durum wheat

Micronutrients deficiency stress is one of the most important dangers for increasing the yield and good production of crops in the world. In order to evaluate genetic diversity of nineteen durum wheat (Triticum turgidum var durum) genotypes to identify the most zinc-deficient stress resistant genotypes and also finding the best stress tolerance indices, an experiment was carried out in the University of Maragheh, Iran during cropping season of 2014 by using a factorial design in the randomized complete block design (RCBD) with three replications. The experiment was done zinc deficient stress (non-Zn application; -Zn) and normal soil application (5 mg Zn/kg soil + foliar application with 0.44 g Zn/liter water at stem elongation and grain filling stages; +Zn) conditions. Results indicated that Zn conditions as well as, wheat genotypes differed significantly for all studied agro-morphological traits in both normal and Zn deficient stress conditions. Our findings indicated that Zn-deficient stress significantly decreased the spike length (SL), peduncle length (PedL), penultimate length (PenL), plant height (PH), spike weight (SW), peduncle weight (PedW), penultimate weight (PenW), biological yield (BY), grain yield (GY), harvest index (HI), number of grains per spike (NGS), number of fertile spikelet per spike (FS) and 1000 grains weight (TGW) by 14, 10.6, 10.4, 12.5, 25.3, 26.2, 27.9, 27.5, 29.4, 5.0, 25.5, 17.7 and 5.4%, respectively. Among durum wheat genotypes, ‘G2’ had the highest and also ‘G10’ and ‘G19’ had the lowest SW, PedW, BY and FS, respectively; while the highest and the shortest GY and NGS was observed in ‘G17’ (0.763 g/plant and 23.2 grain) and ‘G10’ and ‘G19’ (0.372 and 367 g/plant and 8.9 and 9.5 grain) genotypes, respectively. This indicating the presence of variability, which can be exploited through selection for further breeding programs. According to results of stress tolerance indices, ‘G17’, ‘G16’ and ‘G3’ genotypes have higher GY and STI index than other genotypes in two Zn conditions and identified as suitable genotypes for production in Zn deficient stress condition.   

In order to study the effect of different N fertilization levels on dry matter remobilization of durum wheat cv. Seymareh at different planting densities, a study was conducted at Agriculture Research Station of Islamic Azad University, Ardabil Branch, Ardabil, Iran in 2009 as a split plot experiment based on a Randomized Complete Block Design with three replications. The main plot included plant densities at three levels of 300, 350 and 400 seeds.m-2 and the sub-plot included N fertilization at four levels of 0, 70, 140 and 210 kg.ha-1. Results revealed that as N fertilization level was increased, straw dry weight and biological yield were increased whereas dry matter remobilization rate from whole plant and stem to grain and contribution of dry matter remobilization and stem reserves to grain yield were decreased. Also, the application of 140 kg N.ha-1 gave rise to the highest grain yield, the highest number of spikes, 1000-grain weight and harvest index and further increase in N fertilization level resulted in loss of grain yield and other traits. As plant density per unit area was increased, all studied traits were increased except 1000-grain weight and harvest index. Therefore, in order to increase the contribution of dry matter remobilization and grain yield, to avoid environmental contamination and to decrease (excessive) fertilization application which increases production costs, it is recommended to use N fertilization level of 140 kg.ha-1 and the density of 400 plants.m-2 under the conditions of the current study.

Since coefficients of correlation may not provide thorough information about the relations of different traits and given the various advantages of multivariate statistical analyses for deep understanding of data structure, factor analysis can be used. Accordingly, to evaluate the potential grain yield of durum wheat genotypes under drought stress conditions and to examine the relationship of some quantitative traits with grain yield for selecting superior genotypes, a study was carried out on 30 durum wheat genotypes originated from Iran and Azerbaijan in Agriculture Research Station of Islamic Azad University – Ardabil Branch, Ardabil, Iran in 2008. Results of analysis of variance revealed significant differences in the measured traits under stress and no stress conditions. In addition, genotypes showed significant differences in plant height, main spike length, 1000-grain weight and yield. According to factor analysis through decomposition to main components, five factors altogether explained 82.58% of variations. Results of factor analysis proved the importance of fertile tiller number, main spike grain weight, 1000-grain weight and harvest index in selecting optimum genotypes for drought conditions.

Given that drought is a natural disaster and poses a major threat to agriculture in most parts of the world, especially Iran, selecting drought resistant, high-yielding genotypes is necessary. Therefore, to evaluate the drought tolerance of durum wheat genotypes, an experiment was carried out on 35 indigenous landraces in Ardabil, Iran in 2009 under normal and drought-stressed conditions. The experimental design in each water treatment was a randomized complete block design with two replications. The results of analysis of variance showed that irrigated conditions significantly affected plant height, grain number per main spike, main spike weight, 1000-grain weight, yield and harvest index. The landraces of Boeuffi and Africanum had the highest grain yield under both optimum and stressed conditions. They also had optimum harvest index, 1000-grain weight, grain number per main spike and plant height. In addition to having high yield under optimum conditions, they exhibited acceptable tolerance to water stress, too. The stress tolerance index (STI) and mean productivity (MP) had the highest positive, significant correlation with each other and were found to be the most effective indices for selecting drought resistant cultivars.

Genetic diversity is the basis of plant breeding and selection depends upon the existence of an appropriate diversity for the trait being selected for. Given that the yield of crops is a function of genotype, environment and their interactions and that to realize a high yield, the selection is more efficient when conducted for the yield components rather than yield itself, the study of the relationship between yield and its components is crucially important in breeding programs. In the current study, 30 durum wheat genotypes originated from Iran and the Republic of Azerbaijan were planted on the basis of a Randomized Complete Block Design with two replications under rain-fed and irrigated conditions in Ardabil, Iran. The results of the analysis of variance of the evaluated traits showed that the effects of genotype and the interaction between genotype and environment were significant. Since the interaction between genotype and environment was significant, genetic correlation rather than phenotypic correlation was used for studying the relations among the traits. The results of genetic correlation analysis between yield and the traits remained in ridge regression model showed that 1000-grain weight had the highest direct effect on yield, but the highest indirect effect of this trait was applied through plant total weight, although 1000-grain weight showed the highest direct effect in phenotypic correlation analysis, too. Moreover, fertile tiller number had the strongest negative direct effect on yield.