Effects of Biochar on Growth and Yield of Summer Maize

Biochar has capacity to increase soil organic carbon content, retain soil nutrients and hold soil water, thus enhancing plant growth and yield. In the present study, a field experiment with four biochar rates was conducted to investigate the effects of biochar on the growth and yield of summer maize:1000 kg·hm-2(T1), 5000 kg·hm-2(T2), 10 000 kg·hm-2(T3)and control(CK, no biochar). The SPAD(Soil and Plant Analyzer Development)values, leaf area index(LAI), chlorophyll content and net photosynthetic rate of leaves, dry biomass were measured at seeding stage, elongation stage, tasseling stage and filling stage. Grain yield was measured after harvest. Biochar application significantly improved the yield of summer maize, with the highest grain yield observed in the T1 treatment, whose yield was 8.8% higher than that of CK. However, kernels per spike were significantly higher in T3 than in both T1 and CK. Biochar supply increased dry biomass of maize in T2 and T3 treatments by 9.2%~20.5% and 11.5%~36.7%, respectively, relative to CK. At the early growth stage, higher rates of biochar notably increased LAI and leaf net photosynthetic rates, whereas at the later growth stage biochar application at lower rates was favorable to sustain the LAI and net photosynthetic rates, and higher biochar resulted in early senescence. The harvest index was 57.4% in the T1, which was 8.3%, 13.2%, and 6.5% higher than that of T2, T3 and CK, respectively. These results show that low amount of biochar enhances the transfer of photosynthetic product to and accumulation in grains of summer maize.