12 research outputs found
Chemical weed control in Spinach (Spiniacia oleracea)
No full textIntroduction Spinach (Spinacia oleracea) is an annual plant of family Chenopodiaceae. It is cultivated in temperate and cold regions in Khouzestan in autumn and winter. Weeds are the main problems that limit the production of vegetables. Competition ability of spinach against weeds is very low and weeds cause the loss of quality and quantity in this plant. Weeds reduce germination and establishment and growth of spinach. Weed management in spinach should be done at the beginning of the season. Hand weeding is the best way to control weeds spinach, although due to the high cost it is not cost effective, but is steel common in large areas. Weed control spinach, using chemical methods, the number of weeds are kept below the threshold of economic damage.
Materials and Methods The experiment was conducted in a randomized complete block design with 15 treatments and three replications. Treatments included pre-plant application of EPTC at 5 and 6 lit ha-1, pre-plant application of Trifluralin at 2 lit ha-1, pre-plant and pre-emergence application of Pendimethalin at 3 lit ha-1, pre-emergence and post-emergence application of Meteribouzin at 300 g ha-1, pre-emergence and post-emergence application of Meteribouzin at 400 g ha-1, pre-emergence and post-emergence application of Imazethapyr at 0.7 lit ha-1, pre-emergence and post-emergence application of Imazethapyr at 1 lit ha-1, weedy and weed free checks. Each plot the size of 2.5 × 2 meters and 10 row cultivation with distances between rows of 15 cm and the distance between the plants 25 cm and the sowing depth was 3 cm. The herbicide treatments were applied to the back sprayer with Flat fan nozzle with volume of consumption of 240 lit ha-1 solution. The final harvest was about 50 days after emergence. Sampling of weeds 10 days before harvest was performed with using quadrate 0.5 ×0.5.
Results Discussion Important broad-leaf and narrow leaf weeds observed in the field, included field bindweed (Convolvulus arvensis), Common lambsquarters (Chenopodium album), Malva (Malva spp.), Chamomile (Anthemis altissima), Purple nutsedge (Cyperus rotundus), canary grass (Phalaris minor), mouse barley (Hordeum morinum) and Japan brome (Bromus japonicus), respectively. The results of variance analysis showed that the effects of treatments on the number of broadleaf and weed narrow leaves were significant. Meteribouzin and Pendimethalin herbicides (pre-emergence), had better control on broadleaf weed than other herbicides. Low amounts of herbicides EPTC (5 lit ha-1) and imazethapyr (0.7 lit ha-1) were the least effective broadleaf weed control. Trifluralin herbicide reduced approximately 44% broadleaf weed density compared to control plots without control. The minimum weight of broadleaf weed at all doses studied allocated to herbicides Pendimethalin and Meteribouzin. Most of reducing the number narrow leaves was belonged to Meteribouzin and Pendimethalin herbicides as pre-emergence with doses of 300 g and 3 lit ha-1, respectively. The effect of treatments on petiole length, number of leaves per plant and the spinach fresh yield was significant in 1% probability level. Meteribouzin damage in spinach was 100%. It was reported that the half-life in soil herbicide Meteribouzin is about 30-60 days. It seems spinach a high sensitivity to the herbicide and relatively long survival in the soil that causing damage spinach was perfect, while maximum weed control amounts in all methods of used allocated to this herbicide. Number of leaves per plant trait was that less affected by weed interference. Both components of leaves per plant (r= 69.0**) and petiole length (r= 87.0**) showed significant positive correlation with the spinach fresh yield. The highest spinach yield was obtained in Trifluralin herbicide after treatments control. The difference between spinach yield in Trifluralin and control treatments was not significant.
