فصلنامه تحقیقات غلات
سال ششم شماره 4 (زمستان 1395)

Adequate knowledge of the interrelationships among traits is essential in planning and evaluating breeding programs for rice improvement. The objectives of this research were to study the stability of seven rice genotypes over the studied environments, determining the interrelationships among traits and identifying suitable traits for indirect selection to improve rice grain yield. Six promising rice lines selected from preliminary yield trial in 2011-2012, including Shirodi as control cultivar were evaluated using randomized complete block design with three replications in two locations of Mazandaran province (Tonekabon and Sari) during three growing seasons from 2012-2014. Combined analysis of variance showed significant effects of genotype and genotype × environment interaction for grain yield. The GGE biplot analysis showed that genotype 6 (G6) with the highest grain yield (6218.06 kg.ha-1) was ranked in second place in term of stability. The GT biplot analysis revealed that grain yield was positively correlated with number of filled grain, number of total grain and plant height and negatively correlated with number of tillers per plant and panicle length. Therefore, number of filled grain, number of total grain and plant height were suitable traits for indirect selection to improve rice grain yield. In conclusion, G6 [No. 39 from IR 67015-22-6-2-(A37632) × (Amol3 × Ramzanalitarom)] and G5 [No. 126 from IR 67015-22-6-2-(A37632) × (Amol3 × Ramzanalitarom)] were the best genotypes that can be considered to release the new varieties.

Different rice varieties, due to their inherent characteristics, show different reactions to changing the drying conditions and milling operations. Hence, determining the optimum drying conditions and selecting the appropriate milling system can play an important role in reducing the losses in the milling process. In this regard, in order to study the effects of the paddy drying parameters and type of whitener on whole kernel percentage and the quality characteristics of two local and two high yielding rice varieties in the north of Iran, the factorial experiment with four factors in a completely randomized design was used. The four factors were including the rice variety in 4 levels (Hashemi, Tarom, Gohar and Keshvari), type of whitener in 2 levels (abrasive and friction), paddy final moisture content in 2 levels (9-10 and 11-12%) and drying air temperature in 2 levels (40 and 50°C). Results revealed that water absorption of Gohar and Keshvari was lower than that of Hashemi and Tarom, however the effect of milling system was not significant on water absorption. Higher and lower solid loss related to Gohar and Taroom, respectively. In total, results of this research showed that drying of paddy with 40°C, final moisture content of 11-12% and applying the abrasive type whitener for milling of local and high yielding rice varieties achieved more whole kernel, butfor milling of paddy with friction type system, final moisture content of 9-10% lead to more whole kernel.

Quantification of fertilizers losses is important to ensure sustainability of soil fertility, surface and ground water resources and for the development of crop nutrient management. Due to evaluation the effect of organic and chemical fertilizers under different irrigation regimes on chemical properties of soil, a split plot experiment in a randomized complete block design with three replications was conducted at Rice Research Institute of Iran, during 2013 and 2014. Irrigation regimes were 1.3, 1 and 0.7 times of evaporation from evaporation pan as the main plot while six different kinds of fertilizers as the sub plots,C1= no fertilizer, C2=N60- P30- K60 kg.ha-1, C3= C2 compost (5 t.ha-1), C4= N60 kg.ha-1 compost (5 t.ha-1), C5= P30- K60 kg.ha-1) compost (5 t.ha-1), and C6= compost (5 t.ha-1). Soil water extractions were gathered in 15, 25 and 50 days after seedling (i.e. 4 to 5 days after urea fertilizer application) and measured their salinity, pH, total nitrogen and potassium. The results showed that despite the significant effects of treatments on measured properties, the amount of irrigation water will be saved 21.18 and 42.46 percent by changing the irrigation method from flooded to 1 and 0.7 of evaporation, respectively. Using compost instead of chemical fertilizers in the soil will be reduced 39.19 percent of total nitrogen and 48.15 percent of total potassium in the soil extraction. The results of this research indicated that using a combination of compost (5 t.ha-1) and nitrogen (60 kg.ha-1) together with irrigation regime of one times evaporation from pan can save water and protect the environment and at the same time also produced the highest yield.

