In this study 32–92% heterosis was obtained over mid-parent and 19.78% over better parent for pod number. For seed yield, 9.52% heterosis over mid-parent and 7.27% over better parent and in-breeding depression have been reported. Inbreeding depression was observed to the extent of 9.28%.

The percentage of heterosis for seed yield in F1s over their respective mid-parents ranged from 1.61 to 293.11 and over the better parent, the range was –44.21 to 166.91. Three top-crosses involved low x high yielding parental lines; out of 6, which did not express significance, 4 crosses fell in low x low group. In almost all the crosses, heterosis in yield was accompanied by heterosis in pod number/plant. Negative heterotic effects were recorded for 100 seed weight over better parent in most of the crosses. Pods per plant contributed positively to yield of F1s followed by pod width.

Five elite genotypes (RW, Co.8, HA-4, I-76 and RT) of different degree of maturity and genetic diversity were crossed in all possible combinations. F1s along with their parents were grown during kharif season of 1977 in a randomized block with 3 replications. And the same 5 parents, 10 F1s, 10 F2s and 10 F3 s were repeated in 1979.

Significant GCA and SCA variance for all the characters indicated the involvement of both additive and dominance gene action. The ratio of GCA/SCA variance was greater than unity for most of the characters. It is clear here that additive gene action is involved. 

The magnitude of GCA variance remained almost the same in F1, F2 and F3 generations. Even though the magnitude of SCA variance declined towards F3, it still remained high. This shows the operation of additive x additive type of epistasis. 

Combining ability analysis revealed that the parents HA-4 followed by CO.8 were the best combiners for early flowering, early maturity, high harvest index, inflorescence length and less plant spread. The parent L-76 was the best combiner for yield and other yield components. 

The genetic and graphic analyses and heritability obtained in the narrow sense further confirmed the influence of predominant additive gene effect with partial dominance. But the characters like days to maturity, inflorescence number, pods per plant, seed yield, pod yield and plant spread exhibited over dominance.

On overall basis, pod yield showed low heritability and the remaining characters showed moderate to high heritability. The predominance of dominant gene expression was observed for all the characters except harvest index. For harvest index, only F1 (1979) analysis indicated excess of dominant genes

Higher SCA effects and heterosis for seed yield were found to be associated with more inflorescence number and pods per plant. Hence these characters could be used as selection criteria for yield improvement. 

For the important yield components like inflorescence number and pods per plant as well as seeds per pod, additive (d.) and additive x additive (î) type of gene action was predominant. Hence for the improvement of these characters, simple pedigree breeding method was suggested. In addition to additive (d.) and additive x additive (î) type of gene effects, the remaining characters also showed the influence of dominance (h) or dominance x dominance (î) type of gene effects. Hence bulk breeding method adopting single seed descent to advance generations and further single plant selection for rapid improvement of these characters was suggested 

Nine field bean genotypes were subjected to genetic analysis of 14 quantitative characters through a complete diallele technique and association analysis in order to investigate the nature of inter- relationships among these characters.The GCA variance was higher than SCA variance in respect of 12 characters, indicating the operation of additive and / or additive x additive or still higher order interactions between additive genes for these characters. 

In respect of parental mean performance, Bangalore local, Chikkaballapur local, L-76 and Ginnu were found to be the best parents for most of the characters studied. The parents Bangalore local, Chikkaballapur local and L-152 were found to be the top general combiners for most of the characters. The cross L.152 x L. 76 gave highest heterosis for pods per plant and pod yield per plant. L-152 x RW gave the highest heterosis for seed yield per plant. 

Five parents, viz., Rajani, 6802, KT2, KT1 and 7001 were crossed in half-diallele to get 10 F1s in 1973–74. F1s were advanced to F2 generation next year. The experimental material consisted of 15 treatments (10 F2s + 5 parents). They were grown in RBD with 3 replications in 1975–76. 

Variation was significant for all the characters. The estimates of mean sums of squares due to general and specific combining ability were highly significant, indicating the importance of additive as well as non-additive gene effects. However, the influence of the latter is more predominant. To exploit the different types of gene action as revealed in this study, the population breeding in the form of biparental mating between selected recombinants and mating of selected segregants between crosses in F2 generation may prove most effective in improving the populations. Further, this approach is likely to break the possible undesirable linkages and subsequently result in establishment of rare desirable recombinants. Parents Kalyanpur type –2, 6802 and Rajani are best general combiners for yield and most of the component traits. It was observed that both the parents and crosses with significant general and specific combining ability, respectively, for yield/plant invariably showed average to significant combining ability effects for number of pods/plant, pod length, pod width, number of seeds/pod, number of pods/ raceme, etc.  

