Mehdi Rahimi

Evaluation of tea (Camellia sinensis L.) biochemical traits in normal and drought stress conditions to identify drought tolerant clones

Abiotic stresses, such as drought, can induce different morphological, physiological and molecular responses in the tea plants. Since there have not been any experiments on the screening of tea genotypes in terms of drought tolerance, this study was conducted to screen the drought resistance of 14 tea clones of Iran germplasm in a randomized complete block design with three replications, separately in two stressed and non-stressed conditions at Fashalam tea station. The results of grouping the clones under normal and stress conditions and comparing their results with the results of mean comparison of the agronomic and biochemical traits showed that in all cases, clones 100, Bazri and 399 were in the group that can be identified as the drought-tolerant group. Also, the results showed that in the most cases, clones 278, 276 and 285 were placed in a group that had low values for all of the traits and could be considered as a group that are susceptible to drought stress.

Bayesian inference for the genetic control of water deficit tolerance in spring wheat by stochastic search variable selection

Drought is the main abiotic stress seriously influencing wheat production. Information about the inheritance of drought tolerance is necessary to determine the most appropriate strategy to develop tolerant cultivars and populations. In this study, generation means analysis to identify the genetic effects controlling grain yield inheritance in water deficit and normal conditions was considered as a model selection problem in a Bayesian framework. Stochastic search variable selection (SSVS) was applied to identify the most important genetic effects and the best fitted models using different generations obtained from two crosses applying two water regimes in two growing seasons. The SSVS is used to evaluate the effect of each variable on the dependent variable via posterior variable inclusion probabilities. The model with the highest posterior probability is selected as the best model. In this study, the grain yield was controlled by the main effects (additive and non-additive effects) and epistatic. The results demonstrate that breeding methods such as recurrent selection and subsequent pedigree method and hybrid production can be useful to improve grain yield.

Identification of informative markers of agronomic traits in different ecotypes of sand plantain (Plantago psyllium)

To investigate the relationships between agronomic traits and molecular markers in sand plantain ( Plantago psyllium ), a set of 17 ecotypes collected in Iran were evaluated. Twelve ISSR primers were tested through multiple regression analysis to identify the marker-trait association between ISSR data and agronomic traits. Finally, the 12 primers amplified 129 fragments (loci) among ecotypes: 91 fragments (70.54%) of the 129 fragments showed polymorphism with an average of 7.58% per primer and the rate of this polymorphism ranged from at least 57.14% for UBC824 primer up to 54.62% for UBC813 primer. Polymorphic information content ranged from 0.27 (UBC814) to 0.41 (UBC813), with an average of 0.36. Stepwise regression analysis between the molecular data as independent variables and the studied traits as dependent variables was performed to identify informative markers associated with the agronomic traits. Seventy ISSR fragments were found associated with eight morphological traits. Some of ISSR markers were associated with more than one trait in multiple regression analysis that may be due to the pleiotropic effect of the linked quantitative trait locus on different traits or is linkage of different genes. However, for a better understanding of these relationships, preparation of a segregating population and linkage mapping are necessary. Also, these result could be useful in marker-assisted breeding programmes when no other genetic information is available.

Seleksiyon Endekslerini Kullanılarak Kuraklık Stresi ve Stres Olmayan Koşulları Altında En İyi Çeltik Çeşitlerinin Seçimi

Tane verimi ve bitkilerde kantitatif kalitimli ve dogrudan secme yontemini kullanilan ekonomik onemi olan ozelliklerin cogunun buyuk bir gelisme gostermedigi saptanmistir. Dolayisiyla, etkili bir ozellige sahip tane verimi artirmak icin en etkin yontemlerden dolayli secimlerinden biri, seleksiyon endeksini kullanilmaktadir. Bu arastirmada 42 adet Iran yerel ve gelismis pirinc cesidi, 2014 yili boyunca normal sulama ve kuraklik stresi olmak uzere iki ayri kosulda uc tekerrurlu olarak tesadufi tam blok deneme deseninde incelenmis ve 12 ozellik degerlendirilmistir. Her iki kosulda optimum ve baz indekslerine dayanan 10 farkli secim indeksinin tahmin edilmesi, ekonomik agirlik olarak dogrudan path katsayilarinin kullanilmasiyla bitki basina tane verimi, 1000 tane agirligi, basakta dolu tane sayisi, kanopi sicakligi ve stres olmayan kosullar altinda bitki basina basak sayisi, bitki basina tane verimi ve stres kosullarinda 1000 tane agirligi ve her bir basakta basakcik sayisinin populasyonun iyilestirilmesi icin uygun bir secim kriteri olacagini isaret etmektedir. Sonuclar, her iki kosulda da optimum ve baz indekslerine dayali secilen cesitlerin neredeyse benzer oldugunu gostermistir. Boylece, stres olmayan kosullarindaki optimum ve baz indeksleri, stres kosullarinda yuksek verimli cesitlerin secimi icin bir kriter olarak onerilmektedir.

Determining the most effective traits to improve saffron (Crocus sativus L.) yield

To determine the effective traits to improve saffron yield, a split plot design based on RBCD was done in Mashhad region in Iran for three years (2012–2014). The results showed that all traits except number of daughter corm, fresh weight of daughter corm and dry leaf weight had low general heritability. Results of genotypic and phenotypic coefficients of variation and genetic advance demonstrated that the majority of traits had a low diversity and the selection did not have any effect in improving the traits. As a result, the best way to increase saffron yield is improvement of farm management. It was also found that saffron yield had the highest phenotypic and genotypic correlations with fresh and dry weight of daughter corm and dry and fresh flower weight. Therefore, the efforts to improve these traits will increase saffron yield. According to the present study 5-Jun to 5-Jul was found to be the best sowing date for planting saffron. Also, the Mashhad and Torbat ecotypes were the best ecotypes in this study. Phenotypic and genotypic path analysis showed that in the first step three traits number of daughter corm, fresh flower weight and flower number and in the second step traits fresh weight of daughter corm, dry flower weight and dry leaf weight interred to the regression model and had the highest positive direct and indirect effects on saffron yield. Mainly, it can be derived that the implementation of correct farm management including appropriate sowing date, saffron ecotypes, proper density, bigger and higher quality saffron corm can play an important role in improving yield components and subsequently increasing saffron yield.