G × E interaction and heterosis in elite tomato hybrids for growth, earliness and fruit parameters in diverse agro-climatic zones of Punjab Naveen Garg*, S.K. Jindal1, M.S. Dhaliwal1 and D.S. Cheema1 Regional Research Station, Punjab Agricultural University Bathinda - 151 001, Punjab, India *E-mail: naveen@pau.edu ABSTRACT Six promising tomato hybrids selected from a pool of 60 F 1 hybrids were evaluated for seven traits, along with the check hybrid (TH-1) at two locations falling under different agro-climatic zones of Punjab, India. G × E interaction was significant for early yield, fruit weight and total fruit yield, whereas, it was non-significant for fruit number, locule number, pericarp thickness and vine length. Overall higher mean-early-yield, fruit number, fruit weight and total yield at Ludhiana, rather than at Bathinda, may be due to higher organic carbon, available phosphorus and available potash and low electrical conductivity of the experimental soil at Ludhiana. Pooled analysis showed that hybrid TH-21 had the maximum early-yield (3.73 tha-1 ), fruit weight (72.7 g) and locule number (2.65), whereas, TH-23 had the highest fruit number per vine (53.7) and total fruit yield (51.2 tha-1). The magnitude of pooled standard heterosis was maximum for vine length (140.7%), followed by early yield (114.8%), total yield (88.3%), fruit number (49.7%), fruit weight (27.6%), pericarp thickness (16.4%) and locule number (-21.6%). On the basis of stability and superiority for fruit weight, fruit number, early and total yield, TH-21 was found to be the most promising hybrid, followed by TH-23. Key words: Fruit number, fruit weight, hybrid, stability, tomato, yield INTRODUCTION Tomato (Solanum lycopersicum L.) is one of the most important vegetable crops of Punjab, cultivated over 7,580 hectare in 2014-15 and produced 1,85,900 metric tonnes with average productivity of 24.525 metric tonnes ha-1 (Anon., 2015). At the national level, productivity of tomato has increased from 15.74 metric tonnes ha-1 in the year 2001 to 19.45 metric tonnes ha- 1 in 2011 (Anon., 2014). This substantial increment is partly due to availability and adoption of high-yielding tomato hybrids in the country. Tomato hybrids are very popular among farmers because of earliness, high yield, uniformity of the produce and higher adaptability to unfavorable environment (Yordanov, 1983). The high cost of hybrid seeds is not an obstacle in their popularity as it is compensated by the realized higher profits obtained from their cultivation (Cheema and Dhaliwal, 2005). Three F 1 hybrids of tomato, viz. TH-2312, TH- 802 and TH-1, have thus far been released for commercial cultivation at the State level the Punjab Agricultural University. The last hybrid, i.e. TH-1, was released in the year 2003 (Singh et al, 2004). Before recommending any hybrid for commercial cultivation, its evaluation in diverse agro-climatic locations is very important owing to the genotype × environment interactions due to variations in soil fertility, irrigation- water quality and other agro-climatic conditions pre va le nt a t differe nt zones. Genetic stability (homeostasis) in the hybrids refers to reduced genotype × environment interaction. A majority of quantitative traits are significantly affected by environmental factors, and, heterosis too is dependent on environment. Therefore, evaluation of a given tomato hybrid, when grown at different locations, is necessary for obtaining reliable information on its overall performance. This kind of information is of great importance to tomato breeders, as, it can help them make intelligent decisions J. Hortl. Sci. Vol. 11(2): 124-130, 2017 1Department of Vegetable Science, Punjab Agricultural University, Ludhiana 141004, India 125 on cultivar selection (Atanassova and Georgiev, 2007). There fore, the present study was conducted to estimate G × E interaction among seven promising tomato F1 hybrids, and, to ascertain the magnitude and direction of heterosis over a standard Check hybrid for plant growth, yield and fruit parameters two, in diverse agro-climatic