Eighty-one genotypes of field bean comprising 32 exotic and 49 indigenous collections were subjected to canonical and multivariate analysis for twenty characters.
The Canonical variable analysis has shown that the first three vectors accounted for 71.34% of the total variability produced by all the 20 characters. Of these, three vectors, days to flower, days to maturity length of pods and seed protein contributed maximum towards divergence.
16 clusters were formulated based on D2 value calculated over 20 characters. The clustering pattern did not follow geographical distribution but was at random. It was observed that early and medium maturing genotypes had slightly higher percent of seed protein than the late maturing genotypes. These two groups could be clearly demarcated since they aggregated separately on two sides of the graph. As in Canonical variate analysis, discrimination was marked for days to flowering, days to maturity and seed protein. Great diversity existed among most important characters which might have resulted due to long term selection in different directions by natural and human forces.
In another experiment, the F2 and F3 generations of four intervarietal crosses: HA.3 x CB (cross A), HA.3 x US.8 (cross B), HA.1 x 208 and HA-1 x 169 (crosses C and D, respectively) were evaluated with the objective of assessing the variability, choosing the desirable cross and sibs within the selected cross, assessing the dependability of F3 performance over that of F2 and finally to understand the impact of genetic distance on the selection of parents for hybridization.
In the F2 generation, the crosses A, C and D exhibited high mean and variability for number of pods per plant, weight of pods and seed yield per plant.
The mean of the F3 was considerably reduced for all these characters. In the F3, the crosses A and C maintained their superiority over the other two crosses in their performance and variability, especially the most important yield contributing character, number of pods per plant.
In the F2, high heritability with high genetic gain was observed for number of pods per plant, number of inflorescences per plant, weight of pods and seed yield which revealed the usefulness of these characters in formulating selection indices. Number of pods per plant, weight of pods and seeds per pod exhibited strong correlation with seed yield per plant and between themselves as seen in the D2 experiment.
Transgressive segregation beyond the parental mean was observed in the F3 generation, which indicated that selection could be commenced in the F3 generation. A random ten percent of the F2 segregants were advanced to F3 generation. The results revealed the adequacy of this proportion of the selected plants for further evaluation .
The overall performance of all the four crosses revealed that maximum coefficient of variation with high mean values for three quantitative characters, namely, number of pods per plant, weight of pods and seed yield per plant were higher in cross A (HA.3 x CB) which had the maximum inter-cluster distance of 491.92. The number of transgressive segregation was also highest in this cross. Thus there appears to be an influence of genetic distance in the selection of parents with high coefficient of variation for important yield contributing traits in field bean.
Nayar reported that days to flower, days to maturity, and length of pods and seed protein content contributed maximum towards genetic divergence. He studies 81 genotypes those were grouped into 17 clusters. It was observed that early and medium maturing types possessed higher seed protein percentage. IC 3244 (UP) had the highest seed protein (31.59%) as against IC 10191 (Rajasthan) which contained 18.29%. The clustering pattern did not follow the geographical classification. Chikkaballapur and Hebbal Avare 3 which had maximum inter cluster distance resulted in maximum transgressive segregation on crossing.
Commonly grown varieties of Dolichos lablab in different agro climatic regions of the state (MP) along with some improved ones were tried in randomized block design with five replications at JNKVV, Jabalpur. Observations were made on 10 characters. Mahalanobis Statistics was used to measure the genetic divergence.
The genotypes formed 13 Clusters, six of which were single variety Clusters. Cluster IV included the largest number of varieties (13). Bold seeded varieties, Jabalpur-4, Jabalpur-3 and small seeded Indore Choudy and CBS No.32 formed independent Clusters mainly differing in 100-seed weight. The 100-seed weight being 50.28, 45. 48. 11.81 and 13.67 g, respectively. The genetic distance was found to be maximum (72.4) between groups VI (Jabalpur-10, Jablpur-11) and XIII (CBS-32) followed by single variety groups- Jabalpur-8 and Sarguja -1 (69) indicating that these varieties had higher divergence. It was minimum (13.166) between groups VIII and II followed by (13.241) between groups IV and III indicating they are very close to each other. A single variety Cluster VIII was noted to be genetically closer to multivariety Clusters II, I, IV and III and single variety Clusters; groups XII and XIII were closer while other single variety Clusters were highly divergent. In general, multivariety Clusters were found to be closer with each other.
