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G. Najafian

Bio: G. Najafian is an academic researcher. The author has contributed to research in topics: Grain quality & Drought tolerance. The author has an hindex of 8, co-authored 22 publications receiving 176 citations.

Papers
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Journal Article
TL;DR: The results indicated that AMMI is an informative method of stability and adaptation analysis to be employed in practical plant breeding and subsequent variety recommendations.
Abstract: Eighteen wheat breeding lines were evaluated along with two check cultivars across nine locations of temperate zone of Iran during two crop seasons (2003-2004 and 20042005). Field records were taken for some important traits especially grain yield. Combined ANOVA for nine locations in the first season and for seven locations in both seasons was undertaken. In each case, additive main effects and multiplicative interaction analysis (AMMI) was employed and the biplot of the Interaction Principal Components (IPC) were evaluated for stability and adaptation relationships among genotypes and locations. IPC1, IPC2 and IPC3 accumulatively defining 78.4% of genotype×environment (G×E) interaction variation were found out as significant in the first crop season. Biplot of first two IPCs identified at least two sub-regions among the locations. Some genotypes (M-82-7 and M-82-17) showed specific adaptation toward one of the drought-prone subregions. For the combined data of both seasons, only IPC1 was significant defining 41.5% of G×E interaction variation. Thus, plot of IPC1 along with grain yield means were employed for an interpretation of adaptation relationships. Entries M-82-8, M-82-9, M82-11 and M-82-15 showed specific adaptation to Mashhad station which was interactive and particular in behavior. The results indicated that AMMI is an informative method of stability and adaptation analysis to be employed in practical plant breeding and subsequent variety recommendations.

34 citations

Journal ArticleDOI
TL;DR: In this paper, a set of 98 bread wheat landraces from different geographic regions of Iran were used across 2013-2014 and 2014-2015 to determine the phenotypic diversity and relations between thousand grain weight (TGW), grain morphology and grain quality.
Abstract: Grain characteristics, particularly grain weight, grain morphology, and grain protein content (GPC), are important components of grain yield and quality in wheat. A set of 98 bread wheat landraces from different geographic regions of Iran were used across 2013-2014 and 2014-2015 to determine the phenotypic diversity and relations between thousand grain weight (TGW), grain morphology and grain quality. A high-throughput method was used to capture grain size and shape. The genotypes were significantly different (P < 0.001) for all traits which reflects the high levels of diversity. A moderate to high broad sense heritability was found for all traits and ranged between 0.68 and 0.95 for grain yield and factor from density (FFD), respectively. Significant positive correlations were observed between TGW and grain size (or shape) exception of aspect ratio (AR) and roundness. However, grain quality traits, especially GPC had significant negative correlation with TGW. Based on stepwise regression analysis by taking TGW as dependent variable, grain volume, FFD, width, perimeter and Hardness Index (HI) were recognized as the most important traits and explained more than 99.3% of total variation of TGW. The path analysis revealed that FFD has maximum direct effect on TGW followed by volume, whereas perimeter and width had relatively less direct effect on TGW. According to cluster analysis, landraces separated into 5 clusters, and cluster III and IV had the maximum and minimum average for the most traits, respectively. Our study provides new knowledge on the relations between TGW, grain morphology and grain quality in bread wheat, which may aid the improvement of wheat grain weight trait in further research.

28 citations

01 Jan 2006
TL;DR: It can be coneluded that exogenous application of CK at cell division stage in grain growth phase may significantly improve biomass and grain yield, while in contrary, exogenousApplication of ABA increased ABA concentration of developing grains, while had inverse effect on IAA of the same grains.
Abstract: Saeidi, M., F. Moradi, A. Ahmadi, K. Poostini and G. Najafian. 2006. Effect of exogenous application of ABA and CK at different stages of grain development on some physiological aspects of source and sink relationship in two bread wheat cultivars. Iranian Journal of Crop Sciences. Vol. 8, No. 3, pp 268-282. Plant growth regulators are the most important internal regulatory agents that adjust plant growth and development in relationship to gentic and environmental conditions. Among the plant growth regulators, cytokinins (CK) and abscisic acid (ABA) not only regulating the process of senescence and remobilization, but also have major roles on formation of sink and source strength and capacity. This study carried out to determine effect of exogenous application of CK and ABA (50 μM) on some physiological aspects of source and sink strength of two wheat cultivars (Marvdasht, Zagros), using a split plot arrangment based on Randomized Complete Block Design (RCBD) with three replications, in experimental field of the univereisty of Tehran, in 2005-2006 growing season. Results showed that when these plant growth regulators applied at different stages of grain growth including cell division (CD) and grain filling (GF), grain yield, biomass, harvest index (HI), 1000 grain weight and grain no. spike, significantly changed. Application of CK at CD stage, led to higher grain yield, biomass and grain no. spike. However, ABA at GF stage and CK at CD stage increased HI and significantly affected soluble proteins, chlorophyll content, photosynthesis rate, stomatal conductance and ABA and CK concentrations in flag leaves. In contrary, exogenous application of ABA increased ABA concentration of developing grains, while had inverse effect on IAA of the same grains. It can be coneluded that exogenous application of CK at cell division stage in grain growth phase may significantly improve biomass and grain yield.

