Mahalanobis D2 Research Articles

Study of Genetic Diversity in Indian Barnyard Millet Genetic Resources [Echinochloa frumentacea (L.)

Sixtyfour Indian barnyard millet genetic resources were studied to assess the extent of genetic divergence for 18 quantitative traits using Mahalanobis D2 Statistic. Sixtyfour genetic resources of Indian barnyard millet were evaluated during kharif, 2020 in a lattice square design, replicated twice at Regional Agricultural Research. Based on Tocher’s method, the entire genetic materials were separated into eight distinct and non-overlapping clusters suggesting availability of genetic diversity. Cluster I has highest number of accessions (57) and the remaining were mono genotypic clusters II, III, IV, V, VI, VII and VIII containing only one accession each indicating high degree of heterogeneity among the genotypes. The widest inter-cluster distance was recorded between clusters IV and VII. Therefore, it is concluded that the genotypes to these clusters has to be intercrossed in order to create more diversity and improving grain yield in barnyard millet. The traits, grain yield per plant and panicle weight contributed maximum towards total divergence has scope of crop improvement through those traits. Diversity of parent paly main role for the successful of any breeding programme. So the crosses can be made among the parents having widest divergence would more likely to yield desirable recombination in segregating generations.

Exploring agro-morphological profiles of Phaseolus vulgaris germplasm shows manifest diversity and opportunities for genetic improvement

Common bean (Phaseolus vulgaris) is a seed crop with huge potential to contributing to food security in developing countries. In crop improvement, assessing genetic variability is a decisive step, requiring characterization of available crop germplasm. The present study aims at characterizing 39 common bean genotypes from various locations in Cameroon and five from Kenya using 19 qualitative and 36 quantitative traits of high descriptive values. Diversity among germplasm was assessed by determining diversity indices and carrying out multivariate analysis. Seventeen out of the nineteen qualitative traits (89.47%) were polymorphic, displaying each at least two phenotypic classes. High diversity was found. Average observed and expected number of phenotypic classes per trait were 3.74 and 2.53 respectively. Nei's genetic diversity value of 0.49 and Shannon-Weaver diversity index estimates of 0.74 were found. Significant differences were observed among genotypes for all measured quantitative traits. Yield traits showed significant correlation with other related quantitative traits. Cluster analysis separated the studied germplasm into three distinct groups, with the clustering pattern not showing any connection with location. The test of equality revealed significant difference between these clusters for most quantitative traits. Mahalanobis D2 statistics revealed germplasm of cluster I and III as potential parents for future breeding programs. This study identified genotypes with desirable agronomic traits such as higher number of seeds per pod, lower number of days to maturity, higher number of pods per plant, and higher yield. These and other important discriminatory traits are discussed and proposed for genetic improvement of common bean.

Assessment of selection criteria using multi-year study for effective breeding program of Zingiber officinale L.

Ginger has been an important cash crop with numerous applications since ancient times. As the demand for ginger is ever-growing and being a seasonal crop, a high-yielding variety of ginger would be economically profitable. In this study, 150 germplasm were collected from different regions of NE India and evaluated for three years in CRBD design with three replications. The present study thus focused on the variability, association, and diversity studies for the first time on 150 ginger germplasm from across North East India. The genotypic and phenotypic coefficient of variation, heritability, correlation, and path analysis were evaluated for the germplasm. Analysis of variance (ANOVA) revealed considerable differences among the studied germplasm for studied characters, revealing sufficient variability in the materials. The Mahalanobis D2 and Tocher methods grouped the 150 ginger germplasm into ten clusters. Based on the results of the path coefficient analysis determined for essential oil yield and rhizome yield per plant, it can be concluded that the characters' initial rhizome weight, the weight of mother rhizome, and weight of secondary rhizome were the most important and appeared promising in improving the overall yield potential of ginger rhizome and essential oil yield. Thus, selection based on the identified traits would lead to an effective ginger breeding program for higher rhizome and essential oil yield.

