GERMINATION AND VIGOUR IN SEEDS OF THE COWPEA IN RESPONSE TO SALT AND HEAT STRESS

Luma Rayane de Lima Nunes,Kelly Andressa Peres Lima,Alek Sandro Dutra,Charles Lobo Pinheiro,Paloma Rayane Pinheiro

doi:10.1590/1983-21252019v32n115rc

Luma Rayane de Lima Nunes, Kelly Andressa Peres Lima + Show 3 more

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https://doi.org/10.1590/1983-21252019v32n115rc

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Journal: Revista Caatinga	Publication Date: Mar 1, 2019
Citations: 10	License type: CC BY 4.0

Affiliation: Universidade Federal do Ceará

Abstract

ABSTRACT Salinity is prejudicial to plant development, causing different types of damage to species, or even between genotypes of the same species, with the effects being aggravated when combined with other types of stress, such as heat stress. The aim of this study was to evaluate the tolerance of cowpea genotypes (Vigna unguiculata L. Walp.) to salt stress at different temperatures. Seeds of the Pujante, Epace 10 and Marataoã genotypes were placed on paper rolls (Germitest®) moistened with different salt concentrations of 0.0 (control), 1.5, 3.0, 4.5 and 6.0 dS m-1, and placed in a germination chamber (BOD) at temperatures of 20, 25, 30 and 35°C. The experiment was conducted in a completely randomised design, in a 3 × 4 × 5 scheme of subdivided plots, with four replications per treatment. The variables under analysis were germination percentage, first germination count, shoot and root length, and total seedling dry weight. At temperatures of 30 and 35°C, increases in the salt concentration were more damaging to germination in the Epace 10 and Pujante genotypes, while for the Marataoã genotype, damage occurred at the temperature of 20°C. At 25°C, germination and vigour in the genotypes were higher, with the Pujante genotype proving to be more tolerant to salt stress, whereas Epace 10 and Marataoã were more tolerant to high temperatures. Germination in the cowpea genotypes was more sensitive to salt stress when subjected to heat stress caused by the low temperature of 20°C or high temperature of 35°C.

Highlights

The cowpea is a legume of great socioeconomic importance for the North and Northeast of Brazil, being a direct source of employment and an important staple food due to its high nutritional value (FREIRE FILHO et al, 2011)
The species is considered moderately tolerant to salinity as it can withstand values for electrical conductivity of up to 3.3 dS m-1 for the irrigation water and 4.9 dS m-1 for the soil saturation extract (AYERS; WESTCOT, 1999)
The experiment was conducted at the Seed Analysis Laboratory of the Centre for Agricultural Sciences (CCA), at the Federal University of Ceará, Pici Campus, in Fortaleza in the State of Ceará

Summary

Introduction

The cowpea is a legume of great socioeconomic importance for the North and Northeast of Brazil, being a direct source of employment and an important staple food due to its high nutritional value (FREIRE FILHO et al, 2011). Several authors have reported a decrease in cowpea production in the Northeast of Brazil, which can be explained by the saline soils and water found in the region, intensified by the high rate of evapotranspiration and low rainfall (FERREIRA et al, 2017; NASCIMENTO et al, 2017; OLIVEIRA et al, 2017). Increases in the salt concentration of the soil solution may induce conditions of stress in the plant, mainly due to the fall in the water potential of the solution. Excess salts compromise the physiological and biochemical functions of plants and the use of essential nutrients due to the accumulation of toxic ions (CALVET et al, 2013)

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