Genetic variances, heritability, correlation and path coefficient analysis in yellow maize crosses (Zea mays L.)

AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: 2151-7517, ISSN Online: 2151-7525 2010, ScienceHuβ, http://www.scihub.org/abjna Genetic variances, heritability, correlation and path coefficient analysis in yellow maize crosses (Zea mays L.) Ali Akeel wannows 1,Hasan Kameel Azzam 2 and Samir Ali AL- Ahmad 3 1 M.Sc. student. G.C.S.A.R. Duma. Damascus. Syria. www.aliwannows@yahoo.com 2 Department of Agronomy, Fac. Agric. Damascus University. Syria. 3 Researcher. Department.of Maize Res. G.C.S.A.R. Duma. Damascus. Syria. ABSTRACT The present study was undertaken to study the gene action, narrow sense heritability, interrelationships among traits and path coefficient analysis for grain yield and its components, plant and ear height, leaf area index (LAI), specific leaf weight (SLW) and physiological maturity (Ph. M). Fifteen hybrids produced using a half diallel fashion in 2008 season were evaluated for grain yield and its components and morpho- physiological traits during 2009 season. The obtained results indicated that all estimates of additive (VA) and dominance (VD) variance were significant for all characteristics with exception of additive variance for specific leaf weight Also, dominance variance for leaf area index, plant and ear height, ear length, and number of kernel per row. However the magnitude of VA was consistently larger than that of VD for all characteristics with exception of specific leaf weight, silking date, stay green, 100- kernel weight and grain yield where VD values were larger than VA values.high narrow sense heritability estimates were detected for leaf area index (96%), number of kernel per row (86%), plant height (85%), ear height (83%), physiological maturity (82%), number of rows per ear (77%), ear length (73%) and ear diameter (62%) and Emphasizing that the additive genetic variance was the major component of genetic variation in the inheritance of these traits and the effectiveness of selection for improving these traits. However, moderate narrow sense heritability estimates were obtained for leaf angel (48%), specific leaf area (46%) and 100- kernel weight (44%). While estimates were low for grain yield (39%), silking date (34%), stay green (27%) and specific leaf weight (26%). These results indicated the importance of choosing the suitable segregating generations for exhibiting the best expression of gene of different studied traits. Correlation coefficients among traits indicated that grain yield was positively and significantly associated with number of kernel per row (0.589), ear length (0.465), and leaf area index (0.497).The path coefficient analysis was calculated to detect the relative importance of characters contributing to grain yield. Data showed that each of leaf area index, ear diameter and physiological maturity had high positive direct effects on grain yield. Keywords: Corn, Gene action, Narrow sense heritability, Correlation and path coefficient analysis. INTRODUCTION Yield of corn (Zea mays L.) is considered as a complex inherited character therefore, direct selection for yield per se may not be the most efficient method for its improvement, but indirect selection for other yield related characters, which are closely associated with yield and high heritability estimates will be more effective. Several researches (El- Hefnawy and El- Zeir, 1991; Nawar et al., 1991 and Mohamed, 1993) studied the genetic variance and heritability in corn, Concerning narrow sense heritability, it was found to be high for ear height, ear diameter, 100- kernel weight and grain yield (Robinson et al., 1949; EL- Agamy et al., 1992 and Mourad et al., 1992 and). Robinson et al., (1949) found that additive genetic variance had more important role in the expression for plant and ear height. Amer and Mosa, (2004) reported that heritability estimates in narrow sense were 44% for silking date, 39% for plant height, 44% for ear height, 27% for ear length, 31% for ear diameter, 29% for number of rows per ear, 23% for number of kernel per row and 36% for grain yield. Yassien, (1993) found that the narrow sense heritability estimates were 65% for plant height, 51% for ear length, 63% for ear diameter, 44% for number of rows per ear, 66% for number of kernel per row, 42% for 100- kernel weight and 27% for grain yield. Many investigators determined the associations among different characters in corn Moursi et al., (1975) mentioned that number of kernels per row, ear diameter and 100- kernel weight had consistent positive and significant correlations with grain yield. Katta, (1976) found positive and significant

