Efeitos da aplicação de acetilcolina em plantas de milho (Zea mays) sob estresses térmico e hídrico

Abstract

Maize (Zea mays) is a cereal grown worldwide and has great economic importance. Due to the substantial increase in global temperature and the consequent increase in drought, the crop has reduced its productive potential. An important bioregulator produced in small quantities by the plant is Acetylcholine (ACh), which acts on germination, reproduction, growth, development, cellular metabolism of the crop and is capable of mitigating the effects of stress. The objective of this work was to evaluate the effects of applying acetylcholine to maize plants subjected to thermal and water stress. The experiment was carried out in a completely randomized, double factorial design, in two conditions: normal (temperature 31.9 ºC/19.9 ºC max./min and irrigated) and stressful (38 ºC/28 ºC day/night and suspension of irrigation) x 3 application modes (0 mmol L-1 (C); seed (TS) and foliar (F) treatments, both were treated with 1 mmol L-1 of ACh, leaf water potential analyzes were carried out, gas exchange measurements , chlorophyll a fluorescence, antioxidant enzymes (SOD, CAT and APX), O2-, H2O2 and lipid peroxidation (MDA) contents, acetylcholinesterase enzyme (AChE), total phenols and flavonoids, biometrics and biomass (height, diameter, dry masses of leaves, stem and ear) and weight of 100 grains. The data were evaluated using analysis of variance and the means compared using the Tukey test (p<0.05) and multivariate analysis by principal components (PCA) with the statistical program PC-Ord. There was a better physiological adjustment of maize plants under stressful conditions with foliar application of 1 mmol L-1 of ACh. In addition to an increase in CAT in TS and F, accompanied by a decrease in MDA content, morphologically, a decrease in the dry mass of the leaves was observed, however, there was an increase in the weight of 100 grains. Concluding that the application of ACh positively influences the physiological, biochemical and morphological parameters in plants, and acts to mitigate the effect of heat and water stress.