فصلنامه علوم زراعی ایران
سال بیست و چهارم شماره 2 (پیاپی 94، تابستان 1401)

Exploitation of heterosis in hybrid breeding and development of synthetic cultivars is an essential procedure in plant breeding programs. The main goal of hybrid breeding programs is to select desirable parental genotypes to maximize the expression of heterosis. However, since development of high yielding hybrids and synthetic cultivars are costly and time-consuming, the accurate prediction of heterotic groups of parental inbred lines for obtaining superior hybrid cultivars is of high priority. Generally, parental genetic distance is the most critical factor in determining the heterosis, from which one may expect to maximize its value. It is, hence, an efficient method which enhances conventional methods for categorizing a large number of inbred lines originated from diverse germplasm sources into heterotic groups. In addition to the parental genetic distance the relative rate heterosis also depends on environmental factors. Environmental stresses may variably influence the performance of parental lines and hybrids, and the relationship between parental distance and heterosis, thereby the rate of heterosis can either increase or decrease depending on traits and genetic materials. Under conditions of climate change, water is likely to become more limited in many areas of Iran agricultural lands. Considering that forage crops show high genetic diversity in their populations, which makes them adaptable to a wide range of environmental conditions, breeding these crops and developing drought-tolerant cultivars with high yield potential is an effective approach towards the development and rehabilitation of part of the country's degraded rangelands. In this way, one of the most important strategies is to use diverse genetic resources to select parents and take advantage of their differentiated diversity toward exploitation of heterosis for development of desirable hybrids and synthetic cultivars. The efficiency of molecular markers in parental selection and the effect of parental genetic distance on progeny performance in forage crops suggest the existence of heterotic effects in hybrids and synthetic cultivars and emphasizes the benefit of marker-assisted breeding for selecting polycross parents to achive maximum yield and improve drought tolerance in successive generations.

Crop simulation models are valuable tools for prediction of crop performance under various weather conditions and allow designing methods to limit the negative impacts of adverse environmental constraints. Agricultural Production Systems sIMulator (APSIM) is a comprehensive model that simulates the performance of a wide range of crops in response to climatic, soil and management factors. In this study, the performance of APSIM-Wheat model in simulating dryland wheat phenology and grain yield was evaluated for the first time in the dryland wheat belt of west and northwest of Iran. Model calibration and evaluation was performed using information of 91 experiments from 11 research field stations in five western and northwestern provinces of Iran from 2001 to 2016. Results showed that the mean observed and simulated days to flowering and physiological maturity were 215 and 218, and 252 and 252 days after sowing (DAS), respectively. These were further supported by an acceptable range of statistical indices of nRMSE (0.29 and 0.16%), CRM (-0.018 and 0.002) and D-index (0.091 and 0.013), for flowering and physiological maturity, respectively. The observed and the simulated mean grain yield were 2245 and 2249 kg.ha-1, respectively. The values of nRMSE (7.21%), CRM (-0.002) and D-index (0.037) showed that APSIM-Wheat performed quite satisfactorily and could be considered in planning to increase dryland wheat production in west and northwest of Iran. The overall results of this study showed that the APSIM-Wheat model can be used to determine the best crop management practices, yield gap analysis, climate change impact assessment and climate change adaptation strategies in dryland wheat fields in western and northwestern of Iran.

This study was conducted to evaluate the performance of different herbicides options for weed control in chickpea and their residual effect on bread wheat performance in crop rotation under rainfed conditions. The experimental design was randomized complete block with four replications conducted in Mahidasht Agricultural Research Center located in Kermanshah province, Iran during 2018-2019 and 2019-2020. The experimental treatments included: pre-plant sulfentrazone (Espartan 50% WP); 100 and 300 g.ha-1, pre-emergence sulfentrazone; 100 and 200 g.ha-1, pre-emergence pyroxasulfone (Sakura 85% WP); 100 g.ha-1, pre-emergence flumioxazine (Shato 50% WP); 100 g.ha-1, pre emergence metribuzine (Sencor 70% WP); 200 g.ha-1, pre-emergence of sulfentrazone (100 g.ha-1)+metribiozin (200 g.ha-1), pre-emergence of sulfentrazone (100 g.ha-1)+pyroxasulfone (100 g.ha-1), preemergence of sulfentrazone (100 g.ha-1)+flumioxazine (100 g.ha-1) and hand weeding. The results showed that application of sulfentrazone+pyroxasulfone at flowering stage of chickpea reduced 95% and 94% weed biomass and density, respectively and sulfentrazone+flumioxazin reduced 93% and 82% of weed biomass and density, were the most effective treatments. The highest increase in chickpea seed yield (67% and 60%, respectively) after hand weeding was achieved by these treatments. The pre-emergence treatment of sulfentrazone 300 g.ha-1 had the least positive effect (10%) on the increasing of chickpea seed yield. The results related to the effect of herbicide residues on the wheat yield in rotation showed that wheat grain yield as a result of applying preplant sulfentrazone (200 g.ha-1) was reduced by 32% compared to the control (untreated). The residues of pre-emergence sulfentrazone (300 g.ha-1) also had the most negative effect on both plant height and wheat grain yield  by 8.2% and 32.7% reduction, respectively. In conclusion, results of this experiment showed that, sulfonetrazone (Spartan)+flumioxazin (Shato) and sulfonetrazone (Spartan)+pyroxasulfone (Sakura) herbicides can be suggested for weed control in rainfed chickpea, because of their high efficiency in weed control and improving chickpea seed yield and minor negative residues effect on bread wheat performance in in crop rotation.

