Abstract
BackgroundSalt stress significantly inhibits the growth, development, and productivity of cotton because of osmotic, ionic, and oxidative stresses. Therefore, the screening and development of salt tolerant cotton cultivars is a key issue towards sustainable agriculture. This study subjected 11 upland cotton genotypes at the seedling growth stage to five different salt concentrations and evaluated their salt tolerance and reliable traits.ResultsSeveral morpho-physiological traits were measured after 10 days of salinity treatment and the salt tolerance performance varied significantly among the tested cotton genotypes. The optimal NaCl concentration for the evaluation of salt tolerance was 200 mmol·L− 1. Membership function value and salt tolerance index were used to identify the most consistent salt tolerance traits. Leaf relative water content and photosynthesis were identified as reliable indicators for salt tolerance at the seedling stage. All considered traits related to salt tolerance indices were significantly and positively correlated with each other except for malondialdehyde. Cluster heat map analysis based on the morpho-physiological salt tolerance-indices clearly discriminated the 11 cotton genotypes into three different salt tolerance clusters. Cluster I represented the salt-tolerant genotypes (Z9807, Z0228, and Z7526) whereas clusters II (Z0710, Z7514, Z1910, and Z7516) and III (Z0102, Z7780, Z9648, and Z9612) represented moderately salt-tolerant and salt-sensitive genotypes, respectively.ConclusionsA hydroponic screening system was established. Leaf relative water content and photosynthesis were identified as two reliable traits that adequately represented the salt tolerance of cotton genotypes at the seedling growth stage. Furthermore, three salt-tolerant genotypes were identified, which might be used as genetic resources for the salt-tolerance breeding of cotton.
Highlights
Salt stress significantly inhibits the growth, development, and productivity of cotton because of osmotic, ionic, and oxidative stresses
Determination of optimum salt concentration In this study, 11 cotton genotypes were subjected to four different salt concentrations and one control treatment to identify the target salt concentration
The regression values of total biomass (TB), leaf area (LA), shoot length (SL), gsw, SK+/Na+, leaf numbers (LN), and MDA were 0.986 7, 0.983 9, 0.978 5, 0.965 4, 0.953 5, 0.949 3, and 0.922 3, respectively. These results indicated that both leaf relative water content (LRWC) and photosynthesis can be considered as two potential traits for the salt tolerance evaluation of cotton genotypes at the seedling growth stage
Summary
Salt stress significantly inhibits the growth, development, and productivity of cotton because of osmotic, ionic, and oxidative stresses. Salinity is the second-most prevalent abiotic stress after drought, which limits plant growth and progressively decreases the optimal yield of crops worldwide (Gao et al 2016). Salt-resistance is considered multifarious phenomena and plants have developed several mechanisms to counteract this form of stress at the cellular, subcellular and organ levels. Salt tolerance is a relative measurement and the negative impacts of salt stress depend on various factors, such as the phase of plant growth, the duration of exposure to salinity, the salt concentration, the plant species, and/or the method of evaluation (Higbie et al 2010). Evaporated water was refilled with de-ionized (dH2O) water every day to retain the target volume
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