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Showing 11 results for Selection
Saeed Khavari Khorasani, Abdonaser Mahdi Poor,
Volume 5, Issue 1 (9-2018)
Abstract
Selection based on proper selection indices can be one of the most effective methods for indirect selection of yield and yield components, simultaneously. In order to determination of selection index for improvement of maize yield, 60 single cross maize hybrids were planted in two separate experiments (drought stress and normal conditions) based on randomized complete block design (RCBD) with three replications in Torogh agricultural station of Khorasan Razavi agricultural and natural resources research and education center, Mashad, Iran in 2013-2014. Morphological and phenological traits, yield and yield components were recorded. Selection indices were calculated based on results of stepwise regression considering to phenotypc, genotypic and economic values. Based on stepwise regression results in normal condition, physiological maturity, plant height, kernel depth, kernel no./row and tassel length totally could explain 60.68 percent of gain yield variation, then these traits were used to calculate selection index. In drought stress condition, kernel no./row, plant height, ear height, 1000 kernel weight, ear length and leaves no. above ear could explain 63.77 percent of grain yield variation that these traits were used to calculate of selection index. We used 5 optimum selection indices (smith-hazel) and one basic selection index as Pesk-Baker to screen the maize genotypes. The results showed that the relative efficiency of selection index based on yield and expected genetic gain for all of measured traits in selection index 2 was higher than others in both normal and drought stress conditions. Based on grain yield and selection indices, 20 percent of the best genotypes were selected by each selection indices. Based on derived results in normal condition, genotype no. 60 (ksc704 commercial hybrid) were selected by all of selection indices as the best genotype, but in drought stress condition, different genotypes were selected by different selection indices like genotypes 16 (ME77006/1×K1263/1), 22 (ME77006/1×K1263/1) and 34 (ME78005/2× A679), that these genotypes at least were selected by 2 or 3 selection indices.
Seyed Ali Mohammad Mirmohammadi Maibody, Pooran Golkar,
Volume 6, Issue 1 (9-2019)
Abstract
Plant Breeding has utilized a wide range of techniques and methods to improve the quality and quantity of plants. The molecular markers are the tools that have provided a new perspective for plant breeding advancements. This article has reviewed the various advantages and uses of molecular markers and the utilization of the high potential of natural polymorphisms within communities, combined with the abilities of conventional plant breeding methods. The marker attributes are not subject to environmental influence and their high frequency of these markers in their number, high structural diversity are as part of their benefits in identifying identities, determining the genetic diversity of species and studying relationship between populations. They may aid in discovering more information about protecting and maintaining genetic stock collections, identifying varieties, determining genes with chromosomal location and the number of genes controlling traits. Genome sequencing, the preparation of physical and genetic maps, genomic fingerprinting of plants are some of the other applications of this tool in plant breeding. The high efficiency of selection with the help of markers in selection of genotypes has been emphasized as the parent of crosses and selection with the help of a marker in breeding programs and genomic selection. New technologies offers new opportunities to shape genetic variation in the improvement of specific plant breeding programs. Nowadays development of next-generation sequencing technology, genome sequencing and high throughput approaches for markers have facilitated EST-derived simple sequence repeat (EST-SSR) marker development as well as single nucleotide polymorphism (SNP) marker. These markers can be successfully employed in accelerating research and plant breeding programs.
Abbas Saberi Kuchesfahani, Atefeh Sabouri, Amin Abedi, Ali Aalami, Teimour Razavipour,
Volume 7, Issue 1 (9-2020)
Abstract
water stress and, in this regard, it is necessary to improve rice cultivars to tolerance to environmental stresses. In this research 154 recombinant inbred lines (F9) derived from a cross between Shah-Pasand and IR28 in three conditions (non-stress, osmotic stress -0.3 and -0.6 Mpa induced through polyethylene glycol-6000) were evaluated as a factorial experiment in randomized complete block design. In addition, for molecular polymorphism experiment, 110 SSR and EST-SSR markers were assessed on parents of population and among them, 41 markers identified which had proper polymorphism between two parents. The regression analysis between germination components and molecular markers revealed the most coefficient of determination were found in RM211 for allometric coefficient (17%) under non-stress, RMES10-1 for Plumule dry weight (18%) under -0.3 MPa; and RM273 for germination uniformity (22.7%) under -0.6 MPa. RM3496, RM452, and RMES6-1 in three conditions had the most number of significant relationships with six, three and eight traits, respectively, and they can be a suitable candidate for simultaneous improvement of several traits in breeding programs of marker-assisted selection. In addition, after the identification of significant markers associated with germination components, the closest genes to these markers were identified using bioinformatic analysis, and the analysis of their expression were performed by rice transcriptome database. According to the results, the maximum gene expression pattern under drought stress and under non-stress conditions were related to loci LOC_Os01g57220 and LOC_Os01g26039, respectively and this information could be applied in breeding programs.
