EFFECTS OF WATRE AND FERTILIZER OPTIMIZATION ON LODGING RESISTANCE OF RICE IN COLD AREA OF NORTHEASTERN CHINA

A plot experiment was conducted to investigate the relationship between optimization of water and fertilizer and lodging resistance of rice with different densities(25 and 30 per square meter) in cold area of northeastern China.Under the same density,compared to farmers fertilization practice under regular irrigation(FFP-25,FFP-30),the yield of optimal fertilization practice under controlled irrigation(OPT-25,OPT-30) were increased by 8.5%~9.8%(P0.05).At 40 days after heading,stem diameter and wall thickness were increased by 9.4%~17.5%(P0.05) and 12.7%~21.2%(P0.05) compared to FFP,and weight of per 10 cm internode and sugar to N ratio of OPT-25,OPT-30 treatments were significantly enhanced,the great and small vascular bundle appeared approximate circles,the number and area of great and small vascular bundle and thickness of mechanical tissue were significantly increased,the snapping resistance of stems was significantly improved by 30.8%~31.9%(P0.05) and the index of lodging resistance was reduced by 15.4%~21.1%(P0.05).Under the same fertilizer and water management,with the increase of plant density,no significant differences in rice yield and the index of lodging resistance were observed.While compared to FFP-25,the yield of OPT-30 was increased by 15.5%(P0.01) and the index of lodging resistance was reduced by 16.8%(P0.05).These results proved that water and fertilizer optimization management can improve the microstructure of the second basal internodes,facilitate internode filling,and resulted in high lodging resistance of rice.