Difference Of Dry Matter Accumulation, Potassium Absorption And Utilization Among Different Potassium Efficiency Rapeseed Cultivars

Rapeseed is one of the most important oil-bearing crops, they need a lot of potassium. There is great influence on rapeseed yield and quality under potassium deficiency. However, China is short of potassium resources, so screening the rapeseed genotypes with higher potassium efficiencies and investigating the characteristics of different genotypes can not only discover high K-efficiency rapeseed germplasm resources, and also can provide guidance for potassium fertilizer management. Field experiments with K and CK were carried out to study the whole growing period and key growing stage’ potassium characteristics of43rapeseed cultivars which grown widely in Yangtze river basin. The tested rapeseed cultivars were classified into3types (high, middle, low) respectively based on seed yield at CK, K absorption efficiency, K agronomic efficiency and K recovery efficiency by clustering analysis, then study the differences of matter production and potassium characters among different potassium efficiency cultivars. The main results were as follows:1. Under the same potassium treatments, there were significant differences in dry matter weight, seed yield, K concentration, K content, K requirement for100-kg seed and K use efficiency for seed (dry matter) production among different rapeseed cultivars, the differences under CK were larger than K. Contrast to CK, K improved dry matter weight, seed yield, K concentration, K content and K requirement for100-kg seed, but lower K use efficiency for seed (dry matter) production, and the improvement (the decrease) were significantly different among different rapeseed cultivars. Most of the tested rapeseed cultivars performed differently at wintering period, pod period and maturity period.2. Seed yield at CK indicates yield type, K agronomic efficiency indicates K response, K accumulation of overground at maturity under CK indicates K absorption efficiency, K recovery efficiency indicates K utilization efficiency. The classification results showed that, one same rapeseed cultivar’s K efficiency type was different according to different K efficiency indicators, meanwhile, no matter according to which indicator, the high types were less than the low.3. Comprehensively considering yield types and K response,43rapeseed cultivars were divided into7types:2cultivars belonged to high yield high K response type,9cultivars belonged to high yield low K response type,6cultivars belonged to middle yield middle K response type,8cultivars belonged to middle yield low K response type,4cultivars belonged to low yield high K response type,11cultivars belonged to low yield middle K response type,3cultivars belonged to low yield low K response type. Average yield at CK of high yield and middle yield types were476,238kg/hm2higher than low yield types respectively, the relative yield increased by40.7%and20.4%respectively. The K agronomic efficiency of high K response and middle K response types were6.2and3.3kg/kg higher than low K response types respectively, the relative K agronomic efficiency increased by173.5%and90.8%respectively.4. Comprehensively considering K absorption and utilization efficiency,43rapeseed cultivars were divided into9types:1cultivar belonged to high absorption high utilization efficiency,7cultivars belonged to high absorption middle utilization efficiency,3cultivars belonged to high absorption low utilization efficiency,3cultivars belonged to middle absorption high utilization efficiency,8cultivars belonged to middle absorption middle utilization efficiency,3cultivars belonged to middle absorption low utilization efficiency,3cultivars belonged to low absorption high utilization efficiency,8cultivars belonged to low absorption middle utilization efficiency,7cultivars belonged to low absorption low utilization efficiency. K accumulation of overground at maturity under CK of the high absorption and middle absorption efficiency types were26.3and15.6kg/hm2higher than the low, the relative increase was106.9%and62.6%respectively; The K recovery efficiency of high utilization and middle utilization efficiency types were0.43and0.24kg/kg higher than the low, the relative increase was68.3%and38.1%.5. The dry matter weight, K concentration, K content of wintering period, pod period and maturity period was significantly positive correlated with the yield at CK and K absorption efficiency, but the difference of dry matter weight, K concentration and K content between different K efficiencies types performed differently at wintering period, pod period and maturity period. The high efficiencies types achieved higher dry matter, higher K concentration, higher K content, more K requirement for100-kg seed, lower K use efficiency for seed (dry matter) production, while the low efficiencies types was just the opposite.