Crop Production
Year:2015 | Volume:7 | Issue:4|Papers Count:12

Climate change due to increase atmospheric CO2 concentration and other greenhouse gases could have considerable effects on crop production in the future. The aim of this study was climate change impacts on chickpea yield in rainfed condition and generating yield map in Zanjan province, Iran. Investigated scenarios were historical climate (control) and future climate scenario that included both direct effect of doubling CO2 (350 to 700ppm) and its indirect effects (10% reduced rainfall, 4oC increase in temperature). Simulations were done using a simulation model of chickpea and Geographical Information System (GIS) approach was used to produce yield maps. Grain yield and its variability were evaluated in comparison to current trend. The future climate condition will increase crop yield by 33.4% (717 to 957 kg ha-1 depending on location), but yield variability will increase by 21.2%. Increasing in grain yield was a result of positive effect of doubling CO2 on photosynthesis and resultant decrease in transpiration. The results also showed that increasing temperature was the main reason of higher yield variability. Zanjan station with an increase of 46.5% in grain yield showed the greatest yield increase under the future climate but yield variability at this location was also increased by 37.7%. The highest grain yield was simulated for Khodabandeh station under both current (1307 kg ha-1) and the future (1385 kg ha-1) climates.

Temperature and moisture are the main effect on seed germination, which are determine the rate of germination of non-dormant seeds. In order to quantifying the germination-rate of barley (Hordeum vulgare L.) in response to temperature and water potential, germination of this crop was investigated as affected by temperature (5, 10, 15, 20, 25, 30 and 35oC) and water potential (0, -2, -4, -6 and -8 bar) at the Seed Technology Laboratory, Gorgan University of Agricultural Science and Natural Resources. Results showed that the temperatures, the water potentials and their interactions were significantly influenced germination rate and percentage of barley. In this work it has been compared four non-linear regression models (original beta, 3-piece segmented, 2-piece segmented and modified beta) to describe the cardinal temperatures for the germination of barley. The original beta model was selected as the best model to predict germination rate. Based on the model outputs, the base, the optimum, and the maximum temperatures for germination of barley were estimated as -0.9, 27.5 C and 35.7oC, respectively. The biological hours for germination at zero water potential was 23.4 h. Cardinal temperatures were not influenced by water potentials. However, the numbers of biological hours for germination increased 2.6 h/bar by decrease each bar of water potential.

In this experiment, the effects of irrigation water salinity and Zinc fertilizer applications were evaluated. The experiment was conducated in a strip split block design in 3 replications to find out photosynthesis parameters of leaf barley genotypes in Esfahan (Rodasht) drainage and salinity research station. Three water irrigation quality including w1=control, 1-2 ds/m (low salinity), W2=10 ds/m (common salinity in the region), W3=18 ds/m (high salinity) were evaluated in vertical factors. The horizontal factors were foliar spraying including (Nano zinc-oxide, Chelated zinc, mixture of nano and chelated and water spraing as a control). Three different barley including (Moroco as a moderate semi sensitive, Nosrat asa moderate tolerant and Line No.4 as a tolerant) genotypes spilted within vertical factors. While salinity increased the salinity, the stomatal resistance increased and Stomatal conductance and CO2 decreased. Tolerant genotype had higher stomatal conductance, mesophyll conductance and water use efficiency. Line.4 had relative superiority in terms of photosynthetic rate, stomatal mesophyll and water use efficiency. It had the lowest transpiration and sub-stumatal CO2. Zinc treatments had the minimum photosynthetic rate and the highest ub-st0matal CO2. Spraying zinc treatment had higher mesophyll conductance than control. There was a positive and siginicant corroleation between mesophyll conductance and photosynthesis rate and a signicant negative corroleation between mesophyll conductance and sub-stomatal CO2. The maximum and minimum of stomatal conductance were gained at nano and chelated treatments, respectively.

In recent years, soil pollution with heavy metals such as cadmium had a progressive trend and causes serious problem in production of crops in polluted zones. In order to study the effect of cadmium stress on growth and biochemical traits and selection of tolerant genotypes using stress tolerance indices, 25 bean genotypes at 0 (as control) and 4 mg L-1 concentration of cadmium chloride were evaluated as factorial arrangement based on randomized complete design with three replications, in Biotechnology Laboratory of College of Agriculture and Natural Resources, Islamic Azad University, Karaj branch in 2011. Results showed that there was high genetic variation for most of evaluated traits. Cadmium stress decreased root length, shoot length, root to shoot ratio, germination percentage and fresh weight while superoxide dismutase activity, Proline and Abscisic acid content were significantly increased. MP (mean productivity) and GMP (Geometric mean productivity) indices had positive correlation with fresh weight in both normal and cadmium stress conditions. In order to precise evaluation, principal component analysis and biplot was done and four genotypes including G-11867, Taylor, Emerson, D-81083 were identified as tolerant genotypes.

