Poly-γ-glutamic acid (γ-PGA) is a biodegradable and non-toxic and harmless water retention agent, contributing significantly to in the sustainable development of agriculture. This study focused that investigated effect of γ-PGA on soil pore structure, maize growth, grain filling characteristics, maize yield and water use efficiency under mulched drip irrigation, and the optimal application strategy of γ-PGA. The effect of γ-PGA application rates (0, 40, and 80 kg ha) on soil structure was investigated using soil column experiments. Field experiments analyzed the effects of these γ-PGA rates (0, 20, 60 and 80 kg ha) on maize growth. The results showed that γ-PGA changed the position and number of soil pores; with the increase of γ-PGA application rate, the number of soil pores increased. The number of soil pores with an equivalent diameter smaller than 300μm increased by 9–14 times, and those with an equivalent diameter larger than 1000μm increased twelvefold. The soil water storage increased by 2∼27 %. γ-PGA prolonged active grain filling period by 1–3 days, increased the maximum grain filling rate (Vmax) by 3∼15 %, the average grain filling rate (Va) by 7∼27 %, and grain weight by 12∼37 %. γ-PGA treatments significantly increased maize plant height, stem diameter, leaf area index (LAI), ear width, grain number per row and 100-grain weight. Compared with P0, yield and water use efficiency for γ-PGA treatment were increased by 4.9∼21.8 % and 1.0∼18.1 %. Based on the Gaussian optimization model and considering local actual conditions, we recommend that the optimal rate of γ-PGA is 70 kg ha in the region. This study provided a theoretical basis for water-saving irrigation of maize under mulched drip irrigation.

中文翻译：

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聚γ-谷氨酸对膜下滴灌土壤孔隙结构、玉米灌浆、产量及水分利用效率的影响


聚γ-谷氨酸（γ-PGA）是一种可生物降解、无毒无害的保水剂，为农业的可持续发展做出了重大贡献。本研究重点研究了γ-PGA对膜下滴灌土壤孔隙结构、玉米生长、籽粒灌浆特性、玉米产量和水分利用效率的影响，并探讨了γ-PGA的优化施用策略。通过土柱实验研究了 γ-PGA 施用量（0、40 和 80 kg ha）对土壤结构的影响。田间实验分析了这些 γ-PGA 用量（0、20、60 和 80 千克/公顷）对玉米生长的影响。结果表明，γ-PGA改变了土壤孔隙的位置和数量；随着γ-PGA施用量的增加，土壤孔隙数量增加。当量直径小于300μm的土壤孔隙数量增加了9~14倍，当量直径大于1000μm的土壤孔隙数量增加了12倍。土壤储水量增加2∼27%。 γ-PGA使籽粒灌浆活跃期延长1~3天，最大籽粒灌浆率（Vmax）提高3~15%，平均籽粒灌浆率（Va）提高7~27%，粒重提高12~37% %。 γ-PGA处理显着增加了玉米株高、茎粗、叶面积指数(LAI)、穗宽、每行粒数和百粒重。与P0相比，γ-PGA处理的产量和水分利用效率分别提高了4.9～21.8%和1.0～18.1%。基于高斯优化模型，结合当地实际情况，建议该地区γ-PGA最佳施用量为70 kg·ha。本研究为玉米膜下滴灌节水灌溉提供了理论依据。