The intra-cluster distance ranged from 0.0 to 11.70, the maximum being in Cluster V with only 3 genotypes, while Cluster IV with 13 genotypes recorded only 8.97 D2 value. In general, single genotypes recorded only 8.97 D2 value and thus these genotypes were found to be highly divergent as also evidenced from the character means for various Clusters.
The inter-cluster D2 values indicated that Cluster VII was the lowest for petiole length (0.695), pods/plant (0.167) and pod yield/plant (0.041). Cluster III was the highest for leaflet area (5.499) and Cluster II was the lowest (0.052). The same for pod length and 100-seed weight was the highest in Cluster VII (1.414) and the lowest in Cluster I (0.075) as also evidenced from the Cluster for pod length (17.05, 11.18). The trend in the case of 100-seed weight was similar in these two Clusters. The intra-cluster D2 value for days to flowering was the lowest (0.007) in Cluster-VI, while it was the highest (0.858) in Cluster VII. Cluster-IV has the highest D2 value for seed: pod ratio (2.028) and the lowest in Clusters V. Cluster IV had the highest D2 value for yield/plant (0.890) and it was the lowest in VII. The Cluster I had the highest (0.279) for protein content.
The highest contribution towards genetic divergence among the genotypes attributed to 100-seed weight (12.857%), seed: pod ratio (12. 38%) pod length (12.063%) and protein content (11.904%) whereas, pod width and yield/plant contributed minimum to divergence (5.555, 5.837%). This indicated that the protein content of the genotypes is as important as 100-seed weight and pod length in hybridization programme.
Data on 6 agronomically important traits were recorded in 48 strains collected from 8 Indian states. Using the Mahalanobis D2 Statistics, the strains were grouped into 10 clusters, with days to flowering, and number of pods/ bunch contributing most to genetic divergence. Most clusters included varieties from different geographical regions. Canonical analysis confirmed the D2 grouping
Twenty eight genotypes collected from different states including local landraces were tried at Keonjhar (Orissa) in 1994 and 1995 in randomized block with 2 replications. Observations were made on 8 characters and the data were analysed by applying D2 statistics. The genotypes were grouped into different clusters. Principal component analysis (Canonical) was done to know the relative contributions of different traits to the total variation.
Twenty eight genotypes fell into 5 clusters on the basis of D2 values. The distribution pattern of genotypes into clusters indicated that Cluster I was the largest containing 22 genotypes followed by Cluster III with 3 genotypes. Remaining 3 Clusters (II, IV and V) had a single genotype each. The members of the I Cluster had originated from different geographic regions and genetic divergence did not follow the same trend.
The intra-and inter-cluster average D2 values indicated that the geographical distributions could not be related to spatial patterns of the Clusters. Clusters II and V showed maximum divergence between them (285.61) followed by Clusters I and V (272.30) and clusters I and IV (194.06). Minimum divergence was observed between Clusters II and III (69.62), followed by Clusters II and IV (85.66). Cluster I (62.59) had higher intra-cluster D2 value followed by Cluster III (58.19). However, Clusters II, IV and V had no Cluster distance (0) as they were represented by a single genotype each. These results suggest that genetic drift and selection could cause greater diversity than geographic distance.
Differences in cluster means existed for almost all the characters studied. Cluster-I had low mean values for days to first flowering (63.91). Cluster-II had highest pods/plant as well as high 100-seed weight. Higher mean pod girth was associated with Cluster IV. Cluster V had maximum mean pod length, pod weight, seeds/pod and total green pod yield/plant.
