Effects of root exudates of watermelon cultivars differing in resistance to Fusarium wilt on the growth and development of Fusarium oxysporum f.sp. niveum

We studied that effects of different root exudates on spore germination, spore production, mycelial biomass and mycelial growth of Fusarium oxysporum f.sp. niveum. Water soluble root exudates were extracted from the vermiculite and then ungrafted and grafted seedlings were grown in these exudates. Root exudates from ungrafted seedlings of a resistant watermelon cultivar significantly inhibited the F. oxysporum growth and development, whereas, root exudates from ungrafted seedlings of a susceptible cultivar caused significant promotion. Root exudates from ungrafted seedlings of these two rootstocks and from one grafted resistant cultivar inhibited the growth and development of F. oxysporum. Root exudates from the seedlings grafted with pumpkin rootstock were more inhibitory to F. oxysporum than those grafted on bottle gourd rootstock. Selection of resistant watermelon cultivars and grafting onto resistant rootstocks may be used to reduce the accumulation of F. oxysporum in the soil in watermelon monoculture systems.