Combining Ability Analysis for Seed Yield and Component Traits over Season in Blackgram [Vigna mungo (L.) Hepper]

Blackgram [Vigna mungo (L.) Hepper] is an important food legume crop of Indian sub-continent. It is an important short duration crop and widely cultivated in India. It provides easily digestible good quality protein and has ability to improve the fertility of soil through symbiotic nitrogen fixation. The seeds are highly nutritious with protein (20-26%), carbohydrates (60%), fat (1.5%), minerals, amino acids and vitamins. The biological value improves greatly, when wheat or rice is combined with blackgram because of the complementary relationship of the essential amino acids such as arginine, leucine, lysine, isoleucine, valine and phenylalanine, etc. (Mehra et al., 2016). In India, the area under blackgram is about 4.50 million hectares with a production of 3.23 million tonnes (Annonymous, 2018). However, the productivity of blackgram is low which can be increased with the development and release of high yielding cultivars. Combining ability analysis is an important tool in assessing the usefulness of parents and understanding the magnitude of gene action involved in the inheritance of quantitative traits of economic importance. Assessment of combining ability in single season may not be precise as the environment may affect the estimates of combining ability. With this background the present investigation was attempted to estimate the general and specific combining ability of parents and hybrids, respectively for seed yield and its components in blackgram through line ´ tester mating analysis over two seasons.

The experimental material consist of 20 F₁ hybrids developed by four  lines (ADT 5, Vamban 3, CO 5 and MDU 1) and five testers (Mash 114, Mash 1008, VBN (Bg) 4, VBN 6 and VBN 8). All the lines, testers and cross combinations were grown in randomized block design with two replications at the National Pulses Research Center, Vamban during summer 2018 and Kharif 2018. Each cross was raised in single row of 4 m length with 30 ×10 cm spacing. Recommended agronomic packages of practices for Tamil Nadu were followed to raise healthy crop. Nine quantitative characters were recorded viz., plant height (cm), number of branches per plant, number of cluster per plant, number of pods per cluster, number of pods per plant, pod length (cm), number of seeds per pod, 100-seed weight (g) and seed yield per plant (g). Five randomly taken plants per entry were used for measuring traits. The data were subjected to statistical analysis. Pooled analysis for line × tester analysis was carried out using Windostat software (Indostat Private Limited Hyderabad) as per the procedure suggested by Kempthorne (1957).

The pooled analysis of variance due to parents and hybrids for nine characters are presented in Table 1. It revealed that the variance due to environments was significant for all characters. Variances due to genotypes and genotype × environment was significant for all the characters, except number of pods per cluster. In case of analysis of variance for combining ability, variance due to environment was significant for all the traits, except for plant height and number of clusters per plant. Variances due to lines were significant for all the traits, except number of pods per cluster and number of pods per plant. These results indicated that lines had significant differences for gca effect for these traits. Variance due to tester was significant only for plant height. It indicated the presence of significant differences for gca effects of testers for this trait. Interaction effect of lines and testers was significant for number of clusters per plant, number of pods per plant, 100-seed weight and seed yield per plant. It indicates that sca effect of hybrids had significant differences for these traits. Environment × tester was significant for 100-seed weight while environment × line was not significant for any of the traits. It indicated that gca effects of testers for 100-seed weight alone had influence of environment. The gca effects of other traits of testers as well as of lines was not affected by the environment. The environment × line × testers variance was significant for all traits, except for plant height, pod length and 100-seed weight. It indicated that the sca effects of hybrids had significant influence of environment on all traits except plant height, pod length and 100-seed weight. The estimates of additive and dominance variances revealed the preponderance of additive gene action for all the characters, except number of pods per cluster (Table 2). Preponderance of additive variances in the expression of different characters in blackgram was also reported by Baradhan and Thangavel (2011), Cheralu et al., (1999), Dana and Das Gupta (2001), Govindaraj and Subramanian (2001), Singh Mohar (2008) and Thamodharan et al., (2015).
 

 

        
The success of any breeding programme largely depends on the choice of parents used in the hybridization. Gilbert (1958) suggested that the parents with good per se performance would result in better hybrids. Genotypes with high per se performance and high gca effects could be useful in evolving promising genotypes in the breeding programmes. The gca effect is due to additive gene action and fixable (Sprague and Tatum, 1942). Hence parents with desirable per se and gca effects need to be involved in breeding programmes.
        
