Total Genetic Divergence Research Articles

Genetic Variability and Association among Yield and Yield Related Traits of Sesame (Sesamum indicum L.) Genotype

A field experiment was carried out with 42 genotypes of sesame (Sesamum indicum L.) at the Niger Research Station, Navsari Agricultural University, Vanarasi, Ta. Vansda. The study was performed to evaluate the genetic variability, characters association, path analysis and genetic diversity based on yield and yield related traits. The highest genotypic coefficient of variation was observed for seed yield per plant followed by capsules per cluster and harvest index. High estimates of heritability coupled with high genetic advance expressed as percentage of mean were observed for the traits viz., capsule width, capsules per cluster, leaf area, harvest index and seed yield per plant indicating that these characters are under the control of additive gene effect. The seed yield per plant was found to be significant and positively correlated with days to maturity, capsule length, capsule width, capsules per cluster, 1000 seed weight and harvest index at genotypic and phenotypic levels. The maximum direct effects as well as appreciable indirect influences were exerted by harvest index, capsule width, capsule length and 1000 seed weight. D2 analysis indicated wider genetic diversity among the forty-two genotypes which were grouped in ten clusters indicating there is no formed relationship between geographical diversity and genetic diversity. Cluster III and X showed the maximum inter cluster distance of 16.51. Hence, the genotypes belonging to the X, IX and VIII cluster could be used in hybridization program for obtaining a wide spectrum of variability among the segregants. Among different eleven traits studied, leaf area followed by capsules per cluster, harvest index, capsule width, seed yield per plant and capsule length contributed maximum towards the total genetic divergence. Results of mean cluster analysis showed that cluster X recorded highest cluster mean for four important yield attributing characters and cluster IX for two important characters. Genotypes from these cluster may produce progenies with high genetic variation.

Evaluation of sunflower (Helianthus annuus L.) germplasm lines for genetic diversity

In the present investigation, estimation of the genetic diversity among thirty five germplasm lines of sunflower was undertaken by using Mahalanobis D2 analysis. Based on the relative magnitude of D2 values, the experimental material was distributed into six clusters. Out of six clusters, cluster I was the largest comprising of nineteen lines. Single plant yield, plant height, volume weight together contributed maximum (82.85 %) to the total genetic divergence. Maximum inter cluster distance was exhibited between clusters II and IV. The greater the distance between two clusters, the wider the genetic diversity among the genotypes of these clusters. Hence, hybridization between the genotypes from these clusters would produce high heterotic recombinants.

Morpho-Biochemical Characterization of Chayote [Sechium edule (Jacq.)] Genotypes from Sikkim Himalayas

Twenty chayote genotypes with different accession numbers maintained at ICAR-NEH region, Gangtok were used in the study and observations were recorded for seventeen quantitative traits during the year 2018-19. All the genotypes genetically differed from each other based on their mean performance. The phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of variation (GCV) for all the characters. High values for PCV, GCV, heritability and genetic advance as per cent of mean were observed for seed weight (61.2 %, 61.1 %, 99 % and 125.6 %) and non-reducing sugar (59.2 %, 58.1 %, 96 % and 117.4 %) respectively, which indicates a wide range of variation for crop improvement through selection. The correlation coefficient (genotypic and phenotypic) showed that fruit weight expressed significant positive correlation with seed length (0.93), seed breadth (0.92) and total sugar (0.65). Path coefficient analysis revealed that fruit breadth, fruit length, seed weight would be of selection criteria for further crop improvement. The genotypes were grouped into three clusters and the maximum intra-cluster distance was observed in cluster I (25.12) and maximum inter cluster distance was found between the cluster I and III (41.47). Seed weight exhibited the highest percentage contribution towards total genetic divergence.

