The type of polyethylene mulch impacts vegetative growth, yield, and aphid populations in watermelon production

摘要

Polyethylene (PE) films are widely applied as mulches by commercial producers of watermelon. During the last decade the industry has developed a variety of new mulch PE film formulations with numerous positive effects on watermelon production. In order to define the influence of mulching on growth and yield of watermelon and on aphid populations landing in the crop, we carried out field experiments at two locations (Pula and Opuzen) in the Mediterranean part of Croatia. Watermelon was grown on black, brown, clear, green, and white PE films. During the first 60 days after planting (DAP) the highest soil temperatures, at 5 cm depth, were recorded under the clear PE film, Positive correlation of vine length, branch number and early and total yield was found to both sum and average soil temperatures during the first 60 DAP in three of the total of five experiments. Clear PE films had generally positive effects on vegetative growth and early yield while the trend for white PE films was quite the opposite. For the majority of the observed traits we found no difference between semi-transparent (brown and green) mulches. The effects of semi-transparent films (brown and green) on watermelon vegetative growth and yield were similar to each other. During two years in Opuzen, we recorded 70 species of Aphididae of 48 genera, with 11 species making up more than 1% in each year. Toxoptera aurantii (Boyer de Fonscolombe) and Aphis gossypii Glover were the most dominant species in 2004. The number of winged aphids was consistently lower under clear and black PE films. According to our results, clear PE film could be recommended for an early spring planting under conditions of the Mediterranean climate.