Genetic Variability, Heritability and Correlation of Some Morphological and Yield Components Traits in Potato (Solanum tuberosum L.) Collections

The study was conducted with the main objective to evaluate the genetic variability, heritability, and clustering pattern exploration of morphological and yield related traits in potato (Solanum tuberosum L.) collections in the bimodal rainfall agroecological zone of Cameroon using a Randomized Complete Block Design (RCBD) with three replications. The data obtained on morphological and yield traits were subjected to analysis of variance (ANOVA). The results showed that the viability rate of the collections varied from 77.78% to 96.55% respectively for the Maffo and Desiree collections, while the greatest number of tubers per plant varied from 4 to 18 respectively for Synergie and Desiree. The emergence rate varies from 60% to 1.66% respectively for Maffo et Doza collections. However, Desiree presents the highest TL (96.55) while Maffo shows the lowest value (77.78%). The yield per hectare varied from 1.14 to 9.3 t/h for Maffo and Doza respectively. For all the characteristics observed, Phenotypic Coefficients of Variation (PCV) were higher than Genotypic Coefficients of Variation (GCV) suggesting the role of environment in the expression of traits under observation. The highest GCV and PCV 47.55 and 58.94 respectively were observed for Diameter at the collar (DC). Most of the traits showed high GAM (>20%)) except Average Tuber Length (ATL) with a moderate value (19.8). In terms of vegetative development, the Desiree variety showed the highest performance. Based on the growth and yield results, Doza seems to be the most recommendable crop in the study area.

Genetic variability for yield and fiber related traits in genetically modified cotton

Background:Cotton(Gossypium hirsutum L.)is grown for fiber and oil purposes in tropical and sub-tropical areas of the world.Pakistan is the 4th largest producer of cotton.It has a significant contribution in the GDP of Pakistan.Therefore,the present study was performed to assess the genetic variations and genetic diversity of yield and fiber quality traits in cotton and to analyze the associations present among them.Results:Analysis of variance exhibited significant variation for all studied traits except total number of nodes and the height to node ratio.The phenotypic coefficient of variation was higher than the genotypic coefficient of variation for all studied traits.Plant height,monopodial branches,total number of bolls,lint index,seed index,and seed cotton yield displayed high heritabilities in a broad sense with maximum genetic advanee.Correlation analysis revealed that seed cotton yield had a significant positive association with plant height,the nu mber of monopodial branches,the nu mber of sympodia I branches,ginning outturn(GOT),the number of bolls,seed per boll,seed index,uniformity index,the number of sympodial branches,reflectance,and seed index at the genotypic level while a significant positive relationship was observed with plant height,the number of sympodial branches,boll number,and GOT.Plant height,monopodial branches,GOT,boll weight,seeds per boll,and short fiber index exerted direct positive effects on seed cotton yield.The first 6 principal component analysis(PCs)out of the total fourteen PCs displayed eigenvalues(>1)and had maximum share to total variability(82.79%).The attributes that had maximum share to total divergence in eluded plant height,uniformity index,the nu mber of sympodial branches,seed per boll,GOT,seed cotton yield,and short fiber index.Conclusion:The genotype AA-802,IUB-13,FH-159,FH-458,and CIM-595 were genetically diverse for most of the yield and fiber quality traits and could be utilized for the selection of better performing genotypes for further improvement.

Genetic variability of half-smooth tongue sole Cynoglossus semilaevis populations using microsatellite markers

Ten highly variable microsatellite loci were performed in order to evaluate the genetic variability of wild and hatchery samples of half-smooth tongue sole Cynoglossu＇s semilaevis. A group of 200 genotypes belonging to four wild samples, Laizhou （LZ）, Weihai （WH）, Qingdao （QD）, Rizhao （RZ） and one hatchery sample, Mingbo （MB）, were screened. All of the： ten microsatellite loci screened in this study showed marked polymorphism. A total of 70 different alleles were observed over all loci. The number of alleles per locus ranged from 4.2 to 1006 the average of expected and observed heterozygosity ranged from 0.67 to 0.82, and from 0：77 to0.87 respectively. A total of 10, 16, 10, 11 and 5 unique alleles each were found in LZ, WH~ QD：RZ and MB populations. The effective number of alleles varied from 2.87 for HSTS_7 to 6.83 for HSTS_h. The number of average genotypes ranged from 6.0 for HSTS a to 15.4 for HSTS_h： As compared with the wild populations, the hatchery population, MB, showed significant genetic changes such as fewer alleles per locus （P〈0.05）, a smaller number of low frequency alleles （P〈0.05）, a small number of unique alleles and a small number of genotypes （P〈0.05）, all indicative of a reduction in genetic diversity.

