Diversity Analysis and Physico-Morphlogical Characteritics of Indigenous Germplasm of Lablab Bean

Germplasm characterization is an important component of crop breeding program. In characterizing indigenous beans lablab which is used for vegetables as well pulses in Nepal. Twenty three lablab beans germplasm were evaluated for different qualitative and quantitive physico-morphological charecteristics for two years during 2011 and 2012 at Horticulture Research Station, Malepatan, Pokhara. The germplasm showed considerable variations in most of the qualitative and quantitative traits. Leaf size, vine color, flower color, pod color, pod shape, pod type and seed color varied among the genotypes. Variation was also observed in yield attributing characters eg, pod length and width, 10 fresh pod weight, seeds per pod and 100-seed weight. Days to 50% flowering ranged from 81 to 130 days indicating the presence of early varieties. Fresh pod weight of 10 pods was ranged from 45.0 g to 162.5 g. Multivariate analysis indicated four groups in these genotypes, among with ML-02 and ML-10 were distinct in comparioson with other genotypes. Simple selection may be considered to develop high yielding, early type varieties from these gentopypes.


INTRODUCTION
The lablab bean (LababpurpureusL.), also called field bean, Indian bean, Hyacinth bean or Dolichus bean is an old domesticated pulse and multipurpose cropfor human food, animal feed and cover crop (Chakravarti andNaravaneni 2006,Maass 2010). It is called Hiunde Simi,Tate Simi, Laphre Simi and Machhe in Nepal and some farmers cultivate perennially. This bean is a minor winter vegetable in Nepal and grown in most of districts of Mid Hill and Tarai areas. It is considered one of nutritious vegetable in green pod stage while pulse in the form of dry seeds (Chadha 2001). The foliage of the crop can be used as green feed, hay and silage.This crop can also grow well in alkaline and saline soil pH ranges up to 9.0 (Chadha 2001).The vine is grown at the roof top of the homested. This bean is easy to grow with limited LQSXWV 0RVW RI WKH IDUPHU ¶V KRXVHKROGV JURZ WKLV EHDQ having several landraces from Midhill to Tarai zone. Conservation of some landraces has been initiated by National Genebank of Nepal Agricultural Research Council (NARC), Khumaltar (Genebank 2014). However, information on diversity and characterisitcs of Nepalese lablab beans is scant.
Assessment of genetic diversity is important for crop improvement. Characterization is the preliminary works helps to support conservation and utilization effectively (Chakravarthi 2006, Genebank 2014. Lablab is one of the most diverse domesticated legume species with largest agro-morphological diversity in South Asia, even though orginated in Africa (Maass 2010). It is a tropical crop mainly grown in South Asia (specifically India, Nepal and Bangladesh), South East Asia and Africa. Considerable variations have been noticed in this bean in Bangladesh and India (Islam 2014, Rai et al 2010. Great range of variations exists in the plant and pod characters among the landraces grown in Nepal. They differs also by name eg Kerau Simi, Laphre Simi, Machhe Simi, etc. On the basis of physicomorpholoigical traits ODQGUDFHV RI WKLV EHDQ FDQ EH FODVVLILHG LQWR WZR JURXSV QDPHO\ WKH µEXVK\ ILHOG FXOWLYDUV ¶ DQG µWZLQLQJ pole JDUGHQ FXOWLYDUV ¶ 2QO\ SROH W\SH H[LVWs in Nepal which isgenerally grown for home consumption. Since, characterization and diversity assessment are necessary on lablab beans. Therefore, we aimed to collect lablab bean landracesfor diversity characterization based on physicomorpholoigical traits using multivariate analysis tools.

MATERIALS AND METHODS
A total of 23 indigenous germplasmof twining pole genotypes of lablab bean were collected including passport data (Table 1) from seven districts namely, Myagdi, Baglung, Parbat, Syangja, Gulmi, Kaski and Rupandehi in 2010 and 2011. To characterize and assess the diversity among these genotypesfield experiments were conducted inJune to February2011 and same months in 2012 at Agriculture Research Station,Malepatan, Pokhara. Soil type of the experimental plot was sandy loam with having soil pH 5.5 or less.
Unreplicated design was adopted for this study.The plot size was 2m x 2m accommodating four hills per plot. Four seeds per hill were planted initially. In each hill six kilogram of farm yard manure(FYM) was added.Inorganic fertilizers were applied @ 10 kgnitrogen (N), 25 kg phosphorus (P) and 25 kg potassium (K) per ha as basal fertilizers. At knee height stage of seedlings, two seedlings per hills were maintained. First side dressing of 5 kg N was applied one month after seeding and; Second side dressing of 5 kg N was applied 60 days after seeding. Seedlings were supported by bamboo stick. Weeding and irrigation was done whenever necessary. The crop was protected from aphid by spraying Niconim (product of Neem) at the rate of five ml/L of water at 15 days interval. Physicomorphological qualitative and quantitative traits were recorded each year from all four hills of each genotypefollowing the descrioptons of AVRDC (www.avrdc.org) and Sultana (2001).Quantative data were recorded from each hill and averaged over the plot each year. Mean value over the years were presented. These mean data were then subjected to cluster and principal component analysis as described by Joshi et al (2010) for genetic diversity analysis using Mintab software. Fresh pods of 15 genotypes were tested organoleptically providing to 15 different consumers (one genotype to each consumer) in 2011 and their views were recorded.

