Water restriction in cowpea plants [Vigna unguiculata (L.) Walp.]: Metabolic changes and tolerance induction

Abstract

Global climate change tends to intensify water unavailability, especially in semi-arid regions, directly impacting agricultural production. Cowpea is one of the crops with great socio-economic importance in the Brazilian semi-arid region, cultivated mainly under rainfed farming and considered moderately tolerant to water restriction. This species has physiological and biochemical mechanisms of adaptation to these stress factors, but there is still no clear vision of how these responses can not only allow survival, but also ensure yield advances in the field. Besides acclimation mechanisms, the exogenous application of abiotic (salicylic acid, silicon, proline, methionine, and potassium nitrate) and biotic (rhizobacteria) elicitors is promising in mitigating the effects of water restriction. The present literature review discusses the acclimation mechanisms of cowpea and some cultivation techniques, especially the application of elicitors, which can contribute to maintaining crop yield under different water scenarios. The application of elicitors is an alternative way to increase the sustainability of production in rainfed farming in semi-arid regions. However, the use of eliciting substances in cowpea still needs to be carefully explored, given the difficulties caused by genotypic and edaphoclimatic variability under field conditions.

Salicylic acid and proline modulate water stress tolerance in a traditional variety of cowpeas

“…Aires et al ( 2022) reported a reduction in stomatal conductance, intracellular CO 2 content, and chlorophyll fluorescence in plants subjected to 1.3 mM SA. Thus, using a dose four times greater than the dose of SA studied by those researchers, it was observed that the reduction in TSS levels may be related to the inhibitory effects of SA on photosynthetic parameters (Melo et al, 2022a).…”

“…This is most likely due to the fact that SA is a cellular signal that triggers numerous responses that mitigate the negative effects of environmental stresses (Araújo et al, 2018). and Melo et al (2022a) also suggested that cellular protection against free radicals may lead to a reduced response to oxidative stress, which might explain the decrease in stronger enzyme activity observed in attenuator-treated plants under the W50 irrigation regime.…”

“…When the plants were exposed to unfavorable water conditions, osmotic adjustment might have been a factor contributing to the preservation of adequate RWC and %U. The accumulation of compatible osmolytes allows water absorption by plant tissues, ensuring that their physiology remains stable under stress (Melo et al, 2022a).…”

“…An increase in the activity of antioxidative complex enzymes under water-stress conditions is considered a common mechanism of oxidative stress response that helps eliminate reactive oxygen species. This process contributes to the maintenance of the integrity and stability of membranes and cellular structures, enabling osmoregulation (Melo et al, 2022a).…”

“…Osmoregulatory compounds can accumulate in plant tissues, promoting the absorption of water from the soil (Coelho et al, 2018). In addition, antioxidant enzymes enhance the ability of plants to maintain ROS at an adequate level to reduce the damage to cellular structures caused by water stress (El-Taher et al, 2022;Melo et al, 2022a;Santos et al, 2022).…”