Effect of Rootstock and Inoculation with Mycorrhizal Fungi on the Growth, Yield, and Fruit Quality of Greenhouse Cucumber in Soilless Culture Conditions

Introduction Cucumber stands out as a vital greenhouse crop. The continuous cultivation of cucumbers within greenhouse environments, aimed at mass production and the delivery of fresh products, inevitably leads to heightened soil salinity and the onset of soil-borne diseases like Fusarium wilt. Consequently, these factors contribute to a decline in both yield and crop quality, underscoring the necessity for research into methods that enhance the yield and quality of greenhouse produce. Grafting cucumber onto various rootstocks and introducing inoculation with mycorrhizal fungi emerge as the most promising strategies for augmenting the yield and quality of greenhouse-grown cucumbers. With this in mind, the current study was undertaken to examine the impact of different rootstocks and mycorrhizal fungi inoculation on the growth and performance of greenhouse cucumbers under soilless culture conditions.   Materials and Methods In order to investigate the effect of the rootstock and inoculation with mycorrhizal fungi on the growth and yield of greenhouse cucumber under the soilless culture conditions, a greenhouse factorial experiment was conducted based on the Complete Randomized Block Design (CRBD) with three replications. The first factor was grafting of cucumber cv Nagene on the Shintoza rootstock, and none-grafting; the second factor was symbiosis with mycorrhizal fungi (Diversispora versiformis) and non mycorrhizal ones. The Nagene greenhouse cucumber cultivar was obtained as a scion from Enza Zaden Company, Netherlands and the desired mycorrhizal fungus was obtained from the Department of Soil Science, Faculty of Agriculture, University of Tabriz. The scion seeds were planted earlier than the rootstocks. After completing the planting operation, the seedling trays were moved to the greenhouse with a sufficient natural light. The substrate used for planting of seedlings was peat moss and perlite in the ratio of 1:2, impregnated with the desired amount of mycorrhizal fungi inoculum. Seedlings got ready for transplanting at the true single leaf stage and two weeks after planting the scion seeds. Transplantation of splice grafting was done on seedlings both mycorrhizal fungi treatments (inoculated and not inoculated). After 10 days of transplanting, the transplanted seedlings (which we already treated with mycorrhiza inoculation) were transferred to the transplant chamber immediately. Grafted and inoculated seedlings with the control ones were transferred into the 10-liter pots with peat moss and perlite in a ratio of 1:2. At the time of transferring ths seedlings inoculated with mycorrhizal fungi to the pot; to ensure root inoculation with mycorrhizal fungi, the inoculum including spores, hyphae and root fragments was added to the 10-liter pot of peat moss and perlite in the amount of 50 grams per pot with the substrate around the roots of greenhouse cucumber seedlings. All the plants  were fertigated with Hoagland nutrient solution with half strength during the growing period. The pH and electrical conductivity (EC) of the nutrient solution were measured daily. At the end of the research, quantitative and qualitative traits were evaluated.   Results and Discussion Results showed that there was a significant differences between the rootstock and colonization with the mycorrhizal fungi regarding the growth, yield and qualitative traits. Plants inoculated with mycorrhizal fungi and grafted on Shintoza showed a better growth parameter, fruit number, and yield than the other treatments. This treatment with 2115.62 g per plant had the highest fruit yield and the non-grafted non-mycorrhizal control plants with 1569.64 g per plant had the lowest fruit yields. Therefore, the fruit yield increased about 34% in comparison to control. Also, the fruit quality characteristics such as antioxidant capacity and soluble solids (TSS) content were higher in the grafted and colonized plants with mycorrhizal fungi. In addition, there was no significant difference between the treatments in term of pH and total phenol of fruit and titrable acidity of the fruit. These effects show the high potential of mycorrhizal fungi and rootstock in uptake of the nutrients, which provide nutrients that are unavailable to the plant with a special mechanism, and thus affect the growth and yield of greenhouse cucumbers. They have an effect that ultimately improve the growth and yield of the produced crop.   Conclusion Based on this experiment results, it can be concluded that the simultaneous application of mycorrhizal fungi and grafting on Shintoza rootstock in the soilless culture using peat moss and perlite as the substrate (2:1) is of one the most efficient techniques to increase the yield and fruit quality of greenhouse cucumbers and therefore it is recommended.