Abstract: Plants of muskmelon variety "Calypso" were used as scion and non grafted control while two hybrids (Cucurbita maxima x Cucurbita mushata), TZ148 and Ferro as rootstocks. Grafted and non-grafted plants were grown under a monotunnel heated and irrigated by geothermic water in the South of Tunisia. Plants were grown in soilless culture on sand and compost. This trial has revealed that, on sand as well as on compost, grafted plants were more vigorous than self-rooted ones. This vigor was highlighted by values of length and volume of roots, plant height, stem diameter, leaf area and fresh and dry matter of leaves. Indexes of growth represented by LAI, SLA, RGR and NAR were strongly improved by grafting particularly by TZ148. This improvement implied a hasty vegetative growth. Moreover, precocity of production was greater for grafted plants. In addition to their early production, grafted plants produced more fruits on sand and compost. The average weight of fruits was enhanced, too, by this agricultural practice. Thus, the major part of fruits produced by grafted plants had a weight superior to 600g.