فصلنامه تحقیقات غلات
سال هفتم شماره 2 (تابستان 1396)

Salinity stress is one of the serious threats for high productivity of crops, especially in wheat as a key staple food for world population. Understandingthe inheritance of yield and yield components is very important in wheat breeding programs for salinity tolerance. In this research, to evaluatethe gene action of yield and yield components, seven Iranian wheat cultivars including Falat, Bam, Ghods, Roshan, Arg, Kavir and Pishtaz along with their crosses were cultivated in randomized complete block design with three replications under both normal and salinity stress conditions at National Salinity Research Center,Yazd province, Iran,in 2014. All initial assumptions for the traits were indefeasible, therefore combined analysis of variance was done based on Jinks-Hayman approach. The results of analysis of variance showed that all traits including grain yield, biological yield, tiller number, peduncle length, plant height and 100 grain weight had significantly simple additive effect “a” and “a × environment”interaction effect. Also, the simple effect of b3 which is equal to specific combining ability in method 1 diallel analysis, and its interaction with environment were significant for all studied traits. Significant “a” and “b3” terms indicated the important role of additive and dominance effects in the inheritance of trait in both conditions. In this research, the cultivar Roshan had the best combining ability for yield, biomass and tiller number. Generally, the gene type for controlling traits, gene action, potential of dominance and recessive genes in parents,maternal effects and additive and dominance effects were different under twoenvironmental conditions, non-stress and salinity stress. Estimated high broad sense and moderate to high narrow sense heritabilities indicated that thestudied genetic materials could be promisingly used to improve these traits under non-stressconditions aa well as salinitytolerance.Therefore, it ispossibleto select tolerant genotypes to salinity stress in Iranian bread wheat cultivars used in this research.

The most effective approach for genetic improvement of grain yield as a polygenic trait is indirect selection by other traits and simultaneous selection based on the suitable selection indices. The objective of this research was to select the elite lines of bread wheat by selection indices approach. 305 pure lines of bread wheat derived from a cross between Roshan × Falat as well as four check varieties, Roshan, Falat, Mahdavi and Shahpasand, were evaluated as an augmented design at research field of Shahid Bahonar University of Kerman 2013-2014 growing season. In order to apply drought stress, irrigation was cut-off at the emergence stage of the spike and grain yield and other agronomic traits were measured. Among the studied traits, grain weight of main spike, grain weight of single plant, number of grain per plant, 1000- grain weight, number of spike per plant, main spike weight, flag leaf length, spike length and plant weight showed highly genetic correlations with grain yield. Direct and correlated response to selections for grain yield for these traits were calculated. The results indicated that number of spike per plant and number of grain per plant had the highest efficiency for indirect selection. The different selection indices constructed by these traits had the high genetic correlation with grain yield. Moreover, relative efficiency of selection and expected gain of selection index using the Smith-Hazel index was higher than the Pesek-Baker index. Therefore, using the optimum index can be effective in breeding programs of wheat to improve grain yield under drought stress. Finally, 30 elite lines were selected based on each selection index and from their comparison, seven superior and promising lines were identified for further evaluations and introduction to farmers.

Nowadays, many breeding programs of wheat focus on improving bread making quality. Therefore, at first, existent genetic variation in three loci Glu-A1, Glu-B1 and Glu-D1 was studied among 28 recombinant inbred lines (RILs) derived from a cross between Zagros and Norstar wheat varieties and 10 commercial wheat varieties via SDS-PAGE. Then, relationships between the bands and bread making quality traits such as macro-polymeric gluten content, grain moisture percentage, Zeleni sedimentation volume, grain weight, SDS sedimentation volume, grain hardiness, hectoliter weight, water absorbance percentage, gluten index, protein percentage, bread volume and wet gluten were studied via multiple linear regression. According to analysis of molecular variance (AMOVA), a considerable variation was obtained within two groups, RILs and commercial varieties, as same as between them. Based on regression analysis, alleles from the Glu-A1 locus especially allele 1 had the most relationship with bread making quality traits, so that this allele was positively related to protein percentage, Zeleni sedimentation volume, SDS sedimentation volume, gluten index, macro-polymeric gluten content and negatively with wet gluten. Allele 2* from the mentioned locus had positive relationship with grain weight, Zeleni sedimentation volume and negative with grain moisture percentage. Null allele from the Glu-A1 locus was negatively related to protein percentage and positively to grain weight. Allele 2 from the Glu-D1 locus indicated positive relationship with macro-polymeric gluten content and negative with bread volume. The results of this research showed that most important allele affecting the bread making quality traits was allele 1 from the Glu-A1 locus which had a negative significant relationship with the wet gluten and positive with the protein percentage, Zeleni sedimentation volume, gluten index and SDS sedimentation volume. The practical significance of these results is the ability to quickly and appropriately select the genotypes in the early generations of breeding programs.