Study of Genetic Diversity in Forage Sorghum [Sorghum bicolor (L.) Moench

Analysis of genetic divergence through Mahalanobis D2 statistics exhibited considerable genetic diversity among genotypes. The thirty genotypes of forage sorghum were grouped into 6 clusters. The cluster II (14 genotypes) and cluster I (7 genotypes) having the maximum number of genotypes. This envisaged that the genotypes grouped within a particular cluster were more or less genetically similar to each other and apparent wide diversity was mainly due to the remaining genotypes distributed over rest of the other clusters. Percent contribution and expression of characters towards the genetic divergence play an important role in selecting the superior genotypes among diverse genotypes. Plant height had maximum contribution towards the genetic divergence followed by green fodder yield, leaf stem ratio and number of leaves per plant and remaining characters noted very low contribution percent towards the genetic divergence. Maximum intra cluster distance was recorded in cluster IV, indicating greater genetic divergence between the genotypes belonging to these clusters and crosses involving genotypes viz., CSV-15, CSV-17, Pant Chari-8, CSV-16 and Pant Chari-7 are suggested. Crosses in the above combinations are expected to provide enough genetic variability to select high green fodder yield and stable segregates in the segregating generations.

Межгрупповая изменчивость краниометрических характеристик населения Средней Азии в 1500-летней ретроспективе (VII в. до н.э. – VIII в. н.э.)

Introduction. The paper revisits the intergroup craniometric variability in the Early Iron Age, Antiquity and Early medieval Central Asian population. Some new cranial materials are considered within the hierarchical system of the regional populations. Materials and methods. The comparison included 61 cranial samples from all historical and cultural regions of Central Asia with a total of 1100 crania. 12 standard measurements of the facial skeleton were used. First, we conducted Canonical discriminant analysis. Second, the matrix of Mahalanobis D2 distances was obtained using the resulting group coordinates in the space of the canonical vectors. Finally, the distance matrix was subjected to Multidimensional scaling and the Ward’s hierarchical cluster analysis. Results. The first three canonical variates reflect 53.4% of the total intergroup variation and differentiate samples based on bizygomatic breadth, orbit dimensions, nasal bridge height (and width to a lesser extent), horizontal profiling angles and nose protrusion angle. Upper facial height also contributes to intergroup craniometric variability but does not play a decisive role in differentiating among samples of European ancestry in the considered chronological period. Correlation coefficients between canonical variables and multidimensional scaling coordinates suggest similar relative positions of the groups in the scatterplots. Discussion. Considering the mixed nature of the Central Asian population and the difficulty of objective differentiation of morphological types, we caution against unreflective use of terms “East Mediterranean type” and “Pamir-Fergana race”. The results suggest that the Antiquity and Early medieval sedentary populations are difficult to distinguish from nomadic and semi-nomadic groups of the Wusun period. The new materials confirm the morphological similarity between Early medieval population of Sogdiana (ancient Panjakent) and Ushrusana (Kurkat dakhmaks). @ 2023. This work is licensed under a CC BY 4.0 license

Understanding the Genetic Basis of Yield-related Traits in Little Millet (Panicum sumatrense Roth. ex. Roem. and Schultz.) Germplasm through Association and Diversity Analysis

Background: Little millet is an important crop grown by tribal farmers in India. Genetic variability can be exploited to develop new varieties with higher yield. However, yield is complex and depends on multiple interconnected component characters. Diversity analyses, such as D2 analysis, are used to evaluate the diversity among genotypes and determine the traits that contribute the most diversity in a given population. These analyses are crucial for achieving the goal of developing new varieties with increased yield. Methods: In this study, 323 little millet genotypes were evaluated using an Augmented RCBD, focusing on ten quantitative traits. The experiment was conducted during the rabi season of 2020-2021, and good agronomic practices were followed. D square cluster analysis and path analysis were used to analyze the data, with the "R" tool and the "biotools" and "agricolae" packages, respectively. Result: In this study, 323 little millet genotypes classified into thirteen distinct clusters based on Mahalanobis's D2 statistics, reflecting differences in their phenotypic characteristics. The largest cluster (cluster I) included 243 genotypes, while the smallest clusters (Cluster IX, Cluster X, Cluster XI, Cluster XII and Cluster XIII) had only 1 genotype. The inter-cluster distance varied, with the largest value (577.7) between cluster V and XII. This analysis can be useful for identifying desirable genotypes and understanding the population's genetic diversity and structure.

