Chemical weed management programs for cycloxydim-tolerant maize in Iran

In order to introduce new chemical weed management program in maize weed control in Iran, a study was conducted during 2014 and 2015. Experiment were carried out in a randomized complete block design with three replications. 15 treatments of the common maize herbicides, including nicosulfuron, foramsulforon, eradicane and 2,4-D + MCPA were applied in their recommended doses, moreover the treatments related to cycloxydim with dicamba + tritosulfuron were used with different doses and in different times along with two control treatments (weedy and weed-free). Treatments contained 75-150 g a.i. ha-1 of cycloxydim, showed similar results with the common treatments including nicosulfuron, foramsulforon, eradicane and 2,4-D + MCPA. However, treatments with high doses of cycloxydim, had a significant reduction in weed density and weed biomass. There were no significant differences between the effects of treatments on maize grain yield and biomass. Despite the acceptable weed control of the combined treatment of cycloxydim with dicamba plus tritosulfuron, maize canopy could overcome weed growth. Based on the results and by considering cycloxydim efficacy in controlling perennial grassy weeds in maize plantation, this chemical is a suitable option during different growing stages of weeds and maize. Finally, the application of 200-300 g a.i. ha-1 of cycloxydim combined with dicamba plus tritosulfuron was the best option from an economic and environmental safety points of view

Feasibility of Cycloxydim Herbicide Application in Maize (Zea mays) Weed Control

In order to study chemical weed control in cycloxydim tolerant maize (CTM) using cycloxydim herbicide, an experiment was carried out in a randomized complete block design with three replications during 2014. Treatments included conventional corn herbicides application (Nicosulforun, Foramsulfuron, Eradican and 2, 4-D + MCPA) in their recommended doses and combined treatment of cycloxydim + (dicamba + tritosulfuron) at their recommended and reduced doses which were used as split and complete application. Results showed that application of combined treatment of cycloxydim + (dicamba + tritosulfuron) with more than 150 g a.i. ha-1 was more effective in weeds control as compared with other herbicide treatments. The highest weed control was observed in cycloxidim application at 300 and 150 g a.i. ha-1 in 3-4 leaf stage of corn plus application of dicamba + tritosulfuron at 100 + 50 g a.i. ha-1 in 5-6 leaf stage of corn, leading to 85% decrease in weed density and biomass. The lowest weed control was observed in Eradican application at the rate of 4.1 kg a.i. ha-1 + 2,4- D + MCPA 1012 g a.i. ha-1 at 5-6 leaves stage of corn, as it led to only 55% weed control. The effect of herbicide application treatments on corn grain yield and biomass were not significant, however the highest and the lowest yield were observed in above mentioned treatments, respectively. It could be concluded that application of cycloxidim in CTM, particularly when sustainable weed management and weed seed bank management and environmental hazards of chemical weed control are concerned, is recommended. &nbsp

The Effect of Organic and Bio Fertilizers on Maize (Zea mays), and HydroMax Adjuvants Application on Optimizing of Nicosulfuron Herbicide Efficacy

In order to study the effect of adjuvant on nicosulfuron herbicide efficacy improvement in maize weed control under organic fertilizers application, field study was conducted during 2013- 2014 at research field of Ferdowsi University of Mashhad, Iran. Experiment was arranged in completely randomized design with factorial arrangement of treatments with 16 treatments and three replications. Factors in this experiment were application of organic fertilizers (cow manure and vermicompost) and bio fertilizer mycorrhiza, and a plot without fertilizer as control, nicosulfuron dose at 40, and 80 g a.i ha-1 (Cruz®,4% SC) with and without the adjuvant of HydroMax™. Common purslane (Portulaca oleracea), black nightshade (Solanum nigrum L.), and redroot pigweed (Amaranthus retroflexus L) were the dominant weeds in the experimental fields. Black nightshade and common purslane had the highest relative density 20 and 45 days after spraying (DAS). Results showed that application of hydromax adjuvant increased herbicide efficiency, significantly. However dry weight of common purslane, black nightshade and redroot pigweed decreased 84, 71, 86 and 71, 79, 100 %, when nicosulfuron applied at reduced dose (40 g a.i. ha-1) with adjuvant 20 and 45 DAS, respectively. On the other hand, seed yield and dry weight of maize increased 49 and 60 % respectively, when nicosulfuron applied at 40 g a.i. ha-1 with Hydromax pulse cow manure.&nbsp

The Allopathic Effects of Organs’ Extracts of Saffron Plant on the Growth and Germination of Hordeum Murinum L. and Descurainia sophia L.