The mean values of Canonical variates for Z1 and Z2 axes were obtained. The grouping of genotypes done on the basis of Mahalanobis D2 statistics was in conformity with the results of the Canonical analysis. The first Canonical root accounted for 49.89% and the second root for 23.20% of variation. These two vectors accounted for 73.09% of total genetic variation. Sum of all Canonical roots was 1332.68; value of first canonical root, 664.87; value of second Canonical root, 309.18; percentage of variation absorbed by first root is 49.89 and percentage of variation absorbed by second root is 23.20.
The germplasm resources of Dolichos lablab (Lablab purpureus) were investigated in the Quinling-Bashan mountain region, Sichuan. Some 32 germplasm accessions were collected. The distribution area of D. lablab, its cultivation, cultivar types and morphological characteristics are described. Four elite cultivars were recommended.
Lablab purpureus is a fast growing annual multipurpose legume in tropical and sub-tropical farming systems. The ripe seeds and green pods are being used as a vegetable in Asia, while in other tropical regions the whole plant is used as a green cover or as a forage for livestock. Presently, only Rongai and HighWorth released in Australia are being utilized for forage purposes and most of the research carried out on feed quality is focused on these two varieties. Both the Commonwealth Scientific and Industrial Research Organization (CSIRO) and the International Research Institute (ILRI) hold a large collection of forage types of this species. In order to establish a core collection of this tropical legume, a total of 251 accessions was grown in unreplicated, spaced rows at Zwai (Ethiopia - 125 accessions) or Redland Bay, Australia (126 accessions) to study the detailed morphological and agronomic attributes. In both the collections, there was a considerable variation in morphological attributes and a number of indigenous wild types from Africa have been identified in both the collections. While those held at ILRI were large - sized with one to two seeds and originated from Ethiopia, wild types from CSIRO collections had smaller seeds having originated from other East African Countries.
Genetic divergence was determined according to Mahalanobis D2 Statistics (Mahalanobis, 1936) and the genotypes were grouped into clusters. Inter-and intra-cluster distances were also calculated. The clustering pattern followed their respective geographical origin. This suggests that the obvious variation between the clusters might have resulted from the possible genetic drifts and selection.
As a consequence, the character constellations that might be associated with particular regions in nature, lose their individuality under human interference. It is, therefore, important to choose the parents from diverse sources based on D2 analysis rather than geographical isolation for development of improved varieties through hybridization.
The intra-and inter D2 values on pooled basis have shown that clusters IX, XII, XII, XIV and XV had a zero magnitude of intra- cluster distance as they were solitary. cluster VI showed maximum divergence (160.90). The other clusters remained in- between these two values. In the present study, the intra- cluster distance was maximum between cluster VIII and cluster XV (2313.60). This suggests that the genotypes from these clusters were highly divergent from each other. Similarly, clusters XI and XV were also quite diverse (2046.10). The minimum intra- cluster distance was observed between cluster II and cluster V (150.00) which indicates the closeness of the genotypes in these clusters.
The cluster means for 14 characters on pooled basis indicated that the solitary cluster CA with genotype GA-19 had the highest mean in respect of grain yield per plant, branches per plant and pods per plant. The cluster VIII exhibited lowest means for days to 50% flowering, days to maturity and inflorescence per plant. It could, therefore, be concluded that significant genetic diversity exists among 144 genotypes for most of the important characters. This could be explained on the basis of long term selection in different directions-natural and human. In this context, grain yield, pods per plant, inflorescence per plant, branches per plant and days to 50% flowering are the important characters contributing substantially to the genetic divergence. Hybridization between the members of the divergent groups might be rewarding in terms of crop improvement for better yield and quality as well as for early maturity and photo-insensitivity.
