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ThesisItem Open Access Response of citrus rootstocks to salinity for western agroclimatic zone of Haryana(CCSHAU, Hisar, 2021-08-12) Reetika; Dalal, R.P.S.The present investigation was carried out at screen house of the Department of Horticulture, CCS Haryana Agricultural University, Hisar for the two consecutive years during the year 2018-19 and 2019-20 to study the response of citrus rootstocks to salinity. The experiment was laid out in CRD with three replications comprising of nine citrus rootstocks (viz. Rough lemon, Cleopatra mandarin, Pectinifera, Rangpur lime, Alemow, Volkamer lemon, NRCC-3, NRCC-4 and CRH-12) and five salinity levels (viz. control (0.07), 2.5, 4.0, 5.5 and 7.0 dS m-1 NaCl salinity level). The data were recorded on germination parameters of 3-month-old seedlings and growth, chemical and physiological and biochemical parameters of one-year old seedlings. The results of the experiment indicate that the salinity had a significantly negative influence on most of the recorded parameters. The maximum potential of citrus rootstocks of 3-month-old seedlings in respect of the minimum number of days taken for seed germination (14) with Pectinifera and the higher number of seedlings emerged per seed (1.70) in Cleopatra mandarin, a greater number of leaves per plant (27) in Rangpur lime and seed germination (%) was observed maximum (82%) in Volkamer lemon in control (0.07 dS m-1). The minimum reduction in seedling height (39.7%), stem diameter (14.9%), fresh and dry shoot (37.7 and 28%) and fresh and dry root biomass (21 and 26.9%), respectively over control was observed in Rangpur lime, followed by Volkamer lemon and CRH-12. However, minimum reduction (42.8, 41.3 and 18.5%) in plant height, root length and stem diameter were observed in Volkamer lemon and minimum decline in leaf area and number of healthy leaves per plant (61.6 and 48.5%), in fresh (54.6, 52.1 and 49.1%) and dry (48.9, 48.7 and 54.7%) leaf, stem and root biomass, respectively over control was recorded in Rangpur lime, followed by Volkamer lemon and CRH-12. The reduction in growth parameter was less up to 4.0 dS m-1, afterwards there was sharp decline in the above recorded parameters. The maximum accumulation rate of Na+, Cl- and SO42- and the minimum accumulation of Ca2+, Mg2+ and K+ content at 7 dS m-1 when compared with control was recorded in leaves (65.0, 60.7, 36.1, 27.6, 20.3 and 36.4%) and roots (56.5, 56.5, 31.8, 29.0, 20.7 and 29.5%), respectively of Rangpur lime, followed by Volkamer lemon. At 7 dS m-1 salinity level, the highest leaf (12.43, 17.45 and 12.65) and root (12.15, 17.42 and 12.42) proline, glycine betaine and total soluble carbohydrates (μg g-1, μmol g-1 and mg g-1 DW), respectively was recorded in Rangpur lime. Similarly, synthesis of leaf (18.38, 58.27 and 3.46 Units mg-1 protein min-1) and root (18.38, 58.61 and 3.69 Units mg-1 protein min-1) SOD, CAT and APX, respectively enhanced abruptly at 7 dS m-1, however, minimum reduction in chlorophyll stability index (17.2%), leaf and root relative water content (18.7 and 18.9%) and relative stress injury (32.0 and 33.0%), respectively was noticed in Rangpur lime at 7 dS m-1, in addition, the minimum leaf and root MDA (8.46 and 8.12 μmoles g-1 DW) and H2O2 content (907.6 and 876.59 moles g-1 DW), respectively was also recorded in Rangpur lime at 7 dS m-1. It is further concluded that among all rootstocks, Rangpur lime, followed by Volkamer lemon and CRH-12 were found superior with relatively less reduction at 7 dS m-1 over control, however, Cleopatra mandarin, followed by Rough lemon and NRCC-3 exhibited a moderate response with comparatively less reduction, whereas, Pectinifera, followed by Alemow and NRCC-4 were found inferior which showed relatively high reduction at 7 dS m-1 over control in respect of germination, growth, chemical and physiological and biochemical parameters at seedling stage.