Peyman Sharifi, Abouzar Abbasian, Ali Mohaddesi,
Volume 7, Issue 2 (3-2021)
Abstract
Additive main effect and multiplicative interaction (AMMI) and best linear unbiased prediction (BLUP) are two methods for analyzing multi-environment trials (MET). In this study, seven selected rice lines were evaluated along with two check varieties based on randomized complete block design in Tonekabon, Amol and Sari (Iran) in three growing seasons of 2011-14. To quantify the genotypic stability, the best linear unbiased predictions of the genotype by environment interactions (GEI) were estimated, and singular value decomposition (SVD), which is the basis of AMMI analysis, was performed on the resulting matrix. The likelihood ratio test (LRT) showed that the effect of GEI was significant on grain yield, number of tillers, thousand grains weight and panicle length. Therefore, due to the significant interaction of genotype by environment, BLUP analysis can be performed on this data. The biplot of first principal component (PC1) of the environment versus nominal yield showed that genotypes 7 ([IR 67015-22-6-2-(A37632) × (Amol3 × Ramzanalitarom)]39), 6 (IR67015-22-6-2-(A37632) × (Amol3 × Ramzanalitarom)]126) and 2 ([IR64669-153-2-3 - (A8948) × (4Surinam Deylamani)]2), due to the lowest scores of the PC1, had a small share in the GEI and had more grain yield stability. The biplot of grain yield versus WAASB, placed genotypes in four regions, so that genotypes in the fourth region, including genotypes 6, 7, 8 (Line 843, check variety), and 9 (Shirodi, check variety), were due to large value of response variable (high grain yield) and high stability (low values of WAASB) were very productive and had extensive stability. Identification of genotypes with weighted average of WAASB and response variable (WAASBY) criteria showed that genotypes 6 and 7 were high yields and stable. Based on the multi-trait stability index (MTSI), G6 was also selected as the best genotype in terms of grain yield, evaluated traits and stability of each trait. Totally, genotype 6 was stable and superior based on the results of all methods.
Esmaeil Dasturani, Khalil Zaynali Nezhad, Masood Soltani Najafabadi, Mohammadhadi Pahlevani, Hassan Soltanlo, Saeed Bagherikia,
Volume 8, Issue 1 (8-2021)
Abstract
The aim of this study was to determine the haplotype groups and identify the specific alleles associated with desirable agronomic characteristics in bread wheat. For this purpose, 42 local bread wheat genotypes belong to Iran region and nine commercial cultivars along with Chinese Spring variety (reference genotype) were cultivated in the format of augmented design and evaluated based on their 13 phenotypic traits. The results of descriptive statistics showed that awn length and day to flowering had the highest and lowest phenotypic coefficient of variation, respectively. Eight microsatellite markers were used to investigate the haplotype variation of QTLs associated with phenotypic traits located on wheat chromosomes 4B and 7D. The result showed that the genotypes were classified into 13 and 6 haplotype groups according to the allelic comparison with the reference genotype on chromosome 4B and 7D, respectively. In order to investigate the relationship between traits and markers, analysis of variance was performed based on completely randomized design with unequal numbers of replications for each marker. In general, of the 13 traits studied, there was a statistically significant linkage for eight traits and for the three traits, an allele-specific was introduced simultaneously. If the breeders are interested in genotype selection that simultaneously have three desirable characteristics such as early anthesis, semi-dwarfing and a greater number of grains per spike, they can use an allele-specific (153 bp) of Xgwm149-4B marker.
