Effects Of N And K On Lodging Resistance Of Rice In Cold Area

A plot experiment with two N levels and three K rates was conducted to investigate the effects of N and K on lodging resistance of rice in cold area. Stem physical properties, mechanical traits, chemical composition and the microstructure of basal second internodes were measured. The main findings are as following:Compared to N1level (N100kg-ha-1), N2level (N150kg·ha-1) increased plant height, the basal second, third and fourth internodes and the length of the panicle by8.82%,15.3%,5.23%and4.14%, and K only had a significant influence on the third and fourth internodes length, compared with the N1level, the N2level increased the length of third and fourth internodes by7.51%(P<0.05). Compared with N1level, K1improved the stem diameter, cross-sectional area and weight of leaf sheath of N2level by of2.11%,8.01%and25.9%(P<0.05).Under the N2level, K1treatment increased vascular number of by5.26%compared with KO treatment, and under the N1level, the increase was not significant. Under the N1level, K1treatment increased stem wall and mechanical tissue thickness, increased large and small vascular area, by30.6%,29.4%,31.6%and35.3%(P<0.05). Under the N2level, these values were18.4%,19.2%,14.6%and35.3%(P<0.05).Under the N1level, K significantly improved the fracture resistance of the stem, reduced the lodging index. K2treatment increased fracture resistance by17.9%and51.5%compared with K1and K0treatments, lodging index K2treatment decreased by21.5%and23.1%respectively (P <0.05). Under N2level, K had no significant effects on fracture resistance, but reduced the lodging index, K2reduced lodging index by13.6%and13.7%compared to K1and K0(P<0.05).K increased the transportation of soluble sugar from stem to panicle. Foliar spray of K (K2) treatment substantially reduced soluble sugar content in stems of N2from heading to30d after heading by58.2%, K2treatment also decreased sugar/N rate of N2by67.7%.N2increased the number of grains per panicle by6grains, decreased1000-grain weight by0.94g, decreased filled grain rate by1.33percentage points, and increased rice yield by6.38%compared with N1.