Effects of grafting on growth, root morphology and leaf physiology of pepino (Solanum muricatum Ait.) as affected by salt stress under hydroponic conditions

In this study, grafted and ungrafted pepino (Solanum muricatum Ait.) plants were tested under different salineconditions. The nutrient solution experiment was conducted within October – November 2016, by employing thetechnique of Deep-Water Culture (DWC) in an entirely operated automatically climate chamber found in the PlantPhysiology Laboratory of Erciyes University, Agriculture Faculty, Kayseri, Turkey. Plants were examined underthree various salt levels (i.e., 1 dS m-1, 4 dS m-1 and 8 dS m-1) by growing them in a 8 liter pots loaded constantlyin an aerated Hoagland solution. The study was organized with completely randomized block design through threerepetitions. The climate chamber study was performed to investigate effects of salt stress on plant growth, shoot- rootfresh- dry weights, photosynthesis, leaf area formation, chlorophyll content of leaf (SPAD), leaf and root electrolyteleakage, total length of root, volume of root, and diameter of root in grafted and ungrafted pepino plants. Theresults showed that shoot growth, root morphological and leaf physiological responses were considerably (p<0.001)influenced by various levels of salt conditions at the nutrient solution. Increased salt level of the nutrient solutiondecreased significantly root and shoot growth, area of leaf, photosynthetic activity of both grafted and ungraftedplants. Irrespective of being grafted, significant declines were observed in shoot fresh weight (23.6%, 52.1%), rootfresh weight (24.8%, 52.8%), leaf area (21.3%, 51.9%), shoot dry weight (24.3%, 53.0%), root dry weight (15.4%,45.1%), SPAD (5.7%, 18.7%), photosynthesis rate (24.6%, 42.1%), total root length (6.7%, 16.4%), and root volume(3.8%, 5.8%) of pepino plants under 4 dS m-1 salt applications and 8 dS m-1 salt applications, respectively. Graftingpromoted growth of plant in pepino plants under both control and saline conditions, furthermore it was noticedthat under saline conditions biomass production of both grafted and ungrafted ones were significantly depressed.Grafted plants produced 54.1%, 43.0% and 9.6% higher shoot fresh weight; 52.0%, 42.0% and 12.8% higher rootfresh weight; 52.5%, 40.7% and 8.7% higher leaf area; 60.0%, 46.6% and 11.1% higher shoot dry weight; 68.8%,36.0% and 29.3% higher root dry weight; 19.9%, 9.2% and 8.2% higher SPAD; 8.0%, 5.1% and 10.8% higherphotosynthesis rate; 8.6%, 3.6% and 6.6% higher total root length; 3.1%, 6.7% and 2.4% higher root volume thanungrafted plants under 1 dS m-1, 4 dS m-1 and 8 dS m-1 salt applications, correspondingly. Overall, our study showedthat the effectiveness of grafting with respect to expansion of plants growth and development under salinity. Graftingwas demonstrated to be an effective mean to achieve this goal.