Presence Of Genetic Variability Research Articles

Emerging Challenges in Staphylococcus aureus Bloodstream Infections: Insights from Coagulase Typing, Toxin Genes, and Antibiotic Resistance Patterns.

The incidence of complications and mortality associated with Staphylococcus aureus (S. aureus) bloodstream infections has been increasing significantly, particularly in developing countries where control strategies against this virulent pathogen and its resistance to antibacterial agents are insufficient. The aim of this study was to investigate coagulase typing, the prevalence of toxin genes, and the antibiotic resistance profile of S. aureus isolated from bloodstream infections. Antibiotic susceptibility of the isolates was determined by the disk diffusion method. The prevalence of toxin genes was determined using the polymerase chain reaction (PCR) method. Genetic variability of isolates was determined using multiplex PCR based on coagulase gene polymorphism. Out of 120 strains, 55 (46%) were methicillin-resistant S. aureus (MRSA) and 65 (54%) were methicillin-sensitive S. aureus (MSSA). All isolates were susceptible to linezolid and teicoplanin but showed varying levels of resistance to other antibiotics. The highest resistance was observed for ampicillin (92.5%), gentamicin (69.2%), and amikacin (68.3%). Multidrug resistance was observed in all isolates. PCR analysis revealed a higher prevalence of toxin genes in MRSA (tst: 38%, pvl: 29.1%, eta: 10%, and etb: 4.1%) than that in MSSA. According to the coa typing, the most prevalent types were coa III (29.2%), coa II (26.7%), and coa VI (10%). The presence of genetic variability and widespread multidrug resistance in our hospitals emphasizes the circulation of various coa types. Therefore, it is crucial to implement antimicrobial stewardship and infection control measures to prevent and control the spread of these strains.

Study on exploitation of heterosis for yield and yield contributing traitsin sesame (Sesamum indicum L.)

The experiment was undertaken to study the magnitude of heterosis of 32 hybrids obtained by crossing 4 (female) x 8 (male) genotypes in L x T fashion including their 12 parents and 2 standard checks (JLT-408 and PRACHI). The ANOVA revealed significant differences among parents, hybrids and parents vs hybrids for most of the characters, indicating the presence of genetic variability. The crosses SWETHA x V-25, V-34 x TBS-12, V-32 x TBS-7, SWETHA x R-26 and SWETHA x TBS-12 showed high heterobeltiosis and standard heterosis over both checks for seed yield and yield contributing traits. Significant heterobeltiosis and standard heterosis observed for majority of yield and yield attributing traits.

Study on the exploitation of heterosis for yield and yield contributing traits insesame (Sesamum indicum L.)

The present investigation was undertaken with the objective to study the magnitude of heterosis involved in 32 hybrids obtained by crossing 4 (female) x 8 (male) genotypes in L x T fashion along with their 12 parents and 2 standard checks (JLT-408 and PRACHI) evaluated during summer 2019-20 at Oilseeds Research Station, Latur. The analysis of variance for experimental design revealed significance differences among the parents, hybrids and parents vs hybrids for most of the characters indicated the presence of genetic variability among the experimental material. The crosses viz., Swetha til x V-25, V-34 x TBS-12, V-32 x TBS-7, Swetha til x R-26 and Swetha til xTBS-12 found with high heterobeltiosis and standard heterosis over check JLT-408 and PRACHI for seed yield along with other yield contributing traits. Significant heterobeltiosis and standard heterosis for seed yield observedfor majority of yield and yield attributing traits.

