Watermelon (Citrullus Lanatus) is one of the major irrigated vegetables in the Jordan Valley. Watermelon production has increased in the last few years with the introduction of trickle irrigation and plastic mulching, especially in the highlands. In this experiment it is intended to study the effects of different plastic mulching on crop water use and on yields of watermelon. Soil temperature data was also collected in an attempt to study its fluctuation and degree of change under different mulching. Also studied were the root density and distribution. Results indicate significant differences in water applied and in yields between treatments. Highest yield (average = 55.3 MT/HA) was obtained under transparent mulch and with average total water supply of 44.3 cm. Whereas under black mulch an average yield of 13.3 MT/HA was obtained although 40.1 cm total water was applied. Under no mulch, only 10.4 MT/HA was obtained with a highest total water supply of 51.2 cm. Root distribution and density did not show any significant differences. Soil temperature under mulched treatments were higher than those non‐mulched. Heat units determined showed no big difference between transparent and black mulched treatments.

An experiment with squash (Cucurbita pepo L.) was conducted at the University of Jordan Research Station, located in the Jordan Valley in Jordan during the 1984 and 1985/86 seasons. Its objectives were to determine the effects of different plastic mulch using drip irrigation on soil temperature, root growth distribution, and production dates, Earliness in picking dates under mulch was obtained during the relatively warm 1985/86 season, where picking started 13 days earlier under mulch. Root weights, secondary root lengths, and horizontal root distribution were not significantly different between treatments, during each season. Tap roots were not significantly different between treatments during the 1984 season, yet those under transparent mulch were significantly higher (5% level) from those under bare soil conditions, during the 1985/86 season. Density of plant canopy influenced mulching effect on soil temperature. High plant canopy under mulch prevented solar radiation from increasing soil temperature. Whereas, higher soil temperature was obtained under non‐mulched conditions when compared to the mulched ones. This was most probably due to relatively low vegetative cover.

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The effects of different plastic mulching using drip irrigation on yields, soil temperature, crop water requirements, and root density and distribution were determined for muskmelon (Cucumis melo L.) at the Jordan Valley Research Station, Jordan. There were no significant differences among transparent, black, and nonmulched treatments with respect to irrigation amounts, soil moisture depletion, total water supplied, deep percolation losses, and vapotranspiration. Root weights, density, and distribution, horizontally and vertically, were not significantly different among treatments. Transparent mulch treatment yields averaged 14.2 t·ha-1 and were significantly lower (5% level) than average yields (28.7 t·ha-1) of the black mulch treatments. Nonmulched treatment yields averaged 6.0 t·ha-1 and were significantly different from the average transparent mulch (5% level) and from black mulch (1% level). This difference in yield may be attributed to the fact that black mulch treatments received more irrigations than transparent mulch and bare ones. Calculations of expected potential evapotranspiration for muskmelon during the season showed that the plants did not receive their water requirements.

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