To study the stability of 20 bread wheat genotypes forgrain yield and yield components, an experiment was carried outinrandomized complete block design with two replications in five environmentsin East Azarbaijan provience, Tabriz and Meyane agricultural stations, Iran,during 2011-2014. The results of combined analysis of variance showed that the genotype × environment interaction was significant (at least p

To study the effect of water deficit and salinity stresses on morpho-physiological characteristics of wheat seedling cv. Flat, a pot experiment was conducted in completely randomized design with three replications in Faculty of Agriculture, University of Yasouj, Iran, in 2015. The studied treatments were seven treatments including three levels of each water deficit and salinity stresses with similar osmotic potential (-2.47, -4.94 and -7.42 bar) together with a control treatment (Hoagland solution). Salinity and drought stresses were applied using sodium chloride and polyethylene glycol 6000, respectively. The results showed that shoot dry weight significantly decreased under the effect of salinity and drought stresses compared to control treatment. Drought stress increased root dry weight of wheat, so that the highest root dry weight was observed in polyethylene glycol of -7.42 bar. The maximum and minimum sodium content of shoot and root obtained from -7.42 bar salinity and control, respectively which have not significant differences with drought stress levels. The salinity of -7.42 bar significantly reduced shoot and root potassium content. The highest shoot to root potassium ratio obtained form control and the lowest from -7.42 bar salinity stress. Protein content and catalase and peroxidase enzymes activity significantly increased by increasing the salinity and drought levels. In general, the results of this study showed that salinity compared to water stress have higher negative influence on wheat which reduces shoot and root dry weight.

To evaluate the effect of planting date and nitrogen fertilizer on various developmental stages of six wheat cultivars, this experiment was conducted using split split plot in a randomized complete block design with three replications in Rokh plain of Khorasan Razavi, Iran, in 2013-2014. The experimental factors were including planting date in three levels (October 10, November 5 and November 30) as main plots, nitrogen fertilizer in three levels (No fertilizer, 150 and 300 kg.ha-1) as sub plots and six wheat varieties (Zarin, Gascogne, Sayunz, Pishgam, Alvand and Mihan) as sub-sub plots. The results showed that varieties were significantly different at various developmental stages, so that Pishgam showed the highest and Mihan showed the lowest thermal needs from planting to rippening. A delay in planting reduced duration of developmental stages and consequiently reduced growth degree days (GDD), so that planting date from October 10 to November 30 caused a reduction of 656.7 GDD. Application of more nitrogen fertilizer increased duration of double ridges to end spikelet initiation (11.12%) and spikelet initiation to pollination stages (11.35%). The early developmental stages that determines the number of grains per spike as one of the main yield components, had the highest correlation coefficient with grain yield. Therefore, in case of delayed planting date of wheat, it would be possible to postpone wheat developmental stages by applying more nitrogen fertilizer. The results also indicated that in optimum planting date (October 10), Pishgam and in the late planting date (November 5 and 30), Alvand showed better performance than the other varieties.

To evaluate the qualitative and quantitative effects of agricultural managements on the fungal diseases of wheat, a study was carried out at 67 wheat-grown fields located in 8 villages in four geographical sides of Gorgan, Golestan province, Iran, in 2010. Samples were taken using 0.25×0.25 m quadrates. Then pathogenic fungi were identified and used to calculate the biodiversity of pathogenic fungi, heterogeneity index of Shannon-Wiener and Simpson.Qualitative and quantitative state of agricultural managements was provided by a researcher made questionnaires from farmers. The classification and regression trees (CART) procedure showed that nitrogen fertilizer, plant density and potash fertilizer were the most important management factors affecting the Shannon-Wiener diversity index variations, and nitrogen fertilizer, plant density and phosphorus fertilizer were the most important management factors affecting the Simpson diversity index variations. Moreover, the most variability of wheat yield was mainly interpreted by management factors including seeding rate, nitrogen fertilizer and previous two years rotation. Overall, nitrogen fertilizer and seeding rate (plant density) were common between wheat yield and both Shannon-Wiener and Simpson indices, so that, nitrogen fertilizerexplained 38 and 31% of the Shannon-Wiener and Simpson indices variations, respectively, while 46% of the wheat yield variation was explained by seeding rate. The resultssuggest that appropriate amount of nitrogen fertilizer and desirable plant density were effective management options to improve the yield and reduce the fungal diseases in the Golestan province.