Per se performance is an important and foremost criterion in the choice of parents in any plant breeding programmes.In the present study, lines viz., MDU 1 and CO 5 were on par with the best check VBN 8 for seed yield per plant and other characters viz., number of pods per cluster, number of pods per plant, pod length, number of seeds per pod and 100-seed weight (Table 3). Besides Vamban 3, CO 5 and MDU1 exhibited superior per se performance for number of clusters per plant. Among the testers Mash 1008 recorded significantly high mean for number of clusters per plant and number of pods per plant. Parents viz., ADT 5, Mash 114, Mash 1008, VBN 6 and VBN 8 had on par performance for plant height with VBN 8.The second criterion of selection of parents is the general combining ability effect of parents. Among lines MDU 1 recorded significantly positive for seed yield per plant and other characters viz., number of clusters per plant and100-seed weight (Table 4). Vamban 3 had significantly positive gca for number of branches per plant, pod length, number of seeds per pod and 100-seed weight. ADT 5 and Mash 114 recorded significant negative gca effect of plant height. Among testers Mash 1008 was found to be a good general combiner for number of branches per plant, number of clusters per plant. VBN (Bg) 4 had good general combining ability for 100-seed weight. Griffing (1956) suggested that high gca effect is relative to additive type of gene action that represents the fixable genetic variation. Hence the genotypes with good combining ability effects for seed yield and component traits namely, MDU 1, Vamban 3, Mash 1008 and VBN (Bg) 4 may be considered as desirable for recombination breeding programme.
 

        

 
Among the hybrids MDU 1 × Mash 1008 and MDU 1 × VBN 8 recorded significantly superior seed yield per plant than best check VBN 8 (Table 5). These crosses also recorded superior mean for number of branches per plant, number of clusters per plant and number of pods per plant. In addition, the cross MDU 1 × VBN 8 also had superior mean for number of seeds per pod. Among these crosses, Vamban 3 × VBN (Bg) 4 showed superior mean performance for number of branches per plant, number of clusters per plant, number of pods per plant, number of seeds per pods and 100-seed weight. Hence the crosses viz., MDU 1 × Mash 1008, MDU 1 × VBN 8, Vamban 3 × Mash 114 and Vamban 3 × VBN (Bg) 4 were considered as desirable based on mean performance for seed yield and component traits. The specific combining ability is the deviation from the predicted performance on the basis of general combining ability (Allard, 1956).In contrast to gca effects, the sca effects represent dominance and epistatic variation that are not fixable. Among the crosses based on per se performance, the hybrids Vamban 3 × Mash 114 and Vamban 3 × VBN (Bg) 4 showed significant positive sca effect for number of clusters per plant and number of branches per plant, respectively. All other traits had non-significant sca effects in these two crosses. MDU 1 x Mash 1008 and MDU 1 × VBN 8 showed non-significant scafor all the traits, except for number of clusters per plant (Table 6). The present findings were also supported by the findings of Anbu Selvam and Elangaimannan (2010), Isha Parveen et al., (2012), Gill et al., (2014), Vijay Kumar et al., (2014) and Panigrahi et al., (2015). One of the parents involved in these crosses, MDU 1, was found to be a good general combiner for seed yield per plant, number of clusters per plant and number of pods per plant. The gene action involved in these crosses may be of additive type. Hence, MDU 1 × Mash 1008 and MDU 1 × VBN 8 may be used for further selection through pedigree breeding to obtain high yielding segregants.
 

 

        
In the present study, out of nine parents, MDU 1 recorded high per se performance and good general combining ability for seed yield per plant and other yield component traits. The hybrids viz., MDU 1 × Mash 1008 and MDU 1 × VBN 8, recorded high per se and additive type of gene action for seed yield and component traits. Hence, these crosses could be used for further selection through pedigree breeding to obtain high yielding segregants.

Conceptualization of research (N. Manivannan); Designing of the experiments (N. Manivannan, A. Mahalingam, V.K. Satya and C. Vanniarajan); Contribution of experimental materials (N. Manivannan); Execution of field/lab experiments and data collection (K. Vadivel); Analysis of data and interpretation (K. Vadivel and N. Manivannan); Preparation of the manuscript (K. Vadivel, N. Manivannan and A. Mahalingam).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.