About 122 accessions were sown in Redland Bay experiment including cvs. HighWorth and Rongai, while the Zwai experiment contained 127 accessions. Characterization of all the 249 accessions was done using a common set of morphological and agronomic attributes. The data collected were analyzed using multivariate analysis and a classification constructed for each collection. Considerable diversity was observed in most of the attributes measured. Seed weight, time to flower and plant height were the most important attributes in determining group allocation in both classifications.
Sub-species uncinatus was clearly separated from the remainders of the collections in both the classifications. All other groups contained ssp. purpureus except for a few accessions with long, narrow pods of spp. bengalensis. Both collections had a high proportion of L. purpureus, spp. purpureus, especially accessions similar to the Australian cultivars Highworth and Rongai. The two classifications provided an overview of diversity and highlighted the similarities and dissimilarities between the two collections.
A range of maturity types and accessions with long pods, which have potential as dual purpose or grain crops for human consumption were included thus representing a whole range of morphological and agronomic diversity supporting the fact that Lablab has the capacity to become a multipurpose legume for both commercial and small holder agriculture. Cultivation of spp. uncinatus was rare and that landraces of this subspecies have a very restricted regional use. Some of the Ethiopian ssp. purpureus landraces collected from regional markets, semidomesticated and wild accessions from Southern Africa and wild accessions from India were also rare. With these observations, a core- collection of the germplasm was developed for better plant breeding and agronomic studies.
In Southern India the Dolichos beans are widely used as vegetable and a pulse as well. The crop has remained unexploited owing to low productivity, long duration, photosensitivity and indeterminate growth habit. However, with the use of existing germplasm.
Legumes are second only to grasses with more than 650 genera and 16,000 species. In Southern India the Dolichos beans are widely used as vegetable and a pulse as well. The crop has remained unexploited owing to low productivity, long duration, photosensitivity and indeterminate growth habit. However, with the use of existing germplasm, Shivashankar and Kulakarni (1989) developed determinate, early maturing and photoinsensitive varieties for Karnataka region in India. But the efforts to enrich the genetic resources and variability in this underutilized crop were minimal. Therefore, in kharif 2004-05, 237 accessions of Dolichos germplasm, collected from Karnataka and neighbouring states, were sown in kharif 2005 and were phenotypically characterized and documented.
All accessions of Dolichos bean differed significantly for all the seed traits such as seed length, width, thickness and 100 seed weight. Large variation was found for seed length which ranged from 7.515 to 12.873 mm and 100 seed weight from 21.00 to 30.00g. Further, 100 seed weight was significantly positively correlated (P<0.01) with the length and seed width. The germplasm was classified based on plant types: determinate types (156 accessions), indeterminate types (50 accessions) and semi-determinate (15 accessions). From these studies, it was concluded that the cultivated field types were mostly determinate and photoinsensitive types, while indeterminate types were spreading and photo - sensitive.
This study showed that Lablab purpureus L. var. <i class="italic">typicus</i > is widely cultivated in many of the states like Tamil Nadu, Karnataka, Andhrapradesh, Orissa, Madhyapradesh, Bihar, Jharkand, West Bengal and North-Eastern States. The plants of this group in general are indeterminate, photosensitive and vegetable poded with wide variation and diversity in pod shape and colour. An exploration was undertaken with the objective of collecting vegetable Dolichos (pole type) landraces and to understand the variability and distribution pattern in eight central districts of Tamil Nadu, viz., Dindigal, Madurai, Sivaganga, Pudukottai, Thiruvarur, Thanjavur, Tiruchrapalli, and Karur. Totally 97 pole type vegetable poded Dolichos landraces were collected from these eight districts. Maximum number of 22 collections (22.7%) were made in Thiruvarur district followed by Thanjavur-16 (16.5%) and Madurai district-15 (15.5%). In Dindugal and Tiruc hirapalli districts there were 11 colle ctions (11.33%) each and they were closely followed by Sivaganga (10 collections with 10,3%) and Karur district with 9 collections (9.3%). Among all the eight districts explored minimum number of landraces (three) was found in Pudukottai district with 3.1%. During collection, data were recorded on pod length, pod width, pod weight and pod colour. Pod length ranged from 6.5 to 18.3 cm and the maximum pod length was recorded in NM 0486. Similarly, pod width ranged from 1.0 to 4.0 cm with the maximum value in NM 049. The pod weight ranged from 40-180 g (NM 0413). Totally 9 different pod colours were observed. These were light- green, green, greenish-purple, purple-green, pink, deep-pink, purple, deep-purple and cream. Maximum of six different pod colours were observed in Madurai and Karur districts followed by Thanjavur and Tiruchirapalli (5 each). Thus, the study revealed that there is a wide variability and diversity for pod length, pod width, pod weight and pod colour among Dolichos accessions in the Central Districts of Tamil Nadu. The collections are further evaluated to isolate pole type vegetable lines.
