Assessing morphological and physiological responses of local and exotic Rice varieties to salinity stress

This study aimed to evaluate the differential morphological and physiological responses of local and exotic rice varieties growing in arid and semi-arid climates under soil salinity stress. The experiment was laid out in a Completely Randomized Design (CRD) with four replicates and conducted in a greenhouse under natural conditions at the Department of Soil and Environmental Sciences (lath house), Faculty of Agriculture and Environmental Sciences, MNS-University of Agriculture, Multan, Pakistan, during 2023. The pot experiment involved two exotic rice varieties (BR-61 and BR-47) and one local variety (Al-Khalid), tested under two salinity treatments: control (non-saline) and saline (EC = 10 dS m⁻¹). Data on various growth parameters - such as shoot and root length, shoot and root fresh and dry weights, chlorophyll content, and ionic concentrations (Ca²⁺, Na⁺, and K⁺) in leaf tissues - were collected and analyzed statistically using factorial CRD. The results indicated that exposure to NaCl stress significantly reduced shoot and root growth while increasing Na⁺ concentration in the plants. Among the tested varieties, BR-61 exhibited the highest shoot and root dry weight (8.0 g and 1.0 g, respectively), while BR-47 showed the lowest root dry weight (5.6 g and 0.6 g). The maximum Na⁺ concentration (348.7 ppm) in leaf sap was observed in Al-Khalid, which was approximately twice the control, while the minimum (157.4 ppm) was found in BR-61. BR-61 also recorded the highest K⁺ concentration (77.1 ppm), while BR-47 had the lowest (62 ppm) under saline conditions. Based on the findings, the rice varieties were classified into salt-tolerant (BR-61) and moderately tolerant (BR-47 and Al-Khalid) categories at the 10 dS m⁻¹ NaCl level. These insights could be valuable in formulating strategies to enhance salinity stress tolerance in rice varieties and optimize their physiological performance, particularly chlorophyll content, under saline conditions.