GENETIC DIVERSITY AMONG COTTON (GOSSYPIUM HIRSUTUM L.) GERMPLASM FOR YIELD AND FIBRE TRAITS UNDER ARID CLIMATIC CONDITION

Climate change has drastically affected the performance of several agricultural crops. Cotton is an important fibre crop which is severely influenced by the climate change in recent years Presence of genetic variability among germplasm is a key source for selecting the genotypes that are more adapted to the agro-climatic conditions with respect to yield and fibre related traits. For this purpose, 180 cotton genotypes were sown under augmented design with recommended management practices. Data for the morphological, yield and fibre traits viz plant height (PH), CLCuD(%),bolls per plant, boll weight (g), yield/ plant (g), GOT (%), staple length (mm), mike (ug/inch), staple strength (g/tex) were recorded and analysed. The results of variance analysis revealed that significant variability was observed among genotypes for all the traits under study. PCA biplot showed that 26% variability was observed in PC1 and 15.5% in PC2. Genotypes no. 30 was found with distant yield and fibre characteristics. Through cluster analysis, total 180 cotton genotypes were grouped into nine different clusters. Group 7 and group 8 consist of 15 and 03 genotypes respectively. Genotypes among these two groups represent the higher CLCuD resistance, maximum yield per plant with better fibre traits. Phenotypic evaluation of cotton genotypes for different morphological, yield and fibre traits provide the basis for exploitation of best performing genotypes in the future breeding programme.

A Review on Genetic Analysis of Rice (Oryza sativa L.) Crop of Yield Contributing Traits

Rice is the primary source of energy for the international population. In any crop breeding programme, the presence of genetic variability is vital for broadening the gene pool. An excessive magnitude of variability in the population is required for selecting a genotype with excessively applicable traits. The heritability estimates along with the amount of genetic variability provide us with an idea of genetic gain due to choose. Specific direct developments (number of panicles/plants, filled grains/plant, and test weight) and indirect tendencies (tiller number/plant, plant peak) determine the yield component of rice. In the present overview, we draw a clear picture of how variability affects the selection method and also how yield is related to distinct direct and indirect developments. Genotypes show high variability, and suitable characters can be used in a similar breeding programme. A glimpse of molecular advances in rice breeding has also been integrated into the gift overview.

Genetic Diversity, Analysis of Some Agro-Morphological and Quality Traits and Utilization of Plant Resources of Alfalfa.

Alfalfa (Medicago sativa L.) is one of the most important perennial forage crops to build effective diets for livestock producers. Forage crop improvement depends largely on the availability of diverse germplasms and their efficient utilization. The present investigation was conducted at Ismailia Agricultural Research Station to assess twenty-one alfalfa genotypes for yield components, forage yield and quality traits during 2019/2020 and 2020/2021. The genotypes were evaluated in field experiments with three replicates and a randomized complete block design, using analysis of variance, estimate of genetic variability, estimate of broad sense heritability (hb2) and cluster analysis to identify the inter relationships among the studied genotypes as well as principal component analysis (PCA) to explain the majority of the total variation. Significant differences were found among genotypes for all studied traits. The general mean of the studied traits was higher in the second year than the first year. Moreover, the combined analysis showed highly significant differences between the two years, genotypes and the year × gen. interaction for the traits studied. The genotype F18 recorded the highest values for plant height, number of tiller/m2, total fresh yield and total dry yield, while, the genotype F49 ranked first for leaf/stem ratio. The results showed highly significant variation among the studied genotypes for crude protein %, crude fiber % and ash %. Data revealed that the genotypes P13 and P5 showed the highest values for crude protein %, whereas, the genotype F18 recorded the highest values for crude fiber % and ash content. The results revealed high estimates of genotypic coefficient and phenotypic coefficient of variation (GCV% and PCV%) with high hb2, indicating the presence of genetic variability and effective potential selection for these traits. The cluster analysis exhibited considerable genetic diversity among the genotypes, which classified the twenty one genotypes of alfalfa into five sub-clusters. The genotypes F18, F49, K75, S35, P20, P5 and P13 recorded the highest values for all studied traits compared with other clusters. Furthermore, the PC analysis grouped the studied genotypes into groups and remained scattered in all four quadrants based on all studied traits. Ultimately, superior genotypes were identified can be utilized for crop improvement in future breeding schemes.