The estimates of D, which measured the variance due to additive gene effect as well as H, and H which measured the "variance due to dominance gene effect were significant for days to flowering, pod length, pod width (except H), seeds per pod and green pod yield per plant, indicating that both additive and dominance components were important for inheritance of these traits.
Two field experiments-non-pendal (71 local genotypes) and pendal types (43 local genotypes) - were laid out in simple randomized complete block design with two replications at Botany Garden during kharif 2007-2008.
The genotypes were scored for 20 quantitative and 26 qualitative traits. The study revealed a wide range of variability for all the traits. The genetic advance as percent mean in both pendal and non-pendal genotypes was moderate to high for days to 50% flowering, number of primary branches per plant, inflorescence characters, number of green pods per plant, test weight( fresh and dry), shelling percentage (fresh) and green pod yield per plant. The correlation studies revealed that days to 50% flowering, number green pods per plant, test weight, number of racemes per plant and shelling percentage (fresh), showed significant positive association with green pod and seed yield. In pendal types only the pod number recorded the significant positive association with green pod yield per plant. Seventy one non-pendal genotypes were grouped into 13 divergent clusters, where as 43 pendal genotypes produced six clusters in D2 analysis. The cluster II had highest number with 35 and 20 genotypes in non-pendal and pendal types respectively. The inter cluster distance observed was also high revealing the diversity in the local collections studied. Four determinate genotypes showed significantly higher yield over HA-3.
In third experiment 11 genotypes comprising of pendal and non-pendal types, and one lima bean genotype were used for morphological and molecular diversity analysis. The cluster analysis using phenotypic traits resulted in formation of three independent luster one with lima bean, second with semi determinate and determinate types and third with only pendal types. On the other hand, limited molecular diversity was observed among avare genotypes. Further, the molecular diversity was not concurrent with morphological diversity.
A study was conducted at Forage research scheme, Agriculture College, Dharwad during August 2007 to assess the genetic diversity in local collections of field bean [ Lablab purpureus (L.) Sweet]. The study included a total of 68 genotypes from different parts of Karnataka and was evaluated for thirteen characters, viz., days to 50 per cent flowering, days to maturity, plant height, inflorescence length, number of inflorescence per plant, number of primary branches per plant, number of secondary branches per plant, pod length, number of pods per plant, number of seeds per pod, hundred seed weight, protein content and seed yield per plant. The study revealed wide range of variability and high heritability for all the characters. The expected genetic advance as per cent of mean was high for days to 50 per cent flowering, plant height, inflorescence length, number of inflorescence per plant, number of primary and secondary branches per plant, number of pods per plant, protein c ontent and seed yield per plant indicating additive gene action for these traits. From correlation studies, it was observed that seed yield was positively associated with all other characters except with pod length, number of seeds per pod and protein content at both genotypic and phenotypic level. The highest positive direct effect on seed yield at genotypic level was accounted by number of pods per plant. By D2 analysis, 68 genotypes were grouped into eight divergent clusters. Pod length followed by protein content contributed maximum to the divergence. Cluster II contained genotypes with higher mean values for most of the characters studied, which could be utilized to develop promising elite varieties. In screening for pest and disease resistance, the genotypes DA-15 and DA-63 have shown resistance to pod borer and moderate resistance to anthracnose disease and suggested for further evaluation under artificial epiphytic condition.
