福建主要蔬菜氮磷钾营养特性及其施肥指标体系研究 Ⅰ.需肥动态模型及其特征参数分析

Nutrients and NPK Fertilization for Major Vegetables in Fujian Ⅰ.Dynamic Absorption and Parameters of NPK Fertilization

采用盆栽和田间试验以及回归分析方法,建立供试蔬菜根长增长模型和氮磷钾累积吸收动态模型。结果表明,在一个种植周期中,空心菜和苋菜根长增长以及空心菜、莴苣、白萝卜和大白菜氮磷钾累积吸收动态均呈现"S"型特征,2个根长增长模型和30个不同处理的蔬菜氮磷钾累积吸收动态模型均达到统计显著水平。根据根长增长模型和养分累积吸收动态模型,可得到蔬菜根长增长常数l0、养分吸收常数k、最大养分吸收速率Inmax及其时间tmax、最大养分吸收量Umax及其时间tc等根系养分吸收特征参数;施肥对k、Inmax和Umax有明显的正效应;tmax值和tc值主要由品种的营养特性决定,受施肥的影响很小;达到最大养分吸收速率时的肥料利用效率最高,是确定最佳追肥时间的依据;最大养分吸收量出现在生育后期,在生育中后期应追施适量的肥料,以满足蔬菜高产对养分的需要。

Nitrogen,phosphor and potassium are essential elements for vegetable fertilization.Pot and field experiments were conducted using root length to correlate with cumulative NPK absorption to establish a mathematical model by regression analysis.The results showed that,within a growth period,the curves of root length increase and NPK absorption of water spinach,lettuce,radish and Chinese cabbage were all in an ＂S＂ shape.Two root growth models for the water spinach and 30 NPK cumulative absorption models for the pot and field experiments all reached a statistical significance level.Based on the models,the following indices could be obtained： root length increase constant（l0）,nutrient absorption constant（k）,maximum NPK absorption rate（Inmax）,and time（tmax） and maximum NPK absorption amount（Umax） and time（tc）.Results showed that the fertilization had significant positive effect on k,Inmax and Umax.But tmax and tc were determined largely by the vegetable＇s nutrition characteristics and little by the fertilization.The fertilization was most effective at Inmax,and therefore,Inmax should be the base for top dressing NPK applications.Umax appeared during late growth stage.And,fertilization during the mid-to late-growth period ought to provide the needed nutrients for the vegetables.