Relationships between morphological descriptors and RAPD markers for assessing genetic variability in Hippophae rhamnoides L.

Knowledge of genetic relatedness among accessions of germplasm is necessary for the development of breeding strategies to produce improved cultivars. The present investigation on Hippophae rhamnoides was carried out to assess its genetic variability in Himachal Pradesh, India, by employing morphological and RAPD markers. Different areas of Himachal Pradesh were surveyed and eight sites were finally selected Twenty four genotypes were selected for further studies, i.e., three genotypes from each site. On the basis of morphological studies, the genotypes of the Ropa site （Kinnaur） were considered elite genotypes. To assess the variability at the molecular level, RAPD patterns were studied by random primers. The total number of bands amplified was 607, out of which 487 bands were identified as polymorphic, depicting 80.23 per cent variability. Six unique bands were produced from three primers （OPA- 05, OPA-10 and OPD-08） specific for five genotypes, including three genotypes of the Ropa site, Kinnaur District.

Genetic Variability of Pumpkin Landraces in Brazilian Amazon

The family farm of the Upper Solim?es region has maintained the great genetic variability of the pumpkin (Cucurbita maxima Duchesne) by the in situ conservation of the landraces which are widely used as human food. The aim of this study was to estimate the current level of genetic variability of pumpkin landraces by means of estimation techniques of genetic parameters. Landraces areas samples were the family farming production units located in floodplains ecosystems of Benjamin Constant (Upper Solim?es River) and Iranduba (Lower Solim?es River), Amazonas. The split-plot designs were adopted at the treatments where the main plots were the five pumpkin landraces and one commercial cultivar. Each landrace was obtained six half sib families distributed in the sub-plots. Among the results of this study, it can be concluded that the genetic variation within the each landrace is greater than the genetic variation among the landraces. The qualitative morphological characteristics bring together half-sib families collected in geographically distant locations. It can be concluded that, through the estimation of genetic parameters, there is genetic variability among local cultivars collected in family farming of Benjamin Constant and Iranduba, Amazonas.

Molecular Study of the Genetic Variability of Pumpkins Landraces from Brazilian Amazon

The Cucurbita maxima Duchesne is a vegetable crop plant cultivated and maintained by traditional Amazon communities, Brazil. The situation is worsened by the possibility of disappearance of local populations and genetic variability of this specie, taking into account the today changes promoted in family farming. The aim of this study was to estimate the current levels of genetic variability of local cultivars through the use of molecular markers (Amplified Fragment Length Polymorphism—AFLP). We chose to collect in two distinct micro regions in order to identify possible influences of geographic isolation and different levels of market requirements in the conservation of the genetic variability of the C. maxima. For the molecular analysis, bulk samples of fresh leaves of 15 plants/half-sibling family were collected in paper bags. There were 34 samples from the half-sib families. The analysis of the results half-sib obtained by methods of estimation of genetic variation by molecular markers shows that the forms of cultivation and management adopted by family farmers maintain the identities of the local/landraces (native cultivars) and, at the same time, the levels of diversity for the assurance of adaptability macro-environmental.

