STUDIES ON HETEROSIS FOR HEAT TOLERANCE IN TOMATO

Abstract

An investigation was carried out at the experimental field of Horticulture Department, Faculty of Agriculture, SAU during summer season from May 2013 to August 2013 and winter season from October 2013 to March 2014 with a view to characterizing, evaluating and estimating heterosis for yield and yield attributes under high temperature conditions and hybrid seed production potentiality of different tomato cross combinations and their parental lines. Variations in relation to hypocotyl color, stem pubescence, seedling height and fresh weight of seedling at planting stage were observed among the hybrids and parental lines. Hypocotyl color of parental lines and hybrids exhibited only purple and green color. Days to first flowering ranged were from 45.67 to 51.00 days among the hybrids and parental lines. Yield and yield attributes of ten hybrids were much higher compared to the parental lines. The highest number of fruits per plant was recorded from the hybrid C41 FP5 (35.50) followed by C41 X C11 (27.07) while the lowest was recorded from the parental line C51 (10.40). Wide variation was recorded for individual fruit weight among the parental lines and hybrids. The hybrid C11 X C71 had the highest fruit weight (46.27 g) closely followed by FP5 X C71 (44.37 g). Among the 15 genotypes highest soluble solids (%) was recorded from the hybrid C41 X C51 (5.10) while it the lowest was from C41 X FP5 (3.23). Fruit yield per plant of hybrid and parental lines ranged from 0.27 kg to 1.11 kg. The hybrid C41 X C11 yielded the highest amount of fruits per plant (1.11 kg) followed by C41 X FP5 (0.94 kg). The corresponding per hectare yield was also the highest from C41 X C11 (37.74 t/ha) followed by C41 X FP5 (31.96 t/ha). Significant heterosis for better parent for yield and yield attributes were estimated in this study. Among ten hybrids, eight hybrids produced significant and positive heterobeltiosis for number of fruits per plant. The hybrid FP5 X C71 showed the highest heterobetiotic effect for individual fruit weight followed by C41 X C71 indicating suitable combinations for improving fruit weight. The highest better parent heterosis for fruit yield per plant was estimated from the hybrid of C41 X FP5 (203.22%) and the lowest was in C51 X C11 (32.61%). For seed yield and yield attributes among the 15 genotypes, the parental line C51 had the highest seeds per fruit (85.18) and the lowest was cross combination C41 X FP5 (25.27). Among the parental lines and hybrids, the 1000-seed weight of tomato was ranged from 2.5 g to 3.3 g. The highest 1000-seed weight of tomato was recorded in cross combination C41 X C11 (3.3 g) and the lowest in cross combination C51 X C71 (2.5 g). The highest seed yield per plant was found in the parental line C11 (12.47 g) and the lowest was found in the cross combination C41 X FP5 (3.52). The highest seed yield per hectare was estimated from the parental line C11 (274.34 kg) followed by C51 (246.62 kg) and the lowest was from C41 X FP5 (77.44 kg).