In order to examine the allopathic effects of saffron organs on the growth and germination of two species of Hordeum murinum L. and Descurainia sophia L. weeds, an experiment was done in the school of agriculture of the University of Torbat Haydarieh, Iran. The experiment was done as factorial in a completely randomized design with four replications with different levels of organs (leaf, corm and a combination of leaf and corm) and extract concentration (zero, 1, 2.5, 5, 10 and 20 percent). The results indicated that saffron extract has negative effects on growth and germination parameters such as the length and weight of the root, stem and seedlings, the speed of germination, the percentage of germination, the seed vigor index and the number of normal seeds in both species of weeds. The highest germination rate was shown by Hordeum murinum (10.48) that was obtained in the 2.5 percent application in the leaf and corm extractions. In addition, in this weed the highest seed vigor index (21.75) was seen in the application of 2.5 percent of leaf extraction and the lowest seed vigor index was obtained (10.75) in the 20 percent application of leaf and corm extractions. In the D. sophia L. weed the highest seed vigor index was 21 and the number of normal seeds was 15.75, respectively, in the one percent concentration of leaf and corm and the 2.5 percent concentration in the corm extraction and its lowest value was seen in the 20 percent of leaf and corm extraction. The application of leaf and corm combination extraction in comparison with leaf and root separately, significantly lead to a reduction of the germination traits. On the whole, its seems that using the saffron extracts in the concentrations of 10 and 20 percent significantly affect the growth and development of Hordeum murinum and Descurainia sophia weeds negatively in the germination stage

Study of competitive effects of barnyardgrass (Echinochloa crus - galli) and redroot pigweed (Amaranthus retroflexus) on dry bean (Phaseolus vulgaris)

Study of competitive effects of barnyardgrass (Echinochloa crus - galli) and redroot pigweed (Amaranthus retroflexus) on dry bean (Phaseolus vulgaris

Germination response of three Setaria species (S. viridis, S. verticillata, and S. glauca) to water potential and temperature using non-linear regression and hydrothermal time models

Understanding factors influencing the time of weed seedling establishment can contribute to developing predictive models for control measures at early growth stages. Non-linear regression models (Dent-like and Quadratic polynomial) and hydrothermal time models were considered for estimating cardinal temperature and predicting the emergence time of the Setaria species (S. viridis, S. verticillata, and S. glauca) at different constant temperatures and water potentials. Field experiments were also conducted, in which seeds of the species were sown and seedling emergence was recorded daily. The optimum temperature for germination was 27.7, 30.2, and 30.5\ua0°C as estimated by a Dent-like model at 0\ua0MPa water potential for S. glauca, S. viridis and S. verticillata, respectively. According to the hydrotime model, the minimum amount of base water potential (Ψ) was observed at the optimum temperatures, while it reached its highest value at temperatures exceeding the optimum. Overall, at sub-optimal temperatures, with the decrease in water potential, the thermal time (TT) constant increased linearly until − 0.6\ua0MPa, but this trend was downward at supra-optimal temperatures. The hydrothermal time constant (θ) was 213.5, 228.8, and 318.8\ua0MPa\ua0°C h for S. viridis, S. verticillata, and S. glauca, respectively. Non-linear regression and hydrothermal models showed that S. glauca can emerge earlier than other species because of lower base temperature and a higher hydrothermal time constant. Setaria species did not show a significant difference in their tolerance to water stress by similar base water potential (Ψ ~ − 0.5)

Photocontrol of Weed and Application Reduced Dosage of Imazethapyr and Trifuralin on Weed Management of Chickpea

