等高反坡阶对玉米生长及光合特性的影响

[目的] 探讨坡耕地等高反坡台阶措施对玉米生长及光合特性的影响，为云南省坡耕地作物种植提供科学依据。[方法] 以玉米（云瑞668）为供试材料，采用田间试验，试验设置2个布设有反坡台阶的坡耕地样地（2^#和3^#，CR）及1个未扰动的对照样地（1^#，CK），通过野外定位监测方法，测定玉米生长相关指标，净光合速率、蒸腾速率、水分利用效率以及作物产量，研究等高反坡阶对玉米生长特征、光合特性的影响。[结果] 等高反坡阶措施对玉米茎粗、穗位高影响不显著。反坡阶坡中地块对玉米株高促进作用最为显著，增幅为27.9%；反坡阶样地玉米叶面积指数显著高于原状坡耕地，LAI最高达5.01~5.78，灌浆期后可维持相对较高的LAI，而CK组LAI范围为3.78~4.79，且下降较快；反坡阶处理下玉米叶片净光合速率（P_n）、气孔导度（G_s）、叶片瞬时水分利用效率（WUE_L）、作物水分利用效率（WUE）均高于坡耕地；玉米产量分别较坡耕地提高了9.6%，13.8%。[结论] 在云南省坡耕地作物种植地区，通过布设等高反坡阶减少水土流失，提高土壤水分，增加土壤贮水量，进而使叶片维持较高的光合作用以及生理状态，为玉米干物质生产奠定了生理基础，提高了作物产量。自然降雨情况下，坡耕地坡度为15°时布设高反坡阶对玉米光合特性、WUE及产量促进作用最佳。

Effects of Contour Reverse-slope Terrace on Growth and Photosynthetic Characteristics of Maize

[Objective] The effects of contour reverse-slope steps on the water use efficiency and yield of maize crops in sloping land were explored in order to provide scientific basis for crop cultivation in sloping land in Yunnan Province.[Methods] Maize (Yunrui 668) was used as test material. Two sloping farmland plots with contour reverse-slope (2^# and 3^#, CR) and 1 undisturbed control plot (1^#, CK) were set up in the field experiment. The maize growth index, net photosynthetic rate, transpiration rate, water use efficiency and crop yield were measured by field monitoring method to investigate the effects of contour reverse-slope order on maize growth and photosynthetic characteristics.[Results] The effect of contour reverse-slope measure on the ear height of maize and stem diameter was not significan, while the promotion effect on the height of maize plant was the most significant, with an increase of 27.9%. The leaf area index (LAI) of the contour reverse-slope sample plot was significantly higher than that of the undisturbed slope land, with LAI as high as 5.01~5.78. After the grouting stage, relatively high LAI could be maintained, while the LAI of the CK group was ranged from 3.78 to 4.79, which decreased rapidly. The net photosynthetic rate, stomatal conductance, WUE_L (instantaneous water use efficiency) and water use efficiency of maize leaves under the contour reverse-slope was higher than that of sloping land. Maize yield increased by 9.6% and 13.8%, respectively, compared with sloping farm land.[Conclusion] In the slope cultivated land area in Yunnan Province, by increasing soil moisture and soil water storage, the contour reverse-slope measure can promote photosynthesis of leaves and physiological status, which lays a physiological foundation for dry matter production of maize and improves the crop yield. Under the condition of natural rainfall, when the slope was 15°, the contour reverse-slope measure has the best promotion effect on WUE of photosynthetic characteristics and yield promotion of maize.