In recent years, so-called lost crops have been appraised in a number of reviews, among them Lablab purpureus in the context of African vegetable species. This crop cannot truly be considered lost because worldwide more than 150 common names are applied to it. Based on a comprehensive literature review, this paper aims to put forward four theses, (i) Lablab is one of the most diverse domesticated legume species and has multiple uses. Although its largest agro-morphological diversity occurs in South Asia, its origin appears to be Africa. (ii) Crop improvement in South Asia is based on limited genetic diversity. (iii) The restricted research and development performed in Africa focuses either on improving forage or soil properties mostly through one popular cultivar, Rongai while the available diversity of lablab in Africa might be under threat of genetic erosion. (iv) Lablab is better adapted to drought t han common beans (Phaseolus vulgaris) or cowpea (Vigna unguiculata), both of which have been preferred to lablab in African agricultural production systems. Lablab might offer comparable opportunities for African agriculture in the view of global change. Its wide potential for adaptation throughout eastern and southern Africa is shown with a GIS (geographic information systems) approach.
Field investigation with fifteen genotypes was carried out to study the genetic variability during 2008-09. The second experiment was conducted to estimate the heterosis, combining ability of parents and hybrids. The hybrids were obtained by crossing six lines with three testers in line x tester fashion. Eighteen F1s, six lines, three testers and two checks viz., HA3 and local avare were evaluated during 2009-10. The genetic parameters viz., PCV, GCV, heritability and genetic advance were found to be highly significant for inflorescence length, number of inflorescence per plant, number of pods per plant and seed yield per plant indicating the existence of wide range of genetic variability in the material evaluated. The correlation studies revealed strong positive association of yield with number of inflorescence per plant and number of pods per plant. Path coefficient analysis revealed that number of secondary branches per plant had highest positive direct effect on seed yield. The higher magnitude of SCA variance was observed for all the characters compared to GCA variance. Hence, the ratio of GCA variance to SCA variance was lesser than unity for all the traits except number of pods per plant. DA-12 was the best general combiner for number of pods per plant, protein content and seed yield per plant. The cross combinations DA-8 x DA-14, DA-11 x DA-15, DA-12 x DA-14 and DA-12 x DA-15 were found to be promising for seed yield as they had high positive standard heterosis. Genotypes were also screened for pest and disease. Two genotypes viz., DA-6 and DA-14 showed resistant reaction to pod borer. While, DA-1 and DA-9 and crosses viz., DA-11 x DA-13, DA-11 x DA-14 and DA-12 x DA-14 showed resistant reaction to Anthracnose disease.
Dolichos bean, usually grown as a rainfed crop in the topics. It is know as a poor man's bean. It is cultivated either as a pure crop or as a mixed crop with other crops such as Ragi, Jowar, etc., and also grown in home/kitchen gardens. Dolichos bean can be used for its immature and mature green pod apart from its dry seed as pulse. The present investigation was carried out for the development of new lines for its immature pods, mature pods/ dual types. A determinate and photo-insensitive bushy green pod type line was identified from the cross between the GL 554 X HA 4. The selected genotype was identified in the F4 generation. The identified line produces more number of branches, for flowering it takes about 40-45 days and produces green pods for harvest in 70-75 days from the sowing. In addition to green immature pods its immature seeds are also suitable for preparation of various vegetable curries. The bushy vegetable type is suitable for mono-cropping system in irrigated conditions.