Nitrogen (N) is one of the most important nutritious element limiting yield crop. In order to study the effects of rate and time of nitrogen application management on leaf area index at anthesis, biological yield, harvest index, and grain yield in wheat (Triticum aestivum L.), a factorial experiment based on a randomized complete blocks design with four replications was done on the research field of Gorgan University of Agricultural Sciences and Natural Resources during growing seasons 2011-2012 and 2012-2013. Experimental treatments in first year included four net nitrogen fertilizer rates of 0, 100, 175 and 250 kg N ha-1 and 0, 60, 120, 180 kg N ha-1 in second year; which were split in four stages of planting, tillering, stem elongation and booting. The result showed that rate and time of nitrogen application management had significant effect on leaf area index at an thesis, biological yield, and grain yield of wheat. In this study, the maximum yield was 5529.9 kg ha-1 that achieved at 78 kg net N ha-1. Thus, 78 kg net N ha-1 (170 kg ha-1 of urea fertilizer) should be used in splitting manner for gaining the optimum yield of wheat so that 12.5% in planting stage, 37.5% in tillering stage, 37.5% in stem elongation stage and 12.5% in booting stage should be applied and it seems better to apply nitrogen fertilizer earlier in stem elongation stage.

In order to investigate the effects of urea and azocompost on the yield and radiation use efficiency (RUE) of wild majoram, a factorial experiment was conducted based on randomized complete block design with three replications at Yazd and Mashhad, Iran, during 2012-2013 growing season. Four urea levels and four Azocompost levels (to provide 0, 40, 80 and 120 kg N ha-1 each) were considered as the experiment factors. Simple effect did not show significant differences among evaluated charecteristics. The results of combined analysis of two locations revealed significant effects of urea and azocompost on economic yield (P<0.05). The highest yield in urea and azocompost were observed to 1625.94 and 1768.65 kg ha-1 that was obtained from 120 kg N ha-1 treatment, respectively. The most leaf area index and total dry matter obtained at 120 kg organic N ha-1 in two locations. Application of organic and chemical fertilizers increased RUE (radiation use efficiency) compared to control plants in the both regions, which the azocompost caused higher RUE than urea. In general, the results indicated that application of azocompost caused to produce higher yields, dry matter and RUE than urea in oregano plants.

In order to evaluate the effect of inorganic nitrogen on dry matter and nitrogen remobilization in spring barley under water deficit conditions, a factorial experiment based on completely randomized design with three replications was conducted in the greenhouse condition in 2012. Irrigation schedules imposed in pots at three levels (35%, 60% and 85% field capacity ) and the nitrogen fertilizer applied at three rates (40, 80 and 120 kg ha-1) on the EBYTW-11 spring barley genotype. The results showed that the DM remobilization from different parts of plant (stem, flag leaf, other leaves and peduncle) to the grain was affected by water deficit and nitrogen levels, so that the highest amount of dry matter remobilization belonged to other leaves under mild water stress (FC 60%) with 40 kg ha-1 nitrogen. Also, the efficiency of dry matter transferring from the foliar to the grain was influenced by nitrogen application and water deficit. The contribution of DM remobilization from stem and peduncle was significantly affected by water deficit and nitrogen. The maximum efficiency of dry matter allocation to grain belonged to the flag leaf under severe stress with 40 kg ha-1 nitrogen. It seems that under severe stress, the most amount of dry matter is transmitted to the spikes because of earliness, accelerated aging and loss of lower leaves. The results showed that when the plant is exposed to nitrogen deficiency in the soil, nitrogen remobilization efficiency from vegetative organs would be higher.

Determination and identification of effective factors on wheat seed yield under water deficient condition is very important. Nitrogen application causes optimum usage of water and soil resources.  In order to study supplemental irrigation and nitrogen fertilizer effect on drought tolerance index and correlation among some physiological traits and grain yield, an experiment was conducted as a split- plot arrangement based on randomized complete block design (RCBD) with three replications during three crop seasons (1999-2002). The treatments were four levels of supplemental irrigation (rainfed, 95, 151 and 207 mm of irrigation) as main plots and five nitrogen rates (0, 30, 60, 90 and 120 Kg N ha-1) as sub plots. The results showed positive and significant correlations of grain yield with biological yield (r=0.96**), plant height (r=0.93**), straw yield (r= 0.92**), seed number per spike (r=0.87**), spike number per square meter (r=0.84**), TKW (r=0.52**) and harvest index (r=0.49**). Path analysis results showed that seed number per spike, plant height, straw and spike number per square meter had main effect on seed yield. Drought tolerance indices of (Tolerance Index, Mean Productivity, Geometric Mean Productivity, Stress Tolerance Index and Harmonic Mean) showed that 95 mm of full irrigation treatment combined with 60 Kg-N ha-1 substantially increased water productivity.