Abdul Karim Tahmasebi, Reza Darvishzadeh, Amir Fayaz Moghaddam, Esmaeil Gholinezhad, Hossein Abdi,
Volume 8, Issue 2 (3-2022)
Abstract
The selection of genotypes based on multiple traits is a fundamental issue and an important part of the process of plant breeding. In the present study, the efficiency of selection indices based on phenological, morphological and physiological traits was studied to improve sesame grain yield. The evaluation of 25 sesame populations was realized in a completely randomized design with 10 replications under Urmia conditions in 2017.The results showed that phenotypic and genotypic correlations between grain yield and No. of capsules per plant, No. of grains per capsule, No. of branches, leaf temperature, leaf index and biological weight were positive and significant. By regression and path analysis, the No. of capsules and No. of branches were identified as the variables of the first-order cause and biological weight, harvest index, leaf index, plant height and chlorophyll as the second-order cause variables, among which only plant height had a direct negative effect. In order to obtain selection indices, two optimal and basic methods and ten different vectors of economic values of traits were used. The vectors were based on the analysis of correlation, regression, path and broad sense heritability. The third and fourth indices, in which the first-order cause entered the model, showed high relative efficiency and in terms of these two indices, and the sesame populations with code number of 12, 17, 18 and 19 populations were identified as the most desirable populations. Finally, it is suggested that the efficiency of these selection indices be evaluated in the field
Jafar Ahmadi, Amir Abbas Taghizadeh, Mohialdin Pirkhezri,
Volume 9, Issue 2 (3-2023)
Abstract
To determine the ideal genotypes in terms of the quantity and quality of fruit, 32 genotypes of greengage were evaluated in a randomized complete block design with three replications at the research station of Horticultural Research Institute in Karaj during two cropping seasons 2018 and 2019. To evaluate the genotypes and to determine the ideal genotype, 26 traits related to fruit, fruiting and yield were used. Combined variance analysis of data showed that the genotype source of variation was significant for all studied traits at the level of 0.01 probability level. ASIIG index showed that the genotypes CodR, Cod100, Malayer, and Gojeh Siah are the best and most desirable genotypes with an index higher than 55%, respectively. Also, Cod98, Cod99, Gojeh Baghi Qasr Dasht, Gojeh Qomi, and Gojeh Holandi with ASIIG index higher than 49% were ranked next. The grouping of genotypes using ASIIG method diagrams, the genotypes CodR, Cod100, Cod98, Cod99, Gojeh Malayer, Gojeh Siah, and Gojeh Baghi Qasr Dasht were located in the ideal quartile. Using cluster analysis, the genotypes CodR, Cod100, black, and Malayer as well as completely ideal hypothetical genotype (+) were placed in a group at a distance line of 0.018. According to the results of this study, seven genotypes CodR, Cod100, Cod98, Cod99, Gojeh Malayer, Gojeh Siah, and Gojeh Baghi Qasr Dasht were selected as the ideal genotypes in terms of fruit quantity and quality. Finally, due to the high benefits of the ASIIG index, it was suggested that this index can be used in other horticultural products to determine the ideal genotype.
Maryam Ebrahimi, Reza Darvishzadeh, Amir Fayaz Moghaddam,
Volume 10, Issue 1 (9-2023)
Abstract
Protection of food security is one of the basic priorities of any country, which is achieved through the development and introduction of new, high-yielding and stress-resistant crop varieties. Considering the wide range of usage; human nutrition, livestock and poultry nutrition as well as use in industrial products production, maize is of special importance in agricultural development programs. To improve a trait with complex behavior and low heritability, indirect selection by other traits or a suitable index developed based on several traits can be used. In this research, 86 maize genotypes were cultivated in the form of randomized complete block design with three replications in the field in the Faculty of Agriculture, Urmia University under two normal and salt stress conditions. The measurement of the traits was done from the tassel appearance to kernel physiological maturity. In order to speed up genotype selection and increase the acuracy of selecting high yielding genotypes, four selection indices including Smith- Hazel, Pasek- Baker, Brim and Robinson were used and calculated. The results of present study revealed that selection based on the Smith- Hazel index with the highest selection efficiency (∆H) will increase the grain yield in normal and grain yield and plant height in salt stress conditions. This index, with its high correlation with the breeding value is introduced as a superior index. Based on this index, R59 and 6*/88 genotypes were introduced as the superior genotypes under normal and salt stress conditions, respectively. Nonetheless, these genotypes were recognized as the best genotypes considering the results of all other investigated indices. Identifying and introducing genotypes tolerant to salinity stress is of particular importance due to the expansion of saline lands and the limitation of access to water suitable for irrigation. Based on the above results, 6*/88 genotype is recommended for the development of promising hybrids for cultivation in areas with water or saline soil.
