Biochar application improves the yield, lodging resistance, and lignin synthesis mechanism in rice

Abstract

Biochar application elicits positive environmental and agricultural impacts owing to its physicochemical properties; however, the mechanism of biochar in regulating the lodging resistance in rice remains unclear. The present study was conducted to investigate the effects of biochar application on rice yield, lodging‐related traits, and enzymes activity and gene expression related to lignin biosynthesis in two rice (Oryza sativa L.) cultivars, that is, Shennong 265 and Akihikari. The biochar treatments were: 0 (B1), 5 (B2), 10 (B3), 20 (B4), and 40 (B5) t/ha. Results depicted that compared with B1, the B2 and B3 treatments improved the rice yield by 8.36%–27.62% and decreased the lodging index by 7.72%–24.14% for both rice cultivars, respectively. The increase in rice yield was mainly due to an increase in chlorophyll content, net photosynthesis, and dry matter at the heading stage. The reduced lodging index in B2 and B3 was mainly owing to an increase in stem lignin and silicon content by 28.55%–62.80% and 16.27%–50.09%, respectively, that was possibly linked to an increase in lignin synthase activity and its gene expression, that is, phenylalanine ammonia lyase, caffeic acid 3‐O‐methyltransferase, 4CL3 (where 4CL is 4‐coumarate: CoA ligase), and CCR20 (where CCR is cinnamyl coenzyme A reductase). Furthermore, the numbers of large and small vascular bundles were the highest in B2 and B3 treatment for both rice cultivars. However, excess biochar applications had an inhibitory effect on rice yield. Overall, biochar application at 5–10 t/ha is an appropriate dosage to improve lodging resistance and rice yield.

Characterization of an Excellent Hybrid Rice Restorer Line R382 with Enhanced Lodging Resistance

“…In this study, it was identified that although the newly created restorer line R382 has higher plant height and fresh weight above-ground, its lodging index is significantly lower mainly due to stronger stem strength compared to Huazhan (Figures 1, 4 and 6, Supplemental Table S1). It is certainly uncontroversial that the main parameter characterizing stem strength, bending moment at breaking (M), is positively correlated with the outer diameter of the basal stem, culm thickness, sectional modulus, bending stress, and the content of the various chemical constituents that make up the cell wall (Figures 6, S2 and S3), since all of these traits will result in enhanced stalk strength [19,26,41,58]. Our results are similar to those of the previous study on the effect of nitrogen fertilizer application, in which it was found that an increase in nitrogen application led to a reduction in culm thickness, and changes in the number and area of vascular bundles, resulting in less lignin and cellulose deposition, an increase in the hollow area of the stem, and a higher likelihood of lodging in rice [20].…”

“…The stem strength of the basal internodes is identified as one of the most important traits associated with lodging resistance in rice [16,17,21,23,24], along with culm diameter, culm thickness, the thickness of mechanical tissues, and the number and area of vascular bundles [21,24,25]. In addition, the mechanical strength of basal internodes depends mainly on their chemical composition, such as silicon, and the content of non-structural and structural carbohydrates (mainly lignin, cellulose, and hemicellulose) [26][27][28][29]. In general, well-arranged internode length, a low center of gravity height, a high proportion of structural carbohydrates such as lignin and cellulose in the stalks, and short and thick basal internodes with more vascular bundles, positively contribute to the lodging resistance in rice [9,30].…”