Abstract
Glyphosate (GP)-based herbicides have been widely applied to crops for weed control and pre-harvest desiccation. The objective of this research was to evaluate the effects of pre-harvest GP application on maize or how it physiologically alters this crop. Here, we applied four GP treatment (Control, GP150, GP200, and GP250) on maize lines of Z58 and PH6WC belonging to different maturity groups at grain-filling stages form DAP30 to DAP45. GP application significantly decreased the grain moisture content at harvest by 22–35% for Z58 and by 15–41% for PH6WC. However, the responses of grain weight to glyphosate vary with inbred lines and application time. A high concentration of glyphosate (GP250) reduced the grain weight of Z58 and low concentrations (GP150 and GP200) did not affect, while the grain weight of PH6WC significantly decreased under glyphosate treatment. In summary, our results revealed that timely and appropriate GP application lowers grain moisture content without causing seed yield and quality loss. GP application adversely affected photosynthesis by promoting maturation and leaf senescence. Meanwhile, it also enhanced non-structural carbohydrate (soluble sugars and starch) remobilization from the vegetative organs to the grains. Hence, GP treatment coordinates plant senescence and assimilate remobilization. RNA sequencing revealed that glyphosate regulated the transcript levels of sugar signaling-related genes and induced assimilate repartitioning in grains. This work indicates the practical significance of GP application for maize seed production and harvest, which highlights the contributions of source-sink communication to maize yield in response to external stress or pre-harvest desiccant application.
Highlights
Maize (Zea mays) is cultivated worldwide and used for human food, animal feed, and biofuel
Glyphosate improved the quality of maize seeds, the similar result was from previous observations in wheat (Malalgoda et al, 2019)
Our results demonstrate that appropriate GP application lowers the grain moisture content by promoting maturity without compromising yield
Summary
Maize (Zea mays) is cultivated worldwide and used for human food, animal feed, and biofuel. Grain moisture content is a limiting factor in machine kernel harvest (Wang and Li, 2017). Low grain moisture content at harvest reduces post-harvest grain drying costs and seed quality loss during storage. Pre-harvest desiccation economically and effectively enables timely harvest during unfavorable weather conditions. Glyphosate [N-(phosphonomethyl) glycine, GP] is an active ingredient in herbicides and is widely used for weed control (Orson and Davies, 2007). GP-based herbicides have been extensively used for pre-harvest desiccation of soybean
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