Considering rising cereal prices and concern about global food security, researches are increasingly carrying out on the yield gap during recent years. Accurate estimation of the quantity and spatial distribution of the yield gap has many practical applications, such as using in precision farming. This study was aimed to evaluate the yield gap of wheat-grown fields in Qaresoo basin, Gorgan, Iran, using GIS, RS and the SSM model. For this purpose, the SSM model was used to estimate the radiation limited yield; the Landsat 8 to extract crop indices; regression models to relate crop indices and recorded yield in order to provide predicted yield raster layer; received radiation and the radiation-limited yield to provide studied basin’s radiation-limited yield and finally minus function to determine the final yield gap. The radiation-limited yield, predicted yield and yield gap of wheat grown fields, (which were detected using supervised method than other crops-grown fields), varied from 5.42 to 7.94 t.ha-1, 2.27 to 5.39 t.ha-1 and 1.67 to 4.88 t.ha-1 respectively. The results revealed that wheat-grown fields had a remarkable variance with respect to calculated regional yield factor (from 0.32 to 0.76). Considering environmental factors (soil-related, climatic and topographic factors), It is proposed to consider management factors as one of the important determiners of yield gap.

Drought stress and zinc deficiency is an important factor influencing the reduction of the quantity and quality of wheat. In this research, the effect of application methods of zinc sulfate (dry-seed, priming, soil application and spraying) under drought stress conditions (complete irrigation, stress on emergence of flage leaf and stress on emergence of awn) on yield, yield components and traits related to nutritional value of wheat grain, variety Homa, was studied using a split plots experiment based on randomized complete block design with three replications. The results showed that the simultaneous incidence of droght stress and zinc deficiency in the emergence of flage leaf and emergence of awn stages caused a decrease in the quality and quantity of wheat, so that reduced yield and yield components, ability of zinc absorption from the soil, zinc concentration of grain, ability of zinc absorption from grains and protein synthesis. The results of this research indicated that sprying zinc element increased zinc concentration of wheat grain from 7.2 to 40.5 mg/kg (more than 77.19%), priming of zinc element increased seed storage protein from 13.1 to 14.6 percent (17.69%) and soil application of zinc sulfate increased grain yield from 1524 to 1737 kg/ha (at least 11.97%) and also decreased 18.6% of phytic acid and 78.9% of zinc molar ratio during drought stress at emergence of flag leaf stage.

The main purpose of the present study is to evaluate and compare technical efficiency of two groups of paddy farms, under the national plan of increasing rice production and conventional farms in Pirbazar region of Rasht city, Iran, during 2013-2014. The studied inputs in this research included seeds, labor force, fertilizers, pesticides, machinery and acreage and output was the produced rice of each farm. In this regard, data envelopment analysis (DEA) and random sampling method were used. The results revealed that the average levels of technical efficiency for farms under the mentioned national plan for two models of assuming constant returns to scale (CCR) and variable return to scale (BCC) were 99.2% and 99.6%, respectively, while the average levels of technical efficiency for conventional farms at the region considering CCR and BCC were 97.1% and 97.6%, respectively. The results also showed that the most important reason for higher performance and lower production costs in the farms under the mentioned national plan is the different use of inputs. The findings of this research can have positive effects on government’s planning in agricultural sector especially for strategic product of rice, as well as provides proper background for similar and complimentary researches on rice.

Despite of nitrogen is an influential factor in rice production, but its use efficiency is usually lower in paddy rice than in upland crops. To determine the effects of split application urea, sulfur coated urea and nitrification inhibitor on yield, uptake and nitrogen use efficiency in rice (Oryza sativa L.) cv. Khazar, an experiment was conducted using six different treatments based on randomized complete block design with three replications at two agricultural research fields with different soils (Kisum and Soil and Water Stations), Rice Research Institute of Iran. In this experiment, the effects of coated urea fertilizer and nitrification inhibitor (2,5- dimethyl parabanzo quionon) together with urea and urea splitting methods at two and three times was studied. The results showed that the straw yield, grain and straw N uptake and total N uptake by plant were significantly influenced by different nitrogen application methods in Kisum station with light soil texture. In this field, the maximum grain and straw N uptake and total N uptake were obtained using 90 kg net N per ha from urea source at three equal splitting, one-third at each transplanting, tillering and panicle initiation stage (T5 treatment), while the maximum grain yield was observed for 90 kg net N per hafrom coated urea at transplanting stage (T2 treatment). In Soil and Water station, the effects of treatments on grain and straw yield and grain and straw N uptake were significant at 1% probability level, so that the highest grain and straw yield and N uptake were observed in T5 treatment. The results of this research indicated that for high yielding and long growth duration variety, Khazar, urea splitting at three stages in soils with moderate to heavy textures and use of sulfur coated urea together with splitting method in soils with light to moderate textures is the most appropriate method of nitrogen application.