Conclusion: In general, the results showed that the broad and narrow leaf weeds were well controlled by different rates of pre-emergence and post-emergence application of meteribouzin, but this was followed by severe damage in spinach. Trifluralin had the lowest damage effect on spinach leaves. Pre-plant application of trifluralin at 2 lit ha-1 reduced approximately 45% of weed density and increased yield of spinach by 26.6% compared with control treatment. Therefore, this herbicide was recommended to use for weed control in spinach fields. According to the results it seems that the use of herbicide meteribouzin not advisable in spinach whereas causing damage, but due to weed well control is recommended increased resistance spinach to the herbicide through breeding programs. However, it should be noted that spinach leaves are consumed fresh, therefore, investigating the presence of herbicide residues in plant is necessary
Response of Soybean (Williams cv.) Seed Germination to Aqueous Extract of Cocklebur (Xanthium spp.) and Common Lambsquarters (Chenopodium album)
No full textExtended abstract
Introduction: Interference caused through weeds’ and crops’ competition for environmental resources and allelopathy brings about damage in crop species. Allelopathy is defined as a direct or indirect inhibiting or provoking effect of a plant on other plants through the production of chemical compounds introduced into the environment. Although the allelopathic effects of the shoot extracts of Xanthium spp and Chenopodium album on the germination of some crops have already been investigated, very few studies have so far been conducted to evaluate their adverse effects on soybean seedling growth. The aim of this study was to investigate the effect of different concentrations of aqueous extract of cocklebur and lambsquarters on germination and soybean seedling growth indices under Petri and Pot conditions.
Materials and Methods: In order to study the allelopathic effects of Cocklebur and Common lambsquarters on germination and seedling growth of soybean, two separate experiments were conducted under petri and pot conditions. In this experiment, the effects of aqueous extract concentrations (25, 50, 75 and 100%) of cocklebur and common lambsquarters were evaluated on seed germination of soybean in a completely randomized design with three replications. In each pot, five soybean seeds were planted with a depth of 2 cm. The extracts were added to the pots for 2 weeks after emergence.
Results: Allelopathic effect of common lambsquarters extract concentrations was higher than that of cocklebur in both experiments. Germination percentage (GP) reduction under 25, 50, 75 and 100% concentrations of common lambsquarters was 57, 84, 96.7 and 100%, respectively. GP reduction under the same concentrations of cocklebur was 17, 20, 34 and 54%, respectively. In the pot culture conditions, the root dry weight of soybean decreased with increases in extract concentration, so that the highest root dry weight belonged to the control treatment with 64 mg and the lowest values belonged to the effect of aqueous extract of weed with a concentration of 100%. The results on the EWRC scale showed that the soybean leaflet damages increased as the extract concentrations increased. The highest leaf damages were obtained in 75 and 100% of cocklebur and Chenopodium concentrations. The negative impacts of common lambsquarters were higher than those of cocklebur.
Conclusion: In general, the results of this study showed that the effects of different concentrations of the lambsquarters extract on germination and soybean growth of the Williams cultivar were higher under both Petri and pot conditions. The percentage of germination in the concentrations of 25, 50, 75 and 100% of the aqueous extract of cocklebur was 17%, 20%, 34% and 54%, respectively, and in lambsquarters, it decreased by 57%, 84%, 96% and 100%, respectively, compared to the control. On the other hand, spraying the extracts of lambsquarters and cocklebur caused necrosis and drying of soybean leaves. According to the results, in the absence of effective control of weeds, especially lambsquarters, in soybean farms, the damage caused by allelopathic elements will lead to a significant reduction in germination and seedling growth.
Highlights:
In this study, the allelopathic effect of two important soybean weeds on germination and seedling growth of this crop were compared, which had been under-researched.
Seed germination reaction and seedling growth were evaluated for the extract of aerial parts in two seed culture conditions of petri dish and potted seedlings
Integrated weed control (chemical & mechanical) in chickpea (Cicer arietinum L.) under Shoushtar conditions
No full textIntroduction
Chickpea is a poor competitor to weeds because of slow growth rate and limited leaf area development at early stages of crop growth and establishment. Crop yield loss could be be in high extent due to increasing of weed biomass, weed density and weed species. Chickpea yield losses due to weed competition have been estimated to range between 40 and 87% depending on weed species and density. Herbicides play a key role in weed control and are used extensively today. The current tendency in chickpea weed control in the Mediterranean region is to shift from the costly manual mechanical energy to the chemical energy through more usage of effective herbicides particularly with the increased adoption of winter sowing. Several herbicides with different mode of action such as Trifloralin (Treflan) and Pendimetalin (Prowl) are used for weed control in chickpea farms. Nevertheless herbicide application may have several important environmental issues. These include unintended damage occurring both on the sprayed site, and offsite. Herbicide use also injures the human and animals. Integrated weed management (IWM) is the most important strategies to avoid herbicide environmental issue and increasing inputs productivity. Furthermore, integrated weed management strategies attempt to limit the deleterious effects of weed growing on crop plants. The present report describes the effect of integrated methods on weed density and grain yield of chickpea under Shoushtar conditions.
