CROP BREEDING JOURNAL
Year:2012 | Volume:2 | Issue:2|Papers Count:9

The objective of this investigation was to evaluate the magnitude of G×E interaction effects on durum wheat grain yield and to identify superior genotypes adapted to the test environments. Twenty improved durum wheat genotypes were tested in five locations over three growing seasons. Combined ANOVA indicated that the effect of year (Y) was significant and that of the location (L) was not, but that their interaction (Y×L) was highly significant. The main effect of genotype was also significant, as was the genotype×year interaction (G×Y), genotype×location interaction (GL) was not significant, but three-way interactions (G×Y×L) were highly significant. Clustering of genotypes based on intercept and slope parameters of the linear regression model produced three distinct groups, while using only line slopes for clustering produced no groups at all. The coefficient of determination of the linear regression model ranged from 0.84 (G10) to 0.98 (G2), therefore, it can be concluded that this clustering method was somewhat useful for this data set. According to the dendrogram of clustering based on G and G×E interaction of ANOVA, there were 15 genotypic groups, while according to the dendrogram of clustering based on G×E interaction of ANOVA, there were 12 genotypic groups. Considering all clustering methods and mean grain yield, genotypes G8 (2590 kg ha-1) and G13 (2592 kg ha-1) were superior and thus can be recommended as candidates for release in warm rainfed areas of Iran.

In eastern Austria, alfalfa is usually grown as a rainfed crop in crop rotations in organic farming systems, where yearto-year rainfall fluctuations cause different levels of drought stress. To identify the suitability of different alfalfa genotypes and drought tolerance indices, 18 contrasting alfalfa genotypes were evaluated under irrigated and rainfed conditions at the research station of the University of Natural Resources and Life Sciences (BOKU), Vienna, Austria, during 2006-08. The first study year (2006) was considered as the establishment year. Five drought tolerance selection indices were estimated based on shoot dry matter, total biomass yield and biological nitrogen fixation (BNF) data. The correlation between irrigated and rainfed performances increased (from r=-0.17 to 0.56) with decreasing stress intensity from the first to the second year. Genotypes Sitel, Plato ZS, Vlasta and NS-Banat were the best genotypes based on their performance under both conditions. Drought tolerance selection indices TOL and SSI showed high correlations (r=0.32 to 0.81) only with rainfed performance, and SSI was the index that best identified genotypes with high yield potential under rainfed conditions. Indices STI and GMP were the ones that best identified genotypes with high performance under both conditions.

The genus Onobrychis is subdivided into two subgenera: Onobrychis and Sisyrosema. Phylogenetic relationships of 19 species of Onobrychis (Fabaceae: tribe Hedysareae) and one representative each of genera Eversmannia and Ebenus were estimated from DNA sequences of the internal transcribed spacer (ITS) region. Parsimony analysis of the ITS region formed a dendrogram with strong bootstrap support from two groups: Onobrychis subgen. Onobrychis (except O. laxiflora) is in one group and Onobrychis subgen. Sisyrosema is in the other. Within group I, species of the Onobrychissection and species of the Lophobrychis and Dendrobrychis sections form well supported branches A and B, respectively (BP=99% and 91%). The close association between the Onobrychis section and Lophobrychis and Dendrobrychis indicated there is strong sequence homology among them, suggesting that these species are closely related in terms of phylogeny. Also there is strong sequence homology among sections of Sisyrosema subgen. (group II). Species of Heliobrychis, Hymenobrychis and Afghanicae form a branch (branch C) with 77% bootstrap support. Species of the Hymenobrychis section form a clade (clade F) with 82% bootstrap support, which indicates these species are closely related. The present nr DNA ITS data showed that Onobrychis subgen. Sisyrosema appears to be a well-supported monophyletic group (BP=77%), whereas the Onobrychis subgen. Onobrychis is not monophyletic due to the sister group relationship of one species of Onobrychis subgen. (O. laxifolra) to the subgen. Sisyrosema. Cluster analysis of morphological characters showed two major groups separating Onobrychis subgen. Onobrychis (except O. laxiflora) from Onobrychis subgen. Sisyrosema, which are in accordance with molecular phylogenetic groups.