Introduction: Weed cause enormous loss of chickpea yield and its quality. Photocontrol of weeds (soil cultivation in darkness) is a preventive weed control method, the basic aim of which is to reduce the germination of light sensitive weed seeds by excluding light during soil disturbance, in order to reduce the emergence of weeds in the crop. Considerable research has examined the potential use of lower-than-labeled herbicide doses. There are reasons for the potential successful use of reduced herbicide doses: (i) registered doses are set to ensure adequate control over a wide spectrum of weed species, weed densities, growth stages, and environmental conditions; (ii) maximum weed control is not always necessary for optimal crop yields; and (iii) combining reduced doses of herbicides with other management practices, such as tillage or competitive crops, can markedly increase the odds of successful weed control. This study was conducted to evaluate the photocontrol of weeds and application of reduced dosage of Imazethapyr and trifluralin herbicides on weed control and yield of chickpea. Materials and Methods: The experiment was designed as a strip plot based on a complete randomized block with three replications. The experiment had 3 factors: main plot consisted of tillage method at 3 levels (night tillage, day tillage, light-proof cover tillage), subplot consisted of Trifuralin (480, 960 and 1440 grams of active ingredient per hectare) Imazethapyr (50, 100 and 150 grams of active ingredient per hectare), weed infestation and weed free were considered as control. During the growing season, six sampling steps (28 days after planting (410 Growth Degree Day (GDD)), (45 days after planting (715 GDD)), (57 days after planting (975 GDD)), (70 days after planting (1280 GDD), (75 days after planting (1620 GDD)), (90 days after planting (2025 GGD)) were carried out. For statistical analysis the data normality of the distribution were analyzed with Sigma plot software, and if necessary, the data transforming and then ANOVA was performed using MSTATC. The means were compared using Duncan's multiple range test and graphs were drawn using Excel and Sigma plot software. Result and Discussion: In the growing season, the application of herbicide had significant effect (P≤ 0.05) on weed density. In all stages of sampling, weed density was higher in light-proof cover tillage treatments than day and night tillage operations. According to the results based on the type of tillage, night tillage and light-proof cover tillage treatments did not reduce weed density compared to day tillage. In the reduced Imazethapyr application, there was significant difference at 1620 GDD with others, but this amount of application did not effectively control weeds. In treatment of 1280 GDD, the amount of reduced application of Trifuralin was significantly different with other amounts but could not control weeds. However, there was no significant difference between the amounts of Trifuralin from this stage until the end of the growth season. By examining the biomass of chickpea during the growing season in the applied amounts of herbicides, it was determined that the growth of all treatments was the same order of 1200 GDD. From this stage, the difference between treatments increased until the end of the growing season, in the end of the growing season, control of weed control was the highest and control without chickpea was the least biomass. The effect of herbicide application dosage on the density of the weeds was significant (P≤ 0.05). Chickpea grain yield in light -proof cover tillage was 45 percentage lower than night-time tillage and day time tillage treatment and there were no significant differences between night-time tillage and day-time tillage treatment. The lowest and the highest yield was respectively in weed infestation (1151 Kg/ha) and weed control (1977 Kg/ha) and yield in the dosage of herbicides. Did not differ significantly. The results of this experiment show that reduced dosage of herbicides can control weed without negative effects on chickpea yield. Conclusion: The results showed that weed density and weed biomass was more than in light-proof cover tillage treatment compared to night and day tillage and there were no significant differences (P≤ 0.05) between night and day tillage. Weed biomass showed no significant differences between herbicide treatments. The reduced dosage of herbicide in Imazethapyr treatment did not have enough control but there were no significant differences between herbicide treatments. Chickpea yield had no significant difference (P≤ 0.05) between reduced, recommended and increased dosage herbicide

Regeneration capacity after exposure to freezing in wild oat (Avena ludoviciana Durieu.) and turnipweed (Rapistrum rugosum (L.) All.) in comparison with winter wheat