Estimation of Genetic Divergence in Garden Pea (Pisum sativum L.) Germplasm

Genetic diversity among thirty garden pea genotypes was worked out using Mahalanobis D2 statistics. Based on genetic distance, genotypes were grouped into ten clusters of the ten clusters, cluster I was the largest, having 11 genotypes, followed by cluster IV, cluster VIII, cluster III, cluster V and clusters II, VI, VII, IX and X, with one genotype in each. The average intra-cluster distance was maximum in cluster VIII (487.04) and minimum in cluster V (125.72). The maximum inter-cluster distance was observed between cluster VIII and cluster X (3439.67), indicating the genotypes in these clusters are more diverged and they can be used as parents in the hybridization program to obtain superior segregants. Cluster means for various traits revealed that cluster VIII was found superior for plant height at 60 DAS, number of branches per plant at 60 DAS, and number of pods per plant. Thus, genotypes from this cluster could be used as divergent parents to improve these particular characters. Pod yield per plant contributed the maximum (38.16 %) to the genetic diversity among the characters studied.

Genetic Variability and Diversity for Yield and Yield Attributing Traits in M3 and M4 Generations of Butter Bean (Phaseolus lunatus L.)

Background: Butter beans (Phaselous lunatus L) belong to the family Leguminaceae, is one of the oldest cool season food legume crops. A throughout knowledge of existing genetic variation among yield and its yield component traits is essential for developing high yielding varieties in butter bean. Realizing the importance of genetic diversity and variability in key economic characters, the present investigation had been planned to assess the genetic diversity and variability in for yield improvement in butter bean breeding programme. Methods: Investigation was carried at Horticultural Research Station, Tamil Nadu Agricultural University, Kodaikanal, Tamil Nadu during 2019-2021. A total of 2734 M2 mutant lines were evaluated as individual progenies in the previous study. Stringent selection was made based on yield, earliness and plant habit and a total of 35 mutant lines were identified and forwarded to M3 and a total of 12 mutant lines for M4 generations in present study. The data on elevan quantitative were analyzed using Mahalanobis D2 statistic. Result: The present study has assessed the genetic variation among studied traits of butter bean mutants for yield and its component traits. Thus, a total of five mutant lines namely BBMG-7-9-7, BBMG-9-10-6, BBMG-18-9-6, BBMG-25-13-3, BBMG-35-7-2 were identified to be forward to the M5 generation as promising mutant lines for developing high yielding varieties and to test its homogeneity and stability.

Genetic Divergence Study in Groundnut Genotypes (Arachishypogaea L.)

Employing the Mahalanobis D2 statistic, a divergence study was performed on 36 groundnut genotypes and 13 clusters were identified. Indicating that the genotypes of these groups may be more divergent from one another, the maximum inter-cluster distance (D) was found between cluster II and cluster XIII (315.56), followed by cluster III and cluster IX (289.56), cluster III and cluster XII (289.21), and cluster XII and cluster XIII (297.11). The genotypes in the mentioned clusters showed a significant difference in the means for traits that contribute significantly to yield, indicating that the genotypes in these clusters make ideal parents in a hybridization programme to produce transgressive segregants and improve groundnut.

