Leaf gas exchange and δ13C in cowpea and triticale under water stress and well-watered conditions

Lawrence Munjonji,Kingsley Kwabena Ayisi

doi:10.1016/j.heliyon.2021.e07060

Abstract

Leaf gas exchanges play a critical role in determining crop productivity as they control both CO2 gain and water loss. CO2 gain and water loss influence water use efficiency (WUE) and carbon isotope composition (δ13C). Responses in leaf gas exchanges to water stress are species-specific. However, the extent of this variation in C3 crops is less studied. A field study was carried out to investigate the influence of water stress on leaf gas exchanges of triticale and cowpea. Crops were grown under water stress and well-watered conditions and leaf gas exchanges were determined at flowering. The results showed that triticale maintained a higher stomatal conductance (gs), transpiration rate(E) and intercellular CO2 concentration (ci) compared to cowpea but did not differ in photosynthetic rate(A). As a result, triticale discriminated against 13C more than cowpea. These results suggest a higher influence of ci on δ13C than A. Despite triticale maintaining higher rates of ci, A and gs, it had lower WUE compared to cowpea. Consequently, triticale grain yield was more sensitive to water stress than cowpea. The findings of this study showed significant variation in leaf gas exchanges and δ13C between two drought-tolerant C3 crops suggesting differences in their response mechanism to water stress.

Highlights

Drought is the major abiotic restriction to crop productivity and is expected to become progressively severe and more frequent due to climate change
Cowpea (Vigna unguiculata) is an essential C3 legume crop, commonly produced in tropical and subtropical dry areas of the world where the production usually depends on rain as the only source of water supply [2]
The experiment was established as a randomized complete block design in split-plot arrangement where moisture level constituted the main plot treatment and triticale and cowpea genotypes, the subplot treatment

Summary

Introduction

Drought is the major abiotic restriction to crop productivity and is expected to become progressively severe and more frequent due to climate change. Drought has a significant influence on food security, in regions where crop production solely dependents on rainfall. Drought is a major problem in arid and semi-arid areas where rainfall is very low. As a result of climate change and variability, rainfall in many of these areas is predicted to decrease and become even more erratic. Cowpea (Vigna unguiculata) is an essential C3 legume crop, commonly produced in tropical and subtropical dry areas of the world where the production usually depends on rain as the only source of water supply [2]. Triticale yields high; is highly tolerant to many pests and diseases and is adaptable to poor growing conditions [3]

Objectives

Methods

Results