Morphological Diversity of Bambara Groundnut [Vigna subterranea (L.) Verdc.] Landraces in Tanzania

A field experiment was conducted in Tanzania for two seasons to assess the genetic diversity of bambara groundnut landraces based on morphological characters. One hundred accessions collected from a wide range of agricultural zones in the country were evaluated in a 10 × 10 triple lattice block design at Maruku station in Bukoba, Tanzania. For the qualitative characters evaluated, considerable morphological variations were observed for growth habit, pod shape and pod colour. Quantitative morphological characters such as peduncle length, number of leaves per plant, terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant length, pod width, seed length, seed width, number of pods per plant, shelling percentage and days to 50% flowering showed significant variation among accessions for the two test seasons. Multivariate analysis for 15 quantitative morphological traits that showed significant variation indicated that the first four PCs with eigenvalues ≥1 accounted for 63.0 and 65.0% of the total variance among the accessions during the two test seasons, respectively. The most important loadings for PC1 and PC2 for the two seasons were terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant height and pod length, pod width, seed length, seed width, numbers of pods per plant. Cluster analysis grouped bambara groundnut accessions into three major groups with respect to their geographic origins. Based on this present study, bambara groundnut landraces from Tanzania displayed a considerable diversity for morphological and agronomic traits useful for germplasm management and utilization into crop improvement.     

Multivariate analysis of morphological variation in sorghum (Sorghum bicolor (L.) Moench) germplasm from Ethiopia and Eritrea

Multivariate methods, including principal component, cluster and discriminant analyses, were used to assess the patterns of morphological variation and to group 415 sorghum accessions for 15 quantitative characters. The first five principal components explained 79% of the total variation with plant height and days to 50% flowering being the most important characters in the first principal component. Cluster analysis grouped the accessions into ten clusters. A greater proportion of accessions of similar adaptation zones and accessions from regions of origin with similar agro-climatic conditions were grouped together. Moreover, discrimination of accessions was more pronounced when discriminant analysis was based on zone of adaptation rather than regions of origin. Based on the observed patterns of variation, it is concluded that the morphological variation in the material studied is structured by environmental factors. The implications of the results for plant breeding and germplasm conservation programmes arediscussed.     

Morphological biodiversity and local use of the Himalayan pear (<Emphasis Type="Italic">Pyrus pashia</Emphasis>) in Central Bhutan

A survey was undertaken in two valleys of the Bumthang area in Central Bhutan to study the morphological diversity, farmers’ knowledge, management practices, yield and income generation potential of the neglected Himalayan Pear (Pyrus pashia Hamilton ex D. Don). For this study a total of 148 Pyrus pashia accessions were collected and 103 households interviewed. Three quantitative and 14 qualitative traits such as colour, size, shape and texture of fruits and tree habit were used for morphological characterization of the accessions. The results demonstrated a high morphological diversity within the P. pashia trees. Fruit shape varied widely from globose to pyriform, fruit skin colour from light yellow and glossy to brown and dull. The observed diversity is likely due to the fact that under farmers’ conditions trees are propagated through seedlings rather than by grafting. None of the characters were specific and correlated with region or altitude. Distinct local cultivars with specific characters were absent making it impossible to group the pears morphologically. Interviews revealed low numbers of trees per farmers, lacking marketability of the fruits and farmers’ subsequent preference for improved varieties as major obstacles for the in situ preservation of biodiversity in P. pashia in this area.     

Taxonomic status of Oryza glumaepatula Steud. I. Comparative morphological studies of New World diploids and Asian AA genome species

This study was carried out to clarify the taxonomic status of the New World diploid wild rice species, Oryza glumaepatula. The morphological variation of 26 diploid rice accessions in the International Rice Genebank at IRRI from South America and Cuba was compared with that of O. rufipogon and O. nivara from Asia. The 28 morphological characters included 16 spikelet and grain, eight leaf and culm, and four panicle characters, and were analyzed using principal component analysis (PCA) and hierarchical agglomerative cluster analysis. The first two principal components accounted for 53.6% of the total variation. The first component was characterized by leaf and sterile lemma characters, 5-panicle dry weight, and grain length, and the second by anther length and its ratio to grain length, grain width, thickness, and 20-hulled grain weight. The characters effectively differentiated the wild rices from Surinam, French Guiana, and the lower Amazon River basin in Brazil, which showed high negative scores along both axes, from other accessions from Venezuela, Colombia, and Cuba, and the Asian species. Most of the accessions from South America are quite distinct from O. rufipogon, with which they have often been grouped as a single species in some taxonomic treatments. Groupings obtained from cluster analysis corresponded closely with the results from PCA. This study supports a distinct taxonomic status of a group of diploid wild rices from South America as O. glumaepatula.     

