Effect of Salt stress on growth, physiological and biochemical characters of Four kiwifruit genotypes

Salt stress negatively impacted growth and physiological processes in plants, and the effects involved oxidative damages within cell and cell organelles. In this study, four different genotypes (CG, KM, XX, and ZM-H) of Actinidia germplasm resources were exposed to CK, 0.3 %, and 0.6 % NaCl concentrations for 15 days. We measured the growth, physiological and biochemical indicators in leaves, shoots, and roots. The relative lateral branch length (RLBL), plant fresh weight (PFW), plant dry weight (PDW), and plant relative water contents (PRWC) were decreased in all genotypes under salinity stress. Whereas, the Salt damage index (SDI, sodium ions (Na+) and chloride ions (Cl-) increased in all kiwifruit genotypes under high salt conditions. On the contrary, the potassium ion (K+) and K+/Na+ ratio was decreased in all genotypes under higher salt conditions. For organic osmolytes, Proline increased and total soluble sugars (TSS) decreased in all genotypes under high salt. The enzymatic activities of APX, GST, and GR were increased in all kiwifruit genotypes when subjected to higher levels of NaCl stress. The salt tolerance of different kiwifruit genotypes was assessed by principal component analysis (PCA), and the order of salt tolerance was as following: ZM-H > CG > XX > KM. Hence, the ZM-H from A. valvata Dunn. possessed strong tolerance against salt stress and could be an important germplasm resource for the salt tolerance rootstock breeding program of kiwifruit.