Nutrient restrictive factors, nutrient absorption and accumulation of red kidney bean

With important economical and nutritional values, kidney bean (Phaseolus vuglaris) is one of the main grain crops in China. Recently, the planting area of red kidney bean has been gradually increasing in Shanxi Province, China. However, the nutrient absorption characteristics and limiting factors of kidney bean was still not very clear. Nitrogen (N), phosphorus (P) and potassium (K) are essential nutrients for plant growth, and knowledge on periodic uptake, accumulation and allocation of N, P and K in different organs of kidney bean is important to implement nutrient management practices to ensure its’ sustainable production. There were several studies on effect of the fertilization and nitrogen application on yield of kidney bean. However, few studies have investigated the nutrient accumulation and distribution characteristics of kidney bean. In this study, field experiment was conducted with different nutrient application (N absence, P absence, K absence, NPK application and no fertilizer) using the red kidney bean variety ‘British Red’ as the materials in 2014. The nutrient restrictive factors, dry matter accumulation and nutrient uptake and accumulation of red kidney bean were investigated. The samples of NPK application treatment at different growth stages were collected for determining dry matter and nutrient contents in different organs, to illustrate the law of nutrient absorption. This is beneficial to provide theoretical basis for rational fertilization and high yield cultivation of red kidney bean. The results showed that NPK application treatment significantly increased yield of red kidney bean compared to absence of N, P, or K and no fertilizer treatments. Compared to NPK application treatment, yields of N-, P- or K-absence decreased by 14.2%, 8.0% and 11.3%, respectively, which indicated that the order of nutrient restrictive factors of red kidney bean yield was N > K > P. The dry matter accumulation rate of red kidney bean increased firstly and then reduced in the whole growth period. Dry matter accumulation of root, stem, pod shell and pea increased gradually throughout the whole growing period, while dry matter accumulation of leaf decreased at harvest stage. The order of dry matter weight in different organs at harvest was pea > stem ≈ pod shell > leaf > root. The contents of N, P and K of all investigated organs varied at different stages. N contents in steam, leaf and pod shell decreased gradually, and increased in pea throughout the whole period. The contents of P and K in different organs showed a decreasing trend in whole growth period. The highest nutrients level was observed from full-blooming to pod bearing stage, in which, the absorption contents of N, P and K accounted for 28.14%, 49.22% and 56.20% of the total content of whole growth period, respectively. The accumulation amount of N, P and K in different organs was various. The order of N, P, K accumulation was N > K > P in pods, leaves, stalks and stems, while it was order of K > N > P in pod skins. In conclusion, to produce 100 kilogram kidney bean pea, 4.37 kg N, 2.38 kg P₂O₅ and 3.53 kg K₂O application with ratio of 1∶0.54∶0.81 were needed.