Materials & Methods
In order to study the effects of integrated weed management (chemical and mechanical) in chickpea (Cicer arietinum L.) a field experiment was conducted during 2009-2010 at IAU Shooshtar Branch. The experiment was designed as a randomized complete block with four replications. Treatments were consisted of eleven combinations of once and twice mechanical control (using cultivator) with Trifloralin and Pendimetalin herbicides (pre-plant) and two control treatments, consisted weedy and weed-free plots. Herbicides where mixed with soil one week before planting. Weed samples were taken by randomly throwing a quadrate of 0.25 m2 area. Analysis of variance was performed using the SAS Ver 9.1 software and treatment means were compared using LSD (Least significant difference) at 5% of probability.
Results & Discussion
Results showed that the highest weed controls was related to the treatments with twice cultivation+ Trifloralin+ Pendimetalin. Malcolmia behboudiana and Chenopodium album control in this treatment was 87.2 and 91.8%, respectively. The highest weed control with 75.6, 78.85 and 88.86% was in Trifloralin+ twice cultivation, Pendimetalin+ twice cultivation and twice cultivation+ Pendimetalin+ Trifloralin treatments, respectively.
The lowest grain yield was observed in weedy plots without weed control. Grain yield reduction under weedy treatment was 72% lower than weed free plots. There was no significant difference between control treatment without weed control and once cultivation treatment. Integrating weed control had higher controlling impact on weed growth compared with individual use of cultivation and herbicides. Twice cultivation+ Pendimetalin+ Trifloralin treatment had the highest grain yield. Higher grain yield in these treatments was due to increase in lateral branches, the number of pods per plant, and accordingly, the number of grains per plant. The effect of treatments on number of pods per main and lateral branches and also the number of pods per plant was significant. Integrated weed control treatment with twice cultivation plus both herbicides had the highest pod number per plant.
Chickpea biological yield in weedy control showed a significant reduction of 32.4% compared with weed free treatment. The highest chickpea biological yield was belonged to weed free and twice cultivation+ Pendimetalin+ Trifloralin treatments. The effect of weed control treatments on the number of pods per plant was significant.
Conclusion
In general, the results of this study showed that chickpea plants are not poor competitor to weeds only at its early stages, but at later stages of growth had a low ability to compete with weeds. Thereby, treatments such as pre-plant herbicides and once cultivation that control weeds only in the earlier stages of the crop growth are less effective than the combination of herbicide and twice cultivation
Relationships between Canopy Temperature, Leaf Chlorophyll Content and Grain Yield in Wheat Genotypes under Different Nitrogen Levels and Post-Anthesis Heat Stress Conditions
No full textAbstract
In order to study the canopy, spike and flag leaf temperature in wheat genotypes under optimum and post-anthesis heat stress conditions and canopy relationships with some morphological and physiological characters, two separate field experiments were conducted in delayed and optimum sowing dates in Ahvaz, Iran in 2007-2008. The experimental site had a moderate winter and dry, hot summer. Plants with delayed sowing date experienced heat stress post-anthesis. Each split-polt experiment had a randomized complete block design with three replicates. The N application rates were (50, 100, and 150 KgNha-1) assigned in the main-plots. Sub-plots consisted of six bread and durum wheat genotypes. Temperature of canopy, spikes and flag leaf were measured in two growth stages (anthesis and milk stage) using a hand-held infrared thermometer. Results indicated that, organs temperature was affected by genotypeenvironment. Although, organs temperature increased as the N rate decreased, the effect of N treatments on organs temperature was not significant. In post-anthesis heat stress conditions, the genotypes that had higher flag leaf and canopy temperature due to higher growth stage duration (such as Star and D-84-5), lower ability in leaf rolling (such as Showa and D-84-5) and higher leaf width (such as Star and D-84-5), had higher chlorophyll reduction under post-anthesis heat stress conditions.
