Relative tolerance of Japanese apple (Malus spp.) rootstock strains to NaCl stress
Salt stress is a serious problem in arid as well as cultivated lands, especially in some Asian countries including Japan, because these countries sometimes suffer from seawater damage by typhoons and tsunamis. In recent decades, Japanese apple growers have used new kinds of dwarfing rootstock cultivars called JM and Aodai strains; however, there is no information regarding the salt tolerance of these new rootstocks. In this study, we compared the salt tolerance (at 0, 50, 100, and 150 mM NaCl) of 5 rootstock cultivars to reveal their tolerance levels. JM2 indicated high salt tolerance with only limited leaf injury even under 150 mM NaCl. In contrast, JM1 and Malus pruniforia (M. p.) demonstrated low salt tolerance with a high leaf injury index at 150 mM NaCl. Aodai3 and JM7 showed moderate tolerance to salt stress based on the leaf injury index. JM2 exhibited less accumulation of Na and Cl ions in leaves at 150 mM NaCl and suffered less osmotic stress. Moreover, JM2 indicated non-vigorous shoot growth with NaCl treatment but maintained both trunk and structural root growth. Comprehensively, considering other parameters, such as root activity and leaf water potential, we recommend JM2 as a salt stress tolerant rootstock suitable for the Asian apple industry.
Matsumoto, K. and Kobayashi, T. (2020). Relative tolerance of Japanese apple (Malus spp.) rootstock strains to NaCl stress. Acta Hortic. 1289, 9-18
ionic stress, leaf injury, osmotic stress, salinity, tsunami