Genetic diversity, correlation and path co-efficient for yield and yield associated traits in rice (Oryza sativa)

The present investigation was conducted to assess the high grain yielding varieties and their related traits for evolving better genotypes for further breeding programme. Twenty-five rice genotypes were collected from different geographical regions of Tamil Nadu to discern the extent of divergence, variability and character association. The analysis of variance exposed the presence of significant differences among all the genotypes for eight characters studied and indicated the occurrence of considerable amount of deviation in the genotypes. In D2 analysis, 25 rice genotypes were grouped into six clusters. The maximum intra-cluster distance was registered in cluster III (31.88). The maximum inter-cluster distance was found between cluster II and cluster IV (144.96). IR 64, PMK 3 and CO 51 were the potential donors and could be used as a parent as they possessed high per se for yield and majority of its attributes. Number of grains/panicle, 1000-grain weight, plant height, days to 50% flowering and grain yield/plant were the major contributors towards the total genetic divergence among the traits studied. The genetic correlation revealed that number of tillers/plant and panicle length showed positive and significant association with respect to number of productive tillers/plant and number of grains/panicle at both genotypic and phenotypic levels. So, it may be inferred that selection and manoeuvring of anyone of the traits viz., number of productive tillers/plant and panicle length were likely to improve grain yield/plant. Path analysis indicated that number of productive tillers/plant, 1000-grain weight and number of grains/panicle exerted maximum positive direct and all identified genotypes with their resulted traits would be obliging to progress or deploy for further breeding programme.

Reptile richness and genetic divergence patterns were shaped by current and past climate in and around the Irano‐Anatolian global biodiversity hotspot: Implications for conservation

AbstractAimThe Irano‐Anatolian biodiversity hotspot is among the least‐known biodiversity hotspots on earth. In this study, we aim to map the richness and genetic divergence of lizards in the biodiversity hotspot and its surrounding areas and identify the most important determinants of the richness and genetic divergence patterns.LocationIran and Turkey (Irano‐Anatolian biodiversity hotspot).MethodsHere, we mapped the distribution of 211 lizard species in Iran and Turkey using existing occurrence data and generated the first genetic divergence pattern map of the lizard species in the two countries to identify areas of high species diversity and genetic divergence in the Irano‐Anatolian biodiversity hotspot. We also identified determinants of lizard richness and genetic divergence patterns.ResultsResults showed that the Zagros Mountains, Central Iranian Plateau and the northern Persian Gulf have the highest lizard richness. The Zagros Mountains, Central Iranian Plateau, the northern Persian Gulf and the regions around the Lut Desert and Jazmourian Plain have the highest total genetic divergence in Iran. Alborz and Kopet Dag mountains and south western parts of Turkey have the highest average genetic divergence. The annual temperature was the most important predictor of lizard richness, and temperature change velocity was the most influential determinant of genetic divergence pattern. Much to our surprise, species diversity and most areas with high genetic divergence are located outside of Irano‐Anatolian biodiversity hotspot.Main conclusionsThis study showed that lizard richness and genetic divergence patterns are associated with current and past climate. In particular, this study highlights the legacy of past climate changes on lizard genetic divergence distribution patterns. We showed that most of the species‐rich and genetically diverse regions are located outside of the biodiversity hotspot. So conservation efforts that are concentrated inside the biodiversity hotspot may not benefit lizard biodiversity conservation. Thus, future studies and conservation programs on the biodiversity hotspot should also consider its surrounding areas.

Genetic Diversity Analysis of Chickpea Genotypes (Cicer arietinum L.) for Seed Yield and Morpho-genetic Traits

