Journal of Agricultural Science and Sustainable Production
Year:2011 | Volume:21/2 | Issue:3|Papers Count:12

Although the mean of combine losses is about 4-5% in advanced countries, unfortunately in Iran is about 20% and higher. In order to obtain little loss it is necessary that product processes such as cutting, transporting, threshing, separation, … would be optimized expressing the equation of different parts of harvesting is the first step. Threshing is one of these processes which has more effect on combine performance. It is desire to maximize the separation of grain from concave meshes. Because of increasing the separation of grains from concave meshes, because it will decrease load of separation and cleaning mechanisms which lead to reduction of separation system’s losses. Therefore, efficiency of separation and cleaning mechanisms would have been increased when separation efficiency of threshing mechanism was increased. Stem height, feed rate, threshing clearance rate and cylinder speed are parameters which were used in combine design and evaluating of its performance. In order to evaluating of these parameters effect on separation efficiency of threshing cylinder, an experiment was conducted in 4×3×3 factorial pattern with Randomized Blocks design. Independent variables in these experiments were stem height, feed rate, threshing clearance ratio and rotational velocity of threshing cylinder as dependent variables had significant effect on separation efficiency but interaction effects of them were not significant (P<0.01). Separation of grains from concave opening was increased when stem height, feed rate and threshing clearance decreased. As rotational speed of threshing cylinder increased separation of grains in threshing mechanism increased. Multiple regression was used to express relation between dependent and independent parameters. The most compatible model for threshing of materials (y1), separation (y2) and MOG passing (y3) were y2= b0 e(b1c1+b2c2+b3c3+b4c4). Which x1, x2, x3 and x4 were stem height, feed rate, threshing clearance rate and speed of threshing cylinder respectively and b0, b1, b2, b3 and b4 were constants.

In order to investigate the genetic polymorphism among 18 important Iranian and two foreign cultivars of safflower, RAPD marker was used. In this experiment 17 primer sets (ten mer) were used for amplification in reactions. Out of 279 mark able bands, 256 bands were found in the range of 100 to 3000 bp. Cluster diagrams produced by means of the unweighted pair-group method arithmetic average (UPGMA) divided the lines into 4 main classes. Class 1 included two exotic genotypes and class 2 included two Iranian landrace lines and one bred cultivated Iranian. Class 3 included 13 wild and local domestic Iranian genotypes. One improved Iranian line (kw4) and Isfahan line placed in class 4. The most genetic diversity (0.863) was observed between Iranian landrace (KW4) and exotic genotype (S710). But in most Iranian landraces, the genetic diversity was low (0.241). The result showed that there is a relationship between the genetic diversity and geographical distances in exotic and indogenous genotypes. But this relation is not among indogenous cultivars. That might be due to originating from the same parent.

Due to important role of furrow opener to criticize properties of seed slot especially in no tillage driller, a case study about double disk opener was conducted. The main objectives of the project were to improve performance of the opener to separate seed and fertilizer, to reduce hair pinning and increase loosening of soil in the slot. In this way, a new double-disk opener developed which had two additional horizontal disks. To consider performance of novel opener an indoor comparison test between new and common opener was performed in soil bin. The experiment was conducted with three working speeds (3, 6 and 8 km h-1), two bulk densities of soil (1.1and 1.4 Mg/m3) and two levels of residues (1 and 2 ton/ha). The experimental design consisted in a (3×2×2) complete randomized factorial with three replicates for each test. Results showed the separation of seed and fertilizer was done by new opener efficiently. Cone Index was lower in the slot created by new opener and Hair-pinning not observed. Although, amount of soil disturbance was higher by new opener, but it should be noted that this opener put two rows of seeds and enough amount of fertilizer simultaneously. The vertical and horizontal separation of seed and fertilizer were 5 and 4.5 cm, respectively.

This study was conducted to identify the drought tolerant genotypes in bread wheat. In this study, 30 wheat genotypes were evaluated under irrigated and water stress conditions based on randomized complete block design with three replications. Analysis of variance showed that there were significant differences among genotypes for most traits. Under normal condition, genotypes C-81-10, Pishtaz, Alvand, Roshan and Hirmand and under drought stress condition the cultivars Darab2, Pishtaz, Azar2 and Chenab had the highest yield among the genotypes under study. Therefore, it seems that pishtaz has a good yield potential in both environments. Most traits were negatively affected by drought stress, the highest reduction being observed in grain yield. The results of path analysis showed that traits such as main spike weight, plant height, number of fertile spikes, 1000 grain weight and number of tillers were important under non-stress conditions, whereas number of fertile spikes and 1000 grain weight were important under drought stress condition. Cluster analysis carried out for both non-stress and stress conditions. The genotypes were divided in to two groups in the normal condition. The first groups include the genotypes that had the higher values for most traits, while in the second group genotypes had the lower values for most traits. In the stress condition two clusters were also obtained. However, in this condition the first cluster was superior for grain yield, number of grains for spike, 1000 grain weight and harvest index but the second cluster was bethre in terms of plant height, late maturity, tiller nimber and carbohydrates translocation efficiency, which indicates the resistance of genotype by environment interaction and suggests that the genotypes should be evelueted under both normal and drout stress conditions.

