Silicon foliar application attenuates the effects of water suppression on cowpea cultivars

Duval Chagas Da Silva,Alberto Soares De Melo,Anderson Reges Santos,Wellerson Leite De Andrade,Yuri Lima Melo,Liziane Maria De Lima

doi:10.1590/1413-7054201943023019

Duval Chagas Da Silva, Alberto Soares De Melo + Show 4 more

Open Access

https://doi.org/10.1590/1413-7054201943023019

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Abstract

ABSTRACT Silicon and proline play important physiological, metabolic and functional roles in plants, especially under water deficit conditions. Their application can mitigate the adverse effects of stress in crops by increasing water use efficiency and antioxidant activity. The objective of this study was to evaluate silicon (Si) as attenuator of the effects of water deficit on cowpea cultivars, through physiological, biochemical and growth indicators. The experimental design was randomized blocks with four cultivars (BRS Guariba, BRS Itaim, BRS Aracê and BRS Rouxinol) and four irrigation treatments associated or not with Si application (W100 - 100% ETo; W50 - 50% ETo; W50+100Si and W50+200Si, with 100 and 200 mg L-1 silicon, respectively), in a 4 x 4 factorial scheme, with five replicates. Leaf water potential, proline concentration, antioxidant enzymes and growth indicators were evaluated in cowpea plants. Under water deficit conditions, all cultivars showed reductions in leaf water potentials, which compromised plant growth. However, Si applications of 200 mg L-1 in the cultivar BRS Guariba and 100 and 200 mg L-1 in the cultivar BRS Itaim minimized the effects of stress, by increasing leaf water potential and the activity of the enzyme ascorbate peroxidase, in both cultivars, besides increasing proline concentration in the former and reducing proline concentration in the latter, which ensured the maintenance of growth. Despite the no contribution to the increase in water potential, Si applications of 100 and 200 mg L-1 in BRS Rouxinol and BRS Aracê, respectively, reduced the deleterious effects of the stress on their growth by regulating the enzymatic metabolism and proline.

Highlights

In the North and Northeast regions of Brazil, cowpea (Vigna unguiculata (L.) Walp.) constitutes one of the main components of the population diet, especially in the rural area, due to its high nutritional value (Silva et al, 2018)
After Si application of 100 mg L-1 in cowpea plants subjected to the water deficit treatment (W50 + 100Si), there was an increase of 25% in the water potential only in the cultivar BRS Itaim, compared to the treatment W50 (Figure 1)
All cowpea cultivars evaluated showed reductions in leaf water potential, which resulted in losses in most of the growth indicators evaluated

Summary

Introduction

In the North and Northeast regions of Brazil, cowpea (Vigna unguiculata (L.) Walp.) constitutes one of the main components of the population diet, especially in the rural area, due to its high nutritional value (Silva et al, 2018). Disorders in the photosynthetic apparatus, caused by water restriction, lead to the accumulation of electrons in cell metabolism that bind to oxygen molecules, forming reactive oxygen species (ROS) (Campos et al, 2019). These species act as messengers of various cellular processes, including tolerance to different environmental stresses, which depend on the balance between their production and their elimination (Sharma et al, 2012; Martins et al, 2018). ROS are responsible for causing oxidative stress, which may damage photosynthetic components such as chlorophylls, intensify lipid peroxidation in membranes, denature proteins, damage nucleic acids, among others (Maia et al, 2015)

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