فصلنامه علوم زراعی ایران
سال بیست و سوم شماره 3 (پیاپی 91، پاییز 1400)

The interaction of genotype × environment creates complications in yield prediction and is a challenge for agronomy and plant breeding programs. To evaluate grain yield stability and genotype × environment interaction for 18 local and exotic grain sorghum cultivars, lines, and hybrids, a field experiment was conducted using randomized complete block design with three replications in four regions of Karaj, Gorgan, Birjand, and Isfahan, Iran in two cropping seasons (2016 and 2017). Combined analysis of variance showed that locations, genotypes and their interaction effect were signifinat on grain yield. Mean comparisons showed that genotype No. 15 (High yield700) had the highest grain yield (7986 kg.ha-1) followed bygenotypes No. 17, 6, 16, and 8 with grain yield of 6894, 6172, 5960, and 5906 kg.ha-1, respectively. Genotypes No. 15 and 17 had the lowest year within location variance, and in addition to high grain yield stability had optimal grain yield. Analysis of variance by AMMI model and fitting of principal components to the interactions of genotype × environment showed that five main components were significant (P ≤0.01). These five components explained 94.1% of the observed variance of genotype × environment interaction. Cluster analysis identified four genotypic groups based on the first main component of genotype × environment interaction. In this study, high yielding genotypes also had good grain yield stability. AMMI model and AMMI stability value (ASV) parameter showed that genotypes No. 17 (Drought tolerant), 4 (Fast green400), 6 (FGCSI04), 15 (High yield700) and 16 (Human900) had high grain yield and yield stability. Genotypes No. 15 and 17 identiifed as superior genotypes well adapted to different test environments, in this study.

Rice is the staple food of half of the world's population and one of the most important crops in Central and West Asia. To assess variation in some important agronomic traits and grouping of rice genotypes, this study was performed and 49 genotypes from Azerbaijan, Kazakhstan, Afghanistan, Turkey, Kyrgyzstan, Iraq, and Uzbekistan along with 7 genotypes from Iran were evaluated using randomized complete block design with three replications in 2019 and 2020 cropping season in experimental field of Rice Research Institute of Iran, in Rasht, Iran. Analysis of variance showed genotypes were significantly different for all studied traits. Genotype × year interaction effect was not significant for any of the studied traits. The lowest grain yield (2.2 t.ha-1) belonged to BT7 cultivar (Iraq) and the highest grain yield (7.4 t ha-1) belonged to Mishkab2 (Iraq). The shortest plant height (79.3 cm) belonged to QazNIIR-7 (Kazakhstan) and the highest plant height (149.8 cm) recorded for Avanqard (Azerbaijan). Marjan cultivar (Kazakhstan) was the earliest maturity among the studied rice genotypes with 100 days to physiological maturity (after seeding). Correlation studybetween traits indicated negative correlation between grain yield and flag leaf length. Cluster analysis grouped the studied genotypes into seven distinct groups. In general, the existence of high diversity for agronomic traits and grain yield in the studied genotypes showed that this set of germplasm has the potential for to be used in the national rice breeding programs to improve Iranian rice cultivars.

To evaluate fall dormancy of twenty alfalfa local ecotypes and exotic cultivars, this study was conducted in two separate experiments (conventional or dense planting and spaced planting) using randomized complete block design with three replications in three growing seasons 2014, 2015 and 2016 in two locations (Karaj and Khoy), Iran. First growing season was considered as estabilishment season. Three ecotypes of Hamedani population, four ecotypes of Gharah-Yunjeh population, five ecotypes of warm region populations, two ecotypes from central part of the country and six exotic cultivars were included in this study. In conventional planting, each cultivar/ecotype was grown in two rows of 5 m length and 50 cm row spacing using 20 kg.ha-1 seeding rate, based on seed germination percentage. In spaced planting, each cultivar/ecotype was planted in two rows of 5 m length and 50 cm row spacing and 50 cm distance between plants on row. The recorded traits were plant height, stem number per plant/m-2, dry forage yield, and fall dormancy score. Combined analysis of variance of both experiments showed that mean squares of cultivar/ecotype was significant for dry forage yield, plant height and fall dormancy score. Genotype × location interaction efect was also significant for these traits. Mean comparison of dry forage yield of cultivars/ecotypes showed that Baghdadi with 15.02 t ha-1 and Kiseverdai with 12.3 t.ha-1 in conventional planting, and Bami-1 with 29.6 g.plant-1 and Sequel with 22.1 g.plant-1 had the highest and lowest dry forage yield over two locations and growing seasons, respectively. In both experiments, the local ecotypes related to warm region had the higher fall dormancy scores in comparison to ecotypes from cold region. In conventional planting, Nikshahri, Bami-1 and Baghdadi with 6.9, 6.8 and 6.7 scores, and in spaced planting, Baghdadi and Nikshahri with 6.1 and 6.0 scores showed the highest fall dormancy scores, respectively. Commandor had the lowest fall dormancy score with 3.5 and 3.3 in conventional and spaced planting experiments, respectively. In general, the fall dormancy scores were determined in ecotypes of Ghara-yunje and Hamedani populations (cold region) from 4 to 5, ecotypes from temperate region (KFA7 and Yazdi) from 6 to 7 and warm region (Bami, Baghdadi and Nikshahri) from 7 to 9 scores. Assessment of fall dormancy scores in conventaionl planting experiment led to better estimates, however, it did not affect the grouping of cultivars/ecotypes.