14 citations

Journal ArticleDOI
TL;DR: Results indicated that Iranian grown wheat cultivars had high genetic diversity which could be exploited in wheat breeding programs and evaluated polymorphism information content of some wheat SSR primers.
Abstract: The present study was conducted to understand the genetic diversity of bread wheat's that grown in Iran, and to evaluate polymorphism information content (PIC) of some wheat SSR primers. Experiment was done in the genomics Laboratory in Islamic Azad University, Khorramabad branch, Iran in 2012. Ninety-two bread wheat varieties were assayed to study the genetic diversity and polymorphism based on forty whole-genome SSR markers. Eighty alleles were identified and 2 alleles per locus were detected. The majority of SSR markers showed a high level of polymorphism. PIC values ranged from 0.12 (XBARC 148) to 0.80 (XBARC 54), with an average of 0.59 per primer, which indicates that markers were highly informative. According to similarity matrix, genetic similarity value ranged from 0.17 to 0.88. The lowest and highest genetic similarity were observed between ‘Mihan’ and ‘Star’ (No 31 and 57), ‘Azadi’ and ‘Mahdavi’ (No 4 and 6), respectively. Cluster analysis using the UPGMA method based on Jaccard coefficients was performed. Based on cluster analysis, 92 wheat cultivars were grouped in six clusters. Results indicated that Iranian grown wheat cultivars had high genetic diversity which could be exploited in wheat breeding programs.

13 citations


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Journal Article
TL;DR: For the next few weeks the course is going to be exploring a field that’s actually older than classical population genetics, although the approach it’ll be taking to it involves the use of population genetic machinery.
Abstract: So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

9,847 citations

Journal ArticleDOI
TL;DR: The state of the art on DH technology is provided including the induction and identification of haploids, what factors influence haploid induction, the molecular basis of microspore embryogenesis, the genetics underpinnings of haploidal induction and its use in plant breeding, particularly to fix traits and unlock genetic variation.

163 citations

Journal Article
TL;DR: The results of this investigation proved that SI (sustainability index) and I (st stability index) are not suitable stability indices for discriminating stable genotypes with high grain yield.
Abstract: In order to determine stable bread wheat genotypes with high grain yield via a single parameter, field experiments were conducted with 14 genotypes for 3 consecutive years (2008-2011) under two different conditions (irrigated and rainfed) in a complete randomized block design with three replications in each environment. Combined analysis of variance showed highly significant differences for the GE (genotype-environment) interaction indicating the possibility of selection for stable entries. The results of AMMI (additive main effect and multiplicative interaction) analysis indicated that the first four AMMI (AMMI1-AMMI4) were highly significant (P<0.01). The partitioning of TSS (total sum of squares) exhibited that the environment effect was a predominant source of variation followed by GE interaction and genotype effect. The GE interaction was 5 times higher than that of the genotype effect, suggesting the possible existence of different environment groups. AMMI stability value discriminated genotypes 10 and 6 as the stable accessions, respectively. Based on the YSI (yield stability index) and new RS (rank-sum) the most stable genotypes with high grain yield were genotypes 13 and 10. The results of this investigation proved that SI (sustainability index) and I (stability index) are not suitable stability indices for discriminating stable genotypes with high grain yield.

124 citations

Journal Article
TL;DR: It can be concluded that planting wheat variety DN-11 in areas with post-anthesis water stress was recommendable for maximizing grain yield, and tolerant cultivars showed a higher Pn and gs and leaf water content under both moisture conditions compared with susceptible ones.
Abstract: Terminal drought stress during grain filling period has recently become more common in the semiarid Mediterranean regions, where wheat ( Triticum aestivum L.) is grown as an important winter cereal crop. The objective of this experiment was to study the effect of terminal drought stress on grain yield, gas exchange variables, and some physiological traits of nine bread wheat cultivars. An experiment was carried out in a split-plot arrangement using randomized complete blocks design with three replications during the 2010-2011 season at the research farm of Razi University, Iran. Based on the results obtained, post anthesis water deficit significantly decreased grain yield, biomass, 1,000 grain weight, and harvest index of wheat cultivars. Under terminal drought stress and control treatments, there were significant differences between cultivars in terms of all traits studied. Also, terminal drought stress decreased leaf net photosynthesis rate (Pn), stomatal conductance (gs), transpiration rate, Chlorophyll a, b, and a/b, and increased leaf temperature and sub-stomatal CO 2 concentration. Cultivars differed in their response to water stress. In general, tolerant cultivars showed a higher Pn and gs and leaf water content under both moisture conditions compared with susceptible ones. A greater reduction in gs and transpiration rate and smaller reduction in P n under stress condition led to a remarkably higher photosynthetic water use efficiency of the tolerant cultivars. Finally, it can be concluded that planting wheat variety DN-11 in areas with post-anthesis water stress was recommendable for maximizing grain yield.

88 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated performance of five different artificial neural network (ANN) models, including Generalized feed forward (GFF), multilayer perceptron (MLP), Jordan/Elman (JE), and Radial basis function (RBF) with different learning algorithms, transfer functions, hidden layers and neuron in each layer, along with multi-linear regression model to predict seed yield of safflower.

81 citations