Managing faba bean residues to enhance the fruit quality of the melon (Cucumis melo L.) crop

Mulching and/or topsoil incorporation of plant residues from green manure legumes can increase cropping system sustainability, and can supply and retain nutrients. Two field experiments were conducted in Italy over the period of 2006-2007, to investigate the effect of faba bean grown in a temperate environment to fruit morphology, quality and chemical composition of the subsequent melon (Cucumis melo L.) crop. Flowering faba bean plants were managed as mulch on the melon plant rows and cut and incorporated into the soil, in comparison with cultivated soil (control) and black plastic mulch. The plastic mulch increased the soil temperature by about 2°C compared to cultivated soil. Interestingly, melon plants mulched with faba bean plants and plastic produced higher fruit weight and pulp percentage, but the soil management practices also affected fruit chemical composition. Plastic mulch and faba bean plants induced an increase of total soluble solids and a decrease of acidity. Plastic mulch alone induced the lowest glucose content (0.13g100g-1); treatments with faba bean plants favored the highest fructose accumulation in melon fruits (0.23g100g-1). No clear differences emerged among the treatments with regard to sucrose accumulation in 'Baggio', but the faba bean plants managed as mulch induced a high sucrose concentration in 'Yago' fruits. Treatments with faba bean plants induced the highest K+ accumulation (3324 and 3077mgkg-1 f.w.); in fact, K+ scarcely accumulated in melon fruits harvested from plants mulched with plastic (2543mgkg-1 f.w.). Faba bean mulching also drastically increased the PO43- accumulation. However, unclear responses were obtained for SO42- increment for 'Baggio', while 'Yago' showed drastic SO42- accumulation by mulching with faba bean plants. The soil treatments did not affect the accumulation of Mg2+.[...]