Background: Based on D2 analysis 53 chickpea genotypes were grouped into seven clusters. Among the VII clusters, cluster I consists of 30 genotypes forming the largest cluster followed by cluster II with 16 genotypes, cluster VII with three genotypes and cluster III, IV, V and VI with one genotype each. Inter cluster distance were found to higher than intra cluster distance which depicted wide genetic diversity among the chickpea genotypes under study. Contribution of various characters towards expression of total genetic divergence indicated that seed yield (27.77%) contributed maximum (24.74%) followed by biological yield and number of pods per plant (20.43%). The clustering pattern of genotype demonstrated that clustering does not follow any particular cluster pattern with respect to origin. The pattern of cluster analysis of the first principal component had the largest eigenroot 4.18 per cent of total variation followed by 3.53, 2.91, 2.02, 1.45, 1.26 and 1.15 from second to seven principal components. The eigenroot of first principal component accounted for 19.91 per cent of total variation followed by second to seven principal components which accounted for 16.82, 13.84, 9.62, 6.90, 5.99 and 5.48 per cent of total variations present in the genotypes. Methods: The study was carried out at Pulses Research Sub-Station (PRSS), Samba and Advanced Center for Rain-fed Agriculture (ACRA), Rakh Dhiansar during Rabi seasons 2017-18 and 2018-19. The experimental material comprising of 48 chickpea (Cicer arietinum L.) genotypes along with 5 checks were evaluated in augmented block design. Result: The genotypes of cluster II, V and VII had highest inter-cluster distances as well as higher cluster means for most of the yield component traits indicating that these genotypes were most diverse can be used as parents in hybridization programme of chickpea breeding. The variation present in the chickpea genotypes under study can be exploited through selection and hybridization among identified genotypes for breeding high yielding chickpea genotypes.

Estimating genetic diversity of bread wheat (Triticum aestivum L.) in different environments

An experiment was conducted to evaluate the genetic diversity in 48 genotypes of wheat for 25 traits under two environments i.e., timely and late sown conditions, at Wheat and Barley Section, Department of Genetics and Plant Breeding, CCS HAU, Hisar during rabi, 2019-20. The genetic diversity analysis revealed the formation of seven clusters in both environments. Based on the genetic distance, it was concluded that crossing of genotypes from cluster V with clusters I and IV to get a broad spectrum of variation for both environments. Cluster VII for timely sown and cluster V for late sowing conditions contained genotypes with high mean performance for grain yield and other traits and therefore these genotypes can be utilized for yield improvement. Based on the analysis of percent contribution of different traits to total genetic divergence, it was found that under timely sown condition CTD 1, total gluten content and for late sown condition zinc content, CTD 2 contributed the most. Keywords:  Cluster mean, D2 statistic, environment, genetic divergence, wheat.

Determination of Genetic Variability and Diversity in Bread Wheat for Yield and Yield Contributing Traits

A study was conducted to estimate genetic variability and genetic divergence for 8 traits in 52 diverse genotypes of bread wheat (Triticum aestivum L.) under normal sowing condition. For all of the features studied, the analysis of variance revealed extremely significant differences in mean square owing to genotypes. Grain yield per plot and tillers per meter have high genotypic and phenotypic coefficients of variation. High heritability coupled with high genetic advance as percent of mean was observed for grain yield/plot and tillers/meter and plant height. Genetic divergence was assessed by Mahalanobis D2 statistic, which grouped 52 genotypes into seven clusters. Maximum genetic divergence was observed between cluster V and VI followed by that between VI and VII (D=34.61). Cluster IV had desirable rating for spike length, spikelets/spike, thousand grain weight and yield/plot. Cluster VII had desirable rating for tillers/meter and had highest contribution towards total genetic divergence.

Estimation of Genetic Diversity in Mungbean [Vigna radiata (L.) Wilczek] Genotypes Grown in Gujarat

