جستجوی مقالات مرتبط با کلیدواژه « non » در نشریات گروه « زراعت »

In order to get rid of single-product economy, trade of agricultural products is emphasized by the government. As Iran is the biggest producer and exporter of this strategic product in the world, the analysis of factors affecting export of Iran's saffron, can result in better policy making. Accordingly, this study is aim to investigate the short-term and long-term effects of exchange rate volatility beside the other factors affecting the export of this product using panel data for Iran's major trading partners during 1992-2014. For this purpose and to avoid the limitation of symmetric approaches to calculate instability indices, the exchange rate volatility index was firstly calculated by using asymmetric method of Exponential Generalized Auto-Regressive Conditional Heteroskedasticity (EGHARCH). Then, this index was used along with other variables to estimate of proposed model using the Fully Modified Ordinary Least Squares (FMOLS) method. The results showed that although countries income and real exchange rate have positive and significant effects on saffron export, exchange rate volatility has a negative and significant effect on export of this product. Therefore, if the government’s goal is to support the export of this product, it is vital to achieve stability in exchange rate market. Moreover, the results of estimating error correction model indicate that the speed of disequilibrium adjustment towards long-run equilibrium relationships is substantial. Therefore, policy-making would be hopeful in the short-term

To evaluate the effects of four kinds of organic non-living mulches (wheat straw, sawdust, coco peat and peat moss) and metribuzin (herbicide treatment) on weed control and yield of tomato cv. "CH" an experiment was designed in randomized complete blocks with 7 treatments and 3 replications at the College of Agriculture, Shiraz University in 2012. According to the results all mulch treatments showed lower efficiency in weed control than the metribuzin. Also, all mulch treatments showed higher weed density compared to metribuzin. When straw, among non-living organic mulches, showed lowest weed control (62.3 weed.m-2). According to the results the highest tomato yield per unit area was produced by using peat moss mulch (from 5.7 kg.m-2) and the lowest yield from weedy plots (1.2 kg/m-2). To calculate the percentage of predicted performance of each of the treatments, only Gompertz model was applied and only the beginning of weed interference between the treatments was taken into account.

Although the non-Iranian primary tritipyrum lines (NIPTLs) have been produce and have shown potential to be a new slat tolerant cereal, however, have a few undesirable traits such as brittle rachis, keep in tiller production and late maturity. In order to remove these traits, the crossing of NIPTLs with Iranian bread wheat cultivars led to new recombinant Iranian secondary tritipyrum lines. In this study the 13 non-Iranian primary tritipyrum lines (NIPTLs: 2n = 6x = 42; AABBEbEb) and Iranian secondary tritipyrum lines (ISTL: F6-F7; 2n=6x=42, AABBD(1-6)"Eb(1-6)"), 6 Iranian bread wheat cultivars and 1 promising triticale line were evaluated at two research centers using an alpha lattice design with two replications under normal (1 dS m-1) and salinity stress ( 12dS m-1) conditions during growing seasons of 2014-2016 at Kerman province of Iran. The results indicated grain yield was strongly affected by salinity with reduction ratio of 11.06, 9.37, 4.30, 4.98, 7.98, 12.58, in Iranian chromosomally recombinant secondary individuals tritipyrum plants obtained from crosses such as (Cathlicum × Ma/b), (Falat× Ma/b), {Omid × (Ka/b)(Cr/b)}, {Niknejad × (Ka/b)(Cr/b)}, (Shotordandan × ka/b), (Roushan × Az/b), respectively, in comparison with Non Iranian Primay Ttritipyrum Lines (NIPRLs) (3.48), Iranian bread wheat cultivars (19.90) and promising triticale line (15.87) The evaluation of stress tolerance indices showed that STI could effectively be used for screening of salinity tolerant genotypes because it had the highest correlation coefficients with grain yield. The (Cr/b) × (Ka/b) line of NIPTLs and the lines obtained from Niknejad × (Ka/b)(Cr/b) and Omid × (Ka/b)(Cr/b) crosses showed the highest average breeding value which will be suitable for breeding programs of ISTLs lines with high yield potential in saline soils and brachish waters.