Study on the heterosis for yield and yield contributing traits in sesame (Sesamum indicum L.)

The present investigation was undertaken with an objective to study the magnitude of heterosis involved in 32 hybrids obtained by crossing four (female) x eight (male) genotypes in L x T fashion along with their 12 parents and two standard checks (JLT-408 and PRACHI) evaluated during summer, 2019-20 at Oilseeds Research Station, Latur. Data were recorded on yield and its different contributing traits. The analysis of variance for experimental design revealed significance differences among the parents, hybrids and parents vs hybrids for most of the characters indicated the presence of genetic variability among the experimental material. The crosses viz., SWETHA x V-25, V-34 x TBS-12, V-32 x TBS-7, SWETHA x R-26 and SWETHA x TBS-12 found with high heterobeltiosis and standard heterosis over check JLT-408 and PRACHI for seed yield along with other yield contributing traits. Significant heterobeltiosis and standard heterosis for seed yield were observed for the majority of yield and yield attributing traits. Selection of high heterotic hybrids with high per se performance would be reliable in the improvement of sesame. Keywords: Sesame, heterosis, heterobeltosis, standard heterosis

Genetic Analysis in Pre-breeding Lines of Greengram [Vigna radiata (L.) Wilczek

Background: Greengram is third most important pulse crop which is widely adapted and can improve soil fertility. The genetic variability and association studies help in selection which would increase the yield potential of greengram. Methods: Two hundred stabilized lines (F9) obtained from the cross VBN (Gg) 2 and Vigna radiata var. sublobata were evaluated. The yield and yield contributing traits were recorded to evaluate genetic variability, heritability, genetic advance as % of mean and correlation among the yield and its component traits. Result: Analysis of variance exhibited significant differences among the lines for all the ten quantitative traits indicating the presence of genetic variability. The high GCV values were found for the traits viz., single plant yield (30.18) and the number of pods per plant (26.80). High heritability combined with high genetic advance as per cent of mean was observed for the number of pods per plant (90.19, 52.43), single plant yield (89.58, 58.84), the number of pods per cluster (79.28, 22.70) and the number of clusters per plant (69.50, 30.22) which indicates additive gene effects. In the present study, the number of pods per plant had a high positive direct effect (0.919) on a single plant yield. Therefore, the selection for these characters would improve yield in greengram.

A Review on Genetic Analysis of Rice (Oryza sativa L.) Crop for Yield and its Contributing Characters

Rice provides major source of calories in the global population. In any crop breeding programme, presence of genetic variability is essential for broadening the gene pool. For selecting a genotype having high desirable traits, high magnitude of variability should be present in the population. The heritability estimates along with amount of genetic variability give us an idea about genetic gain due to selection. Different direct traits (number of panicle/plant, filled grains/plant and test weight) and indirect traits (tiller number/plant, plant height) determine the yield component of rice. Present review draw a clear picture of how variability influences the selection process and also how yield is associated with different direct and indirect traits. Genotypes shows high variability and desirable characters can be used in further breeding programme. A glimpse of molecular advances in rice breeding also has been incorporated in the present review.

Estimation of heritability and breeding values for performance and body conformation traits in Harnali Sheep

The present study was conducted to evaluate the effect of non-genetic factors on performance and body conformation traits along with estimation of heritability and breeding values of these traits in Harnali sheep. Nongenetic factors had significant effect on the performance and body conformation traits in Harnali sheep. Heritability estimates varied from low to moderate for performance traits indicating the presence of genetic variability which could be used for further improvement of these traits. Comparatively higher heritability estimates for body conformation traits in the present study indicated towards the presence of genetic variability which might be due to the reason that linear type traits were not included in the selection criterion of Harnali sheep so far. High genetic variability in these traits noticeably indicated the scope of improvement in these body dimensions through selection. Breeding value estimates for different performance and body conformation traits pointed the variability between the genetic merit of individuals which can be exploited through selection for making improvement in the considered traits in Harnali sheep.

