The analysis of variance (ANOVA) exhibited significant differences and confirmed the presence of variations among genotypes for the traits, namely plant height, number of bolls per plant, number of sympodial branches per plant, boll weight, yield of seed cotton, seed index, fiber length, fiber strength and fiber fineness (Table 1). In later stage this data was used for correlation and heritability analysis. The significant results of these traits allowed the researcher to proceed for correlation and heritability analysis.
Correlation coefficient analysis
Correlation coefficient analysis measures the relationship between various plant characters. The estimation of genotypic and phenotypic correlations among studied traits are helpful for initiating breeding programs. If the correlation between two traits is positive and significant then improvement in one trait will exert significant impact on the other. Hence, selection for one character will also improve other associated traits. In present study, plant height exhibited positive and significant linkage with the number of bolls per plant, the number of sympodial branches per plant, ginning outturn (GOT), seed cotton yield, fiber length and fiber fineness whilst non-significant association with boll weight (Table 2). However, plant height showed negative but non-significant relationship with fiber strength. The number of bolls per plant showed positive and significant association with plant height, number of sympodial branches per plant, boll weight, seed index, seed cotton yield and fiber strength whereas negative correlation was observed for fiber length. Number of sympodial branches per plant had positive and significant relationship with all of traits except seed index and staple length. Boll weight had positive and significant correlation with number of bolls per plant, number of sympodial branches per plant, 100-seed weight, staple length and fiber fineness whereas the rest had positive but non-significant association except ginning outturn (GOT) which have positive and significant linkage with plant height, seed cotton yield, number of sympodial branches per plant and fiber length. It had positive but non-significant association with number of bolls per plant. However, ginning outturn (GOT) had negative and non-significant correlation with boll weight, 100-seed weight, fiber strength and fiber fineness. Seed index had positive and significant linkage with number of bolls per plant, boll weight and fiber length while had positive but non-significant correlation with plant height, number of sympodial branches per plant, yield of seed cotton and fiber fineness. It had negative and non-significant relationship with ginning outturn (GOT) and fiber strength.
Seed cotton yield had positive and significant association with plant height, number of bolls per plant, number of sympodial branches per plant, ginning outturn (GOT), staple length and fiber strength. Seed index showed positive but non-significant correlation with boll weight, seed index and fiber fineness whereas negative and non-significant association with fiber strength. Fiber length presented positive and significant linkage with plant height, boll weight, ginning outturn (GOT), seed index, fiber fineness and seed cotton yield while positive but non-significant correlation with number of sympodial branches per plant. Staple length exhibited negative and significant association with fiber strength while negative and non-significant relationship with number of bolls per plant and fiber fineness. Fiber strength had positive and significant association with number of bolls per plant, number of sympodial branches per plant, and seed cotton yield whereas positive and non-significant correlation with boll weight. Whereas, revealed negative and significant linkage with fiber length while had negative and non-significant relationship with plant height, ginning outturn (GOT) and seed index. Fiber fineness had positive and significant correlation with plant height, number of sympodial branches per plant, boll weight, and staple length whereas positive and non-significant association with number of bolls per plant and seed index. It showed negative and non-significant linkage with ginning outturn (GOT), yield of seed cotton and fiber strength.
Estimates of heritability
Heritability (BS) was ranged from medium to high for various yield and fiber related traits (Table 3). The traits namely plant height, number of bolls per plant, ginning outturn (GOT), seed index, seed cotton yield, fiber length, strength and fineness showed high heritability estimates, i.e., 74.48, 53.87, 90.65, 53.42, 54.56, 52.95, 59.66 and 70.42, respectively. While the traits including sympodial branches per plant and boll weight exhibited medium estimates of heritability, i.e., 48.06 and 46.66. The process of selection could be useful for characters with high heritability values.
Mean comparison for certain traits
Among parents, the genotype A555 had the lowest mean value 99.93 cm, while CIM-632 exposed maximum mean value was 124.73 cm for plant height (Figure 1-A). Whereas, Hybrid IUB-222 × NIAB-414 exhibited minimum mean value 88.07 cm, whereas NIAB-414 × CIM-632 showed the highest mean value 127.2 cm. VH-367 exposed minimum number of bolls per plant with the lowest mean value 16.26 whereas IUB-222 showed maximum value 32.13 followed by CIM-632, NIAB-414 and A555 having mean estimates of, i.e., 26.53, 23.26, 23.13 correspondingly (Figure 1-B). Cross, VH-367 × CIM-632 indicated the highest mean value of 32.93 followed by NIAB-414 × IUB222, NIAB-414 × CIM-632 and A555 × IUB-222, having mean values, i.e., 32.53, 31, 30.4 and 28.2, respectively. VH-367 showed the highest mean value of 23.13 followed by A555 (22.66), NIAB-414 (20.93) and IUB-222 (20.93) for number of sympodial branches per plant (Figure 1-C). A555 × IUB-222 revealed minimum mean value of 18.86, whereas VH-367 × NIAB-414 indicated maximum number of sympodial branches of 25.73. Genotype, CIM-632 had minimum mean value for boll weight 1.83 g whereas VH-367 exposed maximum mean value of 2.46 g (Figure 1-D). Hybrids, IUB-222 × VH-367 revealed the lowest but VH-367 × NIAB-414 showed maximum boll weight. NIAB-414 had minimum mean value for ginning outturn (GOT) 38.03 % while IUB-222 had maximum ginning outturn (GOT) 42.32 % (Figure 1-E). NIAB × IUB-222 showed minimum value of 35.46 % whilst hybrid VH-367 × CIM-632 revealed maximum ginning outturn (GOT) 46.33 % followed by CIM-632 × VH-367, CIM-632 × A555 and A555 × NIAB-414 with estimates of 45.62, 44.33 and 43.22%, respectively.
The accessions NIAB-414 and A555 exhibited the minimum and maximum mean estimates 5.07 and 5.64g, respectively for 100-seed weight (Figure 1-F). Hybrid CIM-632 × VH-367 presented minimum seed index 4.62 g whereas CIM-632 × A555 exhibited maximum mean value 5.70g. While studying the seed cotton yield it was observed that IUB-222 revealed maximum mean value 74.81g (Figure 1-G) whilst IUB-222 × A555 showed minimum seed cotton yield 42.39 g but the hybrid VH-367 × CIM-632 revealed the highest mean value 80.17g as compare with A555 × IUB-222 and NIAB-414 × IUB-222 with mean values of 73.95 and 72.84, respectively. CIM-632 indicated the lowest value 24.71mm, while NIAB-414 had maximum fiber length 26.86mm (Figure 1-H). Among the hybrids, A555 × VH-376 had minimum fiber length 24.29 mm, while the highest mean value 28.33 mm was shown by CIM-632 × NIAB-414. In case of fiber strength, VH-367 indicated maximum mean value 29.83 gtex-1 followed by A555, NIAB-414 and CIM-632 having mean values of 26.35, 26.28 and 25.47 gtex-1, respectively (Figure 1-I). Furthermore, CIM-632 × IUB-222 had minimum fiber strength 23.29 gtex-1, while VH-367 × NIAB-414 revealed the highest value 27.96 gtex-1. IUB-222 exhibited the lowest value 3.31μginch-1 for fiber fineness, while NIAB-414 had the highest mean value 5.06 μginch-1 (Figure 1-J). While among the hybrids, IUB-222 × NIAB-414 exposed minimum mean value 3.23 μginch-1, but NIAB-414 × IUB-222 had the highest mean value 5.44 μginch-1.