zones of Punjab. MATERIAL AND METHODS Six promising F1 hybrids of tomato were selected for multi-location testing from a pool of 60 hybrids evaluated at Ludhiana for two years. These six elite hybrids, along with one standard Check hybrid,i.e. TH-1, were evaluated in a Randomized Comple te Bloc k De sign (RCBD) , with thre e replications, at two diverse locations falling under different agro-climatic regions of Punjab, i.e. Vegetable Research Farm, Punjab Agricultural University, Ludhiana (E 1 ) (30o 54’ N latitude, 75o 48’ E longitude, 247 amsl altitude) and Jodhpur Romana Farm, Regional Research Station, Punjab Agricultural University, Bathinda (E2) (30 o 9’ 36" N latitude, 74o 55’ 28" E longitude, 211 amsl altitude) during October 2010 to May 2011. Seeds were sown in well-prepared nursery beds in end-October, 2010. Seedlings were transplanted on the southern side of the beds prepared in East-West direction at a spacing of 1.20 m × 0.30 m, in end-November, 2010. Ten plants from each entry were transplanted in single row in each replication. Recommended cultural and plant-protection measures were followed for raising the crop (Anon., 2013). Irrigation was applied needed and at regular intervals at Ludhiana; however, at Bathinda, irrigation was not applied for three weeks in April, though needed by the crop, due to non-availability of good quality canal water (the tube-well water-being saline-sodic, was not used for irriga tion pur pos e ). Mea n monthly a gr o- meteorological recorded during the crop season at both the loc a tions are pre se nted in Ta ble 1. Characteristics of the experimental soil (0-15 cm soil profile) at the two locations are presented in Table 2. Observations were recorded for seven characters, viz., early yield (t ha-1), fruit number per vine, fruit weight (g), locule number, pericarp thickness (mm), vine length (cm) and total fruit yield (t ha-1). A total of five pickings were made from mid-April to end-May. Yield obtained in the first picking was treated as ‘early yield’. Average weight of ten randomly-chosen fruits from the second, third and fourth pickings was used for estimating fruit weight. Locule number and pericarp thickness were estimated from ten randomly-selected fruits from the third picking. Vine length was recorded after the final picking on five randomly-chosen, competitive plants. Data were analyzed for analysis of variance (ANOVA) using the computer software programme CPCS1. Heterosis over the Check hybrid was estimated and tested for significance using standard methods (Rai and Rai, 2006). RESULTS AND DISCUSSION The mean sum of squares due to genotype was significant for all the traits in both the environments (Table 3), revealing genotypic variability for the traits studied. Pooled analysis (Table 3) showed that the mean squares due to environment were significant for all the traits except locule number and pericarp thickness, revealing the important role played by environment in the expression of most traits. G × E interaction was significant for three traits, viz., early yield, fruit weight and total yield, which meant that performance of the hybrids for these traits was significantly different under the two environments; whereas, environmental conditions did not influence expression of the other traits, viz., fruit number per vine, locule number, pericarp thickness and vine length. Overall mean early-yield, fruit number per vine, fruit weight and total fruit yield at Ludhiana (3.44 t ha-1, 52.8, 62.6 g and 48.3 t ha-1 respectively) were significantly higher than those at Bathinda (2.46 t ha-1, 37.9, 58.6 g and 36.5 t ha-1 respectively) (Table 4). This may be due to the higher organic carbon, available phosphorus, available potash and low electrical conductivity of the experimental soil at Ludhiana, compared to that in Bathinda (Table 2). Secondly, deficit irrigation during the month of April at Bathinda may also have been responsible for reduction in yield and yield contributing traits. According to Kalloo (1986), phosphorus application markedly increases early-yield, whereas, high