Use of floating row cover on summer squash (Cucurbita pepo var. melopepo) in Agadir area

Summer squash (Cucurbita pepo var. melopepo) was seeded in november 15th, 1991 and transplanted in the open field, in december 11th, 1991, on sandy loam soillocated at 17 km south-est of Agadir. Trials are composed of four treatments: a black plastic mulch, two types offloating row cover and a control. These floating covers were put on crops just after tranplanting and put out the 15th of March 1992. Minimal and maximal air temperatures in the floating covers were higher than those of the control respectively by 0.5 to 2°C and 1.4 to 8.5°C. However soil temperatures, at 10 cm depth, were higher by 0.5 to 105°C and by 0.5 to 1°C respectively under floating covers and plastic mulch. Compared to the control, an increase by 30, 145 and 161% in the total commercial yield, was obtained respectively in plastic mulch treatment, in perforated polyethylene cover and in polyester spunbonded cover. Harvest under plastic mulch and floating covers started respectively 12 and 16 days earlier than in the control. 90 days aftertransplanting 100% ofthe control and plastic mulch treatments plants were infected byviruses, however plants grown under floating covers didn't show any virus disease symptoms.