Genetic variability and evolution of rice stripe virus

Rice stripe virus(RSV) is the type member of the genus Tenuivirus.RSV is known to have four segmented,single-stranded RNA molecules and causes rice stripe disease in the rice fields of China,Japan,and Korea.Based on the complete genomic sequences of the determined 6 RSV isolates(from Yunnan,Jiangsu,Zhejiang,and Liaoning Provinces,China) and 27 other RSV isolates(from Yunnan,Jiangsu,Anhui,Henan,and Shandong Provinces of China,also Japan and Korea) downloaded from GenBank,we provided a genotyping profile of RSV field isolates and described the population structure of RSV.All RSV isolates,except isolate CX,could be divided into two subtypes,one including 6 isolates from Yunnan Province,and the other including 26 isolates from different parts of China,Japan,and Korea,which were referred to as subtype II and subtype I,respectively.The amino acid distances between subtypes range from 0.053 to 0.085.RSV isolates in Yunnan Province were genetically differentiated from other parts of China,Japan,and Korea and showed infrequent gene flow.The RSV populations collected from other parts of China,Japan,and Korea were only composed of subtype I and showed very low genetic diversity.We speculated that isolate CX may be the result of recombination of isolates from two subtypes.Two potential recombination events were detected in RNA4 of isolate CX.

Estimation of Genetic Divergence and Character Association Studies in Local and Exotic Diversity Panels of Soybean(Glycine max L.)Genotypes

The availability of favorable genetic diversity is a thriving vitality for the success of a breeding program.It provides a firm basis of selecting superior breeding lines for the development of high yielding crop genotypes.In this context,present investigation aimed to generate information on genetic divergence and character association in a diversity panel of 123 local and exotic soybean genotypes.Analysis of variance revealed significant response of the evaluated genotypes based on studied attributes.It depicted the probability of selecting desirable soybean genotypes by focusing on character association studies and genetic diversity analysis.Correlation analysis revealed that seed yield per plant showed high positive correlation with 100-seed weight followed by pods per plant and plant height.Furthermore,path coefficient analysis exposed that pods per plant had maximum direct contribution in seed yield per plant followed by 100-seed weight,days to flowering and SPAD measurement.Genotype named“G-10”showed maximum yield per plant followed by 24607,G-52,24593,Arisoy,24566,17426,A-3127,24570 and 24567.Genetic diversity analysis grouped the evaluated germplasm into 17 clusters.All clusters showed zero intra-cluster variability;while inter-cluster divergence ranged from 9.00 to 91.11.Cluster V showed maximum inter-cluster distance with cluster XII followed by that of between V and VIII.Moreover,cluster IV with superior genotypes(G-10,24607,24593 and 24566),VI(17426 and 24567),XIII(24570)and X(Arisoy and G-52)showed above mean values for most of the studied characters.Overall,the results of hybridization between the superior genotypes of these cluster pairs might be useful for soybean breeding with improving agronomic traits and adaptability.

Nutritional and nutraceutical variability in neglected niger(Guizotia abyssinica(L.f.)Cass.)accessions from Eastern Ghats of India

The exploitation of neglected niger accessions plays a crucial role in future breeding programs aimed to enhance the quality.Present study evaluated the genetic variation in nutritional and nutraceutical compositions of 30 indigenous niger accessions originating from Eastern Ghats of India,and compare them with three improved varieties of the locality.The proximate compositions(g/100 g)showed significant variations,with moisture ranging from 1.36 g to 4.95 g,ash from 1.06 g to 5.45 g,fat from 28.53 g to 44.11 g,protein from 8.84 g to 18.18 g,carbohydrate from 11.21 g to 35.09 g,fiber from 16.32 g to 26.62 g,and energy from 407.32 kcal to 526.84 kcal.Niger seeds are rich in phenol 41.10–82.20 mg/g,flavonoid 5.32–15.98μg/g,antioxidant 13.59–31.08%across the accessions.Principal component analysis revealed that the first two axis explained 41.8%of the total variation,indicating significant differences among genotypes.The heritability and genetic advance in percent of mean(GAM)ranged from 61.11%to 99.91%and 12.5%–89.1%among the traits across the populations.High heritability and GAM recorded in vitamin C,ash content,antioxidant capacity,flavonoid and phenol suggests that these traits may be important for niger breeding program.Altogether,some indigenous niger accessions such as Mangardora,Ganjeipadar and Kolabnagar had exceptionally rich in fat,protein and energy contents and are nutritionally superior compared to improved variety of the locality.Further,exceptional rich in flavonoid,antioxidant capacity and vitamin C was recorded in Manahar,Badapada and Mahadeiput.These nutrition rich accessions have ample opportunities for future breeding programs aimed to enhance the quality and hold great potential in food industry for making high value functional food.