Background: Genetically diverse parents give an increased chance of genetic recombination and superior expression of hybrid vigour. Mahalanobis D2 statistics is an important tool for calculating the amount of genetic diversity in the populations and for assessing the relative contribution of various components to the total genetic divergence. Methods: Thirty genotypes of mungbean [Vigna radiata (L.) Wilczek] were grown in a randomized block design with four replications at S.D.A.U., Gujarat during kharif, 2019 to study genetic diversity. By using Mahalanobis’s D2 statistics, all possible 435 pairs of thirty genotypes were computed for ten characters. Result: D2 analysis indicated that material was genetically diverse. Twelve clusters were formed by dividing the genotypes. To become highly genetically diverse, the inter-cluster distance should be high (Distance between cluster XI and cluster IX; cluster XI and cluster X), which can be used for hybridization programme. Cluster X followed by cluster I found appropriate for within group hybridization due to the presence of most heterogeneous genotypes indicating high intra-cluster value. Cluster data revealed that genotypes in cluster X, cluster VIII and cluster IV had desirable traits for yield improvement. These clusters could be directly selected for breeding programme. Contribution to total divergence was higher from number of branches per plant, pod length and 100-seed weight.

Genetic Divergence Studies for Yield and Quality Traits in Okra (Abelmoschus esculentus (L.) Moench.)

The objective of the study was to evaluate genetic divergence among okra genotypes based on yield and yield contributing traits. The experiment comprised of 32 genotypes of okra, which were sown in Randomized Block Design with two replications at College of Horticulture, Sri Konda Laxman Telangana State Horticultural University, Rajendranagar, Hyderabad during the period Kharif, 2016. Analysis of variance indicated existence of large variability among the genotypes for all the traits. On the basis of D2 analysis, the 32 genotypes could be grouped into 6 clusters. Cluster I had the highest number of genotypes (15) followed cluster II (11) and cluster III and cluster V (2 genotypes in each group) and remaining clusters, i.e., IV and VI were mono genotypic. Plant height had the highest contribution towards the total genetic divergence (42.94 %) followed by overall YVMV PDI percent (16.73 ). The highest intra-cluster distances were recorded in cluster II (73.17) followed by cluster V (66.30). The maximum inter-cluster distance was recorded between cluster III and cluster IV (775.06) followed by cluster IV and cluster VI (723.37). The genotypes which were in the cluster II, III and VI also exhibited significant performance for fruit yield per plant. Based on per se performance and genetic investigation methods superior genotypes RHBG-1, RHBG-7, VRO-6, IC-42490, IC-10265, IC-111515, Arka Abhay, Pusa A-4, IC-29119, RHBG-12, IC-90219. The identified genotypes are promising for hybrid breeding as parents for yileld and YVMV resistance.IC-04328 and EC-755647 were identified for yield and yield attributing traits and YVMV resistance in okra. The identified genotypes are promising for hybrid breeding as parents for yileld and YVMV resistance.

Genetic Divergence Assessment through K-Means Clustering and Principal Component Analysis for Seed Yield, Zinc, Iron and Protein Content in Vigna unguiculata L. Walp

Cowpea [Vigna unculata (L.) Walp.] with chromosome number 2n=24 is an one of the important crops grown in arid and semi-arid regions of the world. Cowpea is a source of high quality protein consumed in many parts of the world. Malnutrition is a global problems needs to be addressed locally. Identification of micronutrient dense genotypes is the major objective of cowpea Biofortification programme. In the present study, 169 cowpea genotypes collected from different sources were analysed for genetic divergence through K-means clustering followed by Principal component analysis (PCA). Considering mean values, genotypes were classified into eight clusters following K-means clustering algorithm. Cluster VII has highest number of genotypes (56 genotypes) followed by cluster III (43 genotypes). Clusters VI and VIII were solitary with single genotype. Results revealed that crosses could be made between genotypes of cluster V & VIII, cluster III & VIII and cluster VII & VIII. According to PCA, Five principal components (PC) with Eigen values greater than one contributed 70.5% of the total variability. Amongst, PC1 accounted highest proportion of total variance (31.3 %), remaining PCs viz., PC2, PC3, PC4 and PC5 revealed 14.6%, 10.1%, 7.7% and 6.8 % respectively, revealing pod yield-1, seed yield-1, pod length and seeds pod-1 were major contributors to the total genetic variability and divergence.

