Effects of silicon fertilizer application on lodging resistance and grain yield of rice in the rice-duck farming system under preci sion hill-direct-seeding

【Objective】The purpose of this study was to investigate the mechanism of stem mechanics，morphology structure and dry matter accumulation and distribution of rice in the rice-duck farming system under precision hill-directseeding and its relationship with lodging resistance and yield，which provided theoretical and practical basis for the appli cation of rice-duck farming system in light and simplified rice cultivation.【Method】Field experiments were conducted with four treatments， including no silicon fertilizer with raising ducks in paddy field（D）， applying silicon fertilizer with raising ducks in paddy field（DS）， applying silicon fertilizer and no ducks in paddy field（S） and no silicon fertilizer and no ducks in paddy field（CK）by using rice varieties Yuxiangyou 8133（YXY8133）， Yuxiang 203（YX203）， Yuliangyou 86（YLY86）， C Liangyouhuazhan（CLYHZ） and Huanghuazhan（HHZ） . Rice yield and yield components，mechanical indexes， length of internodes，culm diameter，culm wall thickness，leaf area index，stem and leaf sheath dry weight per unit length，stem dry weight per plant，leaf dry weight per plant，panicle dry weight per plant were detected，the relation ship between mechanical characteristics，morphology structure，material accumulation，lodging resistance and yield of rice were analyzed.【Result】Compared with CK， D， S and DS treatments increased grain yield by 3.7%-25.8%， 4.9% -17.3% and 0-23.4%，respectively. Among them，grain yields of YX203， YXY8133 and CLYHZ in DS treatments signifi cantly increased by 17.3%，23.4% and 9.5%， respectively（P<0.05，the same below） . Compared with CK， D， S and DS treatments declined lodging index by 8.8%-12.4%， 8.0%-13.6% and 12.2%-30.2%， respectively. Among them，the de crease of DS treatment reached a significant level，and the trend was consistent among varieties. The stem breaking strength in DS treatment were enhanced by 13.4%-44.7% compared with CK， which contributed to significant reduction in lodging index. Among the varieties，YXY8133， YX203 and YLY86 were attributed to the increase of section modulus， and CLYHZ and HHZ were attributed to the increase of bending stress. Compared with CK， DS treatment increased the basal internode culm，leaf sheath dry weight per unit length，stem diameter and wall thickness，increased the dry weight of single stem sheath at heading stage and mature stage，and improved the stem quality and breaking strength. Correlation analysis showed that spike length，lower internode，middle internode and upper internode were extremely significantly positively correlated with lodging index，and basal internode stem，sheath leaf sheath weight per unit length，stem diam eter，wall thickness，stem dry weight at heading stage and mature stage were significantly or extremely significantly posi tively correlated with breaking strength.【Conclusion】Silicon fertilizer application in rice-duck farming system can en hance the internode diame-ter and wall thickness，improve the internode leaf sheath weight per unit length and stem weight， and then enhance the mechanical strength and lodging resistance of rice stem under precision-hill-direct-seeding.