Lablab purpureus (L.) Sweet usually know as field bean or Dolichos bean is one of the important legume crops cultivated throughout tropics and subtropics. Most of the existing cultivars are landraces except few are released cultivars. With the advancement of crop improvement a new cultivars have been identified suitable for rainfed cropping system. The promising lines have been identified as a high yield indeterminate type, these lines are GL-127, GL-131, GL-66, GL-49, GL-43, GL-124, GL-409 and Doddamagge grown in three replications. Among them GL-66, GL-43 and GL-49 recorded seed yield of 1125 kg/ha, 1115 kg/ha and 1060 kg/ha, respectively. The cultivars GL-66, GL-43 and GL-49 are suitable for rainfed condition as a mono-cropping or intercropping system.
The experimental material comprised of 32 genotypes of dolichos bean (Dolichos lablab L.). Yield and its eight contributing characters were measured by Mahalanobis's D2 analysis. Thirty two genotypes were grouped into five clusters and the highest intra cluster distance was observed for cluster III followed by cluster V, cluster IV and cluster II. The highest inter cluster distance was observed between the clusters III and cluster I followed by cluster IV and I and cluster V and I. The minimum inter cluster distance was noted in between IV and II. Mean performance of individual cluster for different character were showed that cluster I is most suitable to select better genotypes for number pod per inflorescence and green pod yield per plant. The genotypes collected from same geographical location fall in different clusters, revealed that geographical distance does not contribute to genetic divergence.
Development of a reduced representative set of a large base collection enable its enhanced use in crop improvement. Considering the size of current Dolichos bean germplasm (648 accessions) being maintained at AICRP on pigeonpea, ZARS, UAS, GKVK, Bangalore is unwieldy for management, characterization and evaluation and hence increased use in breeding Dolichos bean, an attempt was made to develop a core set from Dolichos bean germplasm. 644 germplasm accessions along with four check varieties were characterized for 21 qualitative traits and evaluated for 20 quantitative traits following Augmented design during Kharif 2012 at ZARS, UAS, GKVK, Bangalore. Substantial polymorphism for qualitative traits and genetic variability for quantitative traits in the germplasm were evident.
A total of 10 core sets were developed using 20 quantitative traits data following standard stratified sampling and heuristic strategies-based approaches. Qualitative traits-based statistics such as chi-square test and 'class coverage', and 'Shannon-Weaver diversity index' were used as validation criteria to examine homogeneity and retention of qualitative traits-based classes, and polymorphism diversity, respectively in the core sets to assess their representativeness. Quantitative traits-based univariate statistics -mean and variance and standardized multivariate statistics such as SMD%, CR%, VD% and VR% were used to assess the representativeness of core sets. Different core sets were representative of the base collection based on different validation criteria. Heuristic approach-based core set of 10 per cent size was identified as the best representative of the base collection. This core set is suggested as a priority resource for use in breeding Dolichos bean.
Taking the cues from beneficial effects of F2 bi-parental (BIP) mating in several self-pollinated crops, an investigation was carried out to assess the impact of inter se mating in F2 population derived from HA 4 (a high yielding photoperiod in-sensitive released variety) ✕ GL 37 (a photoperiod sensitive germplasm accession) on quantitative traits mean, range, variance, additive genetic variance (σ2A), narrow-sense heritability (NS-h2) inter-relationships and frequency of transgressive segregants in Dolichos bean. F2 BIP mating derived (BIP F3) progenies and selfed (F3) progenies of parents of BIP mating were evaluated for 10 quantitative traits (QTs) at the experimental plots of Department of Genetics and Plant Breeding, UAS, GKVK, Bangalore following Augmented design during 2013 kharif season.
Random mating in F2 population in Dolichos bean was effective in increasing the means, variances, σ2A and NS-h2 of traits such as racemes plant-1, fresh pods node-1, fresh pods plant-1 and fresh pod yield plant-1. BIP mating also resulted higher frequency of individuals that surpassed higher scoring parent for racemes plant-1, fresh pods node-1, fresh pod yield plant-1 and 100 fresh seed weight. The results suggested rapid genetic gain per selection cycle for longer-term and better prospects of deriving superior pure-lines with desired traits/combination of traits from inter-mated population. Further, significant shift in correlation coefficient of fresh pod yield plant-1 with racemes plant-1 from -0.33* (in F3 progenies) to 0.19 (in BIP F3 progenies) suggested the possibility of increasing the number of racemes plant-1 without penalty in fresh pod yield plant-1 through selection.