In this research, the effects of different levels of nitrogen fertilizer, crop density and variety were investigated on weeds management of wheat with emphasis on winter wild oat (Avena ludoviciana) and flixweed (Descurainia sophia). The experiment was carried out as split plot factorial based on randomized complete block design with three replications at research field of Plant Protection Research Institute, Varamin, Iran, in 2011. Urea fertilizer was considered as main factor and combination of density-variety as sub factor. Results of this study showed that increasing density of Pishtaz and Toos varieties led to reduce in frequency and dry weight of winter wild oat, flixweed and total weed, so that the lowest frequency of winter wild oat (3.55 and 3.66 plant/m2 in Pishtaz and Toos, respectively) was observed at 700 plant/m2 wheat density and it was 3.33 and 3.66 for flixweed in Pishtaz and Toos, respectively. Hovewer, the frequency and dry weight of winter wild oat, flixweed and total weeds increased by increasing the urea fertilizer levels, so that the minimum frequency of total weeds (9.33 plant/m2) was observed to 250 kg/ha urea fertilizer and 700 plant/m2 density of Toos cultivar. Results showed that grain yield decreased in higher densities because of intra-species competition. Due to the reduce in grain yield of Toos variety, the suitable density for this variety was 500 plant/m2, while Pishtaz variety showed a positive reaction to both fertilizer levels and plant density and therefore, the density of 600 plant/m2 was appropriate to control winter wild oat, flixweed and total weeds in this variety. Although the urea fertilizer increased dry weight of winter wild oat, flixweed and total weeds, however 250 and 450 kg/ha urea fertilizer were satisfactory to achieve suitable grain yield in Tous and Pishtaz varieties, respectively. So for weeds control by increasing the wheat density, fertilizer application should also be increased, therefore to use these methods with a view to reducing herbicide, an appropriate balance between these factors must be established.

To study the effects of water deficit stress on three maize hybrids (SC704, SC740 and NS640), an experiment was conducted in split plot based on randomized complete block design with four replications under non-stress and water deficit stress conditions at the Agricultural Research Station of University of Tabriz, Tabriz, Iran, in 2013. Electrophoretic analysis was performed to evaluate the enzymatic activity of superoxide dismutase (Mn-SOD) by using 8% slab polyacrylamide gels and “density × area” values of the electrophoretic bands onto gels were scored asenzymatic activity using MCID software. Malondialdehyde (MDA) content was also evaluated as cellular oxidation index in the studied hybrids under normal and water deficit stress. The results indicated that water deficit stress significantly decreased grain yield, 100-grain weight, ear diameter, ear length, plant height, plant diameter, leaf temperature, chlorophyll index, tassel branch number and tassel length. The cellular oxidation level (MDA) increased in SC704 by increasing water deficit stress. TheMn-SOD activity also increased in SC704 under water deficit showing an increase inoxygen free radicals. The results of this study showed that SC704 was tolerant to water deficit stress.

In this study, AFLP markers were used to investigate the genetic diversity among 24 genotypes of barley. The eight primer combinations of EcoRI/Tru1I, totally produced 332 scorable bands that 292 (89.15%) were polymorph. Genetic diversity was estimated between 0.29-0.38 using Nei's gene diversity coefficient. Also, genetic similarity of the genotypes varied from 0.20.0 to 0.56. The highest (0.47%) and lowest (0.26%) polymorphism were obtained using primer combinations of EcoRI!Tru1Iࡠ and EcoRI$ Tru1Iࠡ, respectively. Cluster analysis using Jaccard coefficient and UPGMA method assigned genotypes to four main groups. In the first and second groups there were six-rows genotypes and in the third and fourth groups a combination of six- and two-rows genotypes. On the based on similarity matrix the genetic distance between Nimrouz and genotype population Khorasan-Razavi also genotype population of Karaje TN2173 and Line EB-86-3 was low, while the genetic distance between genotype population of Tilabad and cross (F1) ALISOS/CI03909-2 was high. Considering to achieving high rates of polymorphism in the present study can use AFLP marker specially primer combination such as ACG- Tru1Iࡠ ᇊ which produced high level of polymorphism as a powerful tool to distinguish of close genotypes and other barley breeding programs.