Cereal Research
Year:2016 | Volume:6 | Issue:3|Papers Count:10

Drought is the most important abiotic stress affecting growth and production of wheat worldwide. To identify genes controlling grain yield, length and width of flag and second leaves in bread wheat, 121 recombinant inbred lines derived from a cross between drought tolerant Azar2 and high yielding 87Zhong 291 varieties were evaluated under rainfed and supplementary irrigation. Transgressive segregation was observed for all of the studied traits as revealed by phenotypic distribution of the traits. Genetic map consisted of 37 SSR, 16 and 32 AFLP markers covered 1157 cM of wheat genome with an average distance of 17.26 cM between two adjacent markers. Based on composite interval mapping, 59 QTLs were identified for the studied traits under rainfed and supplementary irrigation. For flag leaf length, 4 and 1 QTLs were identified under rainfed and supplementary irrigation, respectively. In addition, 7, 8 and 9 QTLS were mapped for width of flag leaf, length and width of second leaf under rainfed condition, respectively. For grain yield, 20 and 10 QTLs were mapped in the supplementary irrigation and rainfed conditions, respectively. In this study, 8 QTLs were common for the traits under study which could be due to genetic linkage or plieotropy. Considering the importance of genomic region between ISSR25_2-CFA2257 markers in controlling grain yield, with saturation of this region with more markers, their could be used in marker assisted selection program.

Grain yield is the result of interaction among its components. This trait is influenced by genetic and environmental factors. Therefore, yield improvement through plant breeding, especially in early generations is difficult. Selection can be effective if it did base on yield components. In order to study mode of genes action and heritability of grain yield and some of its related traits in bread wheat, generations of cross Gasspard × DN-11 including F1, F2, BC1 and BC2 along with parents (P1and P2) were studied in the research field of Tehran Agricultural and Natural Resources, in a randomized complete block design with three replications. The results of the Generation Mean Analysis showed that in most cases, a digenic model including additive, dominance, and epistasis effects was appropriate to explain the variation of generations mean, so that the six parameters model including mean (m), additive (d), dominance (h), and epistasis additive × additive (i), additive × dominance (j), and dominance × dominance (l) were effective in controlling of traits under study. The epistasis effects including additive × additive, dominance × dominance were distinguished as the most important effects in controlling plant height, number of grain per spikelet, number of sterile spikelets, and grain yield, as well as additive and dominant effects of genes for 1000-grains weight and grain weight per spike, and also the epistasis effects of additive × dominance, and dominance × dominance for traits including spike length, peduncle length, and days to flowering. Thus, it should be considerate the mode of gene action for population improvement, as well as choosing an appropriate breeding method.

Breeding for drought tolerance can prevent from loss of production under drought conditions. Physiological parameters can be utilized as tool for selection of genotypes with high adaption to drought stress. In this experiment, 30 bread wheat genotypes were compared in field in a randomized complete block design by measuring physiological and phenological parameters. Also, osmotic adjustment was evaluated at seedling stage for the same genotypes. According to results, water stress led to reduced leaf relative water content of the wheat genotypes. Also osmotic potential was more negative under stress condition compared with normal condition. During water stress, prematurity was observed for all genotypes. In Vierynak, Fong, Frontana, Tajan, Shiroodi and WS-82-9 the maturity date was sooner than other genotypes. Reduction in leaf relative water content in Sardari was 4.5 fold more than tolerant genotype (Vierynak). Vierynak, WS-82-9 and Frontana employed the mechanisms of escape and avoidance under drought stress. Highest yield under stress condition was belonged to Sardari, Roshan and Tous with 6, 5.46 and 5.37 t/ha, respectively. Therefore, these genotypes had more tolerance to drought stress and can be suggested to cultivate under water deficit conditions.