Growth regulators play a crucial role during plant growth and development and utilizing of them can a possible approach to improving plants economic grain yield. In this experiment, the possiblility of growth improvement of canola during two growth stages by exogenous application of salicylic acid on chlorophyll content, yield and yield components was investigated. Salicylic acid was applied in four concentration (0, 100, 200 and 400 mM) during two different stages (first time in autumn and second time at the end of winter) in two varieties (Licord and RGS tolerant and sensitive cultivar to cold stress, respectively) in randomized complete block design in three replications. Although, all salicylic acid concentration improved the canola yield, the application of 200 mM provided better effect compared to other concentrations. The total chlorophyll content was obtained in second stage of foliar application with 100 mM salicylic acid in tolerant cultivar. Foliar application with 100 mM salicylic acid led to increase seed yield. The highest plant high, 100 seed weight and plant biomass were obtained in tolerant variety. The highest pod number per plants and seed number per silique were observed from Licord which was treated with 200 mM salicylic acid at first time. Also, salicylic acid led to increase in seed yield by 13%. However, results revealed that application of salicylic acid by affecting physiological processes in plant increased canola yield and its component.

One of the major abiotic stresses that affected negatively cereals such as wheat is the heavy metals. Soil pollution with heavy metals, resulting from the industrial development and use of fertilizers containing heavy metals become one of the major environmental concerns in society. One way to counteract the negative effects of heavy metals is the production of active oxygen species by antioxidant enzyme activities in plant cells. In order to study the physiological traits involved in resistance to the stresses an experiment was conducted in a factorial experiment based on completely randomized design with three replications. The first factor consisted of Gonbad (tolerant) and Tajan (susceptible) wheat cultivars. The second factor was  seven levels of heavy metals (mercury chloride at concentrations of 5, 10, 15 and 20 mM, cadmium chloride at a concentration of 0.25 and 0.5 mM and control) and the third factor was sampling times after treatments at two levels (8 and 16 hours). The results showed that the concentration of the total protein and soluble sugar content were increased with cadmium and mercuric chloride treatment. Increasing concentration of mercuric chloride were reduced catalase, peroxidase and polyphenol oxidase activity but increasing concentration of cadmium chloride enzyme activity increased activity of these enzymes. Thus, this study showed that treatment with cadmium and mercuric chloride at micromolar levels can stimulate plant antioxidant enzyme and make plants more tolerant to the stresses such as heavy metals.

In order to examine the effects of fertilizer source on growth, yield and yield components of fenugreek intercropped with black cumin, an experiment was conducted as factorial layout based on a randomized complete block design with three replications at the research farm, College of Agriculture, Shahrekord, during growing season of 2012-2013. Sole cropping of fenugreek (F) and sole cropping of black cumin (B) and three intercropping ratios (F:B; 2:1, 1:1, and 1:2) were evaluated as the first factor and three sources of fertilizer (Chemical fertilizer, broiler litter, and integrated fertilizer 50:50) as the second factor. In this experiment, the plant height, number of branches/plant, pods/plant, seeds/pod, capules/plant, seed/capsule, 1000-seed weight, and seed yield were measured. The results indicated that seed yield in intercropping treatments fertilized with chemical fertilizer was less than sole cropping for both species. However, application of integrated fertilizer and/or broiler increased the seed yield of F: B (2:1) treatment (16 and 27%) compared with F and B treatment, respectively. Increasing black cumin ratio resulted in increasing seed yield, under broiler litter application. The highest land equivalent ratio (1.57) was observed in F: B (1:2) treated with broiler litter. Therefore, medicinal plant grower that prefer organic manure, fenugreek: black cumin (1:2) treatment under broiler litter application not only compensated the reduce of yield in sole cropping treated with broiler litter but also can be increase the production of fenugreek (39%) and black cumin (54%) in comparison to their sole cropping.

In order to reduce the effects of priming with salicylic acid on reducing milk thistle seed aging effect, a factorial experiment was carried out as completely randomized design in 2011. Factors consisted of priming with salicylic acid at five concentration (0, 500, 100, 1500 and 2000 mg L-1), and four accelerated aging (control, 2, 4 and six days of aging). In this experiment germination percentage, germination rate, length vigor index, seed reservoirs using rate, seed reservoirs using efficiency, fraction of utilized seed reservoirs and catalase, peroxidase and polyphenol oxidase antioxidants enzyme activity were measured. The results showed that accelerated aging reduced the germination percentage, germination rate, seedling growth and seed reservoirs using efficiency, fraction of utilized seed reservoirs and antioxidant enzyme's activities whereas seed aging increased seed reservoirs using rate. Priming reduced the effects of accelerated aging, and priming by 1000 mg L-1 salicylic acid had the greatest impact.