09-08-2013, 03:22 PM
Evaluation of antagonists against soil borne pathogens of brinjal
ABSTRACT
Brinjal or eggplant (Solanum melongena L.) is a member of solanaceae family and a common vegetable crop all over the world. India is considered to be the centre of its origin (Zeven and Zhukovsky, 1975) and many varieties of brinjal, varying in shape, size and colour of the fruit are grown here. India is the second largest producer of brinjal in the world next to China. Brinjal crop is attacked by various soil borne pathogens of which Pythium aphanidermatum, Rhizoctonia solani, Sclerotium rolfsii, Fusarium oxysporum f. sp. melongenae, F. solani, Ralstonia solanacearum and Meloidogyne incognita are the most destructive pathogens. These pathogens constitute most important bio-hostile elements of the soil ecosystem that the plants encounter before emergence and also at various stages of growth and development. As the brinjal crop is first raised in nurseries and then transplanted in main fields, in nursery, the crop suffers due to several seed and seedling diseases, seed rot, pre-emergence and post-emergence damping-off presumably caused by soil inhabitants and/ or soil invaders. None of the disease control techniques that are available presently can bring the level of soil sanitation below critical threshold to reduce seed and seedling diseases. The wilt of brinjal is a complex syndrome known to be caused by fungi, bacteria and root-knot nematodes which are known to have synergistic effect on the disease syndrome. During field surveys in the recent past, soil borne diseases of solanaceous vegetables have been observed in an increasing proportion in all the climatic zones of Jammu region, sometimes leading to total crop failure. In certain places the growers have shifted to other crops because of the disease psyche resulting in significant reduction in commercial as well as kitchen garden production. It was observed that most of the fungal and bacterial antagonists tested were found effective against soil borne diseases under in-vitro and in-vivo conditions. Five isolates of fungal antagonists viz., Trichoderma viride (Tv1 and Tv4), T. harzianum (Th1 and Th4) and T. virens (Gv2) and one isolate of bacterial antagonist, Pseudomonas fluorescens (Pf2) was found highly effective against all the soil borne pathogens under in vitro conditions were used for seed, soil and seed + soil treatments in pot experiments to observe their effectiveness on seed germination, seedling emergence and wilt incidence on brinjal cv. Pusa Purple Long. Among fungal antagonists isolates, Tv4 (Trichoderma viride) and among bacterial antagonists isolate Pf2 (Pseudomonas fluorescens) were found most effective against the soil borne pathogens. Pot studies revealed that seed and soil application of antagonists resulted in significantly higher seed and seedling emergence compared to seed and soil application alone. Pot studies further revealed that seed + seedling + soil application of the antagonists resulted in lesser wilt incidence compared to only seed + seedling or soil application of these antagonists.