Salinity tolerance potential of Citrus (Citrus spp.) rootstock genotypes

In semi-arid ecosystem, salinity is major stress which influences the performance of citrus plants. An experiment was conducted at ICAR-Central Citrus Research Institute, Nagpur, Maharashtra during 2015-18 in containerized nursery to screen 4 hybrids (NRCC 2, NRCC 3, NRCC 6, CRH 12) as well as promising citrus (Citrus spp.) rootstock genotypes (Alemow, Volkamer lemon, Shekwasha mandarin, commercially used Rangpur lime and rough lemon) against salinity stress. Salinity gradient 0-80 mili mole (mM) was developed using salt mixture and found inversely proportional to plant growth parameters and leaf content of most of the nutrients. At highest salinity, commercially used rootstocks were unable to survive. At 80 mM salinity level, decrease in plant height (48.9%) and stock girth (14.8%) was lowest in Shekwasha, while lowest defoliation was observed in Alemow (9.7%) rootstock. Lowest reduction in leaf N and P content was observed in Alemow; Ca in NRCC-6 and Mg in Shekwasha. Substantial reduction in leaf K content (2.6-64.0%) was observed in most of the rootstocks with increasing salinity levels except in Alemow, NRCC-6 and Shekwasha. It was found that the parentage of trifoliate orange in hybrids imparted further sensitivity for salt tolerance. In general, it was observed that Alemow and NRCC-6 rootstocks were least affected by salinity treatments as compared to other citrus rootstocks.