The effect of drought stress on the expression of genes TaMOR, TaNAC69-1 and TaExpb23 in different bread wheat (Triticum aestivum L.) cultivars

For evaluating the effects of TaMOR, TaNAC69-1 and TaExpb23 expression on root system architecture and drought tolerance of wheat, 10 bread wheat varieties were compared through germination test, pot experiment and field trial. In germination test, genotypes were evaluated under 0, -3 and -6 bar osmotic potentials. In pot experiment genotypes were compared at 50%, 75% and 100% of field capacity (FC) irrigation regime. In field trial, genotypes were grown under well-watered and rain fed conditions. Based on the results of this experiment, it was concluded that water deficit had significant effect on all of traits except for seminal root numbers. Significant genotypic differences were observed for all of traits indicating the presence of genetic variability among the genotypes. Correlation coefficients showed that TaMOR gene expression had positive correlation with plant yield under 75%FC stress (r=0.733*). TaNAC69-1 gene expression had positive correlations with plant yield and plant biomass under 50%FC (r=0.634* and r=0.711*). TaNAC69-1 gene expression also showed positive correlation with root numbers under 50%FC condition (r=0.622*). TaNAC69-1 gene expression also showed positive correlation with seminal root angle (r=0.648*) under severe stress. TaExpb23 expression showed positive correlation with plant yield and biomass under 75%FC (r=0.663* and r=0.723*). Based on the results of this experiment, it was concluded that under different stress levels, TaMOR, TaNAC69-1 and TaExpb23 gene expressions had significant correlations with traits. Due to significant G×E interactions, it also concluded that the effect of expression of TaMOR, TaNAC69-1 and TaExpb23 genes on traits is different under distinct stress levels.

Genome-Wide Association Mapping for Stomata and Yield Indices in Bread Wheat under Water Limited Conditions

Genome-wide association study (GWAS) was performed for stomata- and yield-related attributes with high-density Illumina 90 K Infinium SNP (single nucleotide polymorphism) array in bread wheat to determine genetic potential of germplasm for scarce water resources with sustainable yield potential. Major yield and stomata attributes were phenotyped on a panel of Pakistani and foreign accessions grown in non-stressed and water shortage environments during two seasons. Highly significant variations were shown among accessions in both conditions for examined characteristics. Water shortage conditions reduced the overall wheat yield and strong positive correlation existed among stomatal frequency, leaf venation and grain yield per plant. Population structure analyses based on 90,000 SNP data classified the accessions into four sub-populations which indicated the presence of genetic variability. Marker-trait association (MTA) analyses revealed that 422 significant SNPs at p ≤ 10−3, after crossing the false discovery rate (FDR) <0.05 threshold, were linked with examined attributes. Pleiotropic loci (wsnp_Ex_c8913_14881924 and Tdurum_contig10598_304) were associated with flag leaf area (FLA), stomata size (SS), stomata frequency (SF), leaf venation (LV), number of grain per spike (NGS) and grain yield per plant (GYP), which were located on chromosome 4B and 6B at the positions 173.63cM and 229.64cM, respectively, under water shortage conditions. Pleotropic loci wsnp_Ex_c24167_33416760, wsnp_Ex_c5412_9564046 and Tdurum_contig81797_369 on chromosomes 7A, 2A and 4B at the positions 148.26cM, 261.05cM and 173.63cM, respectively, were significantly linked with stomata and yield indices such as FLA, SS, SF, LV, NGS and GYP under normal and water shortage conditions. The current experiment not only validated several MTAs for studied indices reported in other studies but also discovered novel MTAs significant under water shortage environments. Associated and significant SNPs will be useful in discovering novel genes underpinning water shortage tolerance in bread wheat for producing high-yielding and drought tolerant wheat varieties to fulfill the wheat demand for growing populations.

