Moderate Biochar Application and Increases in Lignin and Silicon Concentrations in Stalks Synergistically Enhance Lodging Resistance of Rice

Abstract

To clarify the effects of biochar on measuring the lodging-related traits, structural carbohydrates, and the activity and gene expression of enzymes related to lignin synthesis in rice stalks, to screen the optimal dosage of biochar and to investigate the mechanism of biochar in regulating the lodging-resistant ability of rice stalks. SN265 and Akihikari, two rice varieties with evident differences in lodging resistance, were selected and treated with biochar at five dosages: 0,5,10,20,40t/hm2. With increase of the dosage of biochar, The expression levels of COMT, 4CL3, CCR20 and PAL genes related to lignin synthesis were the highest under B3 treatment. The silicon concentration in the two varieties under B3, B4 and B5 treatments was notably higher than that under B1 treatment. The numbers of large and small vascular bundles were the largest in SN265 under B3 treatment and in Akihikari under B2 treatment. Moreover, the two varieties exhibited the highest lignin concentration, the smallest lodging index and the strongest lodging resistance under B3 treatment. A certain amount of biochar can regulate the corresponding enzyme activity by increasing the expression level of lignin synthesis-related genes, and evidently increase the lignin concentration in stalks. The application of rice hull charcoal is able to dramatically raise the silicon concentration in stalks, thus improving the lodging resistance of stalks. The two approaches can synergistically improve the internode traits and breaking strength and strengthen the lodging resistance of stalks. In this study, 5–10 t/hm2 is the appropriate dosage in treatment.