Morphological and Physiological Evaluations of Grafted Tomato Plants in Response to Salinity Stress

Salinity is one of the most limiting factors that adversely affects growth and yield of vegetable crops. The capacity of plants to tolerate high levels of salinity depends on the ability to exclude salt from the root or sequester salt in vacuoles to tolerate high concentrations of salt in cytoplasm. The salt tolerance of vegetable crops are highly desirable as many high value vegetable crops including tomato are particularly susceptible to salinity stress. Grafting has been demonstrated as a useful, promising approach to cope with abiotic and biotic stresses in tomato. The objective of this study was to enhance the salinity tolerance of susceptible tomato genotype by grafting onto a salt-resistant rootstock. Three-week old tomato seedlings of two tomato genotypes, LA (salt-tolerant) and CA (salt-sensitive), were subjected to grafting treatments, i.e., non-graft and self-graft controls and reciprocal-graft. Plants were grown in a 1:1 (v/v) perlite and vermiculite mixture and received a modified Hoagland’s nutrient solution containing either 0 or 100mM NaCl. Salinity reduced morphological parameters of tomato plants in all the treatments, including plant height, the number of leaves, leaf area, leaf length, days to flowering, biomass and root characteristics. However, these reductions were less prominent in tomato plant grafted onto a LA rootstock. Likewise, the Fv/Fm values of young fully expanded leaves were maintained higher when grafted onto a LA rootstock compared to other grafting treatments, where gradual reductions of the values were observed. It is concluded that adverse effects of salinity on tomato plants can be alleviated by grafting sensitive tomato genotype onto a resistant rootstock.