Bull. Spec. CORESTA Symposium, Winston-Salem, 1982, p. 70, P11, ISSN.0525-6240
Performance of mosaic and powdery mildew resistant tobacco varieties in India
Central Tobacco Research Institute (CTRI), Division of Plant Pathology, Rajahmundry (A.P.), India
Initial screening of germ plasm indicated that, among Nicotiana tabacum cultivars,"Kuofan"was resistant to the Indian strain of Erysiphe cichoracearum and"Vamorr-50"was resistant to the Indian strain of tobacco mosaic virus. In India, mosaic is endemic on all types of tobaccos. It is more severe on cigarette tobacco cultivars presently grown in Andhra Pradesh and Karnataka. Very often, yield and quality of flue-cured variety (FCV) tobacco are much (30 to 40%) reduced due to this disease. By utilizing the resistant donor"Vamorr-50"(monogenic dominant), resistance to mosaic disease has been incorporated into the commonly grown susceptible cultivars, viz. CTRI Special, Sp cross, FCV spl., 16/103, and Jayasree, through back cross and pedigree methods. After seven years of breeding and stabilization, the resistant cultivars were tested in on-farm and location trials for two seasons. The performance of two varieties viz. CTRI Special (MR) and Godavari Special is very satisfactory. In addition to mosaic resistance, the yields of cured leaf and bright leaf of these two varieties were 15 to 20% higher than their susceptible counterparts under epidemic conditions of mosaic infection. Powdery mildew (Erysiphe cichoracearum) is another important leaf disease although it is confined to certain pockets in Karnataka and Andhra Pradesh. It is severe on FCV and Lanka tobacco cultivars. Poor quality leaves were often obtained due to powdery mildew infection. Resistance found in"Kuofan"(double recessive) was transferred to Indian cultivars such as CTRI Special, Kanakaprabha, and DR-1 Lanka. Through successive back crosses, undesirable traits of the donor parent were eliminated. Presently mildew resistant FCV cultivars such as 1494, 2359, and 2692-3 and Lanka variety DR-1 (PMR) are being evaluated in location trials. Results show that these resistant cultivars are produced in high yield with good quality parameters. Burley Momi 2 and FCV line 2691-3 were made resistant to b oth mildew and mosaic diseases. They are being evaluated in on-farm tests.