Root-pressure driven xylem sap flow in greenhouse melon (Cucumis melo L.): diurnal change and the effects of shading, growth stage, rootstock and fruit number

Grafted and ungrafted greenhouse melon were used to investigate the effect of diurnal change, shading, growth stage, rootstock and fruit numbers on melon xylem sap flow rate. A clear diurnal change was observed in xylem sap flow rate. Shading of the plant on the previous day decreased the sap flow rate. An increase in the number of fruit on a plant decreased the sap flow rate, but, grafting to squash plant lessened the effect of fruit number. Consideration of timing and environmental factors is necessary when the xylem sap is collected for root study.