Genetic Diversity Studies and Fusarium Wilt Screening in Chickpea (Cicer arietinum L.) Germplasm

Background: The genetic base of chickpea has narrowed substantially during the domestication process (Thudi et al., 2016). Therefore, increasing the genetic divergence of chickpea has been a major goal for breeders. The assessment of genetic diversity of chickpea germplasm can provide a valuable information to the breeder for parental selection strategies in plant breeding programs. Method: Two hundred and eighty chickpea germplasm including two checks (JG-11 and SA-1) were tested with an objective to explore the genetic divergence by using Mahalanobis D2 statistics. The field experiment was carried out during Rabi 2021-22 at Zonal Agricultural Research Station (ZARS), Kalaburagi. The magnitude of genetic divergence was studied using data obtained from five quantitative traits. Results: The 280 genotypes including checks were divided into seventeen clusters based on their D2 values. Out of seventeen clusters, cluster II (89 genotypes) was the largest followed by cluster I (83 genotypes), cluster III (31 genotypes), cluster VIII (29 genotypes), cluster VII (24 genotypes), cluster VII (15 genotypes). Same set of germplasm were also screened for fusarium wilt in wilt sick plot, 30 germplasm lines showed resistant (10.71%), 83 moderately resistant (29.64%), 44 moderately susceptible (15.71%), 31 susceptible (11.07%) and 92 highly susceptible reaction to fusarium wilt. Clusters XIV and XVI had extreme genetic distance and the germplasm lines in these cluster also showed moderate resistance to fusarium wilt.

Genetic Divergence Analysis in Amaranth (Amaranthus spp.) by Using Morpho-agronomic Traits in Western Uttar Pradesh, India

The field experiment was conducted during 2021-22. During the study the analysis of variance for 19 diverse genotypes of Amaranthus were designed in randomized block design and revealed significant difference for all the 12 characters, this indicated the presence of wide spectrum of variability among the genotypes. The analysis of genetic divergence through Mahalanobis D2 statistics revealed that a considerable genetic diversity was found among genotypes. 19 genotypes of Amaranthus were grouped into 5 clusters. Out of these 5 clusters, Cluster II contains maximum number of genotypes that is seven, followed by cluster I which comprising six genotypes, Cluster III comprising four genotypes, whereas cluster IV and V containing only one genotype each. All the desired combinations of traits should be considered, while breeding programme for selecting high yielding genotypes and suitable for breeders to achieving improved plant type.

Characterisation of bell pepper (Capsicum annuum L. var. grossum Sendt.) accessions for genetic diversity and population structure based on agro-morphological and microsatellite markers

Bell pepper (Capsicum annuum L. var. grossum Sendt.) is a leading Solanaceous vegetable crop across the world with immense therapeutic and export potential. Such wide cultivation exposes the crop to various biotic and abiotic stresses. Genetic diversity is one of the major prerequisites for any crop breeding programme. Hence, in this study, an attempt was made to evaluate the genetic diversity and population structure of 24 bell pepper genotypes using 25 agro-morphological [9 distinctness, uniformity and stability (DUS) descriptors; 13 quantitative traits; and 3 quality traits] and 82 microsatellite or simple sequence repeat (SSR) markers. Eight DUS descriptors showed polymorphism with maximum morphological variation (H = 1.29) for fruit shape in longitudinal section. Multivariate analysis using Mahalanobis D2 statistic distinguished the genotypes into 11 clusters. With a mean of 4.08 alleles per locus, a total of 151 alleles were generated from 37 polymorphic SSR primers. The polymorphic information content (PIC) ranged from 0.14 (CAMS 451) to 0.76 (CA 525390) with an average of 0.54. The genotypes were divided into two major clusters based on cluster analysis using the unweighted pair group method with arithmetic mean (UPGMA) algorithm, whereas the cluster tree using the neighbour-joining (NJ) method identified three major groups. The population was classified into three groups based on structure analysis. On comparing agro-morphological and molecular clusters, 11 genotypes viz., BWT-39, BWT-39-BR, BWT-39-DR, BWT-29, BWT-3Y, BWT-3Y-4L, Kandaghat Selection, BWT-48-AC, BWT-49-AC, EC-464107, and EC-464115, were found common. These genotypes also exhibited considerable resistance to bacterial wilt disease. Mantel's test showed a moderate positive correlation between agro-morphological (DUS descriptors) and molecular data. Therefore, a combined approach of agro-morphological and molecular evaluation can facilitate the selection of diverse parental lines followed by subsequent hybridisation between them to introduce new traits in bell pepper.