Drought is a major limiting factor for agricultural production in most parts of the world and landraces are important genetic resources for crop improvement in dry areas. During the 2007-2008 cropping season, 23 chickpea (Cicer arietinum L.) genotypes consisting of 21 Kabuli chickpea landraces provided by the National Plant Gene Bank of Iran and two known commercial varieties (Hashem and Arman) were evaluated under varying drought stress environments imposed using a line-source sprinkler irrigation system. Most measured traits were significantly decreased by drought stress. The reductions in plant canopy width, seed weight per plant, biomass yield and plant weight were proportional to the severity of stress. For all stress treatments, significant variation was observed for seed yield and yield components, and harvest index. The coefficient of variation for these traits increased with the severity of drought stress. Harvest index, pod and seed number per plant, pod and seed weight per plant, total pod weight, plant weight, biomass and plant canopy width showed the highest positive and significant correlation with seed yield, especially under drought treatments, these traits should therefore be taken into account when selecting genotypes under drought conditions. Variation in drought tolerance and susceptibility indices suggested high genetic variation among the genotypes. Geometric mean productivity (GMP) and stress tolerance index (STI) in combination with stress susceptibility index (SSI) were the best indices for selecting drought tolerant genotypes. Accessions 216066, 216084, 215296 and 215664 were superior genotypes as compared to other accessions under drought conditions.

To identify important attributes/factors that contribute to grain and biological yields of wheat, 9912 sets of diverse data from field studies were extracted, and supervised attribute-weighting models were employed. Results showed that when biological yield was the output, grain yield, nitrogen applied, rainfall, irrigation regime, and organic content were the most important factors/attributes, highlighted by 9, 7, 5, 3 and 3 weighting models, respectively. In contrast, when grain yield was the output, biological yield, location, and genotype were identified by 8, 6, and 5 weighting models, respectively. Also, five other features (cropping system, organic content, 1000-grain weight, spike number m-2 and soil texture) were selected by three models as the most important factors/attributes. Field water status, such as the irrigation regime or the amount of rainfall, was another important factor related to the biological or grain yield of wheat (weight³0.5). Our results showed that attribute/factor classification by unsupervised attribute-weighting models can provide a comprehensive view of the important distinguishing attributes/factors that contribute to wheat grain or biological yield. This is the first report on identifying the most important factors/attributes contributing to wheat grain and biological yields-using attribute-weighting algorithms. This study opened a new horizon in wheat production using data mining.

The Persian walnut (Juglans regia L.) is one of the most important horticultural crops grown in Iran. This research was conducted to determine the variation in walnut germplasm grown in the Arak region of Iran during the 2007-2008 growing seasons. All of the selected genotypes originated from seed, and their phenological and pomological characteristics were evaluated. Results indicated that there were promising genotypes within the walnut populations in the studied region. Genotypes MS26, MS6, MS34, MS45, MS70, MS49 and MS54 were late bearing leaves (21 to 25 April). Genotypes MS27 and MS29 were completely homogamous. Bearing habit was lateral and terminal in 38.57 and 61.43% genotypes, respectively. Genotypes MS8, MS10, MS48 and MS66 were early maturing and their nuts matured before 10 September. High variation for nut and kernel characteristics was found among the studied genotypes. Genotypes MS15, MS17, MS19, MS20, MS23, MS26, MS27 and MS29 were identified as promising, because their kernel weight, nut weight and kernel ratio were higher than 6 g, 12 g and 50%, respectively. These superior genotypes could be used for cultivation or as parents in future breeding programs.