Genetic Structure and Diversity Study of Cassava (Manihot esculenta) Germplasm for African Cassava Mosaic Disease and Fresh Storage Root Yield

A better understanding of population structure and genetic diversity among cassava germplasm for African cassava mosaic disease and fresh root yield traits is useful for cassava improvement programme. Phenotype-based selection for these traits is cumbersome due to phenotypic plasticity and difficulty in screening of phenotypic-induced variations. This study assessed quantitative trait loci (QTL) regions associated with African cassava mosaic disease (ACMD) and fresh storage root yield (FSRY) in 131 cassava (Manihot esculenta) genotypes using a genome-wide association study (GWAS). The single nucleotide polymorphism (SNP) loci and associated candidate genes, when validated, would be a valuable resource for marker-assisted selection in the breeding process for development of new cassava genotypes with improved resistance to ACMD and desirable high root yield. Population structure analysis using 12,500 SNPs differentiated the 131 genotypes into five distinct sub-groups (K = 5). Marker-trait association (MTA) analysis using the generalized linear model identified two QTL regions significant for ACMD and three for FSRY. This study demonstrated that DArTseq markers are useful genomic resources for genome-wide association studies of ACMD and FSRY traits in cassava for the acceleration of varietal development and release.

Selection criteria of MPOB-Angola germplasm collection for yield improvement of the oil palm

Oil palm germplasm collected from Angola,Africa in 1991 were subjected to genetic variability potential studies.The collection was planted in the form of open-pollinated families as trials at the Malaysian Palm Oil Board(MPOB)Kluang Research Station,Johor,Malaysia,in 1994.Dura palms from 52 families and tenera palms from 44 families of MPOB-Angola were evaluated for their bunch yield and bunch quality components.The objectives of this study were to determine the genetic variability among the families and performance of MPOB-Angola germplasm for yield improvement.The analysis of variance(ANOVA)revealed highly significant differences between the dura and tenera families for most of the traits,suggesting the presence of high genetic variability,which is essential for breeding programmes.Among the duras,family AGO 02.02 displayed the best yield performance,with a high fresh fruit bunch,oil yield and total economic product at 240.40,29.46 and 37.93 kg palm^(-1)year^(-1),respectively.As for the teneras,family AGO 03.04 recorded the highest FFB yield and oil yield at 249.25 and 45.22 kg palm^(-1)year^(-1),respectively.Besides that,several families with big fruit sizes or producing a mean fruit weight of 14-17 g were also identified.Both dura and tenera from AGO 01.01 recorded the highest oil to bunch(O/B)of 17.76%and 28.65%,respectively.These findings will facilitate the selection of palms from the MPOB-Angola germplasm for future breeding programmes.

Assessment of Variation in Morpho-Physiological Traits and Genetic Diversity in Relation to Submergence Tolerance of Five Indigenous Lowland Rice Landraces

The present study evaluated submergence responses in 88 lowland indigenous rice(Oryza sativa L.) landraces from Koraput, India, to identify submergence-tolerant rice genotypes. In pot experiments, variations in survival rate, shoot elongation, relative growth index, dry matter, chlorophyll, soluble sugar and starch contents were evaluated in two consecutive years under well-drained and completely submerged conditions. Principal component analysis showed that the first three axes contributed 96.820% of the total variation among the landraces, indicating wide variation between genotypes. Major traits such as survival rate, relative growth index, soluble sugar and starch contents appeared to be important determinants of phenotypic diversity among the landraces. Phenotypic coefficient of variance was higher than genotypic coefficient of variance for all the traits and all showed high heritability(90.38%–99.54%). Five rice landraces(Samudrabali, Basnamundi, Gadaba, Surudaka and Dokarakuji) were the most tolerant to submergence. When submerged for up to 14d, Samudrabali, Basnamundi and Godoba were notable for having greater survival rates than a standard submergence tolerant variety FR13 A, and also notable for elongating more vigorously and accumulating more biomass. These three landraces may therefore be especially useful in lowland rice growing areas that are affected by both moderate stagnant water and flash flooding. Molecular genotyping revealed that the submergence tolerance of Samudrabali, Basnamundi and Godoba is linked to the presence of one or more different Sub1 loci and it may well prove useful for breeding improved submergence tolerant rice varieties, thereby assising to improve yield stability in the rainfed lowland agro-ecosystem.

