Grafting as a Tool to Improve TYLCV-Tolerance in Tomato
The purpose of this study was to investigate possible positive effects of grafting and use of different TYLCV-resistant rootstocks on the tolerance/resistance level and tomato fruit yield and quality. Tomato cvs used as scions were TYLCV-susceptible cv. Castlerock and TYLCV-tolerant hybrid cv. TH99806 (Nirouz). The rootstocks were TYLCV-resistant accessions Solanum chilense LA2779, S. habrochaites LA1777 and S. pennellii LA716 and TYLCV-susceptible S. lycopersicum CGN14330 cv. Moneymaker. Cleft grafting method was applied. The following characteristics of grafted and non-grafted plants were recorded: TYLCV mean score, number of days to symptoms appearance, fruit set percentage, average fruit weight, early and total yield, fruit contents of TSS, vitamin C and titratable acidity and pH value. Results showed that grafting increased TYLCV tolerance in susceptible plants, expressed as delay in the appearance of TYLCV symptoms and an increase of yield components compared to non-grafted plants. Grafting TYLCV-tolerant scion 'TH99806' onto wild species S. chilense, S. habrochaites and S. pennellii remarkably lowered early and total yield in comparison to grafting onto other rootstocks due to a reduction in fruit set percentage. The related species S. pimpinellfolium is considered a suitable tolerant rootstock for tomato grafting to improve TYLCV-tolerance, fruit yield and quality.