Screening of Citrus Rootstocks for Salt Tolerance under in Vivo Conditions

摘要

Eight months old nucellar seedlings of three citrus rootstocks viz. Rangpur lime (Citrus limoniarnOsbeck), rough lemon (C. jambhiri Lush.) and trifoliate orange (Poncirus trifoliata Raf.) werernscreened for salt tolerance. Cl- dominated and SO4--dominated salinity types were used with five saltrnlevels, viz. control, 2, 4, 6 and 8 dS/m. The experiment was conducted under the screen house forrneight months. Cl- dominated salinity proved more deleterious because the seedling mortalityrnoccurred at a faster pace in this type of salinity. In trifoliate orange maximum mortality occurred asrnnone of the seedlings survived except in control. Mortality in rough lemon started from 4 dS/m,rnwhereas in Rangpur lime, it started after 6 dS/m. All the plant growth characters were affected byrnthe increase in salinity level, but its effect was severe in trifoliate orange followed by rough lemonrnand Rangpur lime. With increase in salinity level, accumulation of Na+ and Cl- increased in aerialrnparts and K+ and Mg++ decreased. Rangpur lime accumulated lesser amount of Na+ and Cl- inrnaerial parts in comparison to other two rootstocks, whereas the reduction for K+ and Mg++ was alsornless in Rangpur lime. Rangpur lime was graded as tolerant, rough lemon as moderately tolerant andrntrifoliate orange as susceptible to salinity. Further, less absorption or accumulation of Na+ and Clandrnlow Na:K ratio in aerial parts was regarded as reliable chemical markers for screening of citrusrnrootstocks for salt tolerance.