氮磷钾与莴苣生育及产量指标的数学模型和分析

Building and Analysis of Mathematic Models on Relationships Between N-P-K Application and Lettuce Growth and Yield

采用三因子二次通用旋转组合设计，对氮磷钾施肥水平与莴苣生育指标和产量及氮磷钾利用率建立数学模型。分析结果表明，氮磷钾施肥水平对生育指标皆有影响，并存在着氮磷和氮钾正交互作用。本试验条件下，要获得１００克／株以上的产量，氮磷钾配比应为１∶０．５∶１．１。

By means of quadratic rotational combination design, a three-factor (application of N, P, K) pot experiment was conducted in a plastic greenhouse. With the aid of computer, several quadratic regression models were built to demon strate the relationships of lettuce growth indices, yields and N-P-K utilization rates to N-P-K application. The results indicated that under the experimental condi tions, N-P-K levels had different effects on the target characteristics and there ex isted N-P and NK interactions. By analysis of these models, it was found that the effects of N-P-K on dry weights of roots and stems, leaf nitrogen and leaf potassium were bigger than those on plant height, leaf number and leaf phospho rus. Taking lettuce and its soil nutrition as a system, with the controlled factors including N, P, K as input, and with the yield of lettuce as output, a yield predic tion model was built. Thus, the proper combination of applied N, P and K for higher yields of lettuce could be obtained from the model, and the N∶P∶K ratio for yields above 100g/plant was estimated to be 1∶0.5∶1.1.