Studies on Hybrid Vigour in Papaya (Carica Papaya L.) Varieties

Abstract

The present investigation was carried out with ten parents (five lines and five testers) in a line x tester mating design. All parents and their twenty five F1s were grown at Horticulture Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, in Complete Randomized Block Design with three replications during 2011-12 and tested the extent of genetic variability among some cultivars of papaya and the inbred lines on the basis of genetic coefficient of variation, heritability estimates and genetic advance, genotypic, phenotypic and environmental correlation coefficient by the method of path analysis and to study the extent of Heterosis. The characters under study were plant height (em), flower initiation (days), flowering (days), plant height at flowering (em), petiole length (em), plant girth (em), number of leaves at flowering, fruit length (em), fruit girth (em), central cavity (em), pulp thickness (em), TSS ( 0 brix), fruits per plant, fruit weight (g) and fruit yield per plant (kg). The analysis of variance r revealed significant differences among the genotypes and hybrids for all the characters. plant height (119.66 in Pusa Nanha to 182.66cm in Pusa Giant), Initiation of flowering ( 212.66 in Pusa Nanha to 227.66 days in Pusa Giant), flowering (days) (226.66 in Pusa Nanha X Pink Fleshed Sweet to 243.00 in Pant Papaya 1 ), plant height at flowering ( 32.66 em in Pusa Nanha X Pink Fleshed Sweet to 121 .66 em in Pusa Giant), petiole length (36.66 in Pusa Nanha X Pusa Delicious to 58.66 em in Surya), plant girth (31.16 in Pusa Nanha x Pusa Majesty to 38.13 em in Pusa Giant X Pusa Delicious), leaves at flowering ( 22.66 in Pusa Nanha to 35.00 in Pusa Dwarf x Surya), fruit length (19.30 in Pusa Nanha to 36.60 em in Red Lady), fruit girth (31.16cm in Pusa Nanha to 46.26 em in Pusa Gaint), central cavity (8.63cm in Pusa Nanha to 10.63 em in Pusa Giant), pulp thickness (2.56cm in Pusa Nanha to 3.23 em in Papaya 1 x Red Lady), TSS ( 11 .20° Brix in genotype Pusa Nanha to 13.53° Brix in Pant Papaya 1 x Surya), fruits per plant (20.3 in Pusa Nanha to 60.33 in surya), fruit weight (9~8.33 in Surya to 1556.66g in Pusa Giant) and fruit yield per plant (25. 76kg in Pusa Nanha to 7 4.43 kg Pusa Gaint X Surya) were recorded. High heritability was observed for plant height at flowering (98.9), fruit length (98.0), fruit weight (97.9), fruits per plant (94.2), fruit girth (94.0), fruit yield/plant (91.2), petiole length (90.6), plant height (89.1 ), central cavity (84.9), TSS (79.8), flower initiation (79.0), plant girth (77.2), flowering (75.5) while low heritability were observed for number of leaves at flowering (73.2) and pulp thickness (71.9). High GCV(~25%) was observed for fruit weight (97.99), fruit girth (78. 77), number of leaves at flowering (77.11 ), central cavity (51.79), plant girth (44.28), pulp thickness (43.18), plant height at flowering (38.54) and TSS (32.02). High PCV (~25%) was observed for fruit weight (99.05), number of leaves at flowering (90.1 0), fruit girth (81.23), central cavity (56.20), pulp thickness (50.92), plant girth (50.40), plant height at flowering (38.74) and TSS (35.85). Under Path Analysis, fruits per plant displayed high order of direct effect on fruit yield per plant (0.823) followed by fruit girth (0.664), petiole length (0.613), plant girth (0.578), leaves at flowering (0.562), days at flowering (0.530), pulp thickness (0.515), plant height (0.500), central cavity (0.484) and fruit weight (0421 ). Pulp thickness contributed yield per plant via fruit weight. Petiole length contributed yield per plant via fruit weight. Plant girth contributed fruit yield per plant via fruit girth. Plant height contributed fruit yield per plant via petiole length, TSS contributed fruit yield per plant via fruits per plant.Under Heterosis, the highest significant and positive value in plant heigt1t at flowering (em) was observed for cross Pusa Giant x Red Lady (113.58) followed by Pusa Giant x Pink Fleshed Sweet (107.41), Pusa Giant x Surya (93.83), Pusa Dwarf X Pusa Delicious (91.98) and Pusa Dwarf x Pusa Majesty (82. 72). For improvement in yield, emphasis may be given to the characters like central cavity, plant girth, fruit girth, days at flowering, plant heighi, pulp thicl<ness, fruit weight, fruit length, fruit girth and TSS. So, Pusa Giant x Pink Fleshed Sweet, Papaya P s 1 x Surya and Pant Papaya 1 x Red Lady were found promising for commercial cultivation.