Assessments of genetic diversity within a world collection of cultivated hexaploid oat (<Emphasis Type="Italic">Avena sativa</Emphasis> L.) based on qualitative morphological characters

A characterization of 10,105 accessions of hexaploid cultivated oat (Avena sativa L. sensu lato) from 85 countries of the Plant Gene Resources of Canada (PGRC) collection was conducted at Saskatoon, Saskatchewan, Canada. Eight environmentally stable morphological characters (panicle type, panicle erectness, panicle density, lemma colour, dorsal awn of lemma, ligula, major infraspecific group), differentiated into 18 character states, were used to define genetically distinct morphological groups. Comparisons of oat diversity from different countries, among the major infraspecific groups and among Canadian oat cultivars registered between 1886 and 2002 were possible. The 10,105 accessions represented 118 different morphological groups. The number of accessions in each morphological group was unevenly distributed with the 13 most frequent morphological groups including 90% of the accessions. The most frequent morphological groups in the PGRC collection were identical with the most frequent types of Canadian oat cultivars. The greatest richness of diversity was found in oat from countries with temperate climates and intensive oat breeding programmes. The oat accessions comprised 8,754 accessions of common hulled oat, 183 accessions of hull-less oat and 1,168 accessions of red oat. For red oat (A. byzantina C. Koch), West Asia was richest in diversity. The USA could be considered a secondary centre of diversity for red oat and Canada a secondary centre of diversity for hull-less oat. Morphological diversity of oat cultivars released in Canada increased during the twentieth century. The morphological groups were related to formal taxonomical infraspecific classifications of A. sativa. Applications of the concept of defining morphological groups for phenotyping a large germplasm collection are demonstrated discussed.     

Variations in morphological and agronomic traits among Jerusalem artichoke (Helianthus tuberosus L.) accessions

Jerusalem artichoke is a diversely-utilized crop. Selection for high yield, inulin content and other economically important traits are useful for improving this crop. The objectives of the present study were to evaluate genetic variability for qualitative and quantitative traits among Jerusalem artichoke accessions and to identify different groups of accessions using morphological and agronomic traits. Seventy-nine accessions were evaluated in a randomized complete block design with two replications in the late rainy season 2008, the early rainy season 2009 and the late rainy season 2009 at Khon Kaen University agronomy farm, Thailand. Morphological and agronomic characteristics were evaluated for genetic variations. High variations were found among Jerusalem artichoke accessions for qualitative and quantitative characters, and selection for these characters is possible. High variations were observed for tuber width, number of tubers/plant, biomass, fresh tuber yield and tuber size. Correlation coefficient between fresh tuber yield and tuber size was positive and significant (0.58, P ≤ 0.01). Improvement of tuber size is a means to improve yield and tuber quality. Based on morphological and agronomic characteristics, Jerusalem artichoke accessions were clustered into four distinct groups (R² = 0.88). These groups may be used as parental material to generate progenies for further improvement of this crop. This information will enable breeders to make informed decisions about possible heterotic groups for their breeding programs and germplasm conservation.     

Biodiversity in the barnyard millet (<Emphasis Type="Italic">Echinochloa frumentacea</Emphasis> Link,Poaceae) germplasm in India

One hundred ninety four accessions of barnyard millet collected from different eco-geographical regions of India were evaluated for 14 quantitative traits during kharif 2003 and 2005. These accessions were grouped into 5 groups on the basis of place of collection. These groups differed significantly in their mean values for quantitative traits and magnitude of correlation among traits indicates origin based association. The group ‘C’ (source of origin is unknown) was found most diverse group (mean coefficient of variation 17.67%), while rest of the groups recorded mean coefficient of variation between 12 and 13%. Correlation studies indicate that flag leaf width, number of racemes along with internode length should be considered while performing selection in segregating generations. The plotting of first and second principal component axes scores suggests that presence of three distinct morphotypes in the present study. These morphotypes are quite similar to three botanical varieties viz., var. robusta, var. intermedia and var. stolonifera in their morphological traits, while botanical variety laxa (endemic to Sikkim area of India) was completely absent from the present study.     