Wild oat (Avena ludoviciana Durieu.) and turnipweed (Rapistrum rugosum (L.) All.) are the most important annual weed species of winter wheat (Triticum aestivum L.) in the Khorasan Razavi province of Iran. This study investigated freezing tolerance in wheat (cv. Mihan) and these two weeds based on electrolyte leakage (EL), survival (SU), regrowth characteristics and maximum photochemical efficiency of photosystem (PS) II (F'v/F'm). Significant differences in EL% at freezing temperatures were noted between these plant species. By decreasing the freezing temperatures, EL% of the leaf in all three plants was increased. The lowest and the highest temperature causing 50 % EL (T) of leaves belonged to wild oat (−16.6℃) and wheat (−15℃), respectively. At a temperature of -12℃, SU% of wheat and turnipweed decreased by 15 % and 20 % compared to the SU% at 4℃, respectively. However, the decrease in SU% in wild oat from 4℃ to −12℃ was not significant. Lethal temperature for 50 % SU (LT) of wheat, wild oat, and turnipweed was −13.7, −14.3, and −13.5℃, respectively, and there was no significant difference between wheat and turnipweed. A general trend observed in our study was that species with higher freezing tolerance scores had a higher regrowth capacity. During the first 24 h after the freezing treatment, the F'/F' levels in wheat, wild oat, and turnipweed decreased by 33 %, 33 %, and 28 %, respectively, compared to before the freezing stress. Therefore, the presence of these weeds in wheat fields after freezing stress will be possible. Under optimal conditions and lack of integrated weed management programs, these weeds, especially wild oat, will emerge, set seeds and enrich the soil seed bank and thereby continue to be a problem in the cold climates of Iran, especially in the Khorasan Razavi province. Winter weed management using tillage, non-successive planting of annual winter crops, and crop rotation will reduce the dispersal of these weeds

Study of flora and structure of weed communities of saffron (Crocus sativus L.) fields in Khorasan Razavi province

The Khorasan Razavi province is the center of saffron production in Iran and the world. Among factors affecting saffron gap yield, weeds are the most important one. However there is no compiled information about saffron weed flora population and its structural characteristics in the Khorasan Razavi province. In order to identify and determine the density and frequency of weed species on saffron fields in the Khorasan Razavi province, 118 fields in 6 counties during two years (2014 and 2015) were selected based on the cultivation area and yield per area. In each field, weed species were counted in each sampling point and weed population indices including mean relative density, relative uniformity and frequently were calculated and latitude and altitude were recorded by GPS. By using recorded data, population indices of different weed species in the studied saffron farms including mean relative density and relative frequency of species were calculated.  During 2 years, a total of 52 weed species were identified and observed within the saffron fields. Between plant families, Brassicaceae, Asteraceae, Poaceae, Fabaceae and Charyophilaceae were the most abundant families, respectively. The results showed that the highest and lowest number of weed species belong to Kashmar and Gonabad counties, respectively. Based on the frequency index, the important annual weed species on saffron fields of the Khorasan Razavi province wereMouse Barle (Hordeum murinum) and London Roket (Sisymbrium septulatum) and perennial species were Hoary Cress (Cardaria draba) andCommon yarrow (Achillea millefoliam)

Investigating the physiological and morphological responses of Cucumis sativus to Phelipanche aegyptiaca parasitism

A greenhouse experiment was conducted to examine the influence of Phelipanche aegyptiaca on vegetative growth, rate of photosynthesis, chlorophyll fluorescence and leaf chlorophyll content of 35 cucumber genotypes. High demand of assimilates by P. aegyptiaca caused significant reductions in shoot and root dry weight, leaf number, leaf area and plant height in all cucumber genotypes. Once plants were infected by P. aegyptiaca, the leaf chlorophyll content, the photosynthesis rate and the maximum quantum yield of PSII chemistry were significantly less than control, thus implying a reduction in carbon assimilation, photosynthesis efficiency and susceptibility of infected plants to photoinhibition. P. aegyptiaca traits were significantly affected by cucumber genotypes. There was no correlation between P. aegyptiaca traits with the reduction percentage of cucumber shoot dry weight. However, there were correlations between underground attachments number plant-1 (UAN) and percentage of cucumber root dry weight reduction (-0.58), total attachment number plant -1 (TAN) and the percentage of reduction of root dry weight (+0.39). In accordance with the results obtained, the genotypes were classified into 3 groups. It was demonstrated that the genotype number 22 (Khassib) behaved differently to other genotypes and, in particular, they suffered less damage from the presence of P. aegyptiaca.Peer reviewe