Two field experiments were conducted at the Research Farm of Tabriz University in 2002 and 2003, to evaluate effects of shading on rate and duration of grain filling and yield of faba bean cultivars. Seeds of three faba bean cultivars including Barakat, Saraziri and HBP-B were sown by hand on 28 April 2002 and 7 May 2003. Both experiments were split- plot, based on randomizedcomplete block design with three replications. Shading levels and cultivars were allocated to the main and sub-plots, respectively. Shading treatments consisted of no shade (control), 18%, 48% and 70% shade. Grain filling duration was similar for faba bean cultivars. However grain filling rate and maximum grain weight of Barakat and Saraziri were higher than HBP-B. Although, mean grain weight of barakat and saraziri were significantly higher than HBP-B, but HBP-B was clearly superior in production of the number of grain per plant and grain yield per unit area. Grain filling duration under shade was 3-4 days longer than under control, which resulted in producing comparatively larger grains under shade. Consequently, mean grain yield of faba bean per unit area for shaded plants was higher than that for unshaded plants. Therefore, faba bean can be successfully used in intercropping and agro forestry, where shadind is a limiting factor.

Allopathic potential of wheat and genotypic variation among cultivars has been observed in several studies. An experiment was conducted using 70 wheat genotypes, in order to recognize and screening wheat cultivars with high allopathic potential against Avena fatua and Hordeum spontaneous. Wheat genotypes sown in pot and after seedling development, they divided to different parts including leaf, stem and root. After drying four concentrations including 0, 25, 50 and 100% of water extract were studied on germination of wild barley and wild oat. For each weed germination percentage, radicle and hypocotyl length were measured. The results showed considerable variation in inhibitory potential of wheat genotypes. Among different plant parts, leaf and stem have higher allopathic effects than root. The highest inhibitory effects on observed in Rasool, Mahdavi, Navid, Karaj1, Adl1, Gaspard, Gascoigne, Arvand, Baiat and Azadi respectively against the both weeds. The results indicated that some wheat genotypes had more allopathic potential that can be used in weed management programs. There is also, a selective inhibitory in wheat allopathic properties.

In many plants, shading affects growth characteristics and yield due to the reduction of solar radiation. On this basis, two experiments were carried out at the Research Farm of the University of Tabriz (Latitude 38.05´N, Longitude 46o 17´E, Altitude 1360m above sea level) in 2002 and 2003. Both experiments were split-plot, based on randomized complete block design in three replications, with the shading treatments in main plots and cultivars in sub-plots. Shading treatments consisted of no shade (control), 18%, 48% and 70% shade and varieties were Barakat, Saraziri and HBP-B. Results showed that in the most stages of growth (particularly later stages), Dry matter accumulation (DMA), crop growth rate (CGR), and relative growth rate (RGR) were higher for plants under shade, compared to plants under full sunlight. Mean grain yield of faba bean per unit area for shaded plants was higher than that for unshaded plants. HBP-B had higher grain yield per unit area in comparison with other cultivars. Therefore, faba bean as a shade resistant plant can be successfully used in intercropping and agro forestry.

Enough knowledge of genetic variation and germplasm classification is necessary to select suitable parents for breeding purposes. In this study, the data derived from measurements of important agronomic traits was used to classify several Iranian and foreign rice varieties and their crosses. Here, four local cultivars were crossed with five pure lines with IRRI source in a line×tester approach. In the next year, parents and their progenies arranged in randomized block design with three replications and planted at the research field of rice research institute of Iran. Some agronomical and morphological traits such as yield and its components were recorded. Analysis of variance showed significant differences between genotypes for all traits. The result of factor analysis based on principle component showed that three factors accounted %77.72 of total variance. These three factors were named as morphological characteristics, yield and its components and phonological factor. In yield and its components were some important traits such as grain yield, number of filled seed, number of empty seed and seed weight that correlation among these characteristics with grain yield was significant. Cluster analysis by UPGMA method divided genotypes to nine groups.