Genetic diversity in sorghum [<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench] germplasm from Southern Africa as revealed by microsatellite markers and agro-morphological traits

Cultivated sorghum [Sorghum bicolor (L.) Moench] is an important food security crop in the semi-arid regions of the world including Asia and Africa. Its genetic diversity is contained mostly in traditional varieties and modern cultivars used by farmers. In this study, agro-morphological traits and molecular markers were used to assess genetic diversity in 22 accessions of cultivated sorghum from five countries (Botswana, Namibia, Swaziland, Zambia and Zimbabwe) in the Southern African Development Community (SADC) region. The study revealed a significant variation among 22 accessions in both qualitative and quantitative morphological traits, indicating the accessions’ promising potential as breeding material. For molecular analysis, 11 microsatellite primer-pairs were used, and generated a total of 70 alleles across 20 accessions. Analysis of molecular variance revealed a high level of genetic variation; 67 % among the accessions and 10 % among the five countries. The patterns of genetic diversity and the relationships observed in this study should provide insights for genetic resource conservation and utilization of sorghum germplasm in the SADC region.     

Phenotypic diversity in the pigeonpea (<Emphasis Type="Italic">Cajanus cajan</Emphasis>) core collection

The pigeonpea core collection developed at ICRISAT genebank consists of 1,290 accessions from 53 countries. The core collection, which includes selected lines in extra early, early, medium and late maturity groups was evaluated for 18 qualitative and 16 quantitative characters during the 2004 rainy season, to assess the phenotypic diversity and determine the relative importance of different characters in evaluating pigeonpea germplasm accessions. The four maturity groups differed significantly for all characters under study. The medium maturity group showed significantly higher mean number of primary, secondary and tertiary branches, number of racemes, pod bearing length, pods per plant, shelling percent and plot seed yield. Late maturity group showed significantly higher mean for leaf size, plant height, pod length, seeds per pod and 100-seed weight, indicating this group as a good source of vegetable pigeonpea. Significant positive correlations were found between number of secondary branches and pods per plant in extra early group (r = 0.756), late maturity group (r = 0.776) and entire core (r = 0.728) and between number of racemes and pods per plant in all maturity groups and entire core. Principal coordinate and principal component analysis showed that seven qualitative and nine quantitative traits were important in explaining multivariate polymorphism. The Shannon–Weaver diversity index (H′) varied for different maturity groups and traits. Phenotypic diversity, averaged over all the 16 characters, increases from extra early group (0.36 ± 0.04) to late maturity group (0.42 ± 0.04) suggesting that medium and late maturity groups have greater diversity compared to extra early and early maturity groups.     

Wild melon diversity in India (Punjab State)

We present here the first comprehensive genetic characterization of wild melon accessions from northern India. The genetic diversity among 43 wild melon accessions collected from the six agro-ecological regions of the Punjab State of India was assessed by measuring variation at 16 Simple Sequence Repeat (SSR) loci, morphological traits of plant habit and fruit morphological traits, two yield-associated traits, root nematode resistance and biochemical composition (ascorbic acid, carotenoids, titrable acidity). Variation among accessions was observed in plant habit and fruit traits and wild melon germplasm with high acidity and elevated carotenoid content and possessing resistance to Meloidogyne incognita was identified in the collection. A high level of genetic variability in wild melon germplasm was suggested by SSR analysis. Comparative analysis using SSRs of the genetic variability between wild melons from the north and other melons from the south and east regions of India and also reference accessions of cultivated melon from Spain, Japan, Korea, Maldives, Iraq and Israel, showed regional differentiation among Indian melon accessions and that Indian germplasm was not closely related to melon accessions from other parts of the world. A highly drought tolerant accession belonging to var. agrestis Naud. was also identified.     