Multivariate statistical algorithms for landslide susceptibility assessment in Kailash Sacred landscape, Western Himalaya

Landslide susceptibility mapping plays an imperative role in mitigating hazards and determining the future direction of developmental activities in mountainous regions. Here, we used 518 landslide occurrences and nine landslide-conditioning parameters to build landslide vulnerability models in the Kailash Sacred Landscape (KSL), India. Four multivariate statistical models were applied, namely the generalized linear model (GLM), maximum entropy (MaxEnt), Mahalanobis D2 (MD), and support vector machine (SVM), to calibrate and compare four maps of landslide susceptibility. The results demonstrated the outperformance of Mahalanobis D2 for predictability compared to other models obtained from the area under the receiver operating characteristic curve (ROC). The ensemble model data shows that 10.5% of the landscape has susceptible conditions for future landslides, whereas 89.50% of the landscape falls under the safe zone. The occurrence of landslides in the KSL is linked to the middle elevations, vicinity to water bodies, and the motorable roads. Furthermore, the observed patterns and the resulting models exhibit the major variables that cause landslides and their respective significance. The current modelling approach could provide baseline data at the regional scale to improve the developmental planning in the KSL.

Assessment of genetic diversity for yield and yield contributing traits in peanut (Arachis hypogaea L.)

Thirty-three advanced breeding lines of peanut were evaluated during kharif, 2019 using Mahalanobis D2 statistics for 19 characters including physiological, yield and quality traits and were grouped into nine clusters, where cluster IV was the largest containing 11 genotypes followed by cluster III and II with 8 and 7 genotypes respectively. Highest inter-cluster distance was observed between cluster VII and IX (118.10) followed by cluster V and VI (113.29) and cluster V and IX (106.42), respectively. The maximum intra-cluster distance was observed in cluster IV (31.37) followed by cluster III (20.11) and II (13.17). Hundred kernel weight contributed maximum towards genetic divergence followed by sound mature kernel (%), specific leaf area at 45 DAS, oil content and plant height. The crosses viz., TCGS-2141 × TCGS-2117, Narayani × TCGS-1887, Narayani × TCGS-2117, Narayani × TCGS-2111 and TCGS-1887 × TCGS-2141 could be recommended to get desirable transgressive segregants for physiological, yield and quality traits.

Agro‐morphological characterization and diversity analysis of Coffea arabica germplasm collection from INIA, Peru

AbstractCoffee (Coffea arabica L.) plays a major role in the economy of Peru and the world. The present study aims to elucidate the agro‐morphological variability of coffee genotypes maintained in the National Institute of Agrarian Innovation (INIA) germplasm collection. Therefore, 20 vegetative, reproductive, and phytosanitary traits of 162 coffee accessions of INIA's germplasm collection were evaluated and analyzed. Correlation results indicate that a simultaneous selection of characters, such as number of branches per plant, number of nodes per branch, leaf area, and weight of a hundred fruits, can contribute to increase coffee yields. Additionally, coffee yield was negatively correlated with the incidence and severity of coffee leaf rust, and interestingly the occurrence of small and compact coffee plants with high resistance to the disease was also found. The analysis of Tocher and Mahalanobis D2 determined the formation of 10 groups of divergent coffee accessions; where clusters 1 (accession codes 20, 29, 38, 54, 67, 71, 117, 24, 26, and 27), 5 (accession codes 46 and 53), 9 (accession code 159), and 10 (accession code 203) group promising accessions that can be used in breeding programs. Principal component analysis showed that at least five of its principal components managed to explain 70.01% of the total variation in the collection. Finally, the high coefficients obtained for the phenotypic, genotypic, and heritability variation confirm the existence of additive genes in the evaluated population, that would ensure the success of coffee breeding programs based on the selection of traits of agronomic importance.

