Effect of a Brassica juncea cover crop on a mono-succession of melon.

The ban of methyl bromide and the need for low environmental impact of agriculture has recently increased the interest in the biofumigant effects of Brassica species on soil-borne pathogens. Many researches have tested the toxic effects of Brassica green manures on several soil-borne pathogens in vitro, but field studies have not assessed definitely the efficiency of biofumigation at the field scale and the effect on crop development and production quality. The aim of this research was to evaluate the effect of a winter-spring cover crop of Brassica juncea compared to bare soil on a mono-succession of melon. The biomass of the B. juncea plants or of the weeds eventually developed in bare soil, used as control, were managed as follows:(i) crushed and left on the soil as organic mulching; (ii)crushed and incorporated into the soil; (iii) crushed and incorporated into the soil under PE mulching along melon crop rows. Soil changes during the two years trial were monitored by evaluating: organic matter content, availability and content of mineral elements and Cation Exchange Capacity. Marketable and unmarketable production, fruit weight and fruit quality (thickness of the epicarp and pulp, percentage of edible part, soluble solid content, firmness, etc.) were evaluated on melon. The use of Brassica juncea as a cover crop influenced soil characteristics and was effective on melon compared to bare soil when the biomass was incorporated to the soil, while no difference was found on melon production and quality when PE mulching was used.