Qualitative Characters
The sizes of the leaves of each genotype were ovserved visually.Three different sizes of the leaves among 23 genotypes were noted. Fifteen genotypes had medium sized leaves whereas seven genotypes had small sized leaves and one genotype had relatively large sized leaves (Table 2).Chlorophyll content in the plant, expressed by the foliage color of the vegetative part did not have too much variation. Among the 23 genotypes, 17 (73.9%) were observed green and six (26.15%) were purple vine.Three types of flower color were observed. Flower color of 12 (52.17%) was purple, 8 (34.78%) white, and 3 (13.04%) pink.
According to seed coat color, genotypes were classified into five groups (Table 2). These were brown, black, white, black brown and gray brown. Among the 23 genotypes, 12 (52.17%) had brown seed coat followed by 7 (30.43%)genotypes with black coated seeds. Two genotypes had gray black and one brown black and one with white color seed coat. Considering the cooking quality, taste and over all performance of fresh pods, ML-09 was found best among the genotypes (Table 3). ML-09 was preferred by consumers due to small and bold pod with fiberless. It is also known as pea type bean. Other genotpypespreferred by consumers were ML-02, ML-04, ML-08, ML-09, ML-10, ML-15, ML-18, ML-19, and ML-20. Five genoptypes, namely ML-02, ML-05, ML-08, ML-09 and ML-18 were found high yielders and they are recommended for further yield verification trial.

Cluster Analysis
Cluster analysis was undertaken to objectively divide the germplasm into natural groups. Clustering was performed on standardized vriables using Euclidean distance for single linkage method.This clustering in natural groups is represented by a dendrogram progressively dividing the accessions into smaller and smaller groups (KC 2001). There were four clusters, among which cluster I consisted of the highest number of genotypes ie 15 genotypes followed by cluster II with 6 genotypes (Figure 1, Table 5). Two genotpe namely ML-10 and ML-02 made separate clustersindvidually, indicating unique features in these two genotypes among the 23 genotypes of lablab beans.

Principal Component Analysis
The first two principal components with eigen values greater than 1.0 accounted for about 66% of the variation among the collection (Table 6). Third and forth components accounted for 14 and 9% of the total variation. Here principal component reduces the dimensionality of multivariate data by removing interrelations among variables and eigen value represents the variance of principal component (Matus 1999). The first principal component (PC1) which explained 39% variation, was associated mainly with days to 50% flowering, pod maturity, pod length and pod weight. The second principal component (PC2) was responsible for about 26% of the variation and was mainly related to pod width and 100 seed weight. The dispersion of the 23 genotypes in Figure 2 showed considerable amount of variability because of collections from different areas.
Four distinct groups can also be obsereved based on the principal compoenent analysis. ML-02 is located very far from the center and has positively higher value for most of the traits whereas, ML-10 has relatively small value for most of the triats and located in the third quardrant.

DISCUSSION
Germplasm characterization is an important component of breeding program for an effective and efficient management and utilization. Assessment of genetic diaristy is an essential component in germplasm characterization and conservation (Chakravarthi 2006). Morphological markers have been used for assessment of relationships among lab labbean genotypes and for estimating genetic diversity among them (Table 2, 4, Figure 2). The germplasm used in present studies showed a wide variation in morphological traits like number of pods/plant and pod length (Tabe 2, Table 4, Figure 1, Table 6, Figure 2) .The immense genetic diversity of landraces of crops is the most directly useful and economically valuable part of biodiversity. Unlike high yielding varieties, the landraces maintained by farmers are endowed with tremendous genetic variability, as they are not subjected to subtle selection over a long period. Such diversity should be conserved by collecting extensily from the local areas removing duplicates in the collection.
In present findings the colur of vine color we observed was similar to that of Islam (2010) who reported that large portion (43.2%) were green vine color in Bangladesh. Islam et al (2002) divided stem color in two groups such as green and purple, which was also similar with the present results. Pod color is very important in the market and consumer prefer green pod. More than half of the germplasm have greed pod. Islam (2010) also reported 52.3% were green color pod in his study.Pod length is directly related to total economic harvest. Priority should therefore be given to ML-05 for further advancing and selecting the genotypes. Variation in pod length was similar to Islam (2010) who reported variation on it from 3.96 cm to 18.20 cm.
The plant has many outstanding qualities. It is tolerant of high-temperatures and drought, can thrive in deep sands to heavy clays and produces a large bulk of green material with high protein concentration (Kay 1979). These qualities enable the plant to provide food, fodder and soil protection during prolonged dry periods when many other plant species have become desiccated (Schaaffhausen 1963, Wood 1983.Lablab is better adapted to drought than common beans (Phaseolus vulgaris) or cowpea (Vignaunguiculata). Variation therefore observed in these genotypes can be very important soruces for developing site specific variety targeting drought areas eg western Nepal.
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Results obtained from this study are very useful to enhance the genetic management and improvement of this multipurpose crop species particularly to develop high yielding variety.The narrow genetic base for breeding stocks may be increased including these genotypes. Extensive exchange of germplasm among smallholder farmers across the country may dilute the existing diversity. The identified genetically distinct genotypes could be potentially important source for further improvement of lab labbean.

CONCLUSION
The evaluated germplasm showed significant variations in most of the qualitative and quantitative traits. Variation was observed in both phenological and yield attributing characters. Simple location specific evaluation and selection may be sufficient to develop high yielding, early type varieties from these gentopypes.

ACKNOWLDGEMENT
Nepal Agriculture Research Council is highly acknowledged for funding. Appreciation to all those farmers who share their valuable germplasm of lablab beans without any cost.