Variability in Grain Quality Characters of Upland Rice of Assam,India

The grain quality of 100 uplandlahu rice genotypes from Assam, India was assessed. The characteristics measured were grain length, grain width, cooked grain length, cooked grain width, grain elongation ratio after cooking, grain widening ratio after cooking, alkali spreading value, gel consistency, as well as starch, amylose, amylopectin and total soluble sugar contents. Considerable genetic variability among the 100 rice genotypes was observed for the characteristics under study. Analysis of vadance revealed highly significant differences among the genotypes for all the characteristics. The difference between genotypic coefficient of variation （GCV） and phenotypic coefficient of variation （PCV） was very small for all the characteristics analyzed. High GCV and PCV were found in the characteristic of total soluble sugar content followed by alkali spreading value. The high values for these traits signify the scope for selection to develop superior genotypes. High heritability was recorded in all the characteristics analyzed along with diverse genetic advance which varied from 9.71% to 52.83%. The characteristic of total soluble sugar content showed high heritability with high genetic advance, whereas alkali spreading value and grain widening ratio presented high hedtability with moderate genetic advance. This implies that these characteristics are mainly under additive gene effects and could be relied upon further selection based on phenotypic performance. The genotypic correlation coefficient was higher than the phenotypic correlation coefficient, indicating strong inherent associations among the characteristics studied.

Heritability and correlation analysis of morphological and yield traits in genetically modified cotton

Background:Cotton is known for fiber extraction and it is grown in tropical and sub-tropical areas of the world due to having hot weather.Cotton crop has a significant role in GDP of Pakistan.Therefore,the two-years research was conducted to estimate heritability and association among various yield contributing parameters of cotton,i.e.,plant height,number of bolls per plant,number of sympodial branches per plant,seed cotton yield,boll weight,seed index,ginning outturn(GOT),fiber length,fiber strength,and fiber fineness.Results:Association analysis revealed that seed cotton yield had a significant positive correlation with plant height,number of bolls per plant,number of sympodial branches per plant,GOT,staple length and fiber strength.Staple length and fiber strength were negatively linked with each other.Estimates of heritability were high for all of the traits except the number of sympodial branches per plant and boll weight.Conclusion:The parent IUB-222 was found to be the best for plant height,the number of bolls per plant,boll weight,GOT,seed cotton yield,and seed index.The genotypes namely,NIAB-414 and VH-367 were identified as the best parents for fiber length,strength,and fineness.Among the crosses NIAB-414×IUB-222 was the best for the number of bolls per plant,seed index,seed cotton yield and fiber fineness,whereas,the cross of NIAB-414×CIM-632 was good for plant height.The combination of A555×CIM-632 was the best for the number of sympodial branches per plant,boll weight,fiber length,and strength,and VH-367×CIM-632 proved the best for GOT.

Genetic Diversity of Tunisian and Chinese Alfalfa (Medicago sativa L.) Revealed by RAPD and ISSR Markers

Medicago sativa L.) is one of the most important forage crops in the world. The genetic variability analysis of 19 alfalfa populations collected from three sites in South Tunisia (Gabes, Kebili, Tozeur) and 1 from North West China were carried out using Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeat (ISSR) markers. Five RAPD primers amplified 44 bands of which 22 were polymorphic;and five ISSR primers amplified 51 bands of which 33 were polymorphic. The percentage of polymorphic bands detected by RAPD and ISSR was 50% and 64.7%, respectively. The resolving power (Rp) varied between 0.6 and 4.1 with an average of 2.02 for RAPD marker and between 0.7 and 6.5 with an average of 2.28 for ISSR marker. However the Average Informativeness band (AvIb) was ranged from 0.2 to 0.9 with an average of 0.5 in RAPD marker and from 0.29 to 0.7 with an average of 0.624 in ISSR marker. The RAPD marker revealed less within population genetic diversity than ISSR marker. Although Cluster (UPGMA) and Correspondence Factorial Analyses (CFA) indicate that populations’ clustering made independently both from the geographical origin.

