STUDIES ON GENETIC IMPROVEMENT FOR YIELD, QUALITY AND RESISTANCE TO LEAF CURL VIRUS IN TOMATO (Solanum lycopersicum L.)
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Date
2018-01-15
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College of Horticulture, Rajendranagar, HYD-30
Abstract
The present investigation entitled “Studies on genetic improvement for yield, quality and resistance to leaf curl virus in tomato (Solanum lycopersicum L.)” was conducted during Rabi, 2015 and Rabi, 2016 at Horticultural Research Station, Venkataramannagudem, West Godavari district, Andhra Pradesh. The experiment was conducted with a view to screen the available tomato germplasm to identify high yielding lines with acceptable fruit quality, utilizing them in hybridization programme to study heterosis, combining ability, genetic parameters, gene action, correlation coefficient, path coefficient analysis for yield, quality and resistance to tomato leaf curl virus.
Genetic diversity studies for twenty attributes with respect to growth, earliness, yield and ToLCV resistance for sixty genotypes of tomato were carried out during Rabi, 2015. Average fruit weight contributed maximum towards divergence followed by number of fruits per plant and number of locules per fruit. Top five genotypes with highest yield coupled with acceptable fruit quality were selected as lines for heterosis breeding.
Five parental lines (VRSL-17, VRSL-18, VRSL-20, VRSL-22 and VRSL-40) thus identified were crossed with three testers (AVTO-1002, AVTO-1130 and AVTO-1314) which were resistant to tomato leaf curl virus in Line x Tester mating design. The resultant fifteen crosses along with eight parents and two checks (US-618 and Arka Vikas) were evaluated during Rabi, 2016 to identify the promising F1 hybrids with high productivity, good fruit quality and resistance to tomato leaf curl virus.
On perusal of per se performance of F1 hybrids, it was noticed that highest fruit yield per plant was recorded in VRSL-22 x AVTO-1002 which was on par with VRSL-22 x AVTO-1314 and commercial check US-618. Four hybrids have shown highly resistant reaction and eleven hybrids recorded resistant reaction against tomato leaf curl virus incidence under field screening. Whereas one hybrid has shown highly resistant reaction, nine hybrids were resistant, three hybrids were moderately resistant and two hybrids showed moderately susceptible reaction under artificial screening.
Studies on heterosis revealed that the hybrids VRSL-22 x AVTO-1002 and VRSL-22 x AVTO-1314 for fruit yield, VRSL-18 x AVTO-1130, VRSL-20 x AVTO-1130 and VRSL-22 x AVTO-1130 for earliness, VRSL-17 x AVTO-1002, VRSL-17 x AVTO-1314 and VRSL-40 x AVTO-1002 for ascorbic acid content were found to be superior over the better parents. Significant standard heterosis was recorded for characters like average fruit weight in VRSL-18 x AVTO-1002, VRSL-20 x AVTO-1002 and VRSL-22 x AVTO-1002, number branches per plant in VRSL-18 X AVTO-1314 and VRSL-22 X AVTO-1002 and days to first harvest in VRSL-18 x AVTO-1002, VRSL-18 x AVTO-1130 and VRSL-40 x AVTO-1002.
Combining ability analysis revealed that the magnitude of sca variance was greater than gca variance for the characters viz., number of primary branches per plant, days to 50 % flowering, number of clusters per plant, number of flowers per cluster, number of fruits per cluster, fruitset percentage, number of fruits per plant, days to first fruit harvest, fruit length, fruit diameter, number of locules per fruit, average fruit weight, fruit yield per plant, titrable acidity, ascorbic acid content, lycopene content and ToLCV incidence in field screening as well as artificial screening. This indicated the predominance of non-additive gene action governing the inheritance of these characters. Hence heterosis breeding is ideal to improve these traits. The characters plant height, days to last harvest and total soluble solids have shown the ratio of gca variance to sca variance more than unity indicating that these traits were governed by additive gene action and direct selection for these characters would be more useful.
Based on gca effects, parents VRSL-22 and VRSL-20 were superior general combiners for fruit yield, VRSL-17 and AVTO-1314 were superior general combiners for earliness, VRSL-22 and AVTO-1002 were superior general for resistance to ToLCV. The hybrids, VRSL-22 x AVTO-1002 and VRSL-20 x AVTO-1130 for fruit yield, VRSL-22 x AVTO-1002 and VRSL-18 x AVTO-1314 for earliness, VRSL-22 x AVTO-1002 for resistance to ToLCV were the best specific combiners.
It was observed that genotypic correlation coefficients were higher than that of phenotypic correlation coefficients. Studies on correlation revealed that yield per plant had significant and positive correlation with plant height, number of clusters per plant, number of flowers per cluster, percentage fruit set and number of fruits per plant. It was significant and negatively correlated with days to 50% flowering, days to first fruit harvest and ToLCV incidence under field screening as well as artificial screening.
Path coefficient analysis revealed that plant height, number of primary branches per plant, number of clusters per plant, number of flowers per cluster, number of fruits per cluster, fruitset percentage and number of fruits per plant exhibited low to very high positive direct effect on fruit yield per plant which recorded significantly positive correlation. This clearly indicated that direct selection based on these traits would be more effective for higher yield.
Keeping in view of the above facts, by considering all the factors like per se performance, sca effects, standard heterosis the most promising hybrids were VRSL-22 x AVTO-1002 and VRSL-22 x AVTO-1314. These hybrids may be further tested over locations and seasons for recommending them for commercial cultivation.
