The Effect of Chilling and High-Temperature Stresses on the Growth and Physiological Changes of Grafted Cucumber in Iranian Endemic Squash and Cucumbers

To study the effect of grafting on the tolerance of chilling and high temperature, the grafting of Super daminos was done on Cucurbita moschata (Isfahan), (Babol), (Ferro), (Sari) rootstocks and then compared with non-grafted and self-grafted ones as a factorial experiment based on completely randomized design with three treatments. Temperature treatments were optimum temperature (25 °C), low temperature (4 °C) and high temperature (40 °C), with four replicates. The results showed that root length, root volume, rootstock diameter, and fresh and dry weights of shoot were increased in all rootstocks, as compared with the non-grafted ones. The highest fresh and dry weights of the shoot were observed in Sari and Isfahan rootstocks, and the highest dry weight was observed in Ferro rootstock. The interactive effect showed that the highest fresh and dry weights were measured in Isfahan rootstock and at the optimum temperature; meanwhile, the lowest fresh and dry weights were observed in non-grafted one and at the high temperature. Moreover, the highest dry weight was determined at both low and high temperatures in the non-grafted sample. The highest photosynthesis rate was recorded in Babol rootstock and at the optimum temperature, while the lowest one was observed in Babol rootstock and at the high temperature. The interactive effect of rootstock and temperature showed that the highest stomatal resistance and transpiration rate were measured in the non-grafted sample and at the optimum temperature, while the lowest one was recorded in Isfahan rootstock and the optimum temperature; meanwhile, the lowest transpiration rate was observed in Sari rootstock and high temperature. Therefore, the use of Ferro and Babol rootstock for their resistances to high and low temperatures could be recommended. It seems, therefore, that these rootstocks by maintaining photosynthesis rate and chlorophyll and lowering transpiration rate, can decrease the deleterious effect of temperature on growth.