Augmentation of applying the unnatural and mainly chemical inputs by humankind causes increasing rate of disease and arisen environmental problems. In these circumstances, the importance of safe food production is getting clearer. With respect to that, understanding the determinants of consumers' willingness to pay for these safer products is becoming increasingly important in the field of production and consumption planning. In this regard, the purpose of this study is to investigate factors affecting the consumers' willingness to pay the premium for the safer food products. A contingent valuation survey of 180 respondents was conducted during spring and summer of 2009 in Agricultural administration of East Azerbaijan. An Ordered Logit regression model was applied to determine factors effecting consumers' willingness to pay for safer food products. The survey results have shown that about 97 percent of the respondents would be willing to pay a premium. Also, 84 percent of consumers would be willing to pay about a premium between 5 to 25 percent, while about 13 percent of them would be willing to pay more than 35 percent premium for safer food products. Results have revealed that factors like individual's income, family dimensions, environmental concerns and wholesome diet, besides, consumer's awareness of safer food products' characteristics significantly increase their willingness to pay a premium for safer food. Furthermore, females would be willing to pay a higher premium, and those who have people with special circumstances in their family significantly would be willing to pay a higher premium price for these products.

In order to study drought tolerance in sesame varieties and also evaluating stress tolerance indices, an experiment conducted as a split plot based on randomized complete block design with three replications. In this experiment, irrigation as the main factor with three levels (100, 75 and 50 percent of plant water requirement) and ten sesame cultivars as the second factor were studied. In order to calculate the water needs of the sesame, the CROPWAT software (Penman- Monteith method) were used according to FAO-56. Analysis of variance showed significant differences (p£0.01) between stress levels and cultivars in yield but interaction of tow factor were not significant. So, the tolerance indices based on cultivars yield in stress and non stress condition were calculated. Analysis of variance for indices showed significant differences between cultivars in MP, STI, GMP, and HARM. With consideration of correlation between indices and yield under stress and non-stress, these indices were identified as the best indices for isolation and selection of tolerant cultivars. The TOL and SSI indices didn’t have important role in the differentiation of cultivars. Grouping of cultivars using cluster analysis method showed that the Karaj 1, IS and Ultan were water deficit tolerant cultivars with high yield and the Moghan17 and Yellow-white cultivars were sensitive varieties to water deficit stress.

Intercropping is a suitable method towards sustainable agriculture. On this basis an experiment was conducted in a field located in, km 5 of Mianeh-Tabriz road during 2009 growth season. The factorial of treatments was arranged with in Randomized Complete Block Design (RCBD) with two factors; cucumber cultivars (Emperor, Bingo, Superstar and Nefer) and intra row spacing of onion (8, 10 and 12 cm). Results showed that the yield of onion was significantly reduced only in intercropping with Emperor Cultivar. The highest yield of onion was obtained from 10 cm intra row spacing. Cultivars of Emperor and Superstar in comparison with two other cultivars produced more yield. The highest yield of cucumber obtained in sole culture and the yield reduced significantly in intercropping. The highest percentage of onion bulb dry matter obtained from 8 cm intra row spacing. The percentage of cucumber dry matter reduced significantly in intercropping with Nefer cultivar. The highest land equivalent ratio (LER) (1.56) was recorded in treatment of the combination of onion (with intra row spacing of 10 cm) with Superstar cultivar.

In order to assessment of yield, yield components, quality traits and some morphological traits of sixteen rapeseed cultivars (Brassica napus L.) a field experiment was conducted during 2008-2009 in Arak Research Institute Agriculture. In this experiment cultivars were compared in a randomized complete block design with three replications. Effect of cultivars were significant on grain yield, and 1000 seed weight, seed number per siliqua in plant, siliqua number in plant, flowering period, growth period, the percentage of protein and oil, the amount of seed glucosinolate and fatty acids; palmetic acid stearic acid, oleic acid, linoleic acid and linolenic acid percentage. In this experiment, Triangle had the highest and Anatol had the lowest grain yield. The most oil content was observed in cultivar SLM046, while the highest protein content belonged to cultivar Lioness. The lowest glucosinolate was observed in cultivar Talaye and ES Astrid produced the highest it. In order to produce high seed yield cultivars Billy, ES Astrid, GK Helena and GKH 1103 and to produce good quality oil cultivars GKH 305, Billy, Anatol and SLM 046 is recommended, respectively. Cluster analysis indicated that the varieties were divided into four and three groups on the basis of qualitative and quantitative traits, respectively. In classification of quantitative traits, Anatol was in one group by itself, which had the lowest 1000 seed weight and grain yield and the longest flowering period. In classification of qualitative traits, Billy, GKH 305, Anatol and SLM 046 were in one group, they had the highest oil and oleic acid percentage and these varieties had the lowest linoleic acid percentage and amount of glucosinolate.