فصلنامه تحقیقات غلات
سال یازدهم شماره 2 (تابستان 1400)

Water scarcity is the most essential limiting element of agricultural production, particulary in arid and semi-arid areas throughout the world. The line × environment interaction is a major challenge in the study of quantitative characters because it reduces yield stability in different environments and also it complicates the interpretation of genetic experiments and makes predictions difficult. In this regard to analysis of line × environment interaction and determine the yield stability of bread wheat genotypes, 15 new bread wheat lines along with Aftab cultivar were evaluated in a randomized complete block design with three replications in four experimental field stations (Gachsaran, Khoramabad, Moghan and Gonbad) during three cropping seasons. Results of combined analysis of variance indicated that the effects of environments, line and line × environment interaction were significant, suggesting that the lines responded differently in the studied environment conditions. So, there was the possibility of stability analysis. According to mean rank of nonparametric stability parameters, the lines G1, G3, G7 and G15 with the lowest value for mean rank were stable, whereas lines G2, G6, G8 and G10 with highest values were unstable. Also, the results indicated that the nonparametric statistics Si(3), Si(6), NPi(2), NPi(3), NPi(4), KR and Top were associated with mean seed yield and the dynamic concept of stability. Therefore, these methods were suitable for selecting stable and high yielding lines in bread wheat. Finally, G7 line with average grain yield and high general stability was the top line of this test, which after additional tests can be a candidate for a new cultivar to introduce.

Investigating the relationship between the studied traits has an important role in plant breeding and can identify and introduce appropriate selection indices for population breeding. In this study, the relationships between yield related traits and grain quality of 62 rice promising lines were evaluated. The experiment was conducted in a randomized complete block design with three replications at Rice Research Institute of Iran, Rashr, Iran, in 2020. Estimating the phenotypic correlation coefficients between traits showed that there was a positive and significant correlation between grain yield and 1000-grain weight, number of filled grains per panicle, number of panicles per plant and day to 50% flowering, and negative and significant correlation with plant height and panicle length. Narrow-sense heritability of the measured traits ranged from about 32% for number of filled grains per panicle to 49% for flag leaf width and grain length. Path analysis between grain yield and the other studied traits showed that 1000-grain weight, number of panicles per plant and number of filled grains per panicle had a positive and direct effect on grain yield. Factor analysis showed that four main and independent factors that explained 78.50% of the total variance were the latent factors affecting the studied traits. These factors were named as grain yield and plant type, grain appearance characteristics, milling efficiency and fertility rate factors, respectively. Cluster analysis using the Ward’s minimum variance method grouped the studied lines into three separate clusters and the first cluster with 13 lines had the higher grain yield, number of panicles per plant, number of filled grains per panicle and fertility percentage than the other clusters. This cluster had also moderate amylose content and higher values for grain length and cooked rice length related to other clusters. Therefore, it seems that the lines of this group can be introduced as new high yield and qualitative cultivars after evaluation in multi-regional experiments.

Sheath blight disease of rice caused by Rhizoctonia solani AG-1 IA has been recognized as an economically significant disease. No resistant cultivar has been reported so far, and rice ShB management has been mainly leaning on chemical fungicide applications. To prevent resistance to fungicides in pathogenic fungal strains, introducing new fungicides with different effect points and belongs to other groups is essential for integrated disease management. Thus, in 2019, the efficacy of the fungicide Thiflozamide 24% SC was studied on control of rice sheath blight disease in the north of Iran. A research project were designed with a randomized complete block design in three replications and 14 treatments by Thifluzamide, Nativo and Tilt fungicides. Six spray treatments were performed in one step, 24 hours after plant infestation with the casual agent. Another six spray  treatments were performed in two steps, 24 hours and 15 days after plant infestation with the casual agent. Eventually, the efficacy of treatments on relative lesion height (RLH), incidence, and grain yield were surveyed. Data were subjected to the analysis of variance (SAS, 2003). Means among the treatments were compared based on Tukey’s test at the 0.05 probability level. The results showed that one spraying step with Thifluzamide 24% SC fungicide (300 ml/ha dosage) is recommended for Guilan and Mazandaran provinces. If the conditions are suitable for the disease development, it is necessary to repeat the spraying with Thifluzamide 24% SC fungicide (300 ml/ha dosage) 15 days after the first spraying. In order to prevent the possibility of resistance, Nativo and Tilt fungicides are suggested as an alternative or intermittent use of Thifluzamide fungicide.

