旱地玉米、花生产量形成对不同时间降解地膜覆盖的形态生理响应机制

Long-term residual of conventional plastic film, blocking out rainfall infiltration and continuous higher soil temperature under film mulching were contributed to decrease yield of dryland crops in northern China. The key technique to resolve those problems is application of degradable film, but it is unclear that the degradation time of different mulched-crops and when mulching film degradation to increase yield. Film mulching with different degradation times in growing season have the different water utilization and thermal effect to crops during non-degradation and degradation, which affect the different crop yield. However, as there are few researches on field test, and poor morpho-physiological mechanism understanding to dryland crop under film mulching duration, the relationship between water utilization effects, thermal effects and crop productivity was confused. Dryland maize and peanut were selected as materials, the investigation, in which different degradation times of mulching film as treatment, was conducted to study affects of soil water and nutrient, soil temperature and development progress on crop development, biological characteristics, photosynthetic physiology, crop biomass and yield. This study can reveal morpho-physiological progress of crop productivity responds to different water utilization and thermal effect of degradable film during pre- and post-degradation, and optimize time of film degradation using indexes of yield, water and thermal utilization efficiency. Furthermore, this research can provide the theoretical reference for optimizing surface mulched planting technique and farmland management under film mulching in northern dryland of China.

旱地地膜长期残留、覆盖地膜阻隔降水入渗和持续覆膜地温过高等因素，均可导致作物覆膜种植不增产甚至减产。应用降解地膜是解决这些问题的关键技术，但对不同作物何时降解、何时降解利于作物增产尚不明确；生长季内不同降解时间地膜覆盖降解前后对作物水热效应不同，产量响应各异。针对这方面的大田试验验证甚少，尚缺乏对地膜覆盖持续时间条件下作物形态生理学的系统认识，这将严重影响对覆膜农田水热变化与作物产量形成的理解。本研究以旱地玉米和花生为研究对象，以不同降解时间地膜覆盖为处理，在监测土壤水分、养分与地温变化基础上，重点研究玉米和花生生育进程、生物学性状、光合生理、生物量及产量的差异化响应特征，揭示作物产量响应地膜降解前后水热差异的形态生理学协同过程，可实现以产量和水热利用效率为指标对最佳降解时间的优化，并为我国北方旱地覆膜作物生产管理及地表覆盖种植技术的优化改进提供科学理论依据。

项目针对旱地地膜导致作物覆膜种植不增产甚至减产等负面问题，以旱地花生与玉米为研究对象，开展了不同降解（破膜）时间地膜覆盖对作物产量形成的试验研究与文献荟萃分析，表明全生育期覆膜（M全）花生产量显著高于不覆膜（M0）产量18.2%（29.8kg/667m2），花生覆盖60天后降解（破膜）处理（M60）平均产量为214.3kg/667m2，显著（p<0.001）高于M全（193.5kg/667m2）10.7%（20.8 kg/667m2），其产量机制主要是M60的平均芘果重比M全、M0分别降低85%、81%，表明花生覆膜60天破膜降解后，地温与土壤水分适宜，部分产量性状高于全生育期连续覆膜，尤其是降解（破膜）后大幅度降低了土壤因高温导致的瘪果占比，提高覆膜花生产量和品质。而玉米覆盖90天后降解（破膜）处理（M90）平均产量达到764.7kg/667m2，显著（p<0.001）高于M全（743.3kg/667m2）2.79%，显著（p<0.001）高于不覆盖产量（653.3 kg/667m2）13.7%，主要由于灌浆成熟期M90玉米干物质积累量最高，提高了降解破膜的玉米产量。基于荟萃分析(37篇文献和249项研究)覆盖的产量时效（Relative Mulching Duration and yield）体现在根茎类与非根茎作物差异上，非根茎作物最佳覆膜时效（0.5<RMD=<0.75）平均产量显著高于M全5.1%（p=0.005），对于根茎作物最高产量比对应的区间为0.25<RMD=<0.5，显著高于M全10.5%（p=0.001），较之非根茎作物，表明根茎作物对覆膜时效的产量反映更为敏感。本项目研究揭示不同类作物对地膜降解后水热变化的产量差异化形成机制，为优化设计适用于不同作物类型的最佳降解期地膜提供重要参考依据，为残膜适时回收和旱地覆膜作物种植技术改进提供科学理论依据。