间作小麦秸秆还田对地膜覆盖玉米灌浆期冠层温度及光合生理特性的影响

【目的】作物的光合生理特性是影响产量的重要因素,冠层温度反映作物冠层的能量平衡状况,与作物光合生理特性及产量形成密切相关。研究不同覆盖方式下作物冠层温度与光合生理特性及产量形成,旨在优化耕作制度,提高干旱内陆灌区作物生产潜力。【方法】2014—2016年,在西北干旱灌区,通过田间试验,研究不同小麦秸秆还田及地膜覆盖利用方式下,小麦间作玉米模式中玉米灌浆期的冠层温度及光合生理特性。【结果】间作较单作可降低玉米灌浆期的冠层温度,以免耕小麦带25—30 cm高茬收割覆盖还田与玉米带地膜2年覆盖（NTSI2）,免耕小麦带25—30 cm高茬收割立茬还田与玉米带地膜2年覆盖（NTSSI2）处理降低效果更为显著,较传统耕作每年覆新膜单作（CTM）处理分别降低10.3%与7.5%,比传统翻耕小麦带无秸秆还田与玉米带每年覆新膜（CTI）处理分别降低7.6%与4.7%。从冠气温差可知,NTSI2处理随气温变化玉米灌浆期冠层温度变化较小,可减小气温变化对玉米生长发育造成的不利影响。间作较单作可增大玉米灌浆期的光合速率（P_n）、蒸腾速率（T_r）及叶片水分利用效率（WUE_L）,以NTSI2、NTSSI2处理提高幅度较大,较CTM处理玉米P_n提高比例分别为23.0%与18.1%,较CTI处理提高比例分别为13.4%与8.9%;同理,与CTM处理相比,T_r分别提高7.9%与5.8%,与CTI处理相比,T_r分别提高6.1%与4.1%;NTSI2、NTSSI2处理WUE_L较CTM处理提高14.4%与12.0%,较CTI提高7.2%与4.9%,呈现水分高效利用的潜势。相同的净占地面积下,间作较单作玉米具有增产效应,增产幅度达到52.2%,其中NTSI2、NTSSI2处理较CTM处理分别增产57.2%与53.4%,较CTI处理分别增产17.6%与14.7%,说明免耕地膜2年覆盖与秸秆还田同步应用于间作模式可进一步加强玉米增产效应。【结论】在河西绿洲灌区,集成应用免耕秸秆还田与地膜2年覆盖技术是实现高产高效间作模式的理想耕作措施。

Effects of Intercropped Wheat Straw Retention on Canopy Temperature and Photosynthetic Physiological Characteristics of Intercropped Maize Mulched with Plastic During Grain Filling Stage

【Objective】The photosynthetic and physiological characteristics are important factors affecting the yield of crops. The canopy temperature reflects the energy balance of crops, which is closely related to the photosynthetic physiology and yield formation of the crop. Study on crop canopy temperature, photosynthetic and physiological characteristics, and yield formation under different straw and plastic mulching methods is of great significance for optimizing cropping system and improving crop production potential in arid oasis irrigation areas. 【Method】The field experiment was conducted in Hexi oasis irrigation region from 2014 to 2016, to determine the effects of straw retention and plastic mulching approaches on canopy temperature and photosynthetic physiological characteristics of maize in wheat-maize intercopping. 【Result】Intercropping could reduce the canopy temperature of maize in the grain filling stage, compared to sole cropping. No-tillage with 25 to 30 cm straw mulching in wheat strip and two-year plastic mulching in maize strip (NTSI2) and no-tillage with 25 to 30 cm straw standing in wheat strip and two-year plastic mulching in maize strip (NTSSI2) had significant effect at reducing the canopy temperature of maize, and reduced the canopy temperature of maize by 10.3% and 7.5%, respectively, compared to sole maize with annual new plastic mulching (CTM), which reduced canopy temperature by 7.6% and 4.7%, respectively, compared to conventional tillage without straw retention in wheat strip and annual new plastic mulching in maize strip (CTI). According to canopy-air temperature difference, it could be seen that NTSI2 treatment had less changes in canopy temperature with air temperature during maize filling stage, which could reduce the adverse effect of temperature change on the growth and development of maize. Intercropping could increase the photosynthetic rate (P_n), transpiration rate (T_r) and leaf water use efficiency (WUE_L) during the grian-filling stage of maize, compared to sole cropping. The treatments on NTSI2 and NTSSI2 had greater P_n of maize by 23.0% and 18.1% than that of CTM, and greater P_n by 13.4% and 8.9% than that of CTI, respectively. Also, NTSI2 and NTSSI2 had greater T_r of maize by 7.9% and 5.8% than that of CTM, and greater T_r by 6.1% and 4.1% than that of CTI, respectively. Thus, NTSI2 and NTSSI2 increased WUE_L of maize by 14.4% and 12.0% than that of CTM, and increased WUE_L by 7.2% and 4.9% than that of CTI, respectively. The treatment on NTSI2 had the highest increasing effect on WUE_L, it also had the potential for efficient use of water. Intercropping increased maize grain yield by 52.2% over sole cropping. The grain yield of NTSI2 and NTSSI2 was 57.2% and 53.4% greater than that of CTM treatment, and was 17.6% and 14.7% greater than that of CTI treatment, respectively. 【Conclusion】 No tillage and 25 to 30 cm straw retention combined with two-year plastic film mulching was the most feasible technology for realizing high yield and efficient utilization of resources of wheat-maize intercropping in the oasis irrigation region.