nitrogen and potash improve the number of fruits and total fruit yield in tomato. Earline ss is one of the mos t importa nt advantages of heterosis breeding in tomato facilitating the advantage of high prices during the early season, particularly, in regions with short growing-season such as in Punjab (Atanassova and Georgiev, 2007). All the experimental hybrids, except TH-11, gave significantly higher early-yield than TH-1 in both the environments (Table 4). Pooled analysis showed that maximum early- J. Hortl. Sci. Vol. 11(2): 124-130, 2017 Heterosis in elite tomato hybrid for Punjab 126 J. Hortl. Sci. Vol. 11(2): 124-130, 2017 Naveen Garg et al 127 J. Hortl. Sci. Vol. 11(2): 124-130, 2017 Heterosis in elite tomato hybrid for Punjab 128 J. Hortl. Sci. Vol. 11(2): 124-130, 2017 Naveen Garg et al 129 yield was produced in TH-21 (3.73 t ha-1), which was statistically at par with TH-22 (3.62 t ha-1) and TH-23 (3.42 t ha-1). However, due to presence of G × E interaction for this trait, results with respect to the location differed significantly. Hybrid TH-22 gave maximum early-yield (4.73 t ha-1) at Ludhiana, whereas at Bathinda, hybrid TH-21 produced the highest early-yield (3.44 t ha-1) which was statistically at par with TH-23 (3.01 t ha-1) (Table 4). Pooled standard heterosis over TH-1 ranged from 74.6% (TH- 13) to 114.8% (TH-21). Fruit number is an important yield-contributing trait in tomato. Maximum fruit number was recorded in TH-23, which was statistically at par with TH-13 at both the locations. The same trend was observed in total fruit yield, showing a close correlation between these two traits (Table 4). All the experimental hybrids gave significant, positive standard heterosis over TH- 1 for these traits at both the locations, except TH-21 and TH-22 for fruit number at Bathinda (Table 5). Pooled standard heterosis ranged from 10.6% (TH-21) to 49.7% (TH-23) for fruit number and from 39.6% (TH-22) to 88.3% (TH-23) for total fruit-yield. Garg and Cheema (2014) also reported standard heterosis upto 102.28% and 165.88% over TH-1 for fruit number per plant and total fruit-yield, respectively. On the other hand, TH-21 recorded maximum fruit weight at both the locations (Table 4). Standard heterosis of 57.8% exhibited by TH-21 for total fruit-yield was contributed to mainly the 27.6% increase in fruit weight and 10.6% increase in fruit number (Table 5). Locule number and pericarp thickness are important fruit-quality parameters which influencing fruit flavour, firmness, shelf-life and transportation to distant locales. Locule number in all the hybrids varied from 2.00 to 2.65 (Table 4). Maximum locule number (2.65) was seen in TH-21, which was statistically at par with TH-1 (2.55) and significantly higher than all the other hybrids. On the other hand, minimum locule number (2.00) was recorded by TH-16, which was at par with TH-22 (2.05), TH-23 (2.07) and TH-13 (2.15) (Table 4). All the hybrids, excepting TH-21, exhibited significant, negative standard heterosis over TH-1, ranging from -7.8% (TH-11) to -21.6% (TH-16) (Table 5). Garg and Cheema (2014) also observed standard heterosis over TH-1 as ranging from -39.94% to 50.15% for locule number. Table 5. Heterosis over TH-1 (%) for seven traits exhibited by six elite F 1 hybrids of tomato evaluated at two locations of Punjab F1 Hybrid Early yield Fruit number per vine Fruit weight E1 E2 Pooled E1 E2 Pooled E1 E2 Pooled TH-11 3.9 8.9 6.4 25.8* 22.1* 23.9* 6.2 -0.9 2.7 TH-13 63.3* 85.9* 74.6* 45.9* 43.0* 44.4* 8.4* -3.1 2.7 TH-16 69.0* 87.9* 78.4* 37.5* 34.9* 36.2* 1.3 -8.9* -3.8 TH-21 87.1* 142.4* 114.8* 12.2* 9.1 10.6* 28.4* 26.7* 27.6* TH-22 120.2* 76.5* 98.3* 21.4* 9.0 15.2* 13.9* -1.0 6.5* TH-23 77.7* 112.0* 94.8* 46.2* 53.2* 49.7* 10.1* 6.8 8.5* E1= At Ludhiyna E2= At Bathinda Table 5. contd……. F1 Hybrid Locule number Pericarp thickness Vine length Total fruit yield E 1 E 2 Pooled E 1 E 2 Pooled E 1 E 2 Pooled C 1 C 2 Pooled TH-11 -5.3 -10.3* -7.8* 16.4* 16.4 16.4* 119.6* 124.2* 121.9* 33.6* 75.1* 54.4* TH-13 -16.0* -15.4* -15.7* 14.8* 9.0 11.9* 130.6* 150.7* 140.7* 58.1* 95.0* 