Weeds are a major constraint limiting crop yield in agricultural systems and in organic systems in particular. Although herbicides are efficient for weed control, continuous use has caused the development of resistance in weeds against several herbicides. Furthermore, herbicides also pollute the soil, water and aerial environments and herbicide residues in food have deteriorated food quality and enhanced the risk of diseases. Allelopathy is defined as the direct or indirect harmful or beneficial effects of one plant on another through the release of chemical compounds into the environment. Wheat (Triticum aestivum L.) is known to be allelopathic against crops and weeds. The objective of this study was to investigate the allelopathic effect of wheat and barley residues on weeds control and cowpea yield.
An experiment was conducted as randomized complete block design with three replications at the research field (36° 25’E, 54° 58’N, 1349 m a.s.l.) of Agricultural Faculty, Shahrood University of Technology in 2015. Treatments were included; weeding all season, no weeding, trifluralin according to the recommended dose (2 ton ha-1), foliar application of wheat straw extract (concentration of 50%), foliar application of wheat straw extract (concentration of 100%), the application of wheat residue mixed with the soil at a rate of 2 ton ha-1, the application of wheat residue mixed with the soil at a rate of 4 ton ha-1, the application of wheat residue mixed with the soil at a rate of 8 ton ha-1, foliar application of barley straw extract (concentration of 50%), foliar application of barley straw extract (concentration of 100%). Statistical analysis of data was performed with MSTAT-C software and means were compared with LSD test at the 5% level of probability.
The results showed that the effect of treatments was significant (P 0.01) on weed density and dry weight. Soil incorporation with wheat residue at a rate of 4 and 8 ton ha-1 significantly decreased weed density than non-weeding treatment. Seed number per pod, biological and grain yield of cowpea significantly increased in the soil incorporation with wheat residue at a rate of 8 ton ha-1 compared to control. Our results showed that weeding and soil incorporation with wheat residue at a rate of 8 ton ha-1 increased cowpea yield by 78.23 and 80.79% compared to no weeding treatment, respectively. Wheat is a potent source of bioactive phytotoxic compounds representing three main classes as phenolic (hydroxybenzoic, vanillic, pcoumaric, syringic and ferulic acids being most frequently reported and transferulic and trans-pcoumaric acids being the dominant acids), cyclic hydroxamic acids (a class of alkaloids) and short chain fatty acids. It is reported that wheat extract compounds can interfere with basic processes of receiver plants as photosynthesis, cell division, respiration and protein synthesis and indirectly provoke other forms of stresses. Thus, these compounds can reduce weed germination and growth. Another important effect of these allelochemicals is the activation of cellular antioxidant system in response to uncontrolled production and accumulation of reactive oxygen species. The reason for increase in grain yield was the control of weeds and probably the allelopathic effects of crop water extracts promoted the wheat growth which ultimately increases grain yield.
Conclusions : The present study concluded that wheat phytotoxins in straw inhibited germination and seedling growth of weeds, and the inhibition was concentration-dependent. Also wheat straw added to soil increased yield and some traits of cowpea. In general, the results showed that wheat straw can reduce weed suppression and can improve characteristics of plant, moreover, decreased environment risks of chemical inputs and ensure sustainability of production in long time.

Germination is series of biochemical reactions that depends mainly on temperature and moisture. Therefore, seed germination rate of lemon balm (Mellissa officinalis L.) were evaluated in temperatures of 20, 23, 25,27, 30 and 32ºC and water potentials of 0, -0.2, -0.4, -0.6 and -0.8MPa. According to the results, germination temperature window was not very wide in a way that germination temperature range was 23-32ºC. Three non-linear regression models (Dent-like, Segmented and Beta) were used to evaluate cardinal temperatures. According to the indices including RMSE, the coefficient of determination (R2) and correlation coefficient (r), the best model was Dent-like which can better estimate germination rate in response to temperature and water potential. The base, the lower and the upper and the ceiling temperatures of lemon balm were 17.31, 30.26, 31.15 and 35ºC in the optimum conditions of water potential, respectively. Biological time for germination ranged from 41 to 137 h in different water potentials. Biological time decreased about 96 h by increasing 1 MPa in water potential. Estimated parameters and the relations can be used to predict time to germination or emergence in lemon balm under wide environmental conditions from normal to drought stress.

