Effects Of Water And Fertilizer Optimization Under Different Densities On Lodging Resistance Of Rice In Cold Area

A plot experiment was conducted to investigate the relationship between the water and fertilizer optimization under controlled irrigation (OPT-25, OPT -30) and lodging resistance of rice in cold area of northeastern China under different density (25 and 30 per square meter). We measured the morphological index, microstructure, chemical compositions and mechanical features of the second basal internodes. The main results are as follows:Under low density conditions, OPT respectively increased stem diameter, wall thickness and area of cross section by 6.0%,16.2% (P<0.01) and 21.0% (P<0.01) at heading; by 8.7% (P<0.05),19.4% (P<0.01)and 26.9% (P<0.01) at 40 days after heading. Under high density conditions, stem diameter, wall thickness and area of cross section were also increased. Under the same water and fertilizer optimization conditions, the low density treatments significantly improved internodes and sheath weihgt per 10cm. Under low density conditions, OPT reduced the flattening of stem by 5.6%; Under high density conditions, OPT reduced the flattening of stem by 5.6% (P<0.01).Under low density conditions, OPT respectively increased the soluble sugar content and sugar rato to N of the second internode stem by 12.5% (P<0.05) and 4.1% at heading stage, by 9.1% (P<0.05) and 6.2%; at 40 days after heading, at the same time, the K content was also increased. Under high density conditions, the soluble sugar content, sugar rato to N and K content of the second internode of the basal sheath of OPT were aso improved.Under the same density, at heading the number of great and small vascular bundle the second internode of the basal stem of OPT was larger than FFP, the area of great and small vascular bundle and mechanical tissue thickness were all significantly improved; at 40 days after heading, the area of great and small vascular bundle was increased by 36.2%-41.6% (P<0.01), the area of small vascular bundle and the thickness of mechanical tissue were also significantly improved. The the great and small vascular bundle appeared of OPT approximate circles in microstructure photos, and the number starch grain in tine-walledcell was increased. The microstructure like this would improved the snapping resistance of rice. Under low density conditions, OPT improved the snapping resistance by 46.8% (P<0.01), and the index of lodging resistance was reduced by 15.4% (P<0.05); under high density conditions, OPT improved the snapping resistance by 44.6% (P<0.01), and the index of lodging resistance was reduced by 21.1% (P<0.05).Under low density conditions, the grains per panicle of OTP was increased 4.4, filled grain rate 2.4% (P<0.01), rice yield 8.5% (P<0.05); under high density conditions, the grains per panicle was increased 3.0, filled grain rate 1.8% (P<0.01), rice yield 9.8% (P<0.05).Under the same density, by controlling irrigation, reducing total N and N management, and improving total K, improved the sugar content of internodes, enhanced the stem diameter, wall thickness, internodes weight per 10cm of the first and second internodes, facilitated internodes filling degree, reduced the index of lodging resistance, increased the snapping resistance and yield. Under the same water and fertilizer optimization conditions, rice yield was not significant difference with the increase of density, by improving the density and optimizing the water and fertilizer, the rice yield was significantly improved, and the lodging resistance was also improved.