Genetic effects of historical anthropogenic disturbance on a long-lived endangered tropical tree Vatica mangachapoi

The endangered Vatica mangachapoi,a longlived,tropical tree with economic and ecological importance found in Hainan,China,was used to assess the hypothesis that historical human activities in Hainan’s tropical rain forest could have negative effects on the genetic diversity of V.mangachapoi.Three hundred and twenty individuals from 11 natural populations—which were classified into three groups according to levels of disturbance—were sampled and analyzed with ISSRmarkers.Although genetic diversity of V.mangachapoi is high at the species level,it is relatively low within populations.A significant genetic differentiation occurs among different disturbance levels.Significant isolation-by-distance indicated relevant historical anthropogenic changes.Our findings showed that historical human disturbances significantly increase the genetic differentiation and slightly decrease the genetic diversity of long-lived tree V.mangachapoi.Relevant targeting conservation actions were recommended.

Contemporary climate infuence on variability patterns of Anadenanthera colubrina var.cebil,a key species in seasonally dry tropical forests

The distribution of many plant species has been shaped by climate changes,and their current phenotypic and genetic variability refect microclimatically suitable habitats.This study relates contemporary climate to variability patterns of phenotypic traits and molecular markers in the Argentinean distribution of Anadenanthera colubrina var.cebil,as well as to identify the most relevant phenotypic trait or molecular marker associated with those patterns.Individuals from four populations in both biogeographic provinces,Paranaense and Yungas,were investigated.Multivariate analyses and multiple linear regressions were carried out to determine relationships among phenotypic traits and nuclear microsatellites,respectively,to climatic variables,and to identify the phenotypic traits as well as nuclear microsatellite loci most sensitive to climate.Two and three clusters of individuals were detected based on genetic and phenotypic data,respectively.Only clusters based on genetic data refected the biogeographic origin of individuals.Reproductive traits were the most relevant indicators of climatic effects.One microsatellite locus Ac41.1 appeared to be non-neutral presenting a strong correlation with climate variable temperature seasonality.Our findings show complex patterns of genetic and phenotypic variability in the Argentinean distribution of A.colubrina var.cebil related to the present or contemporary climate,and provides an example for an integrative approach to better understand climate impact on contemporary genetic and phenotypic variability in light of global climate change.

Agro-Morphological Characterization and Genetic Dissection of Linseed(Linum usitatissimum L.)Genotypes

Linseed is a multipurpose crop and the crop needs further improvement to increase production and yield due to its high value and demand.This study aimed to assess the extent and pattern of genetic variability of forty linseed genotypes based on diverse agro–morphological and yield attributes.The field experiment was conducted following a Randomized Complete Block Design with three replications.Linseed germplasm showed a wide range of phenotypic expression,genetic variability and heritability for 30 studied traits.A low to high phenotypic coeffi-cient of variation(PCV)and genotypic coefficient of variation(GCV)were observed.The lowest genotypic(σ2 g)and phenotypic variances(σ2 p)were found in capsule diameter(CD),length of calyx(LC),capsule length(CL),seed length(SL),and seed breadth(SB).High broad-sense heritability(h2 b)with high genetic advance as a percentage of mean(GAM)were observed in days to germination started(DGS),days to 80%emergence(DE),plant height at 28 and 40 DAS,number of flowers(NFPP),filled capsules(NFCPP)and yield per plant(YPP)indicating additive gene action exists for these characters.Hierarchical cluster analysis separated 40 genotypes into five clusters,where Clusters I to V assembled with 13,4,4,5 and 14 genotypes,respectively.Considering yield and yield attributes,Cluster-IV(G3,G4,G6,G10 and G31)genotypes showed promising while,Cluster-II(G2,G16,G35,G36)and Cluster-III(G1,G33,G39 and G40)genotypes were dominant on plant morphological traits.Based on principal component analysis(PCA),few characters such as YPP,NFPP,NFCPP,days to first flowering and capsule formation,early emergence,days to branch initiation and plant heights at different growth stages revealed important and effective traits for consideration in the selection of linseed breeding programs.

