Effect of rootstock on growth, fruit production and quality of tomato plants grown under low temperature and light conditions

Abstract

We compared the growth of tomato plants ‘Jack’ grafted onto nine rootstocks with that of self-grafted and non-grafted plants, all grown in soilless culture in a heated greenhouse, to assess the capacity of commercial tomato rootstocks to improve fruit production and quality during the winter period under conditions of low temperature and light intensity. Neither vegetative development, estimated by the plastochron index, nor the thermal time required for a plastochron variation of one unit was significantly affected by the rootstock genotypes. Furthermore, the rootstock genotype did not mitigate the negative effects of low temperature and light conditions on fruit production. By contrast, the effect of the rootstock on the chemical composition of fruits and leaves was reflected by different allocation of N and C. Thus, the rootstocks affected the N contents of fruits and leaves and the C contents of fruits, but did not generally affect leaf C contents. The C/N ratios and mineral contents of fruits and leaves of grafted plants tended to decrease, leading to lower construction costs than in non-grafted or self-grafted plants. Thus, the use of rootstock reduced the energy needed to construct one unit of dry mass. Although the rootstock genotype did not affect fruit juiciness, titratable acidity (TA) or juice pH, it greatly influenced fruit quality parameters such as soluble solid content (SSC), SSC/TA ratio, juice electrical conductivity, ash contents, dry weight, firmness and puree consistency. Under the experimental conditions and in comparison with non-grafted and self-grafted plants, almost all rootstocks tended to be detrimental to the quality parameters considered.