Photosynthetic energy conversion efficiency is characteristic of a system which is determined by interactions between various components of the system. The complex process of photosynthesis has been studied as a whole system which enables in silico examination of a large number of candidate genes for genetic engineering for a higher photosynthetic energy conversion efficiency. One of the most important environmental factors which influence the photosynthesis efficiency is light regime which can cause producing ROS components. To acclimate to such fluctuations, plants have evolved adaptive mechanisms to minimize damage of the photosynthetic apparatus excess light. A fast compatibility response to high light stresses is non-photochemical quenching process (NPQ), dissipating excessive energy to heat. Light harvested state switches into a quenched state by a conformational change of light harvesting complex (LHCII) that regulated by xanthophylls and the PsbS protein within seconds. Low lumen pH activates xanthophyll synthesis via a xanthophyll cycle which consists of the de-epoxidation of violaxanthin to zeaxanthin by violaxanthin de-epoxidase in high light and inversely by zeaxanthin epoxidase in low light which occurs more slowly.
Thale cress (Arabidopsis thaliana) (Chlombia-0) were grown on soil at 25/22 °C day/night temperature, with a 16/8 h photoperiod, and 40-70% (depend of plant species) relative humidity. The light intensity was 150–200 µE m-2s-1 white light. Intensity of chlorophyll fluorescence was measured with PAM-2000 fluorometer (Heinz Walz, Germany) and the manufacturer’s software (PamWin v.2).
In the present study, a dynamic kinetics amplified mathematical model was developed based on differential equations in order to predict short-term changes in NPQ in the process of adaptation to different light conditions. We investigated the stationary and dynamic behavior of the model and systematically analyze the dependence of system key characteristic such as rate constant and pool size. For medium and high light intensity, experimental evidence has been predicted with high accuracy by simulation. In low light intensity (100μE m-2s-1) in a few seconds the light phase, a temporary increase in the rate of NPQ was observed after about 60 seconds it reaches to a steady state level. Model simulation of the induction of NPQ relaxation is more accurate than previous predictions, due to the introduction of more stringent quenching agents (xanthophylls cycle and also the light-harvesting complex protonations). The results showed that the pH drop in the transition from darkness to light and high light intensity increases. For low light intensity quenching process occurs with a more gentle slope to the prediction model based on previous experiments is more realistic. In low light conditions, the proton concentration can easily be balanced by ATP synthase activity. This leads to a reduction in current proton-proton feedback gathered during few seconds is balanced. Thus, at high light intensities ATP levels remained stable in the new model is more consistent with reality.
A simple mathematical model which has been developed in this paper provides a more detailed description of this process and be able to predict the various components and parameters associated with it. Comparison of simulation results with experimental data revealed that protonated light harvesting complex and Zeaxanthin simultaneously induce NPQ quenching processes. The results can be seen as theoretical basis for developing more accurate models to study molecular mechanisms of acclimation processes of the photosynthetic chain.

Due to the limited freshwater, farmers have to use exotic water, such as saline water. The aim of the present study is to propose an effective way of how to use saline water for irrigation of forage sorghum in order to save more freshwater in Sistan region To do this, an experiment was performed as a randomized complete block design with six treatments and three replications in experiment field of Zabol University within 2013 spring. Treatments included: control treatment (100 % freshwater), treated with two-thirds of salty, one-half of salty, one-third of salty, 90% salty and 100% salty water. The investigated cropping indices were dry weight of stem, leaf and aerial organs of plant, plant height and leaf area index. The results indicated that one-third treatment was not significantly (p

The present study was carried out to evaluate phonological and pomological characteristics of five pistachio cultivars (Ouhadi, Badani, Momtaz, Ahmmad Aghaie and Kallehghoochi) in a randomized complete block design with five replications at research station of Mahneshan during 2012-2013. The results showed that the overlapping period of polinizer cultivar with Ouhadi, Badami, Momtaz, Ahmad Aghaie and Kallehghoochi cultivars was 7, 8, 7, 3 and 9 days, respectively. There were significant differences among the cultivars for fruit set, Kallehghoochi cultivar had the highest and Momtaz cultivar had the lowest percentage of fruit set. Cultivars also differed for nut characteristics such as fresh and dry weight of nut, and nut length and width. Kallehghoochi had the highest and Ouhadi and Momtaz cultivars had the lowest values of these characteristics. Momtaz cultivar had the highest and Ahmad Aghaie cultivar had the lowest percentage of blankness of nut. Kallehghoochi cultivar had the highest and Ahmad Aghaie had the lowest percentage of non- split nut. The highes ounce weight of nut was recorded for Badami, Momtaz and Ouhadi cultivars, while Kallehghoochi cultivar had the lowest ounce.