Genealogical structure of the Belarusian black-and-white breed based on the microsatellite analysis of the lines bred at gene pool enterprises

The methods of molecular genetic analysis are widely used to assess the genetic structure and to study the dynamics of population-genetic processes in populations of domestic animals. I n particular, these are the highly polymorphic genetic markers – the microsatellites that are the most common molecular markers in genetic and genomic research. The aim of the research was to develop the genealogical structure of the Belarusian black-and-white breed based on the microsatellite analysis of the lines bred at a gene pool enterprise. The research was carried out with the animals bred at the JSC “SGC “Zarechye”. For the microsatellite analysis of boars of the Belarusian black-and-white breed, the DNA testing was carried out at 9 STR-loci (SО155, SО355, SО386, SО005, SW72, SW951, SО101, SW240, and SW857). In all studied lines, the largest number of effective alleles was at the SО005 locus – 4.00–5.14. The lines of animals with heterozygosity can be used in various breeding schemes, both in purebred breeding (in pedigree pig breeding) and in crossing (in industrial pig breeding). Polymorphism determines the degree of genetic variation in populations. The locus is classified as polymorphic when the frequency of the most common allele of this locus does not exceed 95% (р ≤ 95). The revealed polymorphism of loci in the lines Maket, Tik, and Veseliy indicates the presence of genetic variability in them, which allows using them in breeding and breed-forming processes. Based on the studies made, the genealogical structure of the Belarusian black-and-white breed, consisting of one subcluster and two branches, has been developed, which makes it possible to assess the state and degree of relation of structural units (lines), and reflects the prospect of their further use.

Estimation of Heterosis Among Potato (Solanum tuberosum L.) Crosses in Ethiopia

Determination of heterosis in tetraploid potato crosses is necessary for identification of superior genotypes for variety development or breeding program. However, producing heterotic potato genotypes through local crossing is not a common practice in Ethiopia. Hence, this study was conducted to estimate the magnitude of better, and standard check heteroses in potato clones that are produced from local crossing. This will help identify potential of hybrid for future breeding schemes. Heterosis of 75 clones were evaluated using a 9 x 9 Simple Lattice design. Results of the analysis of variance showed significant differences for all the growth characters, except medium-sized tubers and specific gravity of tuber. These results indicate the presence of genetic variability among the samples. The clones exhibited as high as 55.62 and 58.31 t.ha-1 marketable and total tuber yield, respectively. These clones also displayed mid, better parent and standard heterosis of 118.8%, 90.5% and 239.1%, respectively, for marketable tuber yield. This result indicates the presence of high magnitude heterosis which could be used to exploit the hybrid vigor. In addition, mid, better parent, and standard check heterosis were estimated at 79.36%, 61.04% and 209.17% for total tuber yield, respectively. Our results show the highest chance of getting heterotic offspring than parental and standard check varieties to developing new potato varieties. The information generated from this study would be valuable for researchers who intend to develop high-yielding varieties of potato

Genetic Variability for Yield and Its Related Traits in Green gram [Vigna radiata (L.) Wilczek

Background: Green gram [Vigna radiata (L.) Wilczek] is an ancient and well known pulse crop of Asian countries. Specific traits should be considered for high yield in green gram as selection criteria in future breeding program.Methods: The investigation material comprised of 128 F6 RIL (Recombinant Inbred LINE) population sown at college farm, Professor Jayashankar Telangana State Agricultural University during Rabi-2019-20. The yield and yield attributes were recorded to conduct genetic variability, heritability broad sense (h2), genetic advance (GA) and genetic advance as % of mean (GAM).Result: Analysis of variance revealed significant differences among the RILs, indicating the presence of genetic variability for almost all the traits studied. High PCV and GCV estimates was noticed for number of pods per plant, seed yield per plant, number of cluster per plant and number of pods per cluster. High heritability along with high genetic advance as per cent of mean was observed for number of pods per plant, seed yield per plant, number of cluster per plant, number of pods per cluster, number of branches per plant, number of seeds per pod and plant height indicating the role of additive genes in governing the inheritance of these traits and could be improved through selection. The traits viz. seed yield per plant, number of pods per plant, number of clusters per plant and number of pods per cluster had recorded high PCV, GCV, high heritability along with high genetic advance as per cent of mean indicated these traits were less influenced by environment and possess high genetic variability. Hence these RILs would be suitable for green gram breeding programmes to develop improved varieties. The present findings of the RIL population will be useful for development of high seed yielding variety in green gram.

