Hossein Shahbazi

Correlated response of morpho-physiological traits of grain yield in durum wheat under normal irrigation and drought stress conditions in greenhouse

In order to evaluate the relationship between different traits of grain yield in durum wheat, 20 durum wheat ( Triticum durum Desf.) landraces selected from the northwest of Iran together with five controls were evaluated under normal and drought stress conditions. Environmental mean squares were significant for all the traits studied except for harvest index which showed that drought stress has significant effect on all the traits. In normal condition, fertile tillers, peduncle length, spike length, number of grain spike and harvest index had the most positive direct effect on yield, while under drought stress condition, biological yield and harvest index had the most positive direct effect on yield. In regression analysis (stepwise method) in normal condition, infertile tillers and 1000 grain weight remained in the final model (R 2 = 0.485), while under stress condition, Fv/Fm, Fm and biological yield remained in the final model (R 2 = 0.667). Factor analysis of the total five factors was used to determine 76.708 and 77.128% of the data changes and adjustments in normal irrigated and drought stress conditions, respectively. The multiple statistical procedures used in this study showed that harvest index and biological yield were the most important yield variables to be considered under drought conditions. So, these traits could be used as selection criteria for increasing yield. Key words : Durum wheat, drought stress, chlorophyll fluorescence, chlorophyll content, multivariate analysis.

Effects of drought stress on some agronomic and morphological traits of durum wheat ( Triticum durum Desf.) landraces under greenhouse condition

Although, drought stress has been well documented as an effective parameter in decreasing crop production; developing and releasing new varieties which are adaptable to water deficit conditions can be a constructive program to overcome unsuitable environmental conditions. The present study was carried out to study the effect of drought stress under greenhouse conditions in Islamic Azad University of Ardabil Branch, Iran. The agronomic and morphological traits of 25 durum wheat ( Triticum durum Desf.) genotypes were investigated. The present study was done based on randomized complete block design with three replications in drought stress and normal irrigation conditions in a greenhouse. The analysis of variance has indicated that there are significant differences among the genotypes in all the traits, which indicate that there are great variations among genotypes in order to use in improvement plans. Analysis of variance shows that drought stress has a significant effect on all studied traits except harvest index. The comparison of means indicated that the genotypes; poldash, sari boghda and germi in normal condition and sari boghda, omrabi-5, langan, germi and germi under stress condition, are the superior groups. Grain yield has shown a positive and significant correlation with peduncle length, number of grains per spike, 1000 grain weight, biological yield and harvest index. Cluster analysis divides the genotypes into three groups in each condition. The best genotypes were included in a group which confirms the results of the compared means yield. Key words: Agronomic traits, durum wheat, genetic diversity, yield components.

Behavior of durum wheat genotypes under normal irrigation and drought stress conditions in the greenhouse

Drought is a major problem reducing agronomic crop production worldwide. Increasing the genetic potential of yield in water deficit condition is one of the major objectives of durum wheat breeding programs in Iran and other countries. This study was conducted to determine drought tolerant genotypes with high yield in normal and drought stress conditions. Twenty-five durum wheat genotypes were tested in a randomized complete block design with three replications under greenhouse condition during 2010 and 2011. Eight drought tolerance indices mean productivity (MP), tolerance index (TOL), geometric mean productivity (GMP), stress susceptibility index (SSI), yield index (YI), harmonic mean (HARM), yield stability index (YSI) and stress tolerance index (STI) were applied on the basis of grain yield in drought stress (Ys) and normal irrigation (Yp) conditions. Based on different drought indices, pol-dash (1) and chakmak genotypes were more drought tolerant than the other genotypes. 3D graphs, Bi-plot and cluster analysis confirmed these results. Principal components analysis showed two components which explained 98.0% variation. Genotypes were grouped in cluster analysis (using Ward’s method) based on Yp, Ys and quantitative indices of drought tolerance. Finally, the results of correlation and other analysis showed that the most suitable indices to screen genotypes in drought stress condition were MP, STI, GMP and HARM. Key words : Landrace, screening, bi-plot, principal component, cluster analysis.

Assessment relationship between agro-morphological traits and grain yield in bread wheat genotypes under drought stress condition

To evaluate the genetic diversity in bread wheat landraces along with six controls (Azar2, Fankang, Trakia, Siosson, Gaspard and Gascogne), an experiment based on randomized complete block design with three replications was carried out under drought stress condition in the Agricultural Research Station of Islamic Azad University, Ardabil, Iran. Analysis of variance indicated that there were highly significant differences among the genotypes in all of the traits. There were significant correlations between yield and all of the studied traits. Principal components (PC) analysis showed that five components explained 69.3% of the total variation among traits. The first PC assigned 29% and the second PC assigned 15% and of total variation between traits. The first PC was more related to tiller numbers, fertile tillers, biological yield, grain yield and volume of seed plants. Therefore, selection based on first component is helpful for a good hybridization breeding program. A principal component biplot showed low distance between grain yield and biological yield, volume of seed, plant height and hectoliter. From this study, it was concluded that a good hybridization breeding program can be initiated by the selection of genotypes from the PC1.