Effects of Dual Mulching Under Flat Cropping on Grain Filling Characteristics and Yield of Maize in Semi-Humid Drought-Prone Area

To address the issue of reduced grain plumpness and yield caused by high soil temperatures under plastic film in semi-humid drought-prone areas, this study proposes a dual mulching approach using transparent plastic film and straw (TM+ST) under flat farming. This study analysed the regulatory mechanisms of TM+ST on grain filling characteristics and leaf photosynthetic physiology, aiming to provide theoretical and technical support for stable and high yields in dryland maize production

A field experiment was conducted in Yangling, Shaanxi Province (semi-humid drought-prone area, with an average annual precipitation of 550 mm, accounting for 60% from July to September) from 2021 to 2022. Three mulching treatments were set up with no mulching as the control (CK): transparent plastic film mulching with flat cropping cultivation (TM), black plastic film mulching with flat cropping cultivation (BM), and a flat plot of transparent film mulching with whole maize stalks (TM+ST). The effects of different mulching measures on post-anthesis leaf area index (LAI), SPAD value, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), dry matter accumulation, dynamics of grain weight increment, grain filling characteristics, yield and yield components of spring maize were explored.

Compared with CK, mulching treatments significantly improved the green retention and photosynthetic production capacity of spring maize after anthesis, and improved the grain filling process and grain yield (an increase of 16.5%-48.9%). Compared with the single mulching treatments (TM and BM), TM+ST significantly improved the green retention of leaves, enhanced P_n, G_s, and T_r, and promoted dry matter accumulation after anthesis (an increase of 10.9%-12.6%). Moreover, TM+ST increased the grain weight at the maximum grain filling rate, maintained the highest grain filling rate at the gradual-growing period, prolonged the duration of grain filling at the fast-growing period, and prolonged the active stage of grain filling at slow-growing period. Ultimately, TM+ST treatment increased grain yield (V.S. TM and BM increased by 17.0%-17.2%) by enhancing "source" supply and optimizing grain filling process.

Dual mulching of transparent-plastic film and straw (TM+ST) could improve the green retention and photosynthetic production capacity of leaves after anthesis, optimize the grain filling process, and ultimately drive the maximization of grain weight to improve the yield of maize.