Unraveling the influence of salinity on physiological and biochemical parameters in citrus (Citrus spp.) rootstocks

The present study was carried out during 2018-19 and 2019-20 at Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana to examine the impact of salt stress on physiological parameters of 9 distinct rootstocks of citrus (Citrus spp.) The experimental design followed a completely randomized design (CRD) accompanied with 3 replications, enclosing 45 combinations with 9 citrus rootstocks (Pectinifera, Cleopatra mandarin, Rangpur lime, Alemow, Rough lemon, NRCC-4, Volkamer lemon, CRH-12 and NRCC-3) exposed to 5 NaCl salt stress levels, viz. control (0.07), 2.5, 4.0, 5.5 and 7.0 dS/m. Among the different rootstocks, Rangpur lime exhibited the highest leaf (12.65 mg/g DW) and root (12.42 mg/g DW) total soluble carbohydrates at the 7.0 dS/m salinity level. Additionally, Rangpur lime showcased minimal reduction in chlorophyll stability index (17.2%), leaf and root relative water content (18.7 and 18.9%, respectively), relative stress injury (32.0 and 33.0%, respectively) and leaf and root (Malondialdehyde) MDA content (8.46 and 8.12 mu moles/g DW, respectively) at the same salinity level. Overall, Rangpur lime, Volkamer lemon and CRH-12 demonstrated superior performance by exhibiting relatively higher buildup of total soluble carbohydrates and less drop in CSI, RWC, RSI and MDA content at 7.0 dS/m as compared to control. Conversely, Cleopatra mandarin, Rough lemon and NRCC-3 displayed a relative moderate response, while Pectinifera, Alemow, and NRCC-4 showcased substandard performance, exhibiting contrasting behaviour at 7.0 dS/m as compared to control, particularly concerning physiological parameters at the seedling stage.