Changing in planting date causes changing in plant phenology such as grain filling in wheat. In order to evaluate the effect of planting dates on grain filling trend of some bread wheat genotypes under rainfed condition, an experiment was conducted at agricultural research station of Gonbad-e Kavous, Iran, in 2012-13 growing season. Five planting times i.e.: Dec.2nd, Dec.21st, Jan.9th, Jan. 28th and Feb.17th were considered as first and five wheat genotypes i.e.: line 16, Gonbad, Koohdasht, Karim and line 7 as second factor, respectively. The effect of planting date × wheat genotypes was highly significant for grain filling rate and final grain weight and significant for effective grain filling period, whereas it was not significant for grain yield. With a delay in planting dates, grain yield of the wheat genotypes decreased. The highest and lowest grain yield were produced at the first and fifth planting dates, respectively. The highest grain yield was produced by Karim and the lowest yield was produced by Line 16. With a delay in planting, grain filling rate of the wheat genotypes increased. The highest grain filling rate (1.76 mg.day-1) was obtained with Koohdasht at fourth planting date and the lowest rate (1.44 mg.day-1) was observed in Line 16 at first planting date. The highest variation among genotypes for this trait throughout different planting dates was 0.46 mg.day-1 for Koohdasht and the least variation was for Gonbad cultivar with 0.14 mg.day-1 increase. The effective grain filling period of wheat genotypes decreased from 35.33 days to 18.37 days with a delay in planting dates. The highest final grain weight of the wheat genotypes at various planting dates decreased from 54.14 mg to 29.5 mg and the highest (19.4 mg) and the lowest (13.28 mg) reduction were for Gonbad and Karim cultivars, respectively. With an each 1o C increase in environment temperature from fifth to first planting date, grain filling duration reduced by 4.1 day and for each day delaying in planting date grain yield decreased by 51 kg.ha-1. The results of evaluation showed that the responsible of wheat genotypes on grain filling trend under unusual environmental conditions were different, thus it can be infer that such as studies will be use to identifying and selection of suitable wheat germplasms on wheat breeding programs under rainfed condition at Gonbad region.

To investigatr the effect of different tillage methods and crop residues on yield, yield components and economic efficiency of wheat, an experiment was carried out as split-plot layout based on randomized complete block design with three replications at research station of Gonabad during 2012-13 growing season. Three tillage methods including conventional tillage (CT), reduced tillage (RT) and no tillage (NT) were allocated to main plots and three crop residues containing without residue (R0), 30% (R1) and 60% (R2) of residues retention were assigned in sub plots. Results showed that different tillage methods and rate of residue management had not significantly effects on dry matter accumulation in different developmental stages, biological yield, grain yield and harvest index. Tillage methods had only significantly effect on number of spike per m2. The highest level of biological yield was obtained from RT treatment. With increasing crop residues from zero to 60%, biological and grain yield were increased, so that the highest amount of biological yield was obtained from retention of 60% residues. The highest level of grain yield was related to CT+R2 treatment. However, CT+R1 and RT+R2 treatments were the best treatments in view point of economic and had the highest rate of net income and rate of return.

In this research, the effects of seed priming with three anti-gibberellin regulators were investigated on yield and yield components of wheat cv. Azar-2, based on randomized complete block design with three replications under regular irrigation conditions in research field of University of Zanjan, Zanjan, Iran, in 2012-2013. The experimental treatments were control (non-primed seeds), hydropriming, chlormequat chloride (400, 800, 1200 and 1600mM), paclobutrazol (35, 70, 105 and 140 mM) and ancimidol (10, 20, 30 and 40mM). The biological yield decreased in most treatments compared to control. On the other hand, seed priming with all of the growth retardants increased the grain yield. In contrast, the use of three growth retarder totally improved the grain yield of wheat cv. Azar-2. Among the growth regulators, paclobutrazol in 140, ancymidol in 20 and chlormequat chloride in 800mM had the highest grain yield. Seed priming with mentioned growth retardants increased 1000-kernel weight compared to control. The highest fertile spike/m2 and seed/spike was found in 800 mM chlormequat chloride and 20mM ancymidol, respectively. By increment in the number of fertile spikes, the length of spike decreased significantly. As a result, there are smaller spikes but with large grains in each plant. It seems that Azar-2 cultivar has a potential for increasing both the number of grain/spike and grain weight. Therefore, it is possible to increase grain yield in this cultivar by improving sink straight from both ways.

Excessive consumption of energy in Iran resulted greenhouse gas emissions and related risks to the environment and human health. The aim of this study was to evaluate the effects of tillage and cultivation of wheat (including conventional farming, reduced tillage and direct seeding) on energy consumption and environmental pollution in the Kalpoosh region of Semnan province. Data were collected through interviews in 30 typical fields of wheat production. Data were analyzed with regard to inputs consumption, inputs energy and greenhouse gas emissions from the consumed energy and tillage method. Total inputs energy from the consumed inputs varied between 13900 to 18713 MJ ha-1. Results indicated that in conventional method, fuel consumption had the most share of energy input (37.8 % of total) followed by Nitrogen (26.5%) and seed (17.4%), respectively. Nitrogen had the most share of energy input in reduced tillage (31.7%) and direct seeding (35.7%). Maximum and minimum of greenhouse gas emissions (CO2, CH4 and N2O) were related to conventional seeding (11713 kg equivalent CO2 ha-1) and direct seeding (2721 kg equivalent CO2 ha-1.), respectively. Wheat yield differences in three methods wasn’t significant, maximum and minimum of wheat yield related to reduced tillage, direct seeding, respectively. Maximum and minimum of economical productivity belonged to direct seeding (0.21) and conventional tillage (0.16), respectively. It can be concluded that using conservation tillage (reduced tillage and direct seeding), without a significant decrease in the yield of wheat, reduced fuel consumption, energy and greenhouse gas emissions, and increased energy efficiency and economical productivity.