Multivariate analysis for yield and yield-related traits of amaranth genotypes from Ethiopia

The genus Amaranthus is one of the few dicotyledonous, non-grass mesophytes that use specialized C4 annuals or short-lived perennials to produce significant amounts of edible small-seeded pseudo cereals. In this study, we characterized the genetic diversity of 120 genotypes of amaranths collected from diverse amaranth-growing regions of Ethiopia using multivariate analysis of yield and yield-related traits. The experiments were carried out at Hawassa University, in the years 2020 and 2021. The experimental design was set up using an alpha lattice design and replicated two times. The collected data were examined for 24 descriptors. Principal component analysis showed that the first six principal components with eigenvalues greater than one contributed 80.41% of the variability. However, the first two principal components explained 52.42% of the total variation. The highest contributing traits in the first component were days to flowering, basal stem diameter, plant height at flowering, plant height at maturity, auxiliary inflorescence length, number of branches, terminal inflorescence lateral length, days to maturity, terminal inflorescence stalk length, leaf number, leaf length, top lateral branch length. The traits with the greatest weight on the second component were leaf area, basal lateral branch length, leaf length, and leaf width, grain filling period, grain sinking filling rate, and grain yield. Therefore, selection based on these traits would be effective for yield improvement in amaranth genotypes. Additionally, the hierarchical clustering grouped all the genotypes into five clusters. The pairwise generalized squared distance (D2) among the five clusters based on Mahalanobis's D2 statistics revealed the maximum and highly significant genetic distance was observed between II and III (277.79), while the minimum inter-cluster distance observed between clusters I and II (39.50). The findings suggest that amaranth genotypes in Ethiopia have a lot of genetic variation, which might be used for future breeding and ought to be conserved.

Genetic Parameters and Diversity Studies Among Morphological Traits in Breeding Lines of Garlic (Allium Sativum L.)

Thirty-four promising lines of garlic were grown in randomized block design with three replications under the latesown season in 2019-20 at Vegetable Research Farm of C. S. Azad University of Agriculture and Technology, Kalyanpur, Kanpur. The mean sum of squares showed highly significant differences among the lines for all the traits studied, indicating the presence of a sufficient amount of genetic variability. The moderate to higher magnitude of the coefficient of variation at genotypic as well as phenotypic levels was noticed for number of cloves per bulb, marketable bulb yield, average weight of bulb, average weight of cloves and plant height. High heritability coupled with high genetic advance as percent of mean was observed for plant height, leaf length, leaf width, polar diameter, number of cloves per bulb, average weight of bulb and average weight of cloves. Marketable bulb yield was positively and significantly correlated with the total bulb yield and dry matter content whereas, a significant negative correlation with leaf width. All the thirtyfour lines of garlic were grouped into five clusters based on Mahalanobis D2 statistics using Tocher’s method. The cluster II and V had among the moderate genetic distance having higher total bulb yield performance along with its contributing traits. The genotypes from cluster IV and V had the most divergent clusters and were suitable for high yielding garlic genotypes among the various advanced breeding lines under late sown conditions. Bangladesh J. Bot. 52(2): 225-233, 2023 (June)

Assessment of Genetic Divergence in White Finger Millet [Eleusine coracana (L.) Gaertn.] Genotypes for Yield and Yield Contributing Traits

The present investigation is carried out to study the genetic divergence among 55 finger millet genotypes for fourteen quantitative characters using Mahalanobis D2 statistics during kharif, 2020. D2 statistics indicated that the genotypes studied were genetically diverse. The 55 genotypes of finger millet were grouped into 6 clusters irrespective of geographical diversity, indicating no parallelism between geographic and genetic diversity. Clusters I had highest number of 50 genotypes and remaining all clusters had solitary. A wider genetic diversity was observed for the different traits studied among the genotypes as evidenced by the formation of six clusters. Out of fourteen quantitative traits studied grain yield per plant contributed majorly towards divergence with the value of 15.65% followed by productive tillers per plant contributes (12%), harvest index (10%) and other traits contribute minorly for divergence.

