Six lines, i.e., resistant to Tomato Leaf Curl Virus (TLCV) have been developed witb controlled introgression ol E. birsutum f. glabratum into Eycopersicon esculentum. The disease incidence, 120 days alter inoculation, of those lines derived from E. hirsutum f. glabratum ranged from 8.3 to 35.0 %, whereas in susceptible varieties it ranged from 95.0 to 100 %. The coefficient of infection (CI) values in the resistant lines were very low, ranging from 0.25 to 4.55, whereas m susceptible varieties CI values ranged from 60.56 to 88.96. Line H-2 had the highest resistance by showing the least disease incidence and Cl values. The fruit size and days to maturity in resistant lines were close to those of cultivated susceptible varieties. These lines have the scope for being used as varieties in the TLCV infested areas or as foundation lines for further genetic improvement.
The inheritance of earliness and fruit weight in tomato was studied m four interspecific crosses. Two cultivated varieties, i.e. 'HS 101' and 'HS 102", were hybridized with two wild species, L. hinutum i. glahratum 'B 6013' and L. pimpineihlohum 'A 1921'. Six generations of these crosses were evaluated for these traits and the estimates of gene effects were derived from the generation mean using an epistatic (six parameters) model. There were very wide differences between cultivated and wild species for earliness and fruit weight and in the segregating populations, plants with delayed maturity and stnaller fruit size were recorded with high frequency. It was found that the inheritance pattern was mainly governed by additive gene action. Epistatic effects also contributed towards the inheritance ot both traits.
Lycopersicon, tomato leaf curl virus, resistance, inheritance. SUMMARY Inheritance of resistance to tomato leaf curl virus (TLCV) was studied in the progenies derived from interspecific crosses between TLCV resistant Lycopersicon hirsutum f. glubratum line B 6013 and five susceptible cultivars (HS 101, HS 102, HS 110, Pusa Ruby and Punjab Chhuhara) of L. esculentum. Pt, Pz, Ft, Fz, Bt and B2 progenies of the live crosses were artificially inoculated with local strains of TLCV by means of the vector whitefly, Bemisia tabaci (GENN.), and the disease reaction was studied in all the crosses. Reaction of parents, Fi, Fz and backcrosses suggests fhat resistance derived from L. hirsutum f. glubratum B 6013 is based on two epistatic genes, one from the wild parent and one from the cultivated one, resulting in a 13 : 3 segragation in the Fz.
Diallel analysis was carried out involving eight diverse varieties of tomato, namely Pusa Early Dwarf, Sl-1, S-12, Punjab Tropics, Sl-120, HS-101, Pusa Ruby and Sl-73-1, to characterize the gene action involved in the inheritance of some of the quantitative traits and to correlate array mean and per se performance with general combining ability (gca) and specific combining ability (sca) effects, respectively.The results indicated that the variance component due to general combining ability was higher than that due to specific combining ability for yield and number of fruits, showing preponderance of an additive type of gene action. On the other hand, all other characters - height, number of branches, locule number, T.S.S., acidity and ascorbic acid content - were found to have a high variance component due to specific combining ability, which means excess of non-additive type gene action. In such cases, heterosis breeding, or any other breeding plan which makes use of specific combining ability effects, would be more effective. High correlation between parental array means and gca effects and between per se performance of the crosses and the sca effects was observed. The implications of the results are discussed.
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