One of the most complicated issues in plant breeding programs is genotype by environment interaction. To evaluate seed yield stability of 18 chickpea promising lines, a field experiment was conducted using randomized complete block design with four replications in two cropping seasons (2018-19 and 2019-2020) in four research stations (Maragheh, Kurdistan West Azerbaijan and Hamedan), Iran. Combined analysis of variance (ANOVA) as well as additive main effects and multiplicative interaction (AMMI) were performed to evaluate the genotype × environment interactions. Combined ANOVA showed that of the total variation, 35.62% were explained by "location" and 36.1% by the interaction effect of "year × location". Whereas, "year" explained only 13.06% of the total sum of squares. Based on AMMI analysis, chickpea seed yield was affected by genotype (7.10%), environment (84.8%) and genotype × environment interaction efect (8.04%). The significance of GEI showed that both the performance and ranking of genotypes fluctuated under the influence of GEI. On the other hand, the sum of squares of GEI showed the existence of cross-interaction between genotype and environment. AMMI analysis divided the GEI sum of squares into two main components. These two main components (IPC1 and IPC2) were significant and collectively accounted for 82.9% of the total variation and are, therefore, sufficient to explain the complex patterns of GE interaction. Genotypes were ranked based on AMMI stability value (ASV), and G3 line was designated as the genotype with highest seed yield stabilty. The AMMI1 model also identified the G5 line with high seed yield stability and performance. On the other hand, the AMMI2 bioplot identified the G11 line as a genotype with high general adaptability and seed yield stability. Among the experimental environments, the highest and lowest seed yields were obtained in E5 and E4 environments (Kurdistan in second year and West Azerbaijan in first year), respectively. According to the results of this study, G5 and G3 lines with seed yield of 941.4 and 911.1 kg.ha-1, respectively, were identified as high yielding with yield stability in all environments.

One way to increase crop yield per unit of area is to close the gap between actual and potential yield in cropping systems. This study was conducted to determine the factors that affeced wheat yield gap in Khorramshahr, Iran during 2018-2019 growing season. In this study 60 fields of different areas under cultivation, field management practices and grain yield yield levels were surveyed based on information from agricultural services centers and continuous monitoring. Comparative performance analysis (CPA) method was used to evaluate the grain yield gap. Theaverage grain yield, attainable grain yield and wheat yield gap in Khorramshahr were 3740, 5455 and 1715 kg.ha-1, respectively. Estimated yield gap (31.5%) in this study indicated that the high importance of appropriate management practices on wheat grain yield. Most important variables affected wheat grain yield gap were included Illoxane herbicide application (579 kg.ha-1), farmers education level (292 kg.ha-1), irrigation intervals (279 kg.ha-1), potassium fertilizer application rate (256 kg.ha-1) and planting machinery and equipment (179 kg.ha-1). These factors accounted for 87.45% of the calculated grain yield gap. The results of this study showed that by improving crop management practices, the grain yield gap of wheat fields in Khorramshahr region can be reduced.

To study the response of Hashemi (local) and Gilaneh (improved) rice cultivars to the application of different sources and levels of organic fertilizers, a field experiment was conducted using a randomized complete block design with three replications in 2018-2019 and 2019-2020 cropping seasons in research field of Rice Research Institute of Iran (Rasht), Iran. Experimental treatments include poultry manure (2.5, 5 and 10 ton.ha-1), cow manure (5, 10 and 20 ton.ha-1), sheep manure (10, 20 and 40 ton.ha-1), and two control treatments including chemical fertilizers and no-fertilizer. Traits measured included plant height, number of tiller.plant-1, number of fertile tiller.plant-1, number of panicle.m-2, grain yield as well as amylose content and gelatinization score. The results showed that the effect of organic fertilizers was significant on yield components and grain yield of rice cultivars. Application of 20 ton.ha-1 of cow manure increased plant height (142 cm), number of fertile tillers (14), number of panicle.m-2 (240) and grain yield (3643 kg.ha-1) in Hashemi cultivar and also increased plant height (134 cm), number of fertile tillers (17), number of panicle.m-2 (252) and grain yield (4760 kg.ha-1) in Gilaneh cultivar. Experimental treatments had a significant effect on the gelatinization score of rice grains. The highest grain yield obtained in the treatments of 20 ton.ha-1 of cow manure and Hashemi cultivar (3670 kg.ha-1). The results of this study showed that the application of 20 ton.ha-1 of cow manure increased grain yield by 60 and 64%, in comparison to control treatment of no-fertilizer, and compensated of 86 and 88% of grain yield in Hashemi and Gilaneh rice cultivars, respectively, as compared to the treatment of chemical fertilizers.