Breeders often use generation means analysis to obtain information about inheritance, gene action, and to determine effective breeding methods to improve important agronomic traits, especially under drought stress conditions. To investigate the genetic parameters of agronomic and morphological traits in durum wheat, a field experiment was carried out using F1, F2, BC1 and BC2 generations obtained from crossing of Shotordandan variety and Dena cultivar under non-stress and terminal drought stress conditions. The experiment was carried out using randomized complete block design with three replications in research field of Islamic Azad University, Ahvaz Branch, Iran in 2016-17 cropping season. To apply terminal drought stress, from anthesis stage, the irrigation of the plots was ceased until physiological maturity. The results of weighted analysis of variance of generations revealed that there was significant differences between the generations for all measured traits except number of grain.spike-1 under non-stress conditions and number of tillers and grain weight.plant-1 in drought stress conditions. The results of generations mean analysis for spike length under non-stress conditions and plant height and spike length under stress conditions showed that the three-parameters model had the best fit. However, for other measured traits, significant chi square test (χ2) indicated the presence of non-allelic interactions in the inheritance. Additive and dominance effect played roles in controlling most of the studied traits, but the effect of dominance component was greater than the additive component. Broad and narrow sense heritability of traits under non-stress conditions varied from 11-84% and from 1-75%, respectively, and under stress conditions from 24-70% and from 1-40%, respectively. Considering the greater role of genes with non-additive effect in controlling most of traits, except plant height, spike length and 1000-grain weight, selection in durum wheat advanced breeding generations, when breeding lines are fixed and relative purity achived, is suggested.

Combinining features of the best linear unbiased predictions (BLUP) and additive main effects and multiplicative interaction (AMMI) through “Weighted average of absolutescores of best linear unbiased predictions” (WAASB) index in multi-environment experiments may lead to more percise evaluation of genotypes and assessment of genotype × environment interaction. In the present study, the seed yield stability of 14 advanced lentil lines was evaluated in a multi-environment trials in four locations including; Gachsaran, Khorramabad, Moghan and Ilam, Iran in 2018-2019 and 2019-2020 cropping seasons. The experimental design was s randomized complete block design with three replications. Statistical analyzes were performed using multi-environment trials analysis. Considering the significant G×E interaction based on the results of the relative likelihood test (LRT), it was possible to perform BLUP analysis on the data. The highest predicted seed yield by BLUP method belonged to genotype no. 9 followed by genotypes no. 11, 10, 5, which had higher than average predicted seed yield. To enable simultaneous selection based on both seed yield and yield stability, by combining seed yield (Y) and WAASB, a new index “WAASBY” was created. Considering 50% contribution of each of the two components of seed yield and yield stability, eight genotypes showed above average WAASBY. Genoype no. 9 had considerably higher WAASBY when compared with other genotypes and was identified as the best genotype followed by genotypes no. 10, 1, 2, 12, 14, 7 and 13 were ranked respectively. Both control cultivars (genotypes 15 and 16) had lower than average WAASBY. In conclusion, considering WAASBY index, genotypes 9, 10, 1 were identified as genotypes with highe seed yield and yield stability, and can be considered for being released as new lentil cultivars.

This study was carried out to investigate the relationship between microsatellite markers and some agronomic and morphological traits in wild einkorn wheat populations collected from western parts of Iran. Plant materials included 163 wild einkorn wheat accessions selected from 664 samples collected from 34 regions in of Ilam, Kermanshah and Kurdistan provinces. Seeds of selected accessions were grown in the field and the following agronomic and morphological traits were evaluated and scored in 2014-15 and 2015-16 cropping seasons: leaf length, leaf width, plant height, peduncle length, spike length, number of spikes.plant-1, number of grains.spike-1, 1000 grain weight, days to flowering, days to physiological maturity, grain yield and weight.plant-1. Analysis of variance showed significant differences among genotypes across two cropping seasons for most of the measured phenotypic traits. The genotypic evaluation was performed using 19 microsatellites (SSR) markers on the selected 163 accessions. According to the results of K statistics and two-dimensional graphics based on SSR markers, four possible sub-populations in the germplasm of wild einkorn wheat were identified. Eventually, association analysis was performed using the population structure matrix and statistical models of GLM and MLM. The results showed that based on the GLM and MLM models 87 SSR marker-trait relationships were highly significant. Also 89% markers played roles in identifying allelic locations on the chromosomes for 12 studied traits. In conclusion, the results of this study revealed that integrated uses of agronomic and morphological traits with SSR markers could be useful in evaluating of genetic diversity of wild einkorn wheat and is beneficial for identifing markers associated with important agronomic traits in breeding programs.