GGE biplot method is one of the appropriate methods for analyzing the data with bilateral structure. In the present research, the GGE biplot model was used to identify promising heterotic crosses for paste viscosity parameters in rice (Oryza sativa L.) by using 8×8 full diallel progenies. In direct crosses, parents Deylamani, RI1843046, IR50 and RI184421 were identified as good general combiners for peak viscosity, while in reciprocal crosses, only parent RI184421 was the best combiner for this trait. The parents RI1843046 and RI184421 for breakdown viscosity property and the parents BC4, Deylamani and Tarommahalli for final viscosity parameter were identified as good general combiners in direct crosses, but RI1843046 was the best general combiner for both trait in reciprocal crosses. Although, the parents BC4 and RI184421 were respectively the best general combiners for setback viscosity in direct and reciprocal crosses, but the parent Deylamani was good general combiner for this trait in progenies of both cross. The results of this research showed that the crosses RI1843046 × RI184472, RI184472 × Deylamani and Deylamani × IR50 for peak viscosity, RI1843046 × Line 23, RI184472 × Deylamani and RI184472 × Tarommohali for breakdown viscosity, RI1843046 × RI184472 and RI184421 × IR50 for final viscosity and BC4 × RI1843046 and Deylamani × Line 23 for setback viscosity were the best specific combiners. The good general combiners to organize a new population and the good specific combiners as the suitable heterotic combinations for producing the progenies with suitable paste viscosity properties are suggested.

In this research, the effect of air temperature and and air flow rate was investigated on the broken grains percent, milling recovery and paddy drying time of three rice varieties dried in fluidized bed dryer. The experiment was carried out as factorial in completely randomized design with three replications and the experimental factors were including air temperature at four levels (45, 50, 55 and 60 °C), air flow rate at three levels (0.12, 0.14 and 0.16 m3.s-1) and three rice varieties (Tarom, Fajr and Shirudi). Results indicated that increasing temperature from 55 to 60°C increased the broken grains percent of Shirudi, Fajr and Tarom from 19.10 to 35.97%, 43.30 to 51.36% and 19.82 to 29.06%, respectively. The lowest broken percent (17.17%) was obtained from the air rate 0.12 m3.s-1 and the temperature 45°C and the highest broken percent (40.54%) was registered from the rate 0.16 m3.s-1 and the temperature 60°C. The milling recovery of Shirudi variety at the air rate 0.12 to 0.16 m3.s-1 decreased from 72.37% to 71.74%, but in Fajr and Tarom varieties was not observed significant variation in the milling recovery. Increasing the air temperature from 45 to 60°C at the rate 0.16 m3.s-1 reduced drying time from 13.45 to 5.37 h, respectively, however increasing the air rate from 0.12 to 0.16 m3.s-1 at the air temperature 60°C reduced drying time only from 6.37 to 5.37 h.

Estimating crop yield before harvesting is necessary for any agricultural management scheme. Accurate prediction of crop yield, indeed, reveals the impact of different agricultural inputs on the final yield. One of the new methods for such prediction is the use of so-called growth models. In spite of considerable progresses made for developing these models, their calibration and validation in large scales needs plenty of direct field inspections and sampling. For this reason, the use of satellite images and remote sensing tool is recently considered by different investigators. The objective of this study was to evaluate the possibility of using VSM model and satellite images for prediction of rice yield in Guilan province. Consequently, the MODIS and Landsat-8 satellite images were first obtained. A number of 20 rice farms were selected and the required samples and information including the grain yield were collected from these fields. By using the information of sampling points, the data were then extended to the entire study area by means of interpolation, using ArcGIS10.2 software. The grain rice yield was estimated using the satellite images and VSM model. To evaluate the performance of model, the actual crop yield was compared with those estimated by VSM model that has linear relation with high correlation (>80%) and coefficient of determination of 65%. The obtained results indicated a reasonable prediction of rice yield by VSM model. Furthermore, a strong (>80%) and significant relationship was obtained between the incorporated input parameters and the actual crop yield and satellite imagery has the suitable potential to estimate rice yield as input of VSM model. Considering the obtained results, it is possible to predict rice yield with this model and by calibratinge the satellite data in the studied area the yield for next years can be easily estimated. Consequently, there is no need for large field inspections as well as for spending the related extra costs.