The Effect of Different Cucurbit Rootstocks on Some Morphological and Physiological Traits of Cucumber (Cucumis sativus cv. Super Dominus)

Introduction: Cucumber is one of the most important vegetable crops for the local consumption and exportation. The use of grafted vegetable seedlings has been popular in many countries during recent years. Growing fruit-bearing vegetables, chiefly tomato, cucumber and watermelon through grafted seedlings become a widespread practice worldwide. Grafting is a valuable technique to avoid soil-borne diseases, provide biotic and abiotic stress tolerance, enhance nutrient uptake, optimize water use, and increase fruit yield and quality. Vegetable grafting is a new topic in Iran and there are a limited number of studies on grafted vegetable production. However, attention to grafting by researchers has recently increased. Suitable rootstocks should be identified and characterized for the effective utilization of grafting. The rootstock's vigorous root system increases the efficiency of water and nutrient absorption, and may also serve as a source of endogenous plant hormones, thus leading to increased growth and yield in addition to disease control. In the present study, we investigated the response of two Cucurbita sp. and an Iranian melon as rootstocks for cucumber. Materials and methods: In order to study the effect of cucurbit rootstocks and grafting method on growth, yield and fruit quality of cucumber (Cucumis sativus cv. Super Dominus), an experiment was conducted as a factorial design in the base of RCBD with three replications in the greenhouse and research farm, University of Zanjan. Treatments were included three rootstocks (Cucurbita moschata L., Lagenaria siceraria and Cucumis melo L.) and ungrafted plants (control) and two grafting method (hole insertion and splice grafting). Seeds were sown simultaneously in plastic pots. For obtaining the same stem diameter of scion and rootstocks, cucumber seeds were planted four days earlier than rootstocks seeds. The seedlings were grown in an environment-controlled greenhouse with 25/20 day/night temperatures. When seedlings reached the first true leaf stage (diameter of the leaf was about 2 cm) the grafting was performed. After grafting, grafted plants were transferred to a mist chamber for post-graft care (>95% RH, 27-30 °C) for 10 days, after which the relative humidity was reduced gradually for acclimatization. After 20 days of grafting, surviving grafted plants and ungrafted plants were transplanted to the field. Common agricultural practices like fertilizer application, insects and disease control were adopted. Vegetative growth, yield and fruit quality were measured. Data were analyzed using the SAS statistical program (SAS Institute Inc., Cary, NC, USA), and means were compared by Duncan’s multiple range tests at the 5% probability level. Results and Discussion : The result showed that rootstocks had a significant effect on growth indexes. Cucumber was grafted on cucurbita moschata L. rootstock had the highest stem length and leaf numbers, while, the lowest values of plant height, leaf area, leaf number and yield were recorded with grafted plant on melon rootstock. Fruit numbers were significantly influenced by rootstock. The highest fruit number per plant was observed in cucumber plants that were grafted on cucurbita moschata rootstock. The results of the study showed that cucumber grafting on suitable rootstocks had positive effects on the yield. But rootstock had no significant effects on fruit quality like flesh firmness and total soluble solid. The Soluble solid content of fruit was reported to decrease in tomato, cucumber and eggplant due to grafting. chlorophyll content of leaf showed significantly different between grafted and non-grafted plants. The highest amount of leaf area was obtained from non-grafted plants. Grafting methods had no significant difference in growth, yield and fruit quality. Nitrogen and potassium leaf contents of grafted cucumber and ungrafted plants had no significant difference. The interaction between rootstocks and grafting method had no significant effect on yield and the other growth indexes. Conclusion: Our findings showed that vegetative growth and yield of cucumber were affected by grafting. On the basis of these results, Cucurbita moschata rootstock had the highest effect on growth and yield of cucumber. It may also be concluded that the grafting method had relatively same growth response. Although the cost of a grafted seedling is surely one of the main concerns of growers, especially since grafted seedling costs from three to five times more than non-grafted seedling. However, investigation proved that, on-farm grafted cucumber transplant production can be successful and the results indicate that grafting of cucumber onto cucurbit rootstocks can increase on-farm net returns due to improve growth and yield