76.5* TH-16 -20.0* -23.1* -21.6* 11.5* 11.6 11.6* 123.9* 151.3* 137.6* 39.5* 66.9* 53.2* TH-21 8.0 0.0 4.0 16.4* 11.1 13.8* 117.2* 138.0* 127.6* 44.3* 71.3* 57.8* TH-22 -16.0* -23.1* -19.6* 9.8* 7.9 8.9* 134.6* 139.1* 136.9* 38.4* 40.8* 39.6* TH-23 -20.0* -17.9* -18.9* 13.1* 7.9 10.5* 122.4* 133.8* 128.1* 61.2* 115.3* 88.3* *Significant at 5% level J. Hortl. Sci. Vol. 11(2): 124-130, 2017 Heterosis in elite tomato hybrid for Punjab 130 REFERENCES Anonymous , 2013. Pa c ka ge of Pra c tic e s for Cultivation of Vegetables. Punjab Agricultural University, Ludhiana, Punjab, India, pp. 30-36. Anonymous, 2014. Food and Agriculture Organization of the United Nations. faostat.fao.org. Anonymous, 2015. Ve geta ble a re a , yie ld and production. punjabhorticulture.com (accessed on 13th November 2015) Atanassova, B. and Georgiev, H. 2007. Expression of heterosis by hybridization. In: Genetic improvement of solanaceous crops. Vol. 2: Tomato. Razdan, M. K. and Mattoo, A. K. (eds.). Science Publishers, Enfield, New Hampshire, United States of America, pp. 113-152 Cheema, D. S. and Dhaliwal, M. S. 2005. Hybrid tomato breeding. J. New Seeds, 6(2):1-14. Gar g, N. a nd Che ema , D. S. 2014. Ge ne tic improvement of tomatoes involving rin, nor and alc alleles. Lambert Academic Publishing, Germany. Kalloo, G. 1986. Tomato (Lycopersicon esculentum Miller). Allied Publishers Pvt. Ltd., New Delhi, India, pp. 203-210. Rai, N. and Rai, M. 2006. Heterosis breeding in vegetable crops. New India Publishing Agency, New Delhi, India, pp. 7-9. Singh, S., Dhaliwal, M. S. and Cheema, D. S. 2004. TH-1: a new tomato F 1 hybrid. J. Res. Punjab Agri. Univ. 41(3): 414. Yordanov, M. 1983. Heterosis in the tomato. In: Monographs on theoretical and applied genetics, Vol. 6: Heterosis. Frankel, R. (ed.). Springer- Verlag Berlin, Heidelberg, Germany, pp. 189- 219 Pericarp thickness in all the hybrids varied from 6.20 mm to 7.22 mm. Maximum pericarp thickness (7.22 mm) was obse rved in T H-11, which was sta tistica lly at par with T H-21 (7.05 mm) and significantly higher than in all the other hybrids. On the other hand, minimum pericarp thickness (6.20 mm) was seen in TH-1, which was significantly lower than in all the other hybrids (Table 4). All the experimental hybrids showed significant, positive standard heterosis over TH-1, ranging from 8.9% (TH-22) to 16.4% (TH- 11) (Table 5). Standard heterosis ranging from -21.88% to 71.51% was also reported by Garg and Cheema (2014) for pericarp thickness. Vine length in tomato also contributes fruit yield (Atanassova and Georgiev, 2007). All the experimental hybrids had significantly higher vine length than TH-1 under both the environments (Table 4). Pooled analysis showed that maximum vine length was recorded in TH-13 (170.8 cm), which was at par with TH-16 (168.5 cm), TH-22 (168.5 cm), TH-23 (162.2 cm) and TH-21 (161.6 cm). The magnitude of standard heterosis over TH-1 varied from 121.9% (TH-11) to 140.7% (TH-13) (Table 5). High yield is one of the most importa nt a dva nta ge s of he te ros is bre e di ng in t oma to. Maximum pooled fruit-yield was exhibited by TH- 23 (51.2 t ha-1 ), followed by TH-13 (48.5 t ha-1) and TH-21 (43.5 t ha-1 ) (Table 4). All the experimental hybrids showed significant, positive heterosis over TH-1 ranging from 39.6% (TH-22) to 88.3% (TH- 23) (Table 5). Standard heterosis for total fruit-yield in toma to ra nge s from 66.56 to 165.88% , a s reported by Garg and Cheema (2014). G × E interaction was significant for early- yield, fruit weight and total fruit-yield (Table 4). All the hybrids showed significant differences in early- yield and total fruit-yield, across the two locations. Howe ve r, two hybrids, i.e ., T H-21 and T H-1, exhibited at-par values for fruit weight across the two locations (Table 4). Therefore, on the basis of stability and superiority for fruit weight, fruit number, early and total yield, TH-21 is the most promising hybrid, followed by TH-23. (MS Received 21 November 2015, Revised 28 March 2016, Accepted 28 December 2016) J. Hortl. Sci. Vol. 11(2): 124-130, 2017 Naveen Garg et al