Studies on Heterosis Employing Leaf Curl Resistant Mutant for Several Horticultural Traits Related to Earliness and Yield in Tomato (Solanum lycopersicum L.)

Aim: Determine the degree of heterosis for the yield and earliness component qualities in order to generate hybrids for early and high yield through heterosis breeding.

Study Design: The experiment was laid out in Randomized Block Design with three replications.

Place and Duration of Study: The experiment was conducted at the ICAR-Indian Institute of Vegetable Research in Varanasi, which is located about 20 kilometres to the southwest of the city on the Ganga River's bank at an elevation of 128.93 metres above mean sea level and lies between 82.52 degrees east and 25.10 degrees north (MSL). The experiment was carried out in late Kharif in 2015 and 2016, as well as in the summer of 2017.

Methodology: In total 33 crosses were developed using 14 tomato genotypes, including the tomato leaf curl virus susceptible variety Punjab Chhuhara and the advanced breeding line H-88-78-2, a mutant resistant to leaf curl with altered inflorescence and ripening, in order to evaluate the heterosis for earliness and yield attributes. Three cultivars were the male parents (testers), while eleven cultivars were the female parents (line). As a result, 33 tomato hybrids were developed adopting the line tester method. Each line in this design is paired with one of the "t" testers using a random sample of "I" lines. Over the better parent, the mid parent, and the standard/check (Arka Rakshak) heterosis was estimated according to Singh and Chaudhary (1979).

Results: Based on results from both seasons, the cross P7×P13 showed the highest significant negative heterosis per cent for earliest traits like days to first flower (-46.43, -43.80), days to 50% flowering (-35.66, -50.00), and days to first ripening (-30.09, -28.74) over superior parent in first and second seasons, respectively. The hybrid P9×P13 displayed the highest significant heterosis per cent for the features linked to yield in the first and second seasons, for the number of fruits per plant (71.78, 592.04) and yield per plant (75.11, 425.88). The outcome showed that minimum days of first blooming and first ripening are indicative of earliness, and the maximum yield per plant was associated with the highest possible number of fruits per plant.

Conclusion: Based on the results of both seasons, it was determined that the tomato mutant (P13) generated hybrids had low and negative heterosis for qualities associated to earliness and high and positive heterosis for traits related to yield. As a result, the number of fruits per plant and the number of days before the first fruit ripens are better measures of output and earliness. By altering this particular attribute, it would be possible to improve productivity with early crops. Breeders should therefore concentrate largely on the number of fruits and the days to first ripening in order to achieve a high and early yield.