Morphological variability in cultivated and wild species of Luffa (Cucurbitaceae) from India

Immature fruits of cultivated species of Luffa are commonly used as summer vegetable in India. Rich morphological variability occurs in cultivated species of Luffa in different growing regions of the country. To study morphological variability in cultivated and wild Luffa from different agro-ecological regions of India, a total of seventy accessions were assembled. Morphological variations in leaf, fruit and seed characters were found to delimit cultivated and wild Luffa species. Cluster analysis revealed two major clusters, one comprising of 36 accessions of Luffa acutangula and the other of 30 accessions belonging to L. aegyptiaca. A local cultivar “Satputia” (L. hermaphrodita) was classified along with cultivated L. acutangula and wild L. acutangula var. amara. Wild species namely L. graveolens and L. echinata were clustered closer to the L. acutangula.     

Assessing genetic diversity of <Emphasis Type="Italic">Pyrus</Emphasis> spp. in the central Zagros mountains based on morphological characters

The morphological diversity and relationship among 138 pear genotypes, including 11 commercial cultivars and 127 wild pear accessions from central Zagros mountains located in the west of Iran, based on 64 morphological characters were studied. The higher coefficient of variation indicated that high level of variation was belonged to the petiole stipule, fruit the relative area of the skin color, fruit relative area periphery rust dents end, fruit relative blight on an area of skin, fruit curved tail, fruit dents end, fruit depth dents end, fruit relative area periphery patina tail connection characters. Pyrus communis L. and Pyrus glabra Boiss. species were the highest and the shortest tree, respectively. According to the cluster analysis, 138 genotypes were clustered into nine main groups. Principal components analysis revealed that the first three components accounted for 68.77 % of the total variation in data. Moreover, 19 factors justified 72.57 % of the total variation based on factor analysis. The research results showed that the Zagros mountains are the centers of diversity of pear. Therefore, it is necessary to use the Iranian genotypes as the genetic resources for improving the morphological characters of pear.     

Phenotypic diversity and morphological characterization of Amygdalus L. species in Lebanon

In this paper, we report on morphological diversity of Amygdalus L. species native to Lebanon, following a countrywide survey of almond germplasm whereby a total of 149 accessions were collected throughout the country and characterized by thirteen quantitative and four qualitative traits. The results indicated that the genetic diversity of Amygdalus communis L., Amygdalus korshinskyi Hand.-Mazz., and Amygdalus orientalis Duh. in Lebanon is high. Principal component analysis revealed that nut weight, nut volume, nut width, kernel volume and shell strength had highest loading in the first component that accounted for 38.7% and 46.7% of total variation in A. communis and A. orientalis, respectively. In contrast, leaf traits were present in the second component which accounted for 18% and 23.2% of total variation in each species, respectively. No significant correlations were detected between leaf parameters and fruit traits in both species. The results indicated that quantitative leaf characters for all three species were determined by rainfall and not altitude whereby adjacent accessions located in drier areas had smaller leaf sizes than those located in more humid regions. Quantitative fruit characters did not seem to vary accordingly. Qualitative leaf traits in all three species reflected a variability which was independent of rainfall. A. communis populations showed high variability, suggesting that they could be a valuable source in almond improvement programs.     

Morphological and molecular diversity of an underutilized fruit crop - <Emphasis Type="Italic">Cordia myxa</Emphasis> L. germplasm from the arid region of Rajasthan,India

Twenty two germplasm accessions of Cordia myxa were collected from Rajasthan and established at the field gene bank for conservation and evaluation. Morphological characterization of 10 year-old trees for 17 traits indicated wide variations among the accessions tested. Higher number of flowers per cyme was found in accession ACHM11 and higher pulp:stone ratio in AHCM25. Overall, AHCM22 was found to be a superior germplasm line for most of the horticulturally useful traits among the accessions tested as it had higher percent of fruit set, pulp:stone ratio and fruit weight. High significant positive correlation was obtained between leaf, fruit characters and pulp:stone ratio. However, these characters were found to be negatively correlated with number of flowers per cyme. Out of 50 random decamer primers used for random amplification (RAPD), 25 were polymorphic. Average polymorphism resolved by these markers among these accessions was 69.8% with an average polymorphic information content of 0.43. Genetic diversity revealed by Jaccard’s co-efficient was between 0.44 and 0.94, and three major clusters were identified among these accessions by phylogenetic analysis using NTSYSpc-2.02e software. RAPD markers associated with leaf size and pulp:stone ratio were also identified. This study shows the existence of high genetic diversity among these accessions.