Keywords: Wheat, Post-anthesis heat stress, Canopy temperature, Chlorophyll conten
Two Novel Learning Algorithms for CMAC Neural Network Based on Changeable Learning Rate
No full textCerebellar Model Articulation Controller Neural Network is a computational model of cerebellum which acts as a lookup table. The advantages of CMAC are fast learning convergence, and capability of mapping nonlinear functions due to its local generalization of weight updating, single structure and easy processing. In the training phase, the disadvantage of some CMAC models is unstable phenomenon or slower convergence speed due to larger fixed or smaller fixed learning rate respectively. The present research deals with offering two solutions for this problem. The original idea of the present research is using changeable learning rate at each state of training phase in the CMAC model. The first algorithm deals with a new learning rate based on reviation of learning rate. The second algorithm deals with number of training iteration and performance learning, with respect to this fact that error is compatible with inverse training time. Simulation results show that this algorithms have faster convergence and better performance in comparison to conventional CMAC model in all training cycles
Effects of post-anthesis heat stress and nitrogen levels on grain yield and grain growth of wheat ( T. durum and T. aestivum) genotypes
No full textThe effect of growth regulators and irrigation on remobilization and grain filling of bread wheat in tropical climatic conditions
No full textTo study the remobilization rate affected by growth regulators in wheat a field experiment was carried out in the south of Iran over 2017-2019 with a split-split plot design and three iterations in completely randomized blocks. The main plots were two irrigation regimes (full irrigation and irrigation interruption at the grain-filling stage), two wheat cultivars (Chamran 2 and Durum Karkheh cv.s) were as sub plots, and four growth regulators (control (no growth regulator), salicylic acid, jasmonic acid, and cytokinin) placed in sub-sub plots. Results revealed the significant impact of the triple interaction on grain yield. The highest grain yield (4803 kg/Ha) was observed for Chamran 2 cv. treated with complete irrigation and salicylic acid. Although grain yield declined by 15.5% in the Karkheh cv. with irrigation interruption at the grain-filling stage and non-administration of growth regulators, treatment with salicylic acid managed to attenuate the adverse impact of drought stress in grain yield. The highest current photosynthesis and its contribution were observed in cultivars treated with complete irrigation. Moreover, irrigation regimen and growth regulators each had significant impacts on proline, catalase enzyme, and stomatal conductance. Overall, results suggested that using salicylic acid in Chamran 2 cv. would be advisable to increase growth and grain yield and reduce decline under stress
The Effect of Hypericum Perforarum on Anxiety and Depressant Activity in Wistar Rats Exposed to Phenol
No full textIntroduction: For a Long time, anxiety has been an important issue in psychology and different drugs have been applied to treat it. Various studies have demonstrated that the plant Hypericum perforatum has an antidepressant effect. With the industrialization of human societies, pollutants like phenol can be entered in the life cycle that have adverse effects on body organs. Therefore, this study aimed to investigate the antianxiety and antidepressant effects of Hypericum Perforarum extract in rats that were exposed to phenol.
Methods: In this study, 54 Wistar rats were used in terms of a 3×3 factorial design with 3 levels of Hypericum perforatum extract (0, 250 and 500 mg/kg.bw) and 3 levels of phenol (0, 100 and 200 mg/kg.bw). Rats received the extract and phenol every other day via gavage method for periods of 15 and 30 days, respectively. Thirty min after each gavage, a behavior test was performed by using the open field and elevated plus-maze. Recuperative effects of Hypericum perforatum were assessed within short (first 15 days) and long (second 15 days) periods.
Results: The statistic findings indicated that there were no significant differences between behavior tests with respect to the treatments (P> 0.05).
Conclusion: The study results proposed that the used levels of Hypericum Perforarum extract did not show any significant effects on reduction of anxious and depressant behaviors in phenol exposed Wistar rats
Determination of physiological traits related to terminal drought and heat stress tolerance in spring wheat genotypes
No full textFeasibility Study on Reducing Lead and Cadmium Absorption by Alfalfa (Medicago scutellata L.) in a Contaminated Soil Using Nano-Activated Carbon and Natural Based Nano-Zeolite
No full textThe first risk posed by heavy metal pollution in an ecosystem is metal accumulation in the biomass of growing plants, which has harmful effects on human health. Natural-based nanoparticles are efficient in remediating environmental pollutants because they have a high surface/volume ratio, high chemical activity and produce no harmful side-products. The present study investigates the capacity of natural-based nano-porous adsorbents for reducing the availability of heavy metals to annual alfalfa (Medicago scutellata L.) roots and keeps them in soil. In a factorial experiment based on a randomized design (with four replications), three nano-adsorbents (nano-activated carbon, natural nano-zeolite and modified nano-zeolite) and two heavy metals (lead and cadmium) have been tested. The results demonstrated that applying the highest rate of activated carbon and modified nano-zeolite reduced shoot Pb content by 34% and 33.2%, and shoot Cd content by 35.5% and 46.7%, respectively, compared with the adsorbent-free control