Increased use of genetic resources is necessary to sustain crop improvement. Large numbers of germplasm entries and possible existence of duplicate/redundant accessions are impediments to effective management, evaluation, and utilization. A core collection is a limited set of accessions chosen to represent the maximum genetic spectrum with minimum redundancy of the existing germplasm collection. Six hundred forty-four indigenous and exotic germplasm accessions of Dolichos bean [Lablab purpureus (L.) Sweet] and four check entries were characterized for 21 qualitative traits and evaluated for 20 quantitative traits at the University of Agricultural Sciences, Bangalore, India, during the 2012 rainy season. A core set of size 10% (n = 64 accessions) was developed using software that applies advanced M-strategy with a heuristic search. The core set was examined for its representativeness of the base collection for both qualitative and quantitative traits using univariate and multivariate statistics. The core set retained more than 90% of quantitative traits variability and polymorphism of qualitative traits. The core set is suggested for evaluation across target production environments and years to identify widely/specifically adapted and stable accessions to foster enhanced access and use ofDolichos bean germplasm.
An investigation was carried out to assess the variability among 644 germplasm accessions of dolichos bean which included 540 Indian, 24 Kenyan and 80 accessions of unknown origin at University of agricultural sc iences (UAS), Bangalore for 20 quantitative traits and three qualitative traits. The germplasm accessions along with four check entries were sown in augmented design in 10 compact blocks during Kharif 2012 at the experimental plots of UAS, Bangalore. Substantial variability among the accessions for quantitative traits and polymorphism for qualitative traits were documented. The germplasm accessions could be grouped into six clusters following model-based K-means clustering approach. The quantitative trait means and variances differed significantly among the clusters. Some of the germplasm accessions were superior than the check HA-4. The accessions contrasting for individual and multiple traits were identified. These results are discussed in relation to suitable strategies to be adopted for breeding Dolichos bean for improved productivity.
Development of a reduced representative set of a large base collection enables greater use of genetic resources in crop improvement programs. Efficiency of standard stratified clustering (SSC) and heuristic approaches were compared for developing core sets of Dolichos bean from a base collection of 648 accessions on the basis of data on 21 qualitative and 20 quantitative traits. The SSC approach with a combination of two core sizes (10% and 15%), two sampling strategies (proportional and logarithmic), and two allocation strategies (random and preferred) were used to develop eight core sets. Two additional core sets of 10% and 15% sizes were developed following a heuristic approach. Similarity of classes on the basis of qualitative traits of 10 core sets with the base collection was examined using Chi-square test, Shannon-Weaver diversity index, and 'class coverage' statistics. Univariate statistics, based on quantitative traits, such as mean and variance and multivariate statistics, standardized mean difference (SMD%), coincidence ratio (CR%), variance difference (VD%), and variable difference (VR%) were also used to assess the representativeness of core sets. Heuristic approach-based core sets retained higher CR%, VD%, and VR% based on quantitative traits.
An investigation was carried out with these objectives i) To assess variability in F2 and F3 populations for fresh pod yield and its component traits, ii) To unravel genetics of fresh pod yield and its component traits and iii) To assess quantitative traits inter-relationships, at Dry-Land Agricultural Project (DLAP) during 2014-15 rabi-summer season, results suggested substantial variability in both F2 and F3 populations for most of the traits. Both additive and dominance with a predominance of dominance genetic effects appeared to control the inheritance of most traits in both the crosses. Further most traits are controlled by dominant genes with decreasing effects on the expression of most traits in both the crosses one or to cycles of F2 and or F3 biparental mating followed by recurrent selections are advisable to reduce dominance genetic effects and enhance the frequency of desirable genes in the segregating populations to increase effectiveness of selection for desirable traits.