Oxygation Improves Yield and Quality and Minimizes Internal Fruit Crack of Cucurbits on a Heavy Clay Soil in the Semi-arid Tropics

This study evaluated the effects of aerated irrigation water (oxygation) with subsurface drip irrigation, employing an in-line air injector (Mazzei venturi to introduce 12% air by volume of water) on yield, fruit quality and water use efficiency of watermelon (Citrullus vulgaris) and pumpkin (Cucurbita maxima) in a heavy clay soil. The fruit yield with oxygation increased from 14.5 t ha-1 to 24.6 t ha-1, and 26.3 t ha-1 to 28.9 t ha-1, for watermelon and pumpkin, respectively. The total soluble solids (ºBrix) increased by 19% with oxygation (13.2 vs. 11.1%), and internal fruit crack decreased for watermelon, whereas fruit dry matter increased by 4% (40 vs. 38.4%) and ºBrix by 7% (13.7 vs. 12.8%) in pumpkin. Season long water use efficiency was greater with oxygation compared to the control. The higher yield with oxygation was associated with a more rapid canopy cover, more leaf chlorophyll, and an increase in leaf photosynthetic rate, and leaf transpiration and increase in fruit number and size.