Effect of Grafting and Water Stress on Yield, and Morpho-Physiological Root Properties of Greenhouse Cucumber

 Cucumber is one of the important greenhouse vegetables in Iran and the world. This product, in Iran, has the largest area under cultivation in comparison with other greenhouse vegetables, and according to the statistic in 2020, the Office of herbs, vegetables and ornamental plants Ministry of Agriculture, the greenhouse cucumbers area under cultivation in Iran is 15000 ha. Cucumber is the product of warm and temperate season (with mild winters) and is very sensitive to adverse environmental conditions and even rare changes in soil moisture content will have a significant adverse effect on its growth and yield. Cucumber root is shallow, it is fibrous, and its shallow root causes its sensitivity to drought so that its main root penetrates 5–10 cm in heavy soil and 20-30 cm in light soils. This plant has an extensive and almost thin root system that has the possibility of expansion in a wide range horizontally, and, therefore, it can produce mass root, at the depth of 30 cm. In order to study the effect of grafting and water stress on morphological characteristics greenhouse cucumber (Cucumis sativus L), an experiment was conducted as complete randomized block design with three replications.
 This research has been carried out in the city of Pars-Abad, Ardabil province, Iran. The longitude of Pars-Abad is 47°55ʹ E, latitude is 39°38ʹ N, and its height distance sea level is 32 meters. This research was done in the greenhouse of the Moghan Agriculture and Natural Resources Faculty in a complete randomized block arranged in split plot with three replications. To determine the characteristic curve of soil moisture, soil samples was selected and the weight moisture percentage at pressures of -0.3, -5, -10 and -15 bar, which include the important potential of the soil, was determined by using Pressure plate’s apparatus and soil moisture characteristic curve was mapped and soil parameters characteristic curve was determined. this study, the main factor included water stress in three levels of 90, 60 and 40% field capacity and the secondary factor included three rootstocks of Shintoza cucurbits (Cucurbita moschata × Cucurbita maxima), Flexi Fort cucurbits (Cucurbita moschata × Cucurbita maxima, cucumber varieties Nagen 972 (Cucumis sativus L.) self-grafted and check (ungrafted) cucumber varieties Nagen was studied as a scion. In this study, the grafting method of hole insertion was used as the best grafting method for Cucurbitaceous.
 Duncan test results showed that with increasing stress, the diameter of the main root, at the rootstocks of Shintoza and Flexi Fort, increased almost twice as much as the control. The results showed an approximately 3 times increase in the yield, at the rootstocks of cucurbits at different levels of stress and it had a significant positive relationship at 1% level with the length, diameter and weight of root. The highest yield related to the Flexi Fort rootstocks was obtained 2.99 kg per plant in the water stress condition 90% of field capacity and then Shintoza rootstocks ranked second with 2.617 kg per plant, at 60% water stress. The maximum water use efficiency related to Shintoza rootstocks was at 32% and Flexi Fort rootstocks, Nagen and control, were respectively 30, 22 and 36% of Potential evapotranspiration.
 The results showed that, with increasing water stress, unlike the control, which was associated with decreasing linear trend of yield, Treatments with cucurbits grafting at Shintoza and Flexi Fort rootstock, faced with increased water stress, from 40 % to 90 % of field capacity by minor reducing of product. This can be due to increasing root uptake parameters such as length, weight and length of the main root in these Treatments. Correlation analysis showed a significant relationship at **P<0.01 level between a percentage of roots and yield. The results in all applied water stress also showed a high yield of grafted treatments about three times more than the control. Reducing the yield sensitivity factor in cucurbits Treatments, causes the plant could maintain its performance in irregular watering that encounter the plant with tension. The high water use efficiency in cucurbits Treatments shows that it is possible to perform economic optimization in the production based on water consumption scarcity of water.