Rootstock mediated alteration in morphology and photosystem in sweet orange (Citrus sinensis) scion cv. Pusa Sharad under NaCl stress

There is a dearth of rootstock studies on how salinity stress imparts tolerance to the scion cultivar in citrus [Citrus sinensis (L.) Osbeck]. The impact of sodium chloride on sweet orange cv. Pusa Sharad (PS) grafted on 11 different rootstocks i.e. Jatti khatti (JK), X–639 (X9), CRH–12 (C12), NRCC–1 (N1), NRCC–2 (N2), NRCC–3 (N3), NRCC–4 (N4), NRCC–5 (N5), Troyer citrange (TC), CRH–47 (C47) and Cleopatra mandarin (CM) was evaluated at the nursery unit of ICAR-Indian Agricultural Research Institute, New Delhi, during 2019–22. Irrigation water containing 30 and 60 mM of sodium chloride (NaCl) was applied to scion/rootstock combinations in comparison to control (without NaCl) till the onset of salt injury symptoms i.e. 42 days. Under salinity stress, the PS scion grafted onto CM, X9, C47, N1, and N3 rootstocks exhibited minimum reduction in the scion height, leaf area ratio, root to shoot ratio, total chlorophyll content, total carotenoid content, transpiration rate, photosynthesis rate, internal CO2 concentration and stomatal conductance as compared to PS scions grafted onto JK, C12, N2, N4, N5, and TC rootstocks under 60 mM NaCl stress. Results showed that specific rootstock can enhance salt-tolerance potential by increasing pigment content and strengthening the photosystem. PS scions grafted onto CM, C47, X9, N1, and N3 demonstrated greater NaCl tolerance compared to those grafted onto JK, C12, N2, N4, N5, and TC and hence recommended for areas having salinity level up to 60 mM.