no significant effects on pre-heading specific leaf weight (SLW), nitrogen uptake (NUpre), and leaf area index (LAI) at heading, the ratios of LAI/NUpre and SLW/Nupre, or pre-heading RUE. However, biochar application significantly increased post-heading nitrogen uptake (NUpost), ratios of NUpost/SLW and NUpost/LAI, and post-heading RUE. These results indicate that the application of biochar can improve the plant's nitrogen uptake and RUE in field-grown rice during the post-heading period, which confirms our hypothesis.