Identification of superior progenies between common bean gene groups for root system obtained by recurrent selection

Genetic variability is essential for gains in breeding programs. The cyclic process of progeny recombination is a strategy to raise the chances of selecting better genotype combinations. The objective of this study was to identify superior progenies between common bean genes groups in first recurrent selection cycle for root system traits. Parents of the Andean and Middle American gene groups were hybridized in a complete diallel scheme. Thereafter, the parents and F1 and F2 populations were planted in the field. To establish the base population of recurrent selection (C0), seven segregating populations (F2) with superior performance for root system were selected and intercrossed, resulting in recombinant progenies (C1). To estimate the selection gain, the parents and C0 and C1 genotypes were compared with regard to the following variables: total root length (TRL, cm), projected root area (PRA, cm2), root volume (VOL, cm3) and number of root tips (RT). The difference between genotype combinations indicates the presence of genetic variability and effectiveness of recurrent selection. The mean genetic progress for root system-related traits was 12.9% (TRL), 12.6% (PRA), 12% (VOL) and 11.5% (RT) in the first recombination cycle. The mean phenotypic performance of seven of the C1 progenies exceeded that of their parents for all root system traits. These progenies are promising as base populations of the next selection cycle.

Seleção de genótipos de cana-de-açúcar em três épocas de colheita

Objetivou-se com este trabalho a seleção de genótipos de cana-de-açúcar, para três épocas de colheita, a partir da utilização de técnicas multivariadas. Os experimentos foram conduzidos na área agrícola da Usina União e Indústria, município de Primavera, Pernambuco. Utilizou-se o delineamento em blocos completos casualizados com quatro repetições. Os caracteres agroindustriais avaliados foram: toneladas de pol por hectare (TPH), toneladas de cana por hectare (TCH), fibra (FIB), pol % corrigida (PCC), pureza (PZA), teor de sólidos solúveis (BRIX) e açúcar total recuperável (ATR). Realizaram-se quatro testes multivariados, testes de efeitos entre sujeitos e comparações múltiplas. Realizou-se ainda a análise de componentes principais visando a discriminação dos genótipos quanto ao desempenho agroindustrial nas épocas de colheita. A análise de variância multivariada (MANOVA) revelou que há efeito significativo das épocas de colheita sobre os caracteres dos genótipos. Os testes de efeitos entre sujeitos revelaram, por sua vez, diferenças significativas entre os caracteres nas respectivas épocas de colheita, indicando a presença de variabilidade genética e a possibilidade de seleção de materiais produtivos para as três épocas que correspondem a três segmentos distintos de maturação. O genótipo RB92579 se destaca quanto a produtividade e maior rentabilidade econômica, podendo ser cultivado e colhido em qualquer segmento de maturação.

Mixed models and multivariate approach applied to maize breeding: A useful tool for biofortification

