A Novel Plant Growth Regulator Alleviates High‐Temperature Stress in Maize

Abstract

Core Ideas This study examined a new way to mitigate the effects of HTS on spring maize. B2 had similar effects to ABA on alleviating maize yield penalty caused by HTS. B2 reduced plant height and ear height. Adopting spring maize (Zea mays L.) to replace part of a winter wheat (Triticum aestivum L.)–summer maize rotation system can mitigate agricultural water scarcity in the North China Plain. The main obstacle to increasing spring maize production is high‐temperature stress (HTS) at grain‐filling stage. In this study, a novel plant growth regulator (2,4‐dichloroformamide cyclopropane acid [B2]), based on the structures of abscisic acid (ABA), pyrabactin, and coronatine, was used to reduce maize yield penalty imposed by HTS. Field experiments were conducted to investigate the effects of B2 on alleviating maize yield penalty caused by HTS in 2015 and 2016. The hybrid maize cultivar Zhengdan958, which is widely planted across China, was grown at a density of 67,500 plants ha−1. Water, B2, and ABA were applied to maize foliar surfaces at the ninth‐expanded‐leaf stage. Application of B2 significantly increased grain yield by 8.5% by increasing thousand‐kernel weight and decreasing bare tip length compared with the control. Additionally, B2 significantly increased the SPAD value and ABA content of the ear leaf, enhancing net photosynthesis rate and heat resistance. Application of B2 also improved grain‐filling rate, grain volume, and grain dry weight, which contributed to higher grain yield. Moreover, B2 decreased plant and ear height, neither of which was affected by ABA. These results indicate that B2, with a biological activity similar that of ABA, could help maintain relatively higher photosynthetic capacity, heat resistance, and grain‐filling rate during the grain‐filling stage under HTS, providing a stable method to increase grain yield.

Physiological Mechanism of Abscisic Acid-Induced Heat-Tolerance Responses to Cultivation Techniques in Wheat and Maize—Review

“…When 2,4-D was sprayed on the leaves at the ninth-expanded-leaf stage of spring maize grown under heat stress, the ear leaf had a significantly increased chlorophyll content and ABA content and an enhanced net photosynthesis rate at the grain-filling stage compared with plants that were not sprayed. Spraying also improved the grain-filling rate, grain volume, and grain dry weight and decreased the bare tip length, which increased the grain yield by 8.5% [16].…”

“…ABA also induces the production of energy in the form of adenosine triphosphate (ATP), which is needed for HSP accumulation [13]. Several approaches have been taken to improve crop production under heat stress, such as selecting varieties with improved heat tolerance [14], adjusting the sowing time [15], applying plant growth regulators [16] and different fertilizers [17][18][19][20][21], optimizing irrigation systems [22], subsoiling soil [23] and employing heat acclimation. However, although cultivation and tillage techniques have been used by farmers to improve the heat tolerance of crops and scientific researchers have integrated multiple techniques to develop a system that can allow crops to adapt to high-temperature stress, the mechanisms by which cultivation techniques improve heat tolerance by regulating ABA levels have not been summarized.…”

Plant growth regulators interact with elevated temperature to alter heat stress signaling via the Unfolded Protein Response in maize

“…Gibberellins, auxins, and brassinosteroids contribute to plant height and organ size, but the effects of these hormones are not additive 13 . Agronomic use of these plant growth regulators is focused on amelioration of biotic and abiotic stress in agronomic applications 14–16 . For future discovery and eventual rational design of regulators we will require mechanistic information about mode of action and interactions of these compounds.…”

Plant growth regulators interact with elevated temperature to alter heat stress signaling via the Unfolded Protein Response in maize

“…Gibberellins, auxins, and brassinosteroids contribute to plant height and organ size, but the effects of these hormones are not additive 13 . Agronomic use of these plant growth regulators is focused on amelioration of biotic and abiotic stress in agronomic applications [14][15][16] . For future discovery and eventual rational design of regulators we will require mechanistic information about mode of action and interactions of these compounds.…”