Induction of variability in Abolmoschus manihot var. ghana by irradiation

Abstract

Yellow vein mosaic, a viral disease transmitted by the white fly (Bemisia tabaci) is the most important disease of bhindi affecting the crop at all stages of growth. Pusa Sawani, reported to be resistant to the disease has, of late, become susceptible. A number of wild species have been reported to be resistant/tolerant to the disease. An experiment was planned and carried out during 1981-’82 at the Instructional Farm of the College of Horticulture, Vellanikkara, Trichur to induce variability in a reportedly resistant wild species, Abelmoschus manihot var. ghana and then to isolate edible vegetable type(s), if any. The two sources of A. manihot var. ghana available in the Department of Olericulture were found ‘symptomless carriers’ of yellow vein mosaic virus. A. manihot var. ghana (Source IARI) was found comparatively compatible with A. esculentus. This was proved through F0 fruitset, presence of viable F0 seed, germination of F0 seed, fertility of F1 plant and viability of F1 seed. The interspecific F1 hybrid exhibited heterobeltiosis for days to flower, nodes to first flower, plant height, leaf length, leaf width, fruit length, primary branches/plant, fruiting nodes on main stem, intermodal length, fruits/plant, ridges/fruit, marketable fruits/plant, seeds/fruit and fruit yield/plant. The total genetic distance between the two species were found significant (11D2=228.57). Variability was induced in the wild species using 10 kR, 15 kR and 20 kR gamma rays. Qualitative and quantitative characters of each and every plant in the M1 line were observed. The performance of M0 lines were compared with untreated control and vigour due to irradiation for characters plant height, internodal length and length of leaves were found significant irrespective of doses of radiation given. Maximum variability was observed for fruit yield/plant in the three lines. None of the plants were observed affected by diseases like yellow vein mosaic, cercospora leaf spot, powdery mildew and downy mildew and pests like fruit borer and jassids. Incidence of mites was, however, observed.