Physiological Efficiency of Grafted Cucumbers based on Rootstock Type, Root Zone Temperature and Nitrogen Levels

To evaluate the commercial and local cucumber rootstocks in grafting conditions at different nitrogen (N) levels and temperatures of the rootzone, this research was conducted for a year in the Research Greenhouse of the Department of Horticulture, College of Agriculture, Isfahan University of Technology in 2014. The research was a factorial experiment based on completely randomized design with 3 replications, three N treatments (100% N in Johnson solution (10.11 mM) as control, 75% N in Johnson solution (7.582 mM) and 50% N in Johnson solution (5.055 mM)), two temperatures (15 °C as low temperature in the root zone and 25 °C as optimum root zone temperature) with different rootstocks including Cucurbita Lagenaria siceraria (Rls), Cucurbita moschata cv. Ferro (Rcf), Cucurbita moschata cv. Babol (Rsb), Cucurbita moschata cv. Sari (Rcm), Cucumis sativus cv. Isfahan (Res) and Cucumis sativus cv. DavosII (Rn) as control. Results showed that the highest fresh weight of the shoots and roots and roots dry weight belonged to the Rls, and the Rcm rootstock had the highest dry weight of the shoots. The effect of root zone temperature stress on shoot growth was more than N stress and caused a greater reduction in shoots fresh and dry weight. The effect of low rootzone temperature, compared to N stress, had greater effect on the photosynthesis of Rcm, Rls, Res and Rn rootstocks. It seems that Rcm and Rls had better ability in maintaining of cucumber growth under N stress than temperature stress. The Rcf maintained the best growth conditions in low root zone temperature. In general, comparing the two stresses, (N and low temperature stress in grafting, in growth regulation), different levels of N were more effective than temperature stress