Hosein Astaraki, Mahmoud Lotfi, Sasan Aliniaeifard, Ali Izadi-Darbandi, Payman Sharifi, Hossein Ramshini,
Volume 10, Issue 2 (2-2024)
Abstract
In order to select the most tolerant genotypes of melon to drought stress, 30 landraces and cultivars were evaluated at Broujerd Agricultural Research Station in 2018. Under normal and drought stress conditions genotypes were evaluated in a randomized complete block design with three replications. Drought stress was started when fruits appeared. Based on the rate of evaporation in class A evaporation pan (normal conditions: 50 mm, stress conditions: 100 mm), irrigation was carried out. The results of this study showed that Yield under drought stress and normal conditions showed high correlations with stress tolerance indices such as MP (Mean Productivity), GMP (Geometric Mean Productivity) and STI (Suitability Tolerance Index). The broad sense hereditary under drought stress condition varied from 81% for yield per plant to 97% for the fruit lenght. Under drought stress condition, the highest percentage of genetic coefficient of variation (GCV) was observed for Weight of flesh and skin (49 percent) and the lowest for days to maturity (4 percent). Based on the PCA biplot, the genotypes of Mamaghani, Rish-baba, Garmak and Japuni melon were identified as tolerant and Mazandrani, Uzbak1 and Ginsen Makuwa were classified as sensitive to drought stress. These results could be useful for breeding purposes and the genotypes can be crossed with each other to produce segregating populations and selection of the best plants.
Nasrin Akbari, Reza Darvishzadeh,
Volume 11, Issue 1 (9-2024)
Abstract
Sunflower, one of the important oilseed plants, is affected by drought stress, consequently leading to yield decreases. Direct selection for improving seed yield, as the end result of multiple traits, is often ineffective due to the significant impact of environmental conditions. For many years, indirect selection through other traits or selection indices has been proposed to improve seed yield. In the present experiment, 100 oilseed sunflower genotypes were evaluated in terms of some agro-morphological traits using a simple 10 × 10 lattice design under normal and drought stress conditions during two consecutive croping seasons. In drought stress conditions, irrigation was done after 180 mm of evaporation from class A evaporation pan, compared to 90 mm in normal irrigation conditions. Brim, Smith-Hazel, Robinson and Pesek-Baker selection indices were calculated to select genotypes under two environmental conditions. In order to evaluate and compare the efficiency of selection indices and select the best index, the genetic gain of traits (∆G), expected gain (∆H) and relative efficiency of selection index (RE) were calculated. The results of this study showed that the direct response to selection for the traits including seed oil content, days to maturity and leaf length under both environmental conditions was more favorable compared to the correlated response. However, for head and stem diameter traits, the lowest efficiency of direct selection was observed under both environmental conditions compared to other investigated traits. Considering the two criteria; the genetic gain of traits (∆G) and expected gain (∆H) under normal and drought stress conditions, the two indexes of Brim and Smith-Hazel were introduced as the best index and the genotype ENSAT-254 was introduced as the superior genotype. The selected ENSAT-254 genotype can be considered in developing hybrid cultivars for cultivation under drought stress conditions, provided it is validated at the molecular level by analyzing the expression of genes related to water deficit stress tolerance.
Hossein Mehripour Azbarmi, Jalal Saba, Bahram Alizadeh, Amir Gholizadeh, Farid Shekari,
Volume 11, Issue 1 (9-2024)
Abstract
The genotype × environment interaction is a major challenge in studying quantitative characters because it reduces grain yield stability in different environments. In this regard, to analysis the genotype × environment interactions and to determine the yield stability of winter rapeseed mutant lines, 9 lines and 6 cultivars were evaluated in a randomized complete block design with three replications in six experimental field stations (Esfahan, Hamedan, Karaj, Kermanshah, Qazvin and Zarghan) during 2021–2023 croping seasons. The combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. According to the stability analysis results using the Eberhart and Russel method, the Talaye cultivar with higher grain yield than overall mean and regression coefficient equal to one (bi=1) was identified as the genotype with high general stability for all regions. Based on the simultaneous selection method for yield and stability (YSi), the lines Z-900-6, T-1200-1, and Talaye cultivar with the lowest values were stable, whereas Zarafam, Okapi and Express cultivars with the highest values were unstable. Also, based on the SIIG index, the lines Z-900-6, T-1200-1, and Talaye cultivar with having high SIIG values as well as higher grain yields that total average was recognized as superior genotypes from the point of stability and grain yield. According to the results of cluster analysis, Karaj, Zarghan, Kermanshah and Isfahan locations were located in a group that indicates these locations had high predictability and repeatability power.
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