CHILLING INJURY AND YIELD OF MUSKMELON GROWN WITH PLASTIC MULCHES, ROWCOVERS, AND THERMAL WATER TUBES

Combinations of mulch/rowcover systems were tested using 'Earligold' m elon (Cucumis melo L.) transplanted between 7 and 9 May during each of 3 years. The mulches used were black (B), wavelength-selective green (G), or clear (C), In 1993 and 1994, these three mulches were combined with two rowcover systems, either a clear perforated polyethylene (PO ; 500 holes/m(2)) or a clear nonperforated polyethylene with a water-f illed tube (UT, thermal tube). Controls consisted of mulch-alone treat ments. In 1995, only the green wavelength-selective mulch was tested. A clear mulch combined with an infrared-blocking polyethylene with a t hermal tube (IT) and a spunbonded polypropylene agrotextile (AO) were also tested. The highest air temperatures, sometimes >40 degrees C, we re recorded under the CIT and BUT treatments. Perforated tunnels were less efficient in increasing daytime air temperatures, particularly du ring windy conditions, than the nonperforated tunnels. when combined w ith all tunnel types, the wavelength-selective mulch produced effects intermediate between those of the clear and black mulches for air and soil temperatures, chilling injury, and days to flowering of perfect f lowers. In 1994, only those plants grown with a clear mulch combined w ith an infrared-blocking or standard nonperforated tunnel with a therm al tube (CIT and CUT) survived seven sequential nights with temperatur es between 1.6 and 5.8 degrees C. Plants in the nonperforated tunnels flowered first, had the heaviest biomass at anthesis, and gave the hig hest early yields, both in terms of fruit number and mass. However, to tal yields did not differ significantly between perforated and nonperf orated tunnels. Plants produced smaller fruits in treatments that resu lted in earlier flowering, i.e., nonperforated tunnels.