High heritability in broad and narrow senses for days to flower, pod length, pod width and 100 seed weight indicated the prospect of improving these characters through selection. H.D.18 was a good general combiner: JDL 79 x H.D.18 and JDL 53 x Hebbal were the good specific combiners in desirable directions for improvement of yield and most of its component characters. It is suggested that biparental mating between the selected recombinants and recurrent selection may prove most effective with a view to exploiting the additive and dominance component of variation. 

Fifteen crosses showed positive heterosis over better parent for dry weight of leaf and the value ranged from -65.76 to 70.65% and the maximum being expressed by the cross MS.9488 x CO.1. The role of additive gene effects was suggested. Significant positive heterosis was also observed for dry weight of the stem and the hybrid MS.9495 x CO.1 showed maximum value of 36.76%. The role of both additive and non-additive gene effects was proposed in this case. For dry matter yield, the heterotic value ranged from -61.31 to 57.34% and the highest was recorded with MS 9448 x CO.-1 suggesting the operation of additive gene effects. 

In respect of crude protein, majority of the crosses showed negative heterosis and the same ranged from –25.77 to 15.05%. The maximum was with the cross PLS 966 x CO-1. These results indicate that there is a possibility of getting some segregants better than their parents for early generation selection in the material studied. 

Genetic analyses of 8 quantitative characters were conducted in a 6 x 6 diallele population of Lablab bean, grown under 2 soil fertilities in the field at Mymensingh, Bangladesh during 1994-95. The 2 soil fertilities included one with added N, P2 O5 and K2 applied in the form of urea, triple superphosphate and muriate of potash, respectively (F+), and the other without any added nutrients (Fo). Both general combining ability(GCA) and specific combining ability (SCA) variance were significant for all the characters except SCA variance for number of pods per inflorescence in added fertilizer condition. Diallele analysis suggested predominant role of additive gene action for days to flower, pod width, seeds per pod and 20-pod weight while inflorescences per plant, pods per inflorescence and pod yield per plant were mostly governed by non-additive genetic effects. Parent DS-52 proved to be the best general combiner under both fertilities for majority of characters, including pod yield. For SCA effects, cross KBS-1 x DS-161 provided the best specific combination for yield under F+ condition. For most of the characters, the cross between good general combiners did not produce good specific cross, rather poor x poor and good x poor combinations showed better SCA results. 

Significant heterotic effects and high per se performance with respect to seed yield per plant was recorded by the cross Red Paria x Akw–9304, Red Paria x NVS–31 and 125–36 x NVS–121. Crosses exhibiting high heterosis for seed yield also depicted high heterosis for one or more yield attributing traits over their better parents. 

High heterotic effects were observed for days to maturity and protein content, moderate for days to flowering, number of branches per plant, number of seeds per pod and plant height. High heterotic cross for the seed yield was ND 4 x ND10. High heterotic response for seed yield per plant was mainly due to pods per plant, pod length and number of seeds per pod. 

Seven cultivars (K6802, JDI-79, Chakdah Local, JDL-17, HD-18, JDL-53 and JDL-73) and one cultivar of Dolichos biflorus (Macrotyloma uniflorum) (Hebbal) were used for genetic analysis and for the study of combining ability effects for some seed characters, viz., number of seeds per pod, seed weight per pod, single seed weight, seed length, seed width, seed thickness and seed yield per plant.  

Chakdah Local was the best general combiner for number of seeds per pod and seed yield per plant, whereas JDL-73 x Hebbal, HD.18 x JDL-73 and HD-18 x JDL-53 were identified as potential specific combiners for seed yield per plant. The highest magnitude of heritability in the narrow sense was recorded for single seed weight; minimum heritability in the narrow sense was recorded for seed length and seed yield per plant. The estimates of genetic parameters indicated that most of the characters studied were controlled by additive gene variance.  

Fifteen crosses derived from five female lines along with three improved testers as male were studied for 12 yield contributing, growth and developmental characters. It was observed that heterosis for growth indicated positive heterosis of high magnitude for plant-height in ACCW-165 x Konkan Bhushan. The cross ACCW-113 x Arka Vijay showed high heterotic effect of 81.17% over mid-parent for primary branches per plant. The number of leaves per plant showed high heterotic effect in the cross ACCW-116 x Arka Vijay. The cross ACCW-116 x Hebbal-3 showed highest effect to the tune of 176.18% over mid-parent and 83.38 % over best parent for leaf area. Hybrid ACCW-116 x Hebbal-3 had high negative heterosis for days to first flower and days to first pod maturity. The days to overall maturity had negative heterotic effect shown by cross ACCW-166 x Konkan Bushan. The span of flowering had maximum heterosis of 22.67% as indicated by ACCW-165 x HA 3.  

