Effects of Gibberellin (GA4+7) in Grain Filling, Hormonal Behavior, and Antioxidants in High-Density Maize (Zea mays L.)

Abstract

Dense plant cultivation is an efficient approach to improve maize production by maximizing the utilization of energy and nutrients. However, dense plant populations may aggravate the abortion rate of young grains, resulting in fewer kernels per ear. The rate and duration of grain-filling play decisive roles in maize grain yield. Therefore, to increase plant density, enhancing the grain-filling rate, extending the growth period of individual maize plants and regulating crop senescence would be the first priority. In this study, we examined the regulatory effects of GA4+7 under two application methods: shanks and silks were moistened by cotton full with GA4+7 solution at concentrations of 0, 10, 60, and 120 mg L−1. The results showed that GA4+7 improved the grain-filling rate by increasing the content of auxin, gibberellin, zeatin, and abscisic acid in grains compared to control plants. In addition, the auxin, gibberellin, and zeatin contents in the grains were positively and significantly correlated with the maximum grain weight and the maximum and mean grain-filling rates. Moreover, GA4+7 increased the activities of superoxide dismutases, catalases, and peroxidases and reduced the malondialdehyde content in leaves compared with untreated plants. At the concentration of 60 mg L−1, GA4+7 showed the greatest effect on shank and silk applications (Sh-60 and Si-60) followed by 10 mg L−1 (Sh-10) for shank treatment and 120 mg L−1 (Si-120) for silk treatment. Our results suggest that a concentration of 60 mg L−1 GA4+7 for shank and silk application may be efficiently used for changing the level of hormones in grains and antioxidant enzymes in ear leaves, which may be useful for enhancing grain-filling rate and delaying leaf senescence, resulting in an increase in maize grain yield.

Agro-Techniques for Lodging Stress Management in Maize-Soybean Intercropping System—A Review

“…In addition, shade avoidance response is also a crucial factor that affects the normal growth of crops in dense canopies [ 100 , 101 ]. In a recent study, Cui et al [ 102 ] investigated the effect of Gibberellin (GA) application on the maize hormonal and antioxidant activities and grain filling under high planting densities. They illustrated the significant correlation between GA application and the level of endogenous hormones and antioxidant activities of maize under high planting densities.…”

Biosynthesis and beneficial effects of microbial gibberellins on crops for sustainable agriculture

“…There exist a vast number of articles and patents on the current commercial or potential uses of gibberellins. Despite the existence of 136 gibberellins, only GA 3 and a mixture of GA 4 /GA 7 are currently used commercially (Cui et al, 2020).…”

“…Therefore, the use of GA 3 remains limited mainly to malting, wine growing, and citrus production. In these fields, the use of GA 3 has been a considerable financial success (Cui et al, 2020).…”

“…This specific activity might have commercial and economic importance in the future, since some of the economically most important forest trees having poor natural regeneration due to their long generation times. GA 4 /GA 7 application might enable the conifer tree breeders to accelerate the generation time and to carry out breeding programs more efficiently (Cui et al, 2020). The interaction of other plant growth hormones, such as auxins, with gibberellins has been studied in some crops, resulting in improved tomato production and quality (Rouphael et al, 2021).…”

Applied GA5, GA4, and GA4/7 increase berry number per bunch, yield, and grape quality for winemaking in Vitis vinifera L. cv. Malbec

“…As an example, products with a mixture of GA 4 and GA 7 (referred to as GA 4/7 ) are used to reduce fruit reddishness in apple 9 . Moreover, this mixture is used to induce fruit set and increase fruit size, as observed for pear 10 and maize; 11 and GA 4/7 applied a few weeks after full bloom reduced the drop of peach fruits 12 …”