correlation between grain yield and each of plant height, number of rows per ear, number of kernel per row and 100- kernel weight and emphasized the role of these traits in selection of high grain yield in corn. Also, (AL- Ahmad, 2004; Aydin et al., 2007; Najeeb et al., 2009) indicated that the correlation values were positive and significant between grain yield and each of ear diameter, ear length and number of kernels per row. Efforts made to determine the relative contributions of yield related characters to grain yield variation, revealed that the most sources of variation in plant yield were the direct effects of number of kernels per row (Sary et al., 1990 and Mohamed and Sedhom, 1993) and both number of kernels per row and ear diameter (Yasien, 2000). On the other hand, the direct effect of ear diameter, ear length and number of kernels per row had the highest effect on yield variation (AL- Ahmad, 2004; Sadek et al., 2006). Amin et al., (2003) Also, indicated that number of kernels per row and 100- kernel weight were the highest contributors to variation in grain yield directly or indirectly. The main objective of the present investigation was to estimate of genetic variance, heritability, correlations and path coefficients for some morphophysiological, agronomic and yield traits of 15 F 1 hybrids of yellow maize. MATERIALS AND METHODS This investigation was undertaken to estimate of statistical genetic parameters for some morphophysiological, yield and its components characteristics in 6 6 half diallel set of yellow maize crosses. The experimental work was conducted at the maize researches department (G.C.S.A.R) - Damascus. Syria. In 2008 season for achieving crosses and in 2009 season for evaluating F 1 hybrids plants. Six yellow maize inbred lines i.e. IL.766-06 (P 1 ), IL.792-06 (P 2 ), IL.459-06 (P 3 ), IL.292-06 (P 4 ), IL.565-06 (P 5 ), IL.362-06 (P 6 ) were the source material of this investigation. The parents were chosen on the basis of the presence of wide differences between them with respect to certain plant characteristics. F 1 hybrids were planted in 5 June, 2008 in experiment was designed in randomized complete blocks (R.C.B.D) with three replication. Each, plot consisted of four ridges, 6m long and 70 Cm width. Plants were spaced at 25 Cm within ridge and thinned at one plant per hill after about 21 days of planting. Other recommended cultural practices for maize production were applied during the growing season. Observations and measurements were recorded on 10 guarded plants chosen at random from each plot for the following characteristics: grain yield (GY) Ton/H, silking date (Silk) day, plant height (PH) Cm, ear height (EH) Cm, ear length (EL) Cm, ear diameter (ED) Cm, physiological maturity (Ph. M) day, leaf area index (LAI), specific leaf area (SLA) Cm 2 g -1, specific leaf weight (SLW) g m -2, leaf angel (Lan) degree, stay green (SG), number of rows per ear (No. R), number of kernel per row (No. K), 100- kernel weight (100- KW) g. Griffing, (1956) approach was used to estimate genetic variance components (additive variance VA, dominance variance VD and residual variance VE). Estimates of VA/VP resulted in an estimate of narrow- sense heritability (h 2 ). The phenotypic correlation coefficients were calculated as described by Snedecor and Cochran, (1981) for all possible pairs of the studied characters including grain yield. To obtain more information about the relative contribution of specific characters to grain yield and remaining characters. The path coefficient analysis was performed for all crosses. Partitioning correlation coefficients into direct and indirect effects at phenotypic level was made by determining path coefficients using the method proposed by Wright (1934) and utilized by Dewey and Lu (1959). RESULTS AND DISCUSSION The obtained results of the present study will be displayed according to the calculated parameters as follows: Variability and heritability estimates for the studied traits: Variance components for general (V gca ) and specific (V sca ) combining abilities calculated for each trait were translated in terms of additive (VA) and dominance (VD) genetic variances according to Griffing, (1956) and they are summarized in Table (1). Results indicated that all estimates of VA and VD were significant for all traits except VA for specific leaf weight Also, VD for leaf area index, plant height, ear height, ear length and number of kernel per row. Which these traits were not significant that may be attributable to large magnitude of error variance of these traits. However the magnitude of VA was consistently larger than that of VD for all traits except specific leaf weight, silking date, stay green, ear diameter, 100- kernel weight and grain yield where, VD values were larger than VA this finding shows that the additive genetic variance was more important than the dominance genetic variance in the inheritance of most studied traits, indicating the effectiveness of selection in the early segregating generations in the studied hybrids for improving such traits. 631

