Changes in plant growth, leaf relative water content and physiological traits in response to salt stress in peanut (Arachis hypogaea L.) varieties

Salinity is the main environmental factor accountable for decreasing crop productivity worldwide. The effects of NaCl salinity on plant growth (leaf relative water content (RWC), leaf dry weight (LDW), shoot length (SL), number of leaves (NL), number of branches (NB) and total leaf area (TLA) and physiological characteristics (stomatal conductance (g(s)), transpiration rate (TR), net photosynthetic (P-n), yield of photosystem II (Phi PsII) and the intercellular CO2 concentration (CO2int) in peanut (Arachis hypogaea L.) varieties ('Vanda', 'P244601' and 'Pl184948', widely used in Cameroon, Tanzania and Ghana, respectively, were investigated under hydroponic condition. Plants were subjected to four levels of NaCl (0, 40, 80 and 120 mM) at early seedling growth stage of plant development. Application of NaCl treatment led to a significant decrease in LDW, SL, NL, TLA, P-n, g(s), TR and CO2int concentration of 'Vanda' and 'P244601' compared to untreated plants while the plant growth inhibition was notably noted at 120 mM NaCl in 'P1184948' for LDW, SL and NB. The highest depressive effect was detected in gs of salt-sensitive 'Vanda' while the lowest were recorded in gs of salt-tolerant 'P1184948' at high salinity level. Enhanced NaCl concentrations led to a significant increase in FPSII of 'P1184948' compared to 'Vanda', 'P244601' and untreated plants. Leaf CHL content was significantly increased in moderately-tolerant ''P244601' and salt-tolerant 'P1184948' at 80 mM NaCl compared to salt sensitive 'Vanda' and untreated plants. The depressive effect of salt on RWC was recorded at 120 mM NaCl in peanut leaves of all varieties. Under salt stress 'P1184948' was observed to have relatively higher tolerance on average of all growth and physiological traits than 'Vanda' and P244601' suggesting that it could be grown in salt-affected soils.