To evaluate the grain and forage yield in promising sorghum lines, a two years factorial experiment in a randomized complete block design with three replications was conducted in Seed and Plant Improvement Institute, Karaj, Iran, during 2017 and 2018 cropping seasons. Experimental factors included harvesting time at four levels (milk, soft dough, hard dough and physiological maturity stages of grain) and dual-purpose grain-forage sorghum genotypes at seven levels (KDFGS4, KDFGS6, KDFGS9, KGFGS10, KDFGS16, MDFGS1, and MDFGS2). Maximum and minimum grain yields (6847 and 4061 kg.ha-1, respectively) were obtained from KDFGS6 and KDFGS16 lines, respectively, whereas the maximum and minimum 1000-grain weight (35.27 and 22.03 g, respectively) were recorded in KDFGS6 and MDFGS2 lines, respectively. MDFGS1 line produced the highest silage forage (101.73 ton.ha-1) at the grain soft dough stage, and the highest dry matter (38.13 ton.ha-1) at the grain physiological maturity stage. In total, according to the results of this experiment, KDFGS6 line is introduced as the best dual-purpose genotype for grain-forage production and MDFGS1 line as the suitable genotype for forage production. Furthermore, based on the suitable dry matter percentage of forage for silage production, it is recommended that the forage of promising dual-purpose sorghum lines be harvested at the grain soft dough stage. Therefore, forage harvesting from MDFGS1 promising line at the end of the soft dough stage is suggested as the superior treatment of this experiment for silage production.

Land feasibility provides the conditions for accurate decision making of each crop and its management in each area. For this purpose, Geographic Information System (GIS), Network Analysis Process (ANP) and fuzzy logic were used to evaluate the feasibility of cultivating forage sorghum after autumn grain harvest in Lorestan province. First, data minimum, maximum and average temperature, elevation, slope, pH, texture, available potassium, available phosphorus, organic matter and total nitrogen of soil were collected and after transferring them to GIS, their initial raster layers were prepared in the field of agricultural lands and sing fuzzy functions was standardized. The weight of each environmental factor was determined using ANP. Finally, by combining the weighted layers, the final land suitability layer of study area was produced and zoned into four highly suitable, moderately suitable, marginally suitable and unsuitable classes based on fuzzy logic. The results of land evaluation showed that the highest level of the study area was in the moderately suitable class (92.38%) and highly suitable and marginally suitable were included with 6.99 and 0.63% of the total studied lands, respectively. highly suitable class was observed in the center, southwest and northeast of the province, moderately suitable class in the whole province and marginally suitable class in the east of the province. The study of effective factors on forage sorghum cultivation in Lorestan province showed that the diversity of these factors in different regions reduced the potential of highly suitable class to moderately suitable and marginally suitable and minimum temperature at the end of the growing season, organic matter, total nitrogen and altitude were the most limiting.

Pearl millet (Pennisetum glaucum L.) is one of the most important crops in arid and semi-arid regions that is cultivated for grain and forage. Evaluation and using of new germplasms are essential for breeding new and high-yielding cultivars, adaptation to environmental stresses, and resistance to pests and pathogens. in order to evaluate pearl millet germplasm, 94 accessions from minicar collection with Mehran and KPM1 (as control) were cultivated in lattice design with two replications. The results of ANOVA showed that all the studied traits (number of days to flowering, height, stem diameter, number of leaves, number of tillers and forage yield) except the number of tillers were significant at 1% probability level. Phenotypic coefficient of variation (PCV) showed that the highest diversity was related to stem diameter and forage yield. Means comparison by LSD showed that genotype 63 (with 81.92 t/ha fresh forage yield) had significantly more forage yield than control cultivar (Mehran). The results of cluster analysis and principal component analysis (PCA) showed that the genetic structure of the present population can be assigned to flowering time with three sub-groups (Early, Medium and Late maturity). Substantial genetic diversity and strong population structure based on flowering time suggested the present panel is an important gene pool in pearl millet for using in breeding programs.