Table (1). Heritability (h 2 ) and Variance of additive (VA), dominance (VD), environment (VE) and phenotypic (VP) for all studied traits. 100- Parameter LAI SLW SLA Lan silk Ph. M SG PH EH EL ED No. R No. K GY KW VA 0.54** 2.44 ns 19.24* 14.56** 2.36** 7.68** 9.39** 183.16** 558.46** 1.24** 0.011** 2.02** 12.99** 4.01** 0.74** VD 0.001 ns 4.99* 15.18* 13.70** 4.58** 1.70** 22.29** 14.05 ns 35.39 ns 0.27 ns 0.005* 0.52** 1.11 ns 4.80** 0.90** VE 0.023 2.013 7.030 1.803 0.060 0.037 2.863 18.647 79.447 0.193 0.002 0.100 1.030 0.220 0.250 VP 0.56** 9.44** 41.45** 30.06** 7.00** 9.42** 34.54** 215.86** 673.297** 1.703** 0.018** 2.640** 15.130** 9.030** 1.890** h 2 0.96 0.26 0.46 0.48 0.34 0.82 0.27 0.85 0.83 0.73 0.62 0.77 0.86 0.44 0.39 * and ** indicated to Significant at P= 0.05 and P= 0.01 respectively. Results showed that high narrow sense heritability estimates were detected for leaf area index (96%), number of kernel per row (86%), plant height (85%), ear height (83%), physiological maturity (82%), number of rows per ear (77%), ear length (73%) and ear diameter (62%), emphasizing that the additive genetic variation was the major component of genetic variation in the inheritance of these traits and the effectiveness of selection in the early segregating generations of the studied hybrids for improving these traits. High heritability estimates for plant height, ear height, number of rows per ear and number of kernel per row were also, reported by El- Rouby et al., 1979; El- Rouby and Salm, 1980; Yasien, 1999; Yasien, 2000 and Abd El- Sattar, 2003. However, moderate narrow sense heritability estimates were obtained for leaf angel (48%), specific leaf area (46%) and 100- kernel weight (44%), while such estimates were low for grain yield (39%), silking date (34%), stay green (27%) and specific leaf weight (26%) most of these results are in harmony with those obtained by El- Rouby et al., 1973; El- Hosary and Abd El Sattar, 1998; Khalil, 1999 and Abd El Sattar, 2003. The present results of narrow sense heritability estimates emphasized the portion of additive genetic variance for many of studied traits and suggest the importance of choosing suitable segregating generations for exhibiting the best expression of genes of different characters in the studied hybrids for improving such traits. Correlation among characters: In selecting high yielding genotypes correlation studies supply reliable information on the nature, extent and direction of selection. The knowledge of correlation coefficients between different yield attributes helps the maize breeder to find out the nature and magnitude of the association between these traits which are mostly used to attain better yield of the crop. Values of phenotypic correlation coefficients estimated for all pairs of studied characters including grain yield are presented in Table (2). The data showed that significant and positive correlation coefficients were found between grain yield and each of number of kernel per row (0.589), leaf area index (0.497) and ear length (0.465). such results could help the breeder to select high grain yield through selection for one or more of these characters. This result indicates that selection for long ears and more kernels per row may be accompanied by increasing grain yield of maize. However, non- significant correlations were observed between grain yield and any of the other characters. Similar results were reported by (Shehata, 1975; Mason and Zuber, 1976; Salama et al., 1994; Ahsan, 1999; Abd EL- Aty and Katta, 2002; AL- Ahmad, 2004; Sadek et al., 2006; Soengas et al., 2006; Aydin et al., 2007). Other inter- character correlations revealed that leaf area index gave significant and positive correlations with ear diameter, ear height, plant height and silking date (Salama et al., 1994; Ahsan, 1999; Sadek et al., 2006). specific leaf weight exhibited significant and positive correlation with 100- kernel weight while, it exhibited significant and negative correlations with specific leaf area and number of rows per ear previous studies in this connection (Sadek et al., 2006) confirmed the positive association between specific leaf weight and 100- kernel weight. specific leaf area showed significant and positive correlation with number of rows per ear on the other hand, it appeared significant and negative correlations with 100- kernel weight. 632