Diallele analysis includes combining ability effects and components of genetic variation. They were estimated over two environments for flower characters from a half-diallel cross by involving six parents. Both general combining ability (GCA) and specific combining ability (SCA) were important for all characters with preponderance of additive gene actions. Environment had significant effect on all characters except flowers/ inflorescence. Best general combiners were DS.52, DS.106, DS.112, etc. Complete dominance was observed for flowering date in environment-II, flowers/inflorescence in environment-I and pods/inflorescence in both environments. Over dominance was found for flowering date in environment-I and partial dominance for flowers/inflorescence in environment-II and for inflorescence/plant in both environments. Characters were governed by assymetrical distribution of positive and negative alleles. Dominant and recessive genes were equally distributed for flowering date and inflorescence/plant, whereas unequally distributed for flowers/inflorescence and pods/inflorescence. One or two gene groups were involved in flower characters of Lablab bean.  

This study reported yield components in 15 crosses of from six diverse parents (ACCW- 166, ACCW–113, ACCW–116, Konkan Bhushan, Arka Vijay and HA 3) in a half diallele fashion excluding reciprocals. The crosses showed significant heterosis over mid-parent and also over better parent. The percentage of heterosis for seed yield in F1s over their respective mid parents ranged from –24.296 to 159.824% and over better parents, the range was –32.177 to 101.195%. The top crosses involved medium x low yielding parental lines. In almost all the crosses, heterosis in yield was accompanied by heterosis in pods per plant, harvest index, peduncles per plant and most of the other characters under study. 

Five parents’ viz., Co.9 co.12, Co.13, and COLT. 22 were crossed in all possible combinations (diallele). Four parents with 12 F1 hybrids and F2s were raised in completely randomized block with 5 replications at TNAU, Coimbatore.  

Relative heterosis in some crosses ranged from –37.09% to 253.79% for seed yield, –13.03% to 55. 52% for plant height and –35.05% to 255.22% for number of pods per plant. All the hybrids exhibited positive heterosis for number of seeds per pod ranging from 1.30 to 46.53%, while all the hybrids exhibited negative heterosis for 100 seed weight, which varied from 40.95% to –6.69%. 

Appreciable amount of in-breeding depression was exhibited by almost all the hybrids in F2 generation which showed heterosis in F1 generation. It ranged from –4.40 to 73. 64% for seed yield per plant, 4.67 to 44.71% for plant height and –16.48 to 67.56% for number of pods per plant. Number of seeds per pod exhibited an in-breeding depression ranging from –10.77 to 28.81%, while the seed weight exhibited –35.41 to 14.71%. 

Plant height, number of pods per plant and seed yield per plant showed high heterosis followed by high in-breeding depression indicating non–additive gene action. However, combinations Co 13 x COLT 22 for pod, number of branches per plant and COLT 22 x Co13 for pod length exhibited high heterosis coupled with in-breeding vigour. This may be attributed to epistatic gene action. The crosses COLT 22 x Co12 and Co12 x COLT 22 for pod length showed high heterosis with low depression, which suggests a high proportion of fixable genes in these crosses. Hence, these crosses can be used for pedigree breeding method to obtain useful segregants. For 100 seed weight, Co13 x Co12 showed significant negative heterosis and high in-breeding vigour. This indicates the occurrence of transgressive segregation and presence of additive genes. 

Estimates of GCA effects revealed that parents NW-14, NW-4 and NW-13 were the best general combiners for seed yield/plant. For days to 50% flowering, NW-47 was the best general combiner which exhibited negative significant GCA effects, followed by NW-4. Significant negative GCA effects for days to maturity were recorded by NW-47, NW-4 and NW-13. Desirable GCA effect for plant height was scored by the parents NW-52, NW-5 and NW-49. Parents NW-4 and NW-13 were the best general combiners for pods/plant, whereas, NW-4 was the best for 100 seed weight. The best general combining parents for protein content, pod length and branches/plant were NW-52, NW-49 and NW-4, respectively. 

The crosses with high SCA effects, NW-5 × NW-52 was the best specific combiner for seed yield/plant, whereas crosses such as NW-47 × NW-52 and NW-47 × NW-4 were good specific combiners for seed yield/plant and pods/plant. The cross combinations NW-5 × NW-49, NW-47 × NW-4 and NW-47 × NW-52 had good SCA effects for days to 50% flowering. The best combination for days to maturity was NW-47 × NW-52, followed by NW-47 × NW-4, NW-47 × NW-52 and NW-20 × NW-49 showed maximum SCA effects for seeds/pod, 100 seed weight and pod length, respectively. For plant height, NW-20 × NW-49 and NW-4 × NW-14 were desirable. The cross combinations NW-47 × NW-4, NW-4 × NW-13 and NW-5 × NW-49 were promising for branches/plant.