Genetic diversity of yield related traits in a large subset of exotic and indigenous rice germplasm collection maintained at Tamil Nadu Agricultural University gene bank

The present investigation was carried out to explore the extent of genetic divergence in 95 rice germplasm accessions for twelve characters during kharif, 2018. In D2 analysis, the 95 genotypes were grouped into fifteen clusters. The clustering pattern indicated that there was no parallelism between genetic diversity and geographical origin as the genotypes from same origin were included in different clusters and vice versa. The highest intra cluster distance was registered in cluster V (215.183) followed by cluster IX (209.831), cluster VIII (204.057) and cluster XIV (202.623).The maximum inter cluster distance was observed between cluster II and cluster III (991.049) followed by cluster II and cluster X (974.960), cluster III and cluster XI (963.826), cluster II and XII (962.013), cluster X and cluster XI (932.469) and cluster XI and cluster XII (919.151). Genetically distant parents from those clusters could be able to produce higher heterosis in progenies on hybridization. Grain yield per plant, 100 grain weight and days to 50% flowering were the major contributors towards the total genetic divergence among the genotypes studied. Thus selection could be made based on grain yield per plant, hundred grain weight and days to 50%flowering for the progenies identified.

​Genetic Diversity for Seed Yield and its Components in Clusterbean [Cymopsis tetragonaloba (L.) Taub

Background: Clusterbean [Cyamopsis tetragonoloba (L.) Taub.] (2n=2x=14) is an under exploited legume belonging to family fabaceae. Clusterbean is a versatile legume crop cultivated mostly as animal feed, green manure green leaves as fodder, vegetable and cover crop. Clusterbean is a drought resistant, hardy, deep rooted annual legume crop. D2 statistics provides a measure of magnitude for divergence between two genotypes under comparison. For broadening the genetic base of cultivars, the genetic diversity present in cultivated and wild relatives must be explored. Generally, diverse germplasms are expected to give high hybrid vigor and hence, it necessitates studying genetic divergence among the existing varieties and genotypes for the identification of parents for hybridization programme. Methods: The present investigation was undertaken to study genetic variability in clusterbean [Cymopsis tetragonaloba (L.) Taub] with using a set of 40 genotypes at Agronomy Instructional Farm, Department of Agronomy, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar during Kharif 2019 in randomized block design with four replications. Mahalanobis (1928) D2 statistic was used for assessing the genetic divergence between different populations. Grouping of the genotypes in different clusters was done by using Tocher’s method. The inter-cluster distance was calculated by measuring the distance between clusters I and cluster II, between clusters I and cluster III, between clusters II and cluster III and so on. Likewise, one by one cluster was taken and their distances from other clusters were calculated. Result: The genetic diversity analysis revealed the formation of nine clusters suggested the presence of considerable genetic diversity among the 40 genotypes. The clustering pattern indicated that geographic diversity was not associated with genetic diversity. The analysis of per cent contribution of various characters towards the expression of total genetic divergence indicated that, the number of branches per plant followed by gum content, days to maturity, days to flowering contributed maximum towards total genetic divergence. On the basis of inter cluster distances, cluster IX was found to be more divergent. Therefore, it was concluded that the genotypes belonging to these cluster should be inter crossed in order to generate more variability.

Parental Diversity and Its Relationship with Performance of F1 Hybrid in Rice (Oryza sativa L.)

The present investigation was carried out including 10 parents and their 45 half diallel crosses with the objective to study the relationship between heterosis and diverse genotype. The Mahalonobis D2values resulted in grouping of 10 parents into 3 clusters. Cluster I was comprised of four genotypes, cluster II comprised of five genotypes while, cluster III was found monogenotypic. Cluster II and Cluster III had maximum mean values for 4 traits. Highest intercluster distance was also observed in these 2 cluster followed by cluster I and III . Maximum intra cluster distance was observed in cluster II followed by cluster I. The highest contribution in the manifestation of total genetic divergence was exhibited by grain iron content followed by grain zinc content. The relationship between parental diversity and heterosis indicated that majority of crosses belong to moderate divergence class. The cross P4×P5 exhibiting better parent heterosis for maximum traits also exhibited at par mean performance for 5 traits including grain yield per plant over the better parent. For grain zinc content, two crosses from high and low while, nine crosses from moderate divergence classes reported positive significant heterosis and SCA effects. For grain iron content, 1 cross with high, 2 crosses with moderate while four crosses with low divergence classes reported significantly positive heterosis and SCA effects.

