Effect of potassium nutrition on yield formation, accumulation and distribution of nitrogen, phosphorus and potassium in lotus.

Objective In order to understand the effect of potassium nutrition on yield formation of lotus (Nelumbo nucifera G.),the accumulation and distribution of nitrogen (N),phosphorus (P) and potassium (K) in lotus was investigated in the study.MethodThe study was carried out by a pot experiment supplied with two K levels (-K:0.0 and +K:0.45 g·kg-1) in a whole lotus growth duration.Result Results showed that dry matter accumulations (DMA) in both leaves and petioles were significantly higher in +K treatment than in-K treatment 76 d after transplanting,which began to decrease when the swollen stem was developed about 97 d.At the earlier stage of the swollen stem development,the DMA of the swollen stem in +K treatment was lower than that in-K treatment.However,it increased quickly begun from the 97th d after transplanting,and was significantly higher than that in-K treatment at the 139th d.DMA of the swollen stem for both K treatments turned to be stable after 160 d,indicating the maturity of the swollen stem.At that period,the DMA was 1 204 g?plant-1 in +K treatment,which was 19.7% higher than that at-K treatment.During the critical period of the yield formation (97 d-160 d),the accumulations of N,P and K in swollen stem was 32.8%,10.3% and 74.2% higher than that in-K treatment,respectively.Among the accumulated nutrients,the proportion of N,P and K transported from other organs to swollen stem in +K treatment was 1.20,0.12 and 1.26 g/plant higher than that in-K treatment,respectively,and the directly absorbed N,P and K from the soil by root system in +K treatment was 2.16,0.04 and 5.70 g/plant higher than that in-K treatment,respectively.The ratio of N,P and K accumulated in the swollen stem was 1﹕0.14﹕0.90 in-K treatment,and 1﹕0.13﹕ 1.31 in +K treatment.ConclusionApplication of potassium fertilizer could improve dry matter production and accumulation of lotus,uptake and translocation of N,P and K in swollen stems,which results finally in an increase in yield.