Biofortification and bioactive compounds enrichment of maize genotypes is a great alternative for mitigating micronutrients deficiency in human and animal diet, and also for improving the benefits of maize for human health. This work aimed to estimate variance components and genetic parameters of bioactive compounds and micronutrients to predict superior maize hybrids from different genetic bases, and to apply the RELM/BLUP methodology to multivariate techniques. The inbreed lines were crossed and the F1 hybrids were grown for evaluations in 2014/2015 and 2015/2016 growing seasons, respectively. Then, micronutrients and bioactive compounds related traits were evaluated. The variance components and genetic parameters were estimated by REML methodology. The BLUP methodology was employed to predict genetic values and to verify the percentages of genetic gain with selection. The predicted genetic values were applied to estimate genetic distances by the Mean Euclidean Distance. The relative contribution of each trait to genetic divergence was evaluated and the principal components analysis determined, proposing the genotypes that are potentially capable to increase a given trait. The presence of genetic variability was evidenced among genotypes, while some of them presented potential for increasing specific traits. The top cross hybrid L64XAS1590 showed the highest estimates for increasing antioxidant-responsible traits, and micronutrients contents such as manganese, cooper, iron and zinc. In general, there was the possibility of achieving genetic gains with selection under application of biofortified and bioactive compounds to enhance maize hybrids through conventional breeding. However, it does not applicable for iron content due to its low estimate of broad sense heritability.

Management Practices and Breeding History of Varieties Strongly Determine the Fine Genetic Structure of Crop Populations: A Case Study Based on European Wheat Populations

As the effects of climate change begin to be felt on yield stability, it is becoming essential to promote the use of genetic diversity in farmers’ fields. The presence of genetic variability in variety could fulfil this purpose. Indeed, the level of intra-varietal genetic diversity influences the spatio-temporal stability of yields and the disease susceptibility of crop species. Breeding history of varieties and their management practices are two factors that should influence intra-varietal genetic diversity. This paper describes the genetic diversity of eight wheat samples covering a gradient from modern single varieties to on-farm mixtures of landraces. This gradient discriminates between landrace, historical and modern varieties, considering the breeding history of varieties, between single-varieties and mixtures of varieties, and between ex situ and in situ de facto strategy in terms of management practices. Genetic diversity of these samples was analyzed with the help of 41 single nucleotide polymorphism markers located in neutral regions, through computing genetic indices at three different levels: Allelic, haplotypic and genetic group level. Population structure and kinship were depicted using discriminant analysis and kinship network analysis. Results revealed an increase in the complexity of the genetic structure as we move on the gradient of variety types (from modern single variety to in situ on-farm mixtures of landraces). For the landraces, the highest levels of genetic diversity have been observed for a landrace (Solina d’Abruzzo) continuously grown on-farm in the region of Abruzzo, in Italy, for many decades. This landrace showed an excess of haplotypic diversity compared to landraces or the historical variety that were stored in genebanks (ex situ conservation). Genetic analyses of the mixtures revealed that, despite a very high selfing rate in wheat, growing in evolutionary mixtures promotes recombination between different genetic components of the mixture, a second way to increase the level of haplotype diversity. When management practices such as growing in mixture and on-farm management are combined, they substantially increase the different levels of genetic diversity of the populations (allelic, haplotypic, genetic group diversity), and consequently promote their adaptability. Our results confirm the need to develop and manage evolving diversified large populations on-farm. These results invite crop diversity managers such as genebank curators, community seed bank managers and farmers’ organizations to adapt their management strategies to the type of variety they wish to manage, because we have shown that their choices have a strong influence on the genetic composition of the crop populations.

Study of genetic variability for yield and yield attributing characters in maize (<em>Zea mays</em> L.)

A field experiment with 30 maize inbred lines was conducted to study the genetic variability in maize at Horticulture Research Farm, Institute of Agricultural Sciences, Bundelkhand University, Jhansi (U.P.) during Kharif-2018. The estimates of the mean sum of square due to genotypes were highly significant for all the characters indicating the presence of genetic variability in the existing material. The variation was highest for plant height followed by biological yield per plant, seed yield per cob, seed yield per plant, number of seeds per row and harvest index in maize. High PCV and GCV were observed for plant height, cobs per plant, biological yield per plant that indicating greater variability for these traits and their further improvement through selection. High heritability coupled with high genetic advance as per cent of mean for characters like plant height followed by harvest index, cob ear weight, rows per plant, seed yield per cob, biological yield per plant, days to 50 per cent germination, shelling per cent, days to 50 per cent silking suggested that they can be improved through direct selection.