Table (2). Phenotypic correlation between all studied traits. Traits 1 2 3 4 5 6 7 8 9 10 11 12 13 14 2 LAI 0.497** 3 SLW 0.129 0.187 4 SLA -0.203-0.079-0.841** 5 Lan -0.052 0.028-0.144 0.053 6 Silk -0.02 0.464** -0.222 0.235-0.005 7 Ph. M 0.099 0.505** 0.185-0.122-0.275 0.419** 8 SG -0.141-0.256 0.072-0.011-0.221-0.275 0.077 9 PH 0.065 0.489** 0.062-0.06-0.066 0.471** 0.304* -0.327* 10 EH -0.014 0.570** 0.17-0.153-0.144 0.626** 0.865** 0.01 0.535** 11 EL 0.465** 0.166 0.153-0.186 0.118-0.062-0.138-0.177 0.083-0.233 12 ED 0.167 0.344* -0.115 0.222-0.132 0.318* 0.202 0.232 0.093 0.299* -0.397** 13 No. R -0.193 0.221-0.352* 0.360* -0.066 0.559** 0.209-0.019 0.385** 0.443** -0.546** 0.718** 14 No. K 0.589** 0.142 0.164-0.189 0.052-0.308* -0.178-0.196-0.231-0.351* 0.721** -0.325* -0.641** 15 100- KW 0.218-0.035 0.411** -0.478** 0.035-0.346* -0.108 0.185 0.202-0.114 0.490** -0.276-0.432** 0.237 GY LAI SLW SLA Lan Silk Ph. M SG PH EH EL ED No. R No. K (GY) grain yield, (LAI) leaf area index, (SLW) specific leaf weight, (SLA) specific leaf area, (Lan) leaf angle, (Silk) silking date, (Ph. M) physiological maturity, (SG) stay green, (PH) plant height, (EH) ear height, (EL) ear length, (ED) ear diameter, (No. R) number of row per ear and (No. K) number of kernel per row. * and ** indicated to Significant at P= 0.05 and P= 0.01 respectively. Concerning silking date, significant and positive correlation coefficients were estimated with number of rows per ear, ear diameter, ear height, plant height and physiological maturity. Such results are in accordance with the finding of (EL- Nigoly et al., 1981; Salama et al., 1994; Amin et al., 2003; Ojo et al., 2006; Asrar et al., 2007; Najeeb et al., 2009). While it exhibited significant and negative correlations with number of kernel per row and 100- kernel weight (Sadek et al., 2006). Regarding physiological maturity, significant and positive association with ear height and plant height. Stay green exhibited significant and negative correlations with plant height. Plant height was significantly and positively correlated with each of number of rows per ear and ear height. Similar findings were obtained by (Ahsan, 1999; Guzman and Lamkey, 2000; Mohammadi et al., 2003; Ojo et al., 2006; Sadek et al., 2006; Abou- Deif, 2007). Ear height showed significant and positive phenotypic correlations with each of number of rows per ear and ear diameter, on the other hand, it was significantly and negatively correlated with number of kernel per row. Such results were in accordance with the finding of (EL- Nigoly et al., 1981; Salama et al., 1994; Amin et al., 2003; Sadek et al., 2006; Abou- Deif, 2007). Ear length gave significant and positive correlations with 100- kernel weight and number of kernel per row while it gave significant and negative correlations with each of number of rows per ear and ear diameter. Our results agreed with those mentioned by (Salama et al., 1994; Soliman et al., 1999; Yasien, 2000; EL- Beially, 2003; Mohammadi et al., 2003; Sadek et al., 2006). Concerning ear diameter positive correlation coefficient was found with number of rows per ear but, it was correlated negatively and significant with 633

number of kernel per row. Such results are in harmony with those obtained by (Salama et al., 1994; Yasien, 2000; Amin et al., 2003; Mohammadi et al., 2003). number of rows per ear showed significant and negative correlations with 100- kernel weight and number of kernel per row similar results were obtained by (EL- Hosary et al., 1989; Amin et al., 2003; EL- Beially, 2003; Mohammadi et al., 2003). In general, the existence of positive associations in the present study among grain yield and each of number of kernel per row, ear length and leaf area index suggests that an increment of production may be achieved upon improving either one or more of these traits. Path coefficient analysis: The analysis of path coefficient has been made to identify the important yield attributes by estimating the direct effects of the contributing characters to yield and separating the direct from the indirect effects through other related characters by partitioning the correlation coefficient and finding out the relative importance of different characters as selection criteria. The estimates of direct and indirect effects of the three yield related characters viz. leaf area index, ear diameter and physiological maturity on grain yield in Table 3. Table (3) Direct and indirect effects of leaf area index, ear diameter and physiological maturity vs. grain yield Source of variation Effects 1 X 1 (LAI) vs. grain yield 0.447 Direct effect 0.147 Indirect effect via X 2 (ED) 0.173 Indirect effect via X 3 (Ph.M) 0.767 Total 2 X 2 (ED) vs. grain yield 0.428 Direct effect 0.154 Indirect effect via X 1 (LAI) 0.069 Indirect effect via X 3 (Ph.M) 0.651 Total 3 X 3 (Ph.M) vs. grain yield 0.343 Direct effect 0.226 Indirect effect via X 1 (LAI) 0.087 Indirect effect via X 2 (ED) 0.656 The data showed that the direct effects of leaf area index on grain yield were 0.447. The indirect effects of this trait through both ear diameter and physiological maturity were 0.147 