Genetic Divergence Study in Different Rice (Oryza sativa L.) Genotypes under Irrigated and Drought Stress Condition

Thirty rice genotypes were evaluated to study genetic divergence under irrigated and drought stress conditions in randomized block design at Bagusala farm, M. S. Swaminathan School of Agriculture, CUTM, Odisha, during summer 2019. The main objective of this experiment was to identify reproductive phase drought tolerant genotypes through study the effect of drought stress on yield, yield attributing and biochemical traits performance of selected genotypes using Mahalanobis D2 statistics. Set of 30 genotypes were grouped in to five and nine clusters under irrigated and drought situation. Under irrigated conditions cluster-Ⅰ was largest cluster with 22 genotypes followed by cluster-Ⅱ includes 5 genotypes cluster-Ⅲ, IV and V each consisted with only one genotype. Under drought condition, genotypes were grouped into nine different clusters, cluster-Ⅰ was the largest cluster involving 20 genotypes followed by cluster-Ⅱ having 3 genotypes whereas, cluster-Ⅲ, IV, Ⅴ, Ⅵ, Ⅶ, Ⅷ and Ⅸ were recorded with single genotype. The maximum intra cluster distances under irrigated conditions were found in cluster- Ⅱ (27111.9) followed by cluster-Ⅰ (17587.7). Whereas, in case of stress cluster-Ⅱ had maximum distance (21110.9) fallowed by cluster-Ⅰ (17957.8). Under irrigated maximum inter-cluster distances recorded between cluster-Ⅱ and Ⅴ (62310.8) followed by cluster-Ⅳ and Ⅴ (57656.0). In case of stress maximum inter cluster distances recorded between cluster -Ⅱ and Ⅶ (69865.5) fallowed by cluster- Ⅷ and Ⅸ (67848.9), cluster-Ⅱ and Ⅸ (65239.2). Under irrigate conditions highest manifestation towards genetic divergence was exhibited by chlorophyll followed by plant yield, 1000 grain weight, proline, number of spikelets, carbohydrates, grain weight, phenols, panicle length, panicle weight, flavonoids, number of filled grains, plant height and number of tillers. In case of drought stress, maximum percentage contribution towards to the genetic divergence was observed for Proline followed by carbohydrates, plant height, plant yield, grain weight, chlorophyll, number of spikelets, flavonoids, 1000grain weight, filled grains, phenols, panicle weight, panicle length and number of tillers, while other trait like root length did not contribute to the total divergence. The genotypes grouped under cluster Ⅰ, Ⅲ, Ⅴ, Ⅷ namely MTU1010, MTU1075, MTU1224, RNR2465 and Manipur black rice exhibited maximum drought tolerance under stress conditions. These genotypes can be used as the donor parents for development of drought tolerant lines in crop improvement programme.

Genetic diversity analysis in sponge gourd (Luffa aegyptiaca)

Sponge gourd is versatile summer vegetable having potential applications across many sectors. Twenty sponge gourd genotypes were studied at the Department of Vegetable Science, College of Agriculture, Vellanikkara, Kerala Agricultural University, Thrissur, Kerala for the study of variability in morphological, yield and biochemical traits. Significant difference existed among the genotypes for all the characters under study. In general, Phenotypic Coefficient of Variation (PCV) was higher than Genotypic Coefficient of Variation (GCV) for all the traits evaluated, which indicated the influence of environment on these traits. High estimates of PCV and GCV were recorded for node number of the first staminate flower, number of primary branches per plant, number of fruits per plant, fruit yield per plant, calcium, iron and fibre content. High heritability coupled with high genetic advance as a per cent of the mean were evident in most of the morphological and biochemical traits which suggested the influence of additive gene action for controlling these traits. Genotypes IC-343160, IC-332319 and IC-312949 were high yielders. The sponge gourd genotypes were grouped into seven clusters based on Mahalanobis D2 statistics. Cluster VII had the highest number of genotypes (5) followed by cluster VI (4), and intra cluster distance was maximum in cluster VII. Inter cluster distance was maximum between cluster I and III. Therefore, for exploitation of heterosis, genotypes should be selected from cluster I and cluster III.