河西绿洲灌区减量灌溉下绿肥对小麦光合源及产量的补偿效应

  【目的】  资源性缺水严重制约河西绿洲灌区小麦生长，针对小麦种植模式单一，水资源投入量大、利用效率不高等问题，研究限量供水条件下不同处理对小麦光合源及产量的补偿效应，对该区小麦节水种植模式的构建具有重要意义。  【方法】  河西绿洲灌区麦后复种箭筈豌豆(Vicia sativa L.)的田间定位试验始于2017年，供试小麦品种为‘宁春4号’，箭筈豌豆品种为‘兰箭2号’。试验采用裂区设计，设置传统灌水(540 mm，I₃)、减量50 mm灌水(490 mm，I₂)、减量100 mm灌水(440 mm，I₁) 3个灌水水平和小麦收获后复种并翻压绿肥(WG)、复种但不翻压绿肥(WGr)、休闲(WF) 3种绿肥处理方式。2020―2021年，调查了绿肥小麦光合源(叶面积指数、光合势)和产量补偿效应。  【结果】  从全生育期平均值来看，与2020和2021年I₃处理的小麦叶面积指数(LAI)、光合势(LAD)相比，I₁处理小麦LAI分别显著降低了6.26%和5.84%，LAD分别下降了6.21%和5.87%；I₂处理小麦LAI分别降低3.55%和2.85%，LAD分别下降3.17%和3.13% (P<0.05)；与传统灌水休闲对照(WFI₃)相比，WGI₂的LAI提高了2.31%和3.69%，LAD分别提高了3.07%和4.03%，WGrI₂无显著差异，绿肥翻压显示出对I₂处理下小麦LAI、LAD的补偿效果。与2020和2021年I₃相比，I₁处理小麦干物质累积量分别平均显著降低了16.31%和15.19%，籽粒产量分别平均降低了14.00%和12.98%；I₂处理小麦干物质累积量分别平均降低6.20%和6.58%，籽粒产量分别平均降低1.78%和4.05%；WGI₂小麦干物质累积量较WFI₃分别提高了4.84%和5.30%，籽粒产量分别提高了5.89%和6.01%，显示出绿肥翻压对I₂下小麦干物质累积和产量的显著补偿效应；而WGrI₂产量的补偿效应不明显，且2021年绿肥翻压对I₂下光合源、干物质累积量的补偿效应优于2020年。WG对产量的补偿主要归因于对小麦LAI、LAD的同步补偿。  【结论】  在河西绿洲灌区，复种并翻压绿肥能够获得与常规灌溉量相近的小麦叶面积和光合势以及产量，即可以补偿减少50 mm灌水量对次年小麦造成的负效应，因此，可作为该区实现小麦节水生产的生态技术模式。

Compensation of green manure on photosynthetic source and yield loss of wheat caused by reduced irrigation in Hexi oasis irrigation area

  【Objectives】  Water shortage severely restricts wheat production in Hexi oasis irrigation area. Growing and returning green manure after wheat harvest has been proved to be an effective way of improving wheat yield. We investigated the compensation effect of green manure on wheat growth under condition of irrigation reduction.  【Methods】  A field experiment of multiple cropping green manure after wheat harvest was established in Hexi Oasis irrigation area in 2017, with wheat cultivar Ningchun 4 and Vicia sativacultivar Lanjian 2 as tested materials. Three irrigation levels (i.e., traditional irrigation (540 mm, I₃), reduced irrigation by 50 mm (490 mm, I₂), and reduced irrigation by 100 mm (440 mm, I₁) were setup, and under each irrigation level, three green manure treatments after wheat [i.e., planting and returning green manure to farmland (WG), planting but not returning green manure to farmland (WGr), and kept fallow (WF)] were setup. The photosynthetic leaf area index (LAI), leaf area duration (LAD) and yield of wheat were investigated in 2019–2021.  【Results】  During the whole growth periods, compared with I₃ in 2020 and 2021, I₁ decreased wheat LAI by 6.26% and 5.84%, and LAD by 6.21% and 5.87%, I₂ decreased LAI by 3.55% and 2.85%, and LAD by 3.17% and 3.13% (P<0.05), respectively. Compared with WFI₃, WGI₂ increased wheat LAI and LAD by 2.31% and 3.07% respectively in 2020, and by 3.69% and 4.03% respectively in 2021. However, WGrI₂ had similar LAI and LAD values, indicating the significant compensation of green manure incorporation. Compared with I₃, I₁ decreased dry matter accumulation (DMA) and grain yield (GY) by 16.31% and 14.00% respectively in 2020, and by 15.19% and 12.98% respectively in 2021; I₂ decreased DMA and GY by 6.20% and 1.78% respectively in 2020, and by 6.58% and 4.05% respectively in 2021. Compared with WFI₃, WGI₂ increased DMA by 4.84% and 5.30%, GY by 5.89% and 6.01%, while WGrI₂ had similar DMA and GY, indicating the compensation effect of green manure incorporation. The compensation effect of planting green manure on the photosynthetic source and dry matter accumulation under I₂ in 2021 was better than that in 2020. WG compensation on yield was mainly attributed to the simultaneous compensation of wheat LAI and LAD.   【Conclusions】  In Hexi Oasis irrigation area, planting and incorporating green manure could achieve similar photosynthetic source and yield of wheat in the following year. Overall, compensation for the loss of photosynthetic source and yield of wheat caused by reducing 50 mm of conventional irrigation amount, therefore, it is a practical water saving technology for wheat production.