Biostimulants in Corn Cultivation as a Means to Alleviate the Impacts of Irregular Water Regimes Induced by Climate Change

Abstract

Climate change alters regular weather seasonality. Corn is one of the main crops affected by irregular water regimes. Due to complications in decision-making processes related to climate change, it is estimated that planting corn outside the optimal window results in around USD 340 million in losses per year in the United States' Corn Belt. In turn, exogenous plant growth regulators have been gaining prominence due to their potential to positively influence the morphology and physiology of plants under stress. This study was based on the hypothesis that the use of plant growth regulators can assist in mitigating the adverse effects of climate change on corn plants sown both inside and outside the recommended planting period. In this context, the effects of biostimulant application on gas exchange in corn plants sown within and outside the recommended period were evaluated. The experiment was carried out in randomized blocks in a 4 × 5 × 2 factorial scheme with four repetitions. These were four sowing times, the application of the biostimulants via seeds in five doses, and foliar applications (presence and absence). The biostimulant doses were 0.00, 6.25, 12.50, 18.75, and 25 mL kg^-1. The foliar application used a dose of 500 mL ha^-1. Only in the period (2017/2) higher doses of biostimulants indicated a decrease in the water use efficiency of plants, suggesting the need to evaluate this variable carefully. In this regard, future studies may investigate the ideal doses and application timings of biostimulants for different edaphoclimatic conditions. In general, the combined use of biostimulants on seeds and as a foliar treatment boosted physiological activity and stimulated photosynthetic processes in corn plants. Based on these data, plant regulators can be a useful tool to mitigate the adverse effects of climate change on corn plants sown inside and outside the planting period.

Keywords: Zea mays; climate change; irregular water regimes; phytohormones; water deficit tolerance.

Figure 1

Rainfall (PP), permanent wilting point (PM), actual soil water capacity (CRA), soil water storage (AS) and evaluation of gas exchange in plants (ATG) for the cultivation of corn sown in February (A) and March (B) 2016 and February (C) and March (D) 2017 in Chapadão do Sul, MS.

Figure 2

Regression curves for net photosynthesis rate (A), transpiration (B), stomatal conductance (C), sub-stomatal CO₂ concentration (D), instantaneous water use efficiency (E), instantaneous carboxylation efficiency (F), and leaf area (G), as a function of the application of biostimulants in corn sown at different times. Chapadão do Sul, MS, 2016 and 2017. * or **—Significant at p ≤ 0.05 and ≤0.01 by F-test, respectively.

Figure 3

Regression curves for rate of net photosynthesis (A), transpiration (B), stomatal conductance (C), instantaneous carboxylation efficiency (EIC) (D), and leaf area (E), subjected to doses of the biostimulant on seeds with the presence or absence of foliar application of the same product: Chapadão do Sul, MS, 2016 and 2017. * or **—Significant at p ≤ 0.05 and ≤ 0.01 by F-test, respectively.