Abstract
The tomato is an important horticultural crop, the cultivation of which is often under influence of abiotic and biotic stressors. Grafting is a technique used to alleviate these problems. Shortage of water has stimulated the introduction of new irrigation methods: deficit irrigation (DI) and partial root-zone drying (PRD). This study was conducted in two spring–summer season experiments to evaluate the effects of three irrigation regimes: full irrigation (FI), PRD and DI on vegetative growth, leaf gas-exchange parameters, yield, water-use efficiency (WUE), nutrients profile and fruit quality of grafted tomatoes. In both years, the commercial rootstocks Emperador and Maxifort were used. In the first year, the scion cultivar Clarabella was grown on one stem and in the second year the cultivar Attiya was grown on two stems. Self-grafted cultivars were grown as a control. In both experiments, higher vegetative traits (leaf area and number, height, shoot biomass) were recorded in tthe plants grafted on commercial rootstocks. The stomatal conductance and transpiration rate were higher under FI. Under DI, transpiration was lowest and photosynthetic WUE was highest. Photosynthetic rate changed between irrigation treatments depending on plant type. In both years, the total yield was highest in grafted plants as result of more and bigger fruits per plant. In the 2nd year, grafted plants under FI had higher yield compared to PRD, but not to DI, while self-grafted plants did not differ between irrigation treatments. WUE was highest in DI and PRD treatments and in grafted plants. Leaf N, P, K and Ca was highest in tthe plants grafted on Emperador and Maxifort, while more Mg was measured in self-grafted plants. More Ca and Mg were recorded in tthe plants under DI and PRD. Fruit mineral concentrations were higher in tthe plants grafted on commercial rootstocks. Total soluble solids differed between irrigation regarding plant types, while fruit total acidity was higher in Emperador and Maxifort. In conclusion, our study showed that grafted plants could be grown under DI with minor yield reduction with 30–40% less water used for irrigation. Moderate DI could be used before PRD for cultivation of grafted tomato and double stemmed plants did not show negative effect on tomato yield so it can be used as standard under reduced irrigation.
Highlights
The tomato (Solanum lycopersicum L.) is a leading vegetable and one of the most important horticultural crops
We evaluated growth, gas-exchange parameters, yield, water-use efficiency (WUE) and leaf mineral concentrations and fruit quality of self-grafted and tomato grafted on two commercial rootstocks cultivated in greenhouses in Mediterranean climate under three irrigation techniques: full irrigation (FI), deficit irrigation (DI) and partial root-zone drying (PRD)
These studies for the first time demonstrates the effects of parallel usage of different reduced irrigation techniques on grafted tomato vegetative and generative traits
Summary
The tomato (Solanum lycopersicum L.) is a leading vegetable and one of the most important horticultural crops. The world production of tomatoes is second to only potatoes, with an estimated production of 160 million tons [1]. Tomato production problems with abiotic and biotic stressors as Agronomy 2020, 10, 1297; doi:10.3390/agronomy10091297 www.mdpi.com/journal/agronomy. Agronomy 2020, 10, 1297 results of intensive monoculture often create problems in tomato production. Tomato production losses caused by unfavorable growing conditions can be reduced by grafting onto specific rootstocks. Commercial vegetable grafting started at the beginning of the 20th century, with the primary intention to achieve tolerance to soil pathogens [2]. The widespread use of grafting was expected to improve crop response to water, salt, nutrient deficiency and temperatures stresses and to improve fruit quality [4,5]
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