不同灌水处理对寒旱区紫花苜蓿叶面积指数的影响

摘要

[目的]研究紫花苜蓿叶面积指数变化规律,分析不同生育阶段灌水周期和灌水定额对紫花苜蓿叶面积指数的影响.[方法]对紫花苜蓿在浅埋式滴灌条件下进行大田试验,利用LAI-2200C植物冠层分析仪,测量不同灌水处理在不同生育阶段的紫花苜蓿叶面积指数,运用自定义函数拟合法,拟合紫花苜蓿在最适宜灌水条件下冠层生长模型.[结果]紫花苜蓿在适宜灌水条件下,冠层生长模型为LAI=0.978/(1+exp(5.96-0.271 t+0.002 t2)).对拟合的模型进行检验,实测值和模拟值之间的相关系数r为0.96,平均绝对误差为0.372,拟合的模型对于适宜灌水条件下的叶面积指数具有较好的模拟效果.可为紫花苜蓿高产栽培条件下冠层变化规律提供理论依据.[结论]紫花苜蓿叶面积指数变化基本呈较缓慢生长—快速生长—缓慢下降的规律,在适宜灌水条件下紫花苜蓿叶面积指数生长模型可用改进的Logistic函数进行模拟,且对于适宜灌水条件下的叶面积指数具有较好的预测效果.%[Objective] This project aims to study the variation law of alfalfa leaf area index, and discuss the effects of irrigation cycle and irrigation quota on alfalfa leaf area index in different growth stages.[Meth-od]In 2016, field experiments were carried out under the condition of shallow drip irrigation and the leaf area index of alfalfa was measured by LAI-2200C plant canopy analyzer in different growth stages. The canopy growth model of alfalfa under full irrigation was fitted through self-defining function fitting.[Result]The per-formance of the canopy growth model was LAI=0. 978/(1+exp(5. 96-0. 271 t+0. 002 t2))under suitable irrigation conditions. The fitting model was tested and the correlation coefficient between the measured value and the simulated value was 0. 96, and the average absolute error was 0. 372, the results showed that the fit-ting model had good simulation effect on leaf area index under suitable irrigation conditions, and could provide theoretical basis for canopy variation under high yield cultivation of alfalfa.[Conclusion]The alfalfa leaf area index showed a slow growing, rapid growing and slow declining trend. The alfalfa leaf area index growth model under full irrigation can be fitted through the modified Logistic function, which has good prediction effect for leaf area index under suitable irrigation conditions.