and 0.173 Table (3). These results indicated that the relative importance of leaf area index on grain yield was 48.63% Table (4). Ear diameter proved to have moderate direct effect on grain yield 0.428. the indirect effect of this character through the other traits were low or very low (0.154 and 0.069) Table (3). However, the relative importance of direct and joint effects for ear diameter was 24.25% Table (4). The direct influence of physiological maturity on grain yield moderate also, the indirect effects of this trait through leaf area index and ear diameter were moderate 0.226 and low 0.087 respectively Table (3). On the other hand, relative importance of physiological maturity was 11.76%. These results coincide with those obtained by (Shehata, 1975; Salama et al., 1994; Yasien, 2000; Amin et al., 2003; AL- Ahmad, 2004; Sadek et al., 2006). Generally, it can be concluded that the contribution of leaf area index, ear diameter and physiological maturity for grain yield variation account 84.64% while the residual effect amounted to about 15.36% 634

of the total variation. Leaf area index, ear diameter and physiological maturity seemed to be the most important sources affecting grain yield variation and consequently may be considered as important characters in selection programs aiming to maize yield improvement and the breeder may consider these traits as the main selection criteria. Table (4). Relative importance (direct and joint effects) in percent of grain yield variation CD RI% 1 LAI (X 1 ) 0.1998 19.98 2 ED (X 2 ) 0.1832 18.32 3 Ph.M (X 3 ) 0.1176 11.76 6 (X 1 ) (X 2 ) 0.1316 13.16 7 (X 1 ) (X 3 ) 0.1549 15.49 10 (X 2 ) (X 3 ) 0.0593 5.93 Residual 0.1536 15.36 Total relative importance 84.64% CD denote coefficient of determination RI% denote relative Importance CONCLUSION Leaf area index, ear diameter and physiological maturity had high narrow sense heritability and positive correlations with grain yield also, its total contribution was 84.64% of the total grain yield variation therefore, it seemed to be the most important sources affecting grain yield variation and consequently may be considered as important characters in selection programs aiming to maize yield improvement and the breeder may consider these traits as the main selection criteria. REFERENCES Abd El- Aty, M. S. and Y. S. Katta (2002). Correlation and path coefficient analysis for grain yield and its components in some maize hybrids (Zea mays L.). J. Agric. Sci., Mansoura Univ., 27(6): 3697-3705. Abd El- Sattar, A. A. (2003). Genetic parameters estimation from design-1 and S 1 lines in maize. Minufiya J. Agric. Res., 28 (5): 1387 1402. Abou- Deif, M. H. (2007). Estimation of gene effects on some agronomic characters in five hybrids and six population of maize (Zea mays L.). World. J. Agric. Sci., 3(1): 86-90. Ahsan, M. (1999). Performance of six maize (Zea mays L.) inbred lines and their all possible as well as reciprocal cross combinations. Pakistan. J. of Biol. Sci., 2(1): 222-224. AL- Ahmad, A. S. (2004). Genetic parameters for yield and its components in some new yellow maize crosses. Ph.D. Thesis, Fac. of Agric., Ain Shams Univ., Egypt. Amer, E. A. and H. E. Mosa (2004). Gene effects of some plant and yield traits in four maize crosses. Minofiya J. Agric. Res. 1(29): 181-192. Amin, A. Z.; H. A. Khalil and R. K. Hassan (2003). Correlation studies and relative importance of some plant characters and grain yield in maize single crosses. Arab Univ. J. Agric. Sci., Ain Shams Univ., Cairo, 11 (1): 181 190. Asrar-ur-Rehman, S.; U. Saleem and G. M. Subhani (2007). Correlation and path coefficient analysis in maize (Zea mays L.). J. Agric. Res., 45(3): 177-183. Aydin, N.; S. Gökmen; A. Yildirim; A. Öz; G. Figliuolo and H. Budak (2007). Estimating genetic variation among dent corn inbred lines and topcrosses using multivariate analysis. Journal of Applied Biological Sciences., 1(2): 63 70. Dewey, J.R.; K. H. Lu (1959). Correlation and path coefficient analysis of components of crested wheat grass seed production. Agron. J. 51:515-518. El- Agamy, A. L.; S. B. Mourad and S. E. Sadek (1992). Improvement of grain yield and other characters in two maize pools by S 1 progeny selected method. Egypt. J. Appl, Sci. 7: 300-308. El- Beially, I. E. M. A. (2003). Genetic analysis of yield characters in yellow maize inbred lines. Zagazig. J. Agric. Res., 30(3): 677-689. El- Hefnawy, N. N. and F. A. El- Zeir (1991). Studies on the genetic behavior of some parental lines of maize and their single crosses under different environmental factors. Annals of Agric. Sci., Moshtohor, 29(1):97-116. El- Hosary, A. A.; S. A. Sedhom and S. A. Mohamed (1989). Correlation and path coefficient studies in maize. Annals of Agric. Sci., Moshtohor, 27(3): 1517-1525. 635

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