The optimal mixing ratio of Brassica napus and Brassica juncea meal improve nematode Meloidogyne hapla effects.

The use of rapeseed (Brassica napus L.) or leaf mustard (Brassica juncea L. Czern) meal or both as organic fertilizer not only improves the soil environment and crop productivity by supplying nutrients but also has nematicidal effects. This study aimed to establish the optimal application levels of rapeseed and leaf mustard meal for stronger nematode control in tomato. Tomato is one of the most important solanaceous crops which is severely damaged by nematodes. At first, meal (120 g of varying mixing ratios of rapeseed and leaf mustard meal) was mixed with sterilized soil (1 kg). The optimal ratio of rapeseed:leaf mustard meal for effective nematode control was 20:100 g/kg of soil. Progoitrin and gluconapin were the most abundant glucosinolates found in rapeseed meal, while sinigrin was the most abundant in leaf mustard meal. The amount of sinigrin increased if the leaf mustard meal proportion increased in the meal mixture. Although the content of sinigrin in optimal ratio mixture of rapeseed and leaf mustard meal is lower than only leaf mustard meal, it is presumed that nematocidal effects of the mixture are better than that of the single component due to the high contents of progoitrin and gluconapin. So, we propose that rapeseed and leaf mustard meal mixture at an appropriate ratio can be used as an environmentally friendly nematocide.