Effects Of Potassium On Rice Blast And Yield Under Different Nitrogen Management In Cold Area Of China

Excessive nitrogen applied in early stages, irrational application timing of N and irrationalratio of N, P and K have been common problems in rice production in cold area of NortheasternChina, which cause the increase risk of rice lodging and diseases. Plot experiment was conducted tostudy effects of potassium on dry matter accumulation, disease resistance, yield and quality of riceunder farmers' fertilization practice (FFP) and site-specific nitrogen management (SSNM) in coldarea, and aimed to provide theory references for rational application of fertilizer.Experiments showed that application K treatments decreased incidence rate of rice blast by10.6, 11.9 and 12.4 percentage points compared to no K treatment in SSNM, 0 and lgrades blast ofK treatments accounted for 84.80%, 87.30% and 86.59% of total panicle. Under the same K rate,the disease incidences of FFP were 15.1(p＜0.05) and 15.7(p＜0.05) percentage points higher thanSSNM. Compared with no K treatment, K rate 60 kg/ha and 90 kg/ha decreased disease index ofrice blast by 6.3(p＜0.05) and 7.0(p＜0.05) percentage points.Compared with FFP, SSNM can control ineffective tillering bear and enhance populationquality of rice so that dry matter accumulation was improved after heading by allocating N of basaland tillering fertilizer to panicel and meiosis stage. K promoted nutrient balance and increasedutilization of nitrogen. As K rate increased, the dry matter accumulation increased. The dry matterweight of K rate 90kg·hm^-2 was 13.0%～14.7% higher than FFP.Compared with FFP and no K treatment, SSNM increased grains per panicle by 1.6～6.6, therate of filled grain by 7.7%～11.1%, and 1000-grain weight by 0.88～1.55g. As a result, rice yieldincreased by 3.3%～16.1%. Compared with FFP and no K treatment, SSNM improved the rate ofhead milled rice by 1.00～1.57 percentage points, and reduced chalkiness by 0.33～1.63 percentagepoints, reduced the content of amylose, and increased the content of fat. The results suggested thatProperly K makes rice yield and quality increase because of improving resistance to blast andenhancing population quality of rice.