Evaluation of Genetic Diversity in Bottle Gourd Germplasm Based on Phenotypic Characters for Yield and Yield Associated Traits

The experiment was conducted during Kharif season 2018 at Horticulture Research Centre, Sardar Vallabhbhai Patel University of Agriculture & Technology; Modipuram, Meerut (U.P.) assess the genetic diversity among fifteen genotypes of bottle gourd [Lagenaria siceraria (Mol.) Standl.]. The genetic diversity analysis according to that the formation of five clusters suggesting the presence of wide genetic diversity. The clustering pattern showed that geographical diversity wasn't related to genetic diversity. The analysis of % contribution of assorted characters toward the expression of total genetic divergence showed that the Days to 50% flowering (14.48%) followed Days of fruit set (12.95%), Vine length (m) (11.67%), Number of fruits per plant (10.93%), Number of the primary branches (10.37%), Days to first fruit harvest (10.16%), Average fruit weight (g) (9.44%), Fruit diameter (cm) (6.63%) contributed maximum towards total genetic divergence. Based on the maximum genetic distance. It is advisable to attempt a crossing of the genotype from cluster II (GP-7) with the genotype of cluster I (GP-5), cluster IV (GP-2) and cluster III (GP-1), which may cause to the generation of a broad spectrum of favorable genetic variability for yield improvement in bottle gourd.

↵Genetic Diversity and Principal Component Analysis in Mungbean [Vigna radiata (L.) Wilczek] under Rainfed Condition

Background: Mungbean is a short duration grain legume widely grown in south and Southeast Asia. The extent of variability through Principal Component Analysis (PCA) and cluster analysis in promising mungbean genotypes should be known for possible yield improvement. A study was undertaken to work out the extent of variability among twenty four mungbean genotypes through cluster analysis and Principal Component Analysis (PCA). Methods: The experiment was laid out in a randomized block design with three replications during kharif 2018 and 2019 at the experimental field of Agricultural Research Station, Navgaon (Alwar) under rainfed condition. Result: Principal component analysis revealed that the first three main PCAs amounted 78.80% of the total variation among genotypes for different traits. Out of total principal components, PC1 accounts for maximum variability in the data with respect to succeeding components. Number of branches per plant (28.62%), number of clusters per plant (23.55%) and seed yield (15.58%) showed maximum per cent contribution towards total genetic divergence on pooled basis. Cluster analysis showed that genotypes fall into seven different clusters and their inter and intra cluster distance showed genetic diversity between different genotypes. The maximum number of genotypes i.e., 8 was found in cluster II followed by cluster III comprising of 6 genotypes. Genotypes RMG-1138 and IPM-02-03 representing the mono genotypic cluster signifies that it can be the most diverse variety and it would be the appropriate genotype for hybridization with ones present in other clusters to tailor the agriculturally important traits and ultimately to boost the seed yield in mungbean under rainfed conditions.

Genetic diversity analysis for yield and yield components in rice

The present investigation was carried out to explore the extent of divergence in 55 rice germplasm accessions for twelve characters during Kharif, 2019. In D2 analysis, the 55 genotypes were grouped into fourteen clusters. The clustering pattern indicated that there was no parallelism between genetic diversity and geographical origin as the genotypes of the same origin were included in different clusters and vice versa. The maximum inter cluster distance was found between cluster IX and cluster XIII (1313.049) followed by cluster X and cluster XIII (1152.033), cluster XII and cluster XIII (1039.108), cluster III and cluster XIII (1015.310) and cluster I and cluster XIII (978.369). Genetically distant parents from these clusters could be able to produce higher heterosis in progenies on hybridization. Single plant yield (43.29%) followed by grain length (12.99%), 100 grain weight (12.12%) grain width (11.85%) and days to 50% flowering (11.85%) were the major contributors towards the total genetic divergence among the genotypes studied. Selection could be made based on grain yield per plant, hundred grain weight and days to 50% flowering for the progenies identified.