In this research, the effects of 5-aminolevulinic acid, as a key precursor in the biosynthesis of porphyrin compounds such as chlorophyll, in mitigating salt stress were studied in Lycopersicum esculentum mill. Salinity at three levels (0, 50 and 75 mM NaCl) and ALA treatment at three levels (0, 1 and 2 mM) were applied on plants of this species. Both levels of salt (50 and 75 mM) reduced shoot fresh weight (11, 13%), shoot dry weight (15, 20%), shoot length (13, 25%), leaf area (20, 27.5%), chlorophyll (22.5, 49%), protein (12.5, 33.5%) and K+ content (22.5, 55.5%), and increased lipid peroxidation (84, 117%), H2O2 level (60, 100%), proline (61, 110%) and soluble sugars content (8. 18%), and ascorbate (25, 50%) and glutathione pool (29, 43%) and Na+ content (500, 700%) respectively. 5-aminolevulinic acid application in both levels, increased the leaf area, the amount of chlorophyll, protein, proline and soluble sugars, and ascorbate and glutathione pool by reducing the amount of lipid peroxidation, H2O2 level and Na+ content. The K+ content was not affected by ALA application. These results suggested that application of 5-aminolevulinic acid (1 and 2 mM) improved plant growth under normal condition and increased tolerance of tomato plants to salinity stress via increasing the amount of osmolytes, non-enzymatic antioxidants and chlorophyll cencentration.

Choosing varieties with high weed competitiveness is important in integrated weed management (IWM). This experiment was carried out in order to study weed tolerance and competition indices of 18 wheat genotypes under natural weed interference or without interference at the research field of agricultural faculty, University of Mohaghegh Ardabili, during 2010-2011 growing season. Significant differences were found in the indexes of wheat genotypes. Stress tolerance index of genotypes was between 110.3 to 915.0 kg ha-1. More tolerance indices such as Mean Productivity, Harmonic index and Weed Interference Tolerance Index were higher for N-80-19 and Alvand genotypes and lower for Dabira and Toos than others. Among the tolerance indices, weed interference tolerance index (WITI) and ability of weed competition (AWC) were more efficient to classify wheat genotypes to weed tolerance. Alvand and C-85-9 genotypes had the highest competitive index (CI). This finding can be used for non-chemical weed management programs.

Growth analysis is a valuable method in the study of quantitative of growth، development and crop production. In order to study the physiological growth indices of lentil plant under dry- farming conditions، an experiment was carried out as a randomized complete block design with three replications at the Agricultural Research Station of Lorestan University during 2010. In this experiment two cultivars were used including Gachsaran and Philip، that are appropriate and commonly in the area cultivating. In order to have more accurate study، Growing Degree Day (GDD) index was used for fitting growth curves، and then appropriate model was selected for each growth index using non-linear regression models. The results of the growth indices showed that Gachsaran cultivar has higher priority than Philip cultivar in leaf area index، but Philip cultivar had higher priority than Gachsaran cultivar in crop growth rate، net assimilation rate and dry matter production. Relative growth rate was similar in both cultivars. In total، growth characteristics of Gachsaran cultivar leading to higher seed yield and growth characteristics of Philip variety leading to produce more biological yield.

Water use efficiency is positively correlated with grain yield، and being used for indirect selection of high wheat yield in drought prone environments. Yet little is known about genetic control of water use efficiency. In this research، a half diallel mating design was generated from crosses between 8 bread wheat to study the genetic of water use efficiency. Parents and F1 progenies were planted in drought stress condition in a randomized complete block design with four replications and water uptake، grain yield، water use efficiency، awn length، fertile tiller number، grains per spike، 1000-grain weight and harvest index were evaluated. Additive and dominant effects were significant for all traits. Non-additive variation was more important in genotypic disparity of water uptake، grain yield، water use efficiency، fertile tiller number، 1000-grain weight and harvest index. Accordingly، bulk، single seed descent and double-haploid methods are suggested in breeding program for these characters. Whereas، additive variation had imperative effect on genotypic variation of awn length and grains number per spike. Thus، despite of mentioned breeding methods، pedigree and backcross are recommended for these traits. Significant high correlation (r=0. 88**) between grain yield and water use efficiency demonstrated the importance of water use efficiency in drought stress condition. Therefore، selection for higher water use efficiency would improve grain yield in drought stress condition.

