Effect of Four Plant-based Soil Amendments on Root Knot Nematode Species, Meloidogyne incognita, Infesting Tomato Plants

Abstract

The effect of fresh leaves of three plant species, Betel (Piper betle), "Keppettiya" (Croton lacciferus) and "Maduruthala" (Ocimum tenuiflorum)and their combination, as soil amendments was determined against Meloidogyne incognita infesting tomatoes, in pot experiments. A mixture of 600g of autoclaved sand loamy soil, 30g of chopped leaves and 500 infective juveniles of Meloidogyne incognita w ere placed in plastic pots. Two weeks later, five week-old tomato seedlings were transplanted in the pots and allowed to grow for seven weeks in a screen house. The efficacy of the amendment treatments was evaluated based on the shoot growth enhancement and the severity of root infestation compared to un-amended controls. The findings indicated that all the amendments suppressed root infestation and simultaneously enhanced the shoot growth, compared to un-amended controls. However, the efficacy significantly differed (P<0.0001) among the plant species. The effectiveness of amendments can be ranked as Betel (highest)>"Keppetiya">Combined amendments>"Maduruthala” (lowest). Betel and "Keppetiya” caused complete prevention of root galling while "Maduruthala" (31%) and combined amendment significantly suppressed (P<0.0001) the gall formation (62%) compared to controls. Suppression of egg and female production relating to combined treatment and "Maduruthala" was 75% and 71%, and 51% and 46%, respectively. In all the amendment treatments, shoot length was promoted to a lesser extent than the shoot weight. The maximum enhancement in shoot length and weight was detected as 52% and 118%, respectively, with the Betel amendment. The findings showed that Betel and "Keppetiya” are promising plant-based organic amendments in controlling M. incognita infestations on tomatoes.