Genetic divergence analysis in basmati rice genotypes (Oryza sativa L.) for agro-morphological and quality traits using multivariate approach

Genetic diversity of 30 basmati rice genotypes was analysed based on nine agro-morphological and six quality traits. The results of the principal component analysis showed that the first six principal components explained 89.16% of the total variation in the experimental material. These 30 basmati genotypes were grouped into six clusters which indicated the presence of sufficient diversity among the tested genotypes. Cluster I and cluster III was found to be the largest comprising of 10 genotypes each followed by cluster II having seven genotypes. The highest average intra-cluster distance was observed in cluster III. Highest inter-cluster distance (D2) was observed between clusters III and VI followed by clusters III and V, III and IV & clusters II and III. Cluster II showed high mean value for grain yield per plant, 1000 grain weight, and grain length. The characters viz., amylose content, grain length after cooking, spikelet per panicle, grain width, grain length and 1000 grain weight contributed maximum towards total genetic divergence, suggest their suitability of selection.

Genetic Divergence Study in Maize (Zea mays L.) Inbred Lines under North Western Himalayan Conditions

Genetic divergence in 50 maize inbreds including five checks was assessed based on some morpho-physiological and yield contributing traits using Mahalanobis D2 statistics. The experiment was carried out in an augmented block design at Maize Research Station, SKUAST-J, Udhampur, J&K during Kharif 2019-20. All the inbreds were grouped into ten clusters based on D2 analysis. Maximum numbers of genotypes (12) were grouped in cluster III whereas cluster X (1) was the smallest. Maximum inter-cluster distance was observed between cluster VIII and cluster IX indicating presence of maximum diversity among the genotypes falling within these clusters. The genotypes in the cluster VIII showed better performances having high shelling percentage (%), grain yield per plot (g), cob length, kernels per row and 1000 kernel weight (g). It is expected that crossing of inbred lines belonging to high-medium D2 values may tend to produce high heterosis for yield. Perusal of the data indicated that moisture percentage contributed maximum of 8.90 per cent whereas, days to 50 % silking contributed the lowest of 0.73 per cent to the total genetic divergence.

Coffee genotypes morphophysiological adaptation under coffee leaf rust biotic stress

The identification of morphophysiological traits responsible for a better plant behavior when infected is useful for cultivar selection, and become crucial for breeding. We investigated the morphophysiological behavior of coffee genotypes before and after inoculation with the pathogen Hemileia vastatrix, causal agent of coffee rust. With multivariate techniques we identified the characteristics that most contribute to total genetic divergence of the genotypes. Ten genotypes of Coffea arabica from the Germplasm Bank of Coffee from Minas Gerais were sown in a nursery and then take to a greenhouse with controlled temperature and humidity. After one month of acclimatization, the artificial inoculation with the fungus H. vastatrix was carried out. The anatomical and physiological evaluations were performed 1 day before inoculation and 160 days after inoculation. When the first symptom emerged, plants were evaluated according to a descriptive scale for coffee rust. We observed significant differences in rust severity and ostiole opening betweengenotypes. Different groups were formed by the K-means method, based on morphophysiological characteristics. This shows that genetic variability exists between the coffee genotypes evaluated before and after inoculation with the pathogen. The most important characteristics that contributed to the total genetic divergence were xylem vessel diameter and stomatal conductance. In conclusion, inoculation with H. vastatrix caused a change in coffee genotypes based on morphophysiological characteristics. Key words: Coffea arabica; canonical variables; Hemileia vastatrix.