Growth, biomass distribution, gas exchange and chlorophyll fluorescence in cowpea (Vigna unguiculata (L.) Walp.) under drought conditions

Abstract

Drought modifies plant development and generates losses in agricultural production. The aim of this study was to analyze the growth, biomass distribution, gas exchange, and chlorophyll fluorescence in nine cowpea (Vigna unguiculata) genotypes under drought conditions in the greenhouse condition. A completely randomized experimental design with four replicates was used. The following genotypes (treatments) of LC-006-016, LC-029-016, LC-036-016, LC-021-016, LC-005-016, LC-009-016, LC-014-016, LC-002-016, and Caupicor-50 (control) were evaluated with irrigation for 21 days (after sowing) and 38 days of drought (DD) for a total duration of 59 days. In a simultaneous experiment, other plants of the same genotypes were irrigated for 59 days after sowing (DAS) with replacement of evapotranspirated water every three days. Measures of plant height and number of leaves were taken every four days, biomass at 59 days, gas exchange every seven days and chlorophyll fluorescence at 17, 21 and 38 DD. Moisture losses were quantified by recording the loss of soil weight every three days. The results showed that plant height reached 72.2% lower in plants under drought, while the vegetative biomass decreased by 76.3%. The photosynthesis, stomatal conductance, and transpiration were decreased 64.6%, 93.1%, and 86.9% under drought, respectively. Furthermore, intrinsic water use efficiency (A/gs) was increased almost six times. However, it was decreased when drought progressed towards the soil water content loss more than 0.0827 g.g-1. The quantum yield of photosynthesis (ΦPSII) was decreased 28.4%, 40.3% and 43.5% at 17, 21 and 38 DD, respectively, under drought condition. The principal component analysis (PCA) suggests that the genotypes with higher A/gs and those with higher biomass production show greater resistance to drought.

Root and Agro-Morphological Traits Performance in Cowpea under Drought Stress

“…Higher shoot height and biomass likely translates to a larger photosynthetic apparatus able to sustain higher grain yield [51]. However, in the study of Ayala et al [53], an inversed correlation between shoot development (SDW and PH) and water use efficiency was observed, suggesting that greater shoot development leads to a higher loss of water being prejudicial under drought conditions. Likewise, Iseki et al [15] also found shoot biomass to be related with plant water status, where lower shoot biomass could confer better drought tolerance.…”

Constraints and Prospects of Improving Cowpea Productivity to Ensure Food, Nutritional Security and Environmental Sustainability

“…Another key advantage of cowpea production is that when used as an inter-crop with other crops, it induces the growth of beneficial soil microorganisms and reduces the use of synthetic agrochemicals (Bukovsky-Reyes et al, 2019;Sun et al, 2019). In terms of importance, cowpea production contributes significantly to economic productivity and environmental sustainability in Africa (Martins et al, 2003;Olajide and Ilori, 2017;Ovalesha et al, 2017;Cardona-Ayala et al, 2020).…”

Can Chlorophyll a Fluorescence and Photobleaching Be a Stress Signal under Abiotic Stress in Vigna unguiculata L.?

“…Many scholars defend that the chlorophyll a fluorescence as the first stressor signal [47,60,71,72] while the production of H 2 O 2 and MDA are the stress signals, informing that the antioxidant systems are not able to cope with the ROS and the damage to the membrane phospholipids [66,73,74]. H 2 O 2 has the capacity to initiate lipid peroxidation and degrade proteins.…”