Can grafting affect yield and water use efficiency of melon under different irrigation depths in a semi-arid zone?

The efficient use of water resources in arid and semi-arid regions is very important for sustainable irrigation management. In such areas, proper irrigation management and grafting are considered important water-saving strategies. Therefore, in this study, the effects of grafting on yield and water use efficiency of melon under limited irrigation conditions in Konya in Turkey, which has a semi-arid climate, were determined. The main plot comprised two different plant materials: Dardanos F1 melon cultivar, grafted onto the commercial hybrid TZ148 rootstock in the Cucurbita spp. group, and Dardanos F1 melon variety growing on its own roots (ungrafted). In the sub-plots, including four different irrigation levels (I<inf>100</inf> = 1.00Ep, I<inf>66</inf> = 0.66Ep, I<inf>33</inf> = 0.33Ep, and I<inf>0</inf> = rain-fed), the amounts of cumulative water (EP) evaporated from Class A Pan in 7-day intervals were taken into account. The highest fruit yield (71.2 t ha^–1) was obtained from non-stressed I<inf>100</inf> treatment in the ungrafted plants, and the yield decreased with increasing water stress. The cultivation of melon by grafting it onto the TZ148 rootstock did not increase fruit yield under both full and limited irrigation conditions. Moreover, yields decreased by 5% and 15% in grafted non-stressed treatment I<inf>100</inf> and severe water stress treatment I<inf>33</inf>, respectively. There was no statistically significant difference between the grafted and ungrafted treatments regarding the number of fruits per plant, mean fruit weight, fruit length, width, rind and flesh thickness, soluble solid content (SSC), pH, chroma, and hue values. Furthermore, irrigation water productivity (IWP) was found to be lower in grafted plants compared to ungrafted plants. In other words, grafting did not save water in melon production under both full and deficit irrigations. According to the principal component analysis (PCA), which analyzes the data collectively, the I<inf>66</inf> treatment showed a similar performance to the non-stressed treatment I<inf>100</inf> in terms of yield and fruit quality components. Therefore, it can be concluded that melons could grow on their roots without grafting, allowing 33% of water saving in semi-arid areas. With the treatment I<inf>66</inf>, significant water savings could be achieved for melon production, and larger areas could be irrigated with the available water in semi-arid regions.