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等高反坡阶措施下玉米水分利用效率对坡耕地土壤水分变化的响应
张 洋1, 王克勤1, 段 旭,等2
1.西南林业大学 生态与环境学院;2.西南林业大学 林学院
摘要:
【目的】探明坡耕地等高反坡阶措施下作物水分利用效率对土壤水分变化的响应,为云南坡耕地作物种植提供科学依据。【方法】以玉米为供试材料,在2019-2020年进行大田试验,设置等高反坡阶措施(2个不同坡度布设等高反坡阶的坡耕地样地)与原状坡耕地无处理(1个未扰动的对照样地)两种处理方式,通过野外定位监测方法,分别在玉米播种前及拔节期、抽雄期、吐丝期、灌浆期和成熟期,使用时域反射仪(TDR-300)在坡上、坡中、坡下3个坡位随机选点测定0~10 cm、10~20 cm、20~30 cm和30~40 cm土层的土壤体积含水率,并分析作物群体光合势(LAD)、叶片瞬时水分利用效率(LWUE)的相关响应。【结果】等高反坡阶措施下玉米群体光合势(LAD)高于对照样地,其中以坡中促进效果最为显著,平均增幅为19.3%,且在生长后期保持相对较高的LAD并持续较长时间;等高反坡阶样地玉米蒸腾速率(Tr)与对照样地无显著差异,但净光合速率(Pn)、叶片瞬时水分利用效率(LWUE)均高于原状坡耕地样地;等高反坡阶样地土壤水分表现为坡中>坡下>坡上,布设该措施后土壤水分增高,平均增幅为24.4%,同时提高了土壤水分有效性以及中效水和易效水的占比(90%);LWUE与Pn、LAD呈极显著正相关(P<0.01),与土壤体积含水率呈显著正相关(P<0.05)。通径分析表明,Pn和土壤体积含水率对玉米LWUE起主导作用,等高反坡阶措施可以提高Pn和土壤水分,进而获得较高的LWUE。【结论】布设等高反坡阶措施可以提高坡耕地土壤水分,使玉米叶片维持较高的光合作用并保持最佳的生理状态,可以提高作物叶片瞬时水分利用效率并促进玉米生长发育,进而为玉米干物质生产奠定生理基础。
关键词:  坡耕地  等高反坡阶措施  玉米栽培  群体光合势  水分利用效率  土壤水分有效性
DOI:
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基金项目:国家自然科学基金项目(42067005);云南省基础研究计划面上项目(202001AT070136);云南省重点研发计划项目(2018BB018);云南省万人计划青年拔尖人才专项(YNWR-QNBJ-2019-215,YNWR-QNBJ-2019-226);云南省教育厅研究生基金项目(2020Y0135)
Response of crop water use efficiency to soil water changes on contour-reverse slope
ZHANG Yang,WANG Keqin,DUAN Xu,et al
Abstract:
【Objective】This study explored the response of crop water use efficiency to soil water changes under contour reverse slope measures such as sloping farmland to provide scientific basis for crop planting in Yunnan sloping farmland.【Method】Field experiments were carried out with maize as the experimental material in 2019-2020,and two treatment methods were set up including equi high reverse slope measure (2 contour reverse slope samples with different slopes) and one undisturbed slope farmland as control.According to the field location monitoring method,soil water contents were measured at stages of before maize sowing,jointing,tasseling,silking,grain filling and mature.The changes of soil volumetric water content in tillage layers of 0-10 cm,10-20 cm,20-30 cm and 30-40 cm were measured by time-domain reflectance meter (TDR-300) at three randomly selected points on top,middle and bottom of slopes,and the related responses of crop leaf area duration (LAD) and leaf instantaneous water use efficiency (LWUE) were also analyzed.【Result】The LAD of maize population in contour reverse slope plots was higher than the control with the most significant increase of 19.3% in the middle slope plots.The LAD remained relatively high at late growth stages and its duration was prolonged.There was no significant difference in transpiration rate (Tr) of all fields,while net photosynthetic rate (Pn) and crop LWUE were higher than those of the control.The soil moistures in the contour reverse slopes were in the order of middle slope>bottom slope>top slope,and soil moistures were significantly increased with an average rate of 24.4% in comparison with the control.The proportions of medium and easy available water were also increased (90%).LWUE had significantly positive correlation with Pn and LAD and had positive correlation with soil moisture.The path analysis showed that Pn and soil moisture played a dominant role in LWUE of corn,while the contour reverse slope measures could improve Pn and soil moisture and obtain higher LWUE.【Conclusion】Contour reverse slope measures can increase soil moisture,maintain high photosynthetic and physiological status of leaves,and promote growth and development of maize by improving crop water use efficiency,which provides physiological foundation for corn dry matter production.
Key words:  slope land  contour-reverse slope  maize cultivation  leaf area duration  water use efficiency  soil water availability