Physiological Responses of Cowpea (Vigna unguiculata) Under Irrigation With Saline Water and Biostimulant Treatment

Leonardo Vieira De Sousa,Aurélio Paes Barros Júnior,Toshik Iarley Da Silva,Rayanne Maria Paula Ribeiro,Hugo Ferreira,Manoel Galdino Dos Santos,Francisco Rafael Rodrigues Gerônimo,Antônio Genilson Rodrigues Araújo,Fernando Sarmento De Oliveira

doi:10.5539/jas.v10n12p24

Leonardo Vieira De Sousa, Aurélio Paes Barros Júnior + Show 7 more

Open Access

https://doi.org/10.5539/jas.v10n12p24

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Abstract

Cowpea (Vigna unguiculata) is one of the world&rsquo;s main crops, and it is a fundamental source of protein for semiarid regions population. In these regions, the use of high salts concentration water in irrigation systems is one of the major factors that contributes to reduced cowpea yield. One way to alleviate the negative effects of salinity is through the biostimulants application, which is a product that has beneficial substances to the plants metabolism. The aim of this study was to evaluate the application of biostimulant in cowpea cultivars under irrigation with saline water. The study was carried out in the Agrarian Sciences Center, of the Department of Agronomic and Forest Sciences of the Federal Rural University of the Semi-Arid, in the city of Mossor&oacute;, RN. The experimental design was completely randomized, with four replications. The treatments were arranged in 5 &times; 2 &times; 2 factorial scheme, with five doses of biostimulant (0, 15, 30, 45 and 60 mL L-1), two electrical conductivities of the irrigation water (0.5 and 5.0 dS m-1), and two cowpea cultivars (IPA-206 and BRS Guariba). The evaluated characteristics were: chlorophyll content index, stomatal conductance, net photosynthesis, internal CO2 concentration, transpiration rate, shoot height, stem diameter and shoot dry mass. The biostimulant application was not efficient in attenuating the salinity stress effect on the development of cowpea cultivars. The higher biostimulant concentrations along with the use of saline water increased the negative effects of salinity on the cowpea plants physiology. There was no difference between the cultivars regarding the tolerance to saline stress and the application of biostimulant.

Highlights

The cowpea (Vigna unguiculata (L.) Walp.) is one of the main sources of vegetable protein in tropical and subtropical regions of the world (Santos et al, 2014)
There was a double interaction between cultivar and biostimulant and between salinity and biostimulant
There was an isolated effect of the factors (Table 2)

Summary

Introduction

The cowpea (Vigna unguiculata (L.) Walp.) is one of the main sources of vegetable protein in tropical and subtropical regions of the world (Santos et al, 2014). In this scenario, Brazil is classified as the world’s third largest producer, with estimated production of 749.4 thousand tons for the 2017/2018 harvest (CONAB, 2018). Several factors (low rainfall, salinity of soil and of the irrigation water, high temperature, among others) are responsible for the low cowpea productivity in the Northeast region, the use of water with high salinity levels stands out (Silva et al, 2013). Researchers have observed that the use of saline water in irrigation directly impairs its development, affecting plant height, stem diameter and dry matter production, in addition to interfere in physiological characteristics, such as stomatal conductance, transpiration and net photosynthetic rate (Prazeres et al, 2015; Aquino et al, 2017)

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