Usually, phosphorus after nitrogen is the most important mineral nutrient limiting growth and yield of crops. Phosphate solubilizing rhizobacteria can change non-absorbable forms of phosphorus to absorbable forms. To evaluate the effect of inoculation with Streptomyces sp. bacterium and phosphorus (P) fertilizer rate (0, 20, 40, 60 and 80 kg P per ha) on yield and yield components in wheat (variety Morvarid) and barley (variety Sahra ), a pot experiment was conducted as factorial arrangement in a completely randomized design with four replications in new site of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran, during 2014-2015 growing season. Results of this study revealed a significant linear increase in grain yield of wheat and barley by increase in the fertilizer phosphorus rate. The results showed that grain yield in control treatment (without P fertilizer) was 9.8 gr per pot (2352 kg.ha-1), but with increasing one kg P fertilizer, grain yield increased to 0.13 gr per pot (26 kg.ha-1). With the use of 80 kg.ha-1 P fertilizer, grain yield increased to 20.2 gr per pot (4848 kg.ha- 1), that represents a 106% increase in grain yield than the control treatment. The results showed that increasing grain yield in barley was mainly due to increase in the number of spike per plant and the number of spikelet per spike, but in wheat mainlt due to increase in the number of spikelet per plant and number of grain per spikelet, and the role of grain weight in the changes of grain yield was negligible. Also, the findings of this study showed a linear increase in plant biologic yield due to the use of P fertilizer rate, bacteria inoculation and their interactions. The results clearly showed that the effect of inoculation on the plant growth in the lower amounts of phosphorus fertilizer was more than the higher amounts of phosphorus fertilizer.

The positive effect of irradiation of seeds with ultrasonic waves on seedling growth has recently been considered by researchers. However, most experiments in this regard, have been focused on germination and early establishment of seedlings. The objective of this research was to investigate the response of corn plants to this waves under drought stress conditions. A filed experiment was conducted as factorial based on randomized complete block design with three replications at research field of Shahrood University, Shahrood, Iran, in 2014. The treatments were three levels of drought stress (control, irrigation interruption from flowering stage and irrigation interruption from grain dough stage) and five irradiation times (control, 2, 4, 6 and 8 minutes). The results indicated that unlike the main effects of factors that had significant effect on the most traits studied (except the effect of ultrasonic waves on stem and leaf dry weight), the interaction effect of drought and irradiation was significant on plant stem diameter. This shows that irradiation effect on the most traits studied does not change with thev change in drought stress intensity. Irradiation of seeds with six minutes could increase the average of these traits by 8, 10 and 12%, respectively. In total, irradiation of corn seeds with the ultrasonic waves under both stress and non-stress conditions was resulted to produce the stronger plants, especially under drought stress conditions where irradiation could decrease the unfavorable effect of drought stress.

To evaluate the response of 45 sorghum lines and cultivars to salinity stress, two experiments were conducted in non-stress (EC=2 dS.m-1) and salinity stress conditions (EC=12 dS.m-1) using randomized complete block design with three replications. The experiments were carried out at Ardakan research station of Agricultural and Natural Resources Research Center of Yazd, Iran, in 2014. Salinity stress significantly decreased all measured traits in lines and genotypes. Under salinity stress conditions, stem diameter, stem height, leaf number, leaf area index, fresh forage yield and dry forage yield were decreased 14.45%, 25.24%, 18.06%, 31.86%, 40.19% and 32.36%, respectively. The highest dry forage yield under non-stress and salinity stress conditions was produced by KDFGS23 (28530 kg.ha-1) and Jumbo cultivar (21042 kg.ha-1), respectively. Results of correlation coefficients among dry forage yield under non-stress and stress conditions and tolerance indices showed that GMP, HAM, MP and STI indices were the most suitable tolerance indices. Results of cluster analysis showed that Jumbo, Pegah, Sistan, Sweet sorghum, Ghalami Herat and Speedfeed (Moghan) had higher tolerance to salinity stress, while lines KDFGS23 and KDFGS26 and Nectar cultivar had greater sensitivity to salinity stress. Since line No. 1 (KDFGS1) had greater yield stability, it worth further explorations in future breeding projects.