The genetic diversity of 40 tobacco (Nicotiana tabacum L.) cultivars was analyzed using 12 ISSR primers. The cultivars were evaluated for 14 traits using a simple lattice design (7×7) with two replications. Of 149 amplified bands, 142 (95.3%) were polymorphic. Maximum and minimum bands were generated by primers UBC825 (17 bands and 94.11% polymorphic) and UBC824 (7 bands and 100% polymorphic), respectively. Of the studied primers, UBC824 showed maximum Polymorphism Information Content (PIC) (0.43) and the highest genetic diversity, and thus could be used in future genetic diversity studies. In principal coordinate analysis using a similarity matrix, the first two coordinates, which are the main coordinates, explained 41.97% of the total variance. Cluster analysis was performed to determine the genetic relationship of tobacco cultivars using the un-weighted pair-group method with arithmetic average (UPGMA) based on morphological traits and ISSR markers separately. Plant genotypes were divided into nine main groups of flue-cured tobacco cultivars, and a cophenetic correlation coefficient was calculated (r=0.9), indicating the usefulness of the UPGMA method for clustering plant genotypes. Cluster analysis based on morphological traits divided the studied genotypes into five groups using the UPGMA method. Results of canonical discriminate function analysis using the Fisher Linear method showed that the UPGMA method separated the genotypes with 100% accuracy. Both clusters were consistent with the geographical origins of the cultivars.

Drought is one on the most important factors limiting the productivity of spring chickpea in drylands of Iran. Sixty genotypes of chickpea from ICARDA's germplasm accessions, as well as one drought susceptible check (ILC 3279), were sown in spring of 2010 at two locations, Sanandaj and Maragheh, in the western highlands of Iran for one year. The experiment in each location was laid out in a randomized complete block design with two replications. The results of the analysis of variance for seed yield, 100-seed weight, pods per plant, plant height and days to maturity indicated that genotypic differences were significant. Seed yield ranged from 266 kg/ha (FLIP06-58C) to 1020 kg/ha (FLIP 06-60C). The phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variation (GCV) and the environmental coefficient of variation (ECV) for all traits. The PCV was highest for drought tolerance score (44.54%), followed by plant vigor (32.24%), seed yield (28.47%) and pods per plant (27.59%). Similarly, the GCV was highest for drought tolerance (39.27%), followed by plant vigor, seed yield and pods per plant. The GCV and PCV were lowest for days to maturity, followed by days to flowering and 100-seed weight. Heritability of days to maturity, days to flowering and drought tolerance was greater than the heritability of the other traits. Positive significant (P<0.05) relationships were found between seed yield per plant and traits pods per plant, 100-seed weight and plant height. The genotypic path coefficient analysis based on seed yield per plant as a dependent variable revealed that drought tolerance score, 100-seed weight, plant height and pods per plant exhibited high positive direct effects. Vigor, days to maturity and 100-seed weight showed the highest direct influence. Therefore, this research suggests that drought tolerance score and pod per plant can be good selection criteria for improving seed yield per plant in chickpea for drought stress environments.

Hazelnut is grown in limited areas of Iran with high rainfall and high relative humidity. New cultivars and rootstocks that are tolerant of drought and low humidity are needed to expand hazelnut cultivation. To this end, seeds of 14 local Corylus avellanaL. genotypes (A1, A2, Gerche, Gerde Eshkevarat, Gerde Shok, Mahalli Karaj, Nakhon Rood, Navan1, Navan7, Navan9, Navan10, Pashmineh, Shirvani and Sivri) with relative tolerance to environmental stresses were collected in different areas and sown with seedlings of controls Negret and Daviana. Seed germination, growth characteristics, graft success and chlorophylls of all rootstocks were evaluated. Based on the results, first-year seedlings of six genotypes with high germination and growth vigor were selected and transplanted for field evaluation. Results of the first year showed that seeds of Greche had the highest (69%) germination, and that genotypes Nakhon Rood and Sivri had the longest stems (18.22 and 12.44 cm, respectively), while Pashmineh and Nakhon Rood seedlings had the thickest shoot diameter (2.45 and 2.42 mm, respectively). In the second year, Mahalli Karaj and Nakhon Rood seedlings showed the greatest shoot length and diameter. The highest A and B chlorophyll levels were detected in Nakhon Rood seedlings (3.44 and 1.39 mg/per gram of leaf fresh weight, respectively). Grafts on Shirvani and Sivri rootstocks were the most successful, with 42.18 and 41.07%, respectively. Graft success was not different among different scions.