Exploration of Genetic Pattern of Phenological Traits in Wheat (Triticum aestivum L.) under Drought Stress

Drought is the major detrimental environmental factor for wheat(Triticum aestivum L.)production.The exploration of genetic patterns underlying drought tolerance is of great significance.Here we report the gene actions controlling the phenological traits using the line×tester model studying 27 crosses and 12 parents under normal irrigation and drought conditions.The results interpreted via multiple analysis(mean performance,correlations,principal component,genetic analysis,heterotic and heterobeltiotic potential)disclosed highly significant differences among germplasm.The phenological waxiness traits(glume,boom,and sheath)were strongly interlinked.Flag leaf area exhibits a positive association with peduncle and spike length under drought.The growing degree days(heat-units)greatly influence spikelets and grains per spike,however,the grain yield/plant was significantly reduced(17.44 g to 13.25 g)under drought.The principal components based on eigenvalue indicated significant PCs(first-seven)accounted for 79.9%and 73.9%of total variability under normal irrigation and drought,respectively.The investigated yield traits showed complex genetic behaviour.The genetic advance confronted a moderate to high heritability for spikelets/spike and grain yield/plant.The traits conditioned by dominant genetic effects in normal irrigation were inversely controlled by additive genetic effects under drought and vice versa.The magnitude of dominance effects for phenological and yield traits,i.e.,leaf twist,auricle hairiness,grain yield/plant,spikelets,and grains/spike suggests that selection by the pedigree method is appropriate for improving these traits under normal irrigation conditions and could serve as an indirect selection index for improving yield-oriented traits in wheat populations for drought tolerance.However,the phenotypic selection could be more than effective for traits conditioned by additive genetic effects under drought.We suggest five significant cross combinations based on heterotic and heterobeltiotic potential of wheat genotypes for improved yield and enhanced biological production of wheat in advanced generations under drought.

Salinity Tolerance in Argentinean Population of <i>Bromus catharticus</i>. Variability and Direct and Indirect Effects on Seedling Characters

The aim of this research was to evaluate the salinity tolerance in prairie grass populations at the seedling stage quantifying the variability and the influence of physiological traits related to it. Salinity tolerance, in Bromus catharticus Vahl (prairie grass) populations collected in different environments of the Pampean Phytogeography region (Argentine) was evaluated at the seedling stage, using controlled condition of temperature and light. It was adopted a completely randomized design using 3 plots with three plants each one per population and two levels of treatment: 0 mM and 100 mM NaCl. Morphological, biomass and membrane stability root and shoot traits were studied. A factorial ANOVA with interaction was estimated. Then one way ANOVA for all seedling traits in both treatments allowed estimating variance components, coefficient of genotypic determination (CGD) and variation index (VI). Comparisons between populations were made using Tukey test (at 5% of probability). Phenotypic correlations among traits were calculated and then a path coefficient analysis separated direct and indirect effects at 100 and 0 mM NaCl. No significant interactions “Population × Treatment” were found for any character. The saline stress caused a pairing in the population means for the most traits. Coefficients of variation were mainly higher when the seedlings grew without stress (0 mM) because it allowed a greater potential genotypic expression. The absence of significant interactions denotes a good homeostatic capacity of the prairie grass facing that abiotic stress. Leaf length, shoot length and root dry matter were the variables with the largest direct and indirect effects. Our results showed an increase for them at salt and demonstrated intraspecific variation, possibly in relation with the origin sites. Plants under stress showed a marked resilience, in order to quickly restore the same biomass allocation patterns that occur in non-stress environment.