Fungitoxic properties of leaf extract and latex against storage fungi

Introduction Groundnut (Arachis hypogaea L.) contains on an average 40.1 per cent of fat and 25.3 per cent of protein and is a rich source of calcium, iron and vitamin B complex like thiamine, riboflavin, niacin and vitamin A. It is used not only as a major cooking medium for various food items but also for manufacture of soaps, cosmetics, shaving creams and lubricants. Popularity of soybean [(Glycin max L.) Merrill] crop is due to abundance (43%) high quality protein and a rich source of oil with high unsaturated fatty acids and with no cholesterol (Sharma and Mehrotra, 1988). Sunflower (Helianthus annus L.) oil is derived from sunflower seed carrying nearly 45-50% oil content 25% protein content. In safflower (Carthamus tinctorius L.) oil content varies from 24 to 36 per cent. The oil obtained by dry hot distillation is black and sticky and is used only for greasing well ropes and leather goods exposed to water. Safflower oil has also good dying properties and therefore it is used in the manufacture of paints, varnishes and linoleum. Sesame (Sesame indicum L.) oil content generally varies from 46 to 52%. Its grains may be eaten fried, mixed with sugar or in the form of sweet meats. Sesame oil is used as a cooking-oil in southern India. It is also used for manufacturing perfumed oils and for medicinal purposes. After harvesting seeds are stored in different storage conditions and if these storage conditions are not proper various microbes like viruses, bacteria, fungi and nematode are interacted with these seeds. Among these microbes, fungi play a dominant role in decreasing quality and longetivity of the seeds. Fungi cause various abnormalities to the seeds like discolored seeds, damaged seeds, shrunken seeds, undersized, rotted seeds and reduced in germinability. Fungal organisms plays significant role in infection, altering quality and longevity of seeds during the storage (Christensen and Kaufman, 1969). Such seeds are not fit for human consumption and rejected at industrial level. This ultimately affect on the yield and economy of the country. Pesticides play a vital role in the stabilization and increase of agricultural yield. On the other hand, it is being a possible source of atmospheric pollution, with residual toxicity to mammals and wildlife. The knowledge of extent and mode of inhibition of specific compounds which are present in plant extracts, may contribute to the successful application of such natural compounds for treatment of infection disorder like fungal and bacterial diseases. In this regard, aqueous leaf extract of ten medicinal plants were screened for the antifungal activity against seed-borne fungi. Various workers have screened a large number of plants belonging to angiosperm and gymnosperms for their fungitoxic properties. Mostly the aqueous extract of plants has been used to evaluate their fungitoxic properties (Thapliyal et al., 2000 and Algesaboopathi and Balu, 2002). Considering this fact aqueous leaf extract and latex of some medicinal plants were tested against the storage fungi. Materials and methods Collection of oilseed samples Oilseeds samples of groundnut, soybean, sesame, safflower and sunflower of different varieties were collected from market places, store houses and fields from different parts of Marathwada region of Maharashtra state. Isolation of oilseed mycoflora For detection of seed mycoflora associated with seed samples, the method recommended by ISTA (1966), Neergaard (1973) and Agarwal (1976) were adopted. 10 seeds per presterilized petriplates were equispaced asceptically on autoclaved Potato Dextrose Agar (PDA), Czapek Dox Agar (CZA), Glucose Nitrate Agar (GNA) and Rose Bengal Agar (RBA) media. Plates were then allowed to incubate at room temperature for seven days. Antifungal activity of botanicals Fungitoxic properties of ten selected medicinal plants (10% aqueous leaf extract) screened against test fungi (Nene and Thapliyal, 1993). Glucose nitrate medium was prepared in flasks and sterilized. To this medium, the requisite quantity of the plant extract was added. The plant extract was prepared by collecting fresh plant parts, washed thoroughly in distilled water and grinned in distilled water. The plant extract was thoroughly