Extended Abstract
1.      Introduction: Cucumber (Cucumis sativus L.) is a highly significant vegetable cultivated worldwide. Cucumber belongs to the Cucurbitaceae family and is the third most significant vegetable cultivated globally, following tomatoes and onions. It also has a significant role in the Iranian food basket. The cultivation of various vegetables, including cucumber, is encountering challenges such as harm inflicted by numerous soil-borne fungal diseases and adverse environmental conditions like drought and salinity. However, by grafting cucumber onto appropriate rootstocks, these issues can effectively be mitigated or entirely overcome. Grafting in herbaceous vegetables is a distinctive technique where a commercially viable scion is fused with a compatible rootstock to address both biotic and abiotic challenges in production. This study examines the impact of certain rootstocks on the yield and morphological characteristics of cucumber.
2.      Materials and Methods: To assess the impact of different rootstocks on cucumber yield and morphological characteristics, we used a commercial cultivar, ‘Monza’ as the scion, which was grafted onto three different commercial rootstocks, including ‘Marvel’ (an inter-specific squash), ‘Sentinel’ (a melon type), and a bottle gourd line. The experiment was conducted from November 2019 to August 2020 in a greenhouse located at the Department of Horticultural Sciences, Campus of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. After sowing seeds of both rootstocks and scion, plants were grafted, and for healing grafted plants, they placed them in a grafting room with controlled conditions for humidity (100% RH) and temperature. Grafted plants are held in the grafting room for one week to allow the union of the grafted area, and then, the grafted plants are moved out of the grafting room. Transplants obtained through grafting were hydroponically grown under greenhouse conditions, and the experiment was run based on a randomized complete block design. Growing media was cocopeat and perlite with a 1:1 ratio and filled in pots. Several traits were measured, including yield, fruit juice total soluble solids (TSS), fruit juice pH, number of fruits per plant, mean fruit weight, fruit dry matter percentage, stem length, fresh and dry weights of roots, shoots, stems, leaves, and total fresh and dry weights. In addition, the dry-to-fresh weight ratio was determined for all plant organs, including roots, shoots, stems, and leaves, as well as the ratio of total dry weight of plants to fresh weight.
3.      Results and Discussion: The findings indicated that the self-grafted plants had the highest yield, followed by the non-grafted plants (10331.6 and 10038.1 g/plant, respectively), with no significant difference. The lowest yield was observed in the Setinel rootstock (6686.5 g/plant). Highest yield obtained from Marvel and Bottle gourd rootstocks ( 7760.1 and7693 g/plant, respectively). All rootstocks exhibited lower yield (p<0.01) compared to the self-grafted and non-grafted control groups. The bottle gourd had the highest total soluble solids (TSS) content at 4.12%, while the Marvel had the lowest TSS content at 3.8%. Both rootstocks showed a significant difference compared to the self-grafted and non-grafted controls. The maximum stem length achieved through self-grafting control was 12.69m, followed by plants grafted on Marvel rootstock, while the minimum stem length obtained from the Sentinel group was 8.88cm, which was significantly lower than both the self-grafted and non-grafted control groups. The maximum stem length between rootstocks obtained from the Marvel variety is 12.04cm, which did not show a significant difference compared to the self-grafted and non-grafted controls. The Marvel rootstock yielded the highest fresh and dry root weight compared to all other treatments (p<0.01). No significant difference was observed between the pH of fruit juice in any of the grafted and non-grafted plants.
4.      Conclusion: The interaction between the scion and rootstock yields varying outcomes in grafted plants. The level of compatibility between the scion and rootstock can significantly impact the physiological and morphological characteristics of the grafted plant. The results obtained indicate that ‘Marvel’ and bottle gourd rootstocks were the most compatible with ‘Monza’. On the other hand, the lowest compatibility was observed with the ‘Sentinel’ rootstock, which had the lowest measured indexes in terms of yield, stem length, fresh and dry weight of shoot, root, leaves, and total fresh and dry weight. Further experimentation with altered nutrition and cultivation conditions is necessary to assess the capabilities of rootstocks under various cultivation conditions and enhance the yield and quality of the crop.