Growth analysis is a valuable method in the quantitative analysis of crop growth، development and crop production. In order to evaluate effects of nitrogen rates and plant density on physiological growth indices of safflower، an experiment was conducted at Khorramabad، Lorestan province in 2008. The experiment was carried out as split plot in basis of randomized complete block design with four replications. Three nitrogen application rates were as main plots (N1=control، N2=75 and N3=150 kg/ha net nitrogen) and plant density was as sub plots in 3 levels (D1=40، D2=50 and D3=60 plant/m2). The growth degree day index was used to examine more closely fitting growth curves using non-linear regression models. Appropriate model was selected for each growth index. The results showed that application of nitrogen led to increasing of growth indexes including leaf area، total dry matter and crop growth rate. But، net assimilation rate was reduced. Growth indexes such as، leaf area، total dry matter، did not change with increasing plant density، due to branching of safflower. However، crop growth and net assimilation rate were reduced in plants. Overall، the results show that applied nitrogen has a more positive effect on safflower growth index compared to density changes.

The selection of high performance varieties with high stability is an important objective for canola breeding programs in rain-fed and arid areas. Also, evaluation of G×E interaction is very important for releasing stable varieties in different regions. In this research, the stability and adaptability of 19 advanced lines of canola for grain yield were compared in Gachsaran (semi-warm and dry area) experimental station during 2005 to 2007 cropping seasons. The experimental design in all three years was randomized completely block design with three replications. Combined analysis of variance showed that the effect of variety and year × variety interaction were significant. The different stability methods were used to identify stable genotypes in this research. These methods were parametric including, type I parameters (Environmental variance (S2i), Coefficient of variation (C. V.)), type II parameters (Shukla stability of variance and Wrick equivalence indices, regression (bi)), type III parameters (Deviation of regression (S2di), and Non-parametric method of rank (based on R and SDR parameters). Finally, genotypes Option 500، PP-308-8، PP-401-15E، PP-401-16 and Shiralee with high stability and grain and oil yields were selected and introduced as the most stable cultivars with high oil yield.

GGE (genotype + genotype×environment) biplot is one of the new graphical methods to study genotype×environment interaction in which the effects of genotype and G×E interaction are not separated and selection is based on both of these effects. In the present research, GGE biplot was used to study 14 safflower genotypes over six research stations under water stress and non-stress conditions in spring planting. The results of analysis of variance showed that 93.9% of total variation was due to environment and 6.1% due to genotype and G×E interaction. The polygon-view of GGE biplot recognized six superior genotypes and four mega-environments. The best genotypes within each environment were determined. The seven genotypes located in sectors that no environment was placed indicated that these genotypes were poor in most of the environments. Simultaneous evaluation of yield and stability through average environment coordinate biplot showed that Hartman, Gila and Sina with high seed yield had higher yield stability. Hartman was the nearest variety to ideal genotype (assumed genotype with the highest yield and stability) and Gila and Sina varieties were also close to ideal genotype, too. Biplot of correlation among environments revealed that Shirvan and Kohdasht were similar environments, so that water stress and non-stress conditions were not able to make differences between these locations. Zanjan, Ghamlo, Kohdasht and Sararood environments under non-stress conditions had higher discriminating ability.

The improvement of vegetation due to full or partial protection was depicted by most of rangeland scientists. This study investigated the effect of livestock grazing on percentage of germination (PG)، mean growth time (MG) and germination rate (GR) of the even-aged Atriplex canescens، by comparing two sites across zarand، shahreiar rangelands located in the southwest of Tehran، Iran. For this purpose، the seeds of 30 A. canescens within each of the two study sites were collected and a quantitative analysis of the seeds was carried out by laboratory analysis. The results indicated that، grazing had no significant influence on PG، MGT and GR.