Effect of rootstock on salinity tolerance of sweet almond (cv. Mazzetto)

• The different strategies to overcome salinity of Mazzetto depend on rootstocks.
• The improved crop performance of grafted Mazzetto was attributed to grafting on GN15 more than grafting on GF677.
• The higher antioxidant mechanisms in M/GN15 improve salt tolerance more than M/GF677.

The current work aims to assess whether the rootstock can improve the salinity tolerance of an almond cultivar. The study included a description of the physiological and biochemical adaptations of one-year old scions of Mazzetto grafted onto either GF677 or Garnem rootstocks and exposed to increasing concentrations of NaCl in the growing medium. The plants were watered with a nutrient solution containing 0 mM (control), 25 mM, 50 mM or 75 mM NaCl. There was a significant reduction in shoot extension in response to increasing NaCl concentration in the growing medium especially in the plants grafted onto GF677. The better shoot growth of Mazzetto/Garnem plants appears to be due to their ability to limit the loss of photosynthetic activity by maintaining stomatal conductance and protecting chlorophyll and cytosolic assimilatory enzymes from toxic ions. Leaves of Mazzeto/Garnem had higher gs rates, carotenoids/chlorophyll and anthocyanins/chlorophyll ratios and a better nutritional status (higher K+ and Ca2 + and lower Na+) compared to Mazzeto/GF677. Furthermore, the former maintained higher proline and soluble sugar concentrations and lower leaf water potential. Our results suggest that Garnem offers a degree of protection against salinity which can be exploited in breeding programmes.