Description
The present investigation entitled “Studies on genetic improvement for yield, quality and resistance to leaf curl virus in tomato (Solanum lycopersicum L.)” was conducted during Rabi, 2015 and Rabi, 2016 at Horticultural Research Station, Venkataramannagudem, West Godavari district, Andhra Pradesh. The experiment was conducted with a view to screen the available tomato germplasm to identify high yielding lines with acceptable fruit quality, utilizing them in hybridization programme to study heterosis, combining ability, genetic parameters, gene action, correlation coefficient, path coefficient analysis for yield, quality and resistance to tomato leaf curl virus.
Genetic diversity studies for twenty attributes with respect to growth, earliness, yield and ToLCV resistance for sixty genotypes of tomato were carried out during Rabi, 2015. Average fruit weight contributed maximum towards divergence followed by number of fruits per plant and number of locules per fruit. Top five genotypes with highest yield coupled with acceptable fruit quality were selected as lines for heterosis breeding.
Five parental lines (VRSL-17, VRSL-18, VRSL-20, VRSL-22 and VRSL-40) thus identified were crossed with three testers (AVTO-1002, AVTO-1130 and AVTO-1314) which were resistant to tomato leaf curl virus in Line x Tester mating design. The resultant fifteen crosses along with eight parents and two checks (US-618 and Arka Vikas) were evaluated during Rabi, 2016 to identify the promising F1 hybrids with high productivity, good fruit quality and resistance to tomato leaf curl virus.
On perusal of per se performance of F1 hybrids, it was noticed that highest fruit yield per plant was recorded in VRSL-22 x AVTO-1002 which was on par with VRSL-22 x AVTO-1314 and commercial check US-618. Four hybrids have shown highly resistant reaction and eleven hybrids recorded resistant reaction against tomato leaf curl virus incidence under field screening. Whereas one hybrid has shown highly resistant reaction, nine hybrids were resistant, three hybrids were moderately resistant and two hybrids showed moderately susceptible reaction under artificial screening.
Studies on heterosis revealed that the hybrids VRSL-22 x AVTO-1002 and VRSL-22 x AVTO-1314 for fruit yield, VRSL-18 x AVTO-1130, VRSL-20 x AVTO-1130 and VRSL-22 x AVTO-1130 for earliness, VRSL-17 x AVTO-1002, VRSL-17 x AVTO-1314 and VRSL-40 x AVTO-1002 for ascorbic acid content were found to be superior over the better parents. Significant standard heterosis was recorded for characters like average fruit weight in VRSL-18 x AVTO-1002, VRSL-20 x AVTO-1002 and VRSL-22 x AVTO-1002, number branches per plant in VRSL-18 X AVTO-1314 and VRSL-22 X AVTO-1002 and days to first harvest in VRSL-18 x AVTO-1002, VRSL-18 x AVTO-1130 and VRSL-40 x AVTO-1002.
Combining ability analysis revealed that the magnitude of sca variance was greater than gca variance for the characters viz., number of primary branches per plant, days to 50 % flowering, number of clusters per plant, number of flowers per cluster, number of fruits per cluster, fruitset percentage, number of fruits per plant, days to first fruit harvest, fruit length, fruit diameter, number of locules per fruit, average fruit weight, fruit yield per plant, titrable acidity, ascorbic acid content, lycopene content and ToLCV incidence in field screening as well as artificial screening. This indicated the predominance of non-additive gene action governing the inheritance of these characters. Hence heterosis breeding is ideal to improve these traits. The characters plant height, days to last harvest and total soluble solids have shown the ratio of gca variance to sca variance more than unity indicating that these traits were governed by additive gene action and direct selection for these characters would be more useful.
Based on gca effects, parents VRSL-22 and VRSL-20 were superior general combiners for fruit yield, VRSL-17 and AVTO-1314 were superior general combiners for earliness, VRSL-22 and AVTO-1002 were superior general for resistance to ToLCV. The hybrids, VRSL-22 x AVTO-1002 and VRSL-20 x AVTO-1130 for fruit yield, VRSL-22 x AVTO-1002 and VRSL-18 x AVTO-1314 for earliness, VRSL-22 x AVTO-1002 for resistance to ToLCV were the best specific combiners.
It was observed that genotypic correlation coefficients were higher than that of phenotypic correlation coefficients. Studies on correlation revealed that yield per plant had significant and positive correlation with plant height, number of clusters per plant, number of flowers per cluster, percentage fruit set and number of fruits per plant. It was significant and negatively correlated with days to 50% flowering, days to first fruit harvest and ToLCV incidence under field screening as well as artificial screening.
Path coefficient analysis revealed that plant height, number of primary branches per plant, number of clusters per plant, number of flowers per cluster, number of fruits per cluster, fruitset percentage and number of fruits per plant exhibited low to very high positive direct effect on fruit yield per plant which recorded significantly positive correlation. This clearly indicated that direct selection based on these traits would be more effective for higher yield.
Keeping in view of the above facts, by considering all the factors like per se performance, sca effects, standard heterosis the most promising hybrids were VRSL-22 x AVTO-1002 and VRSL-22 x AVTO-1314. These hybrids may be further tested over locations and seasons for recommending them for commercial cultivation.
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Citation
Sri Konda Laxman Telangana State Horticultural University, Rajendranagar, Hyderabad-30