جستجوی مقالات مرتبط با کلیدواژه « weed dry weight » در نشریات گروه « زراعت »

In order to investigate the effect of different weed control managements on emergence characteristics and morphological growth of rice seedlings in the seedling stage in a direct seeding system, a field experiment has been conducted in the 2020 growing season, Babolsar, Bahnemir, Iran. Being a factorial in a randomized complete block design with three replications, the experiment employs the following treatments: Shiroudi, Khazar, and Hashemi cultivars as well as various weed control management in five levels of seed coating with calcium chloride, seed coating with potassium chloride, weeding, chemical control, and control. The interaction effect of weed management and cultivar shows that coating the seeds with calcium chloride, potassium chloride, and weeding cuts the dry weight of grasses by 55%, 68%, and 85% in Shiroudi cultivar, by 79%, 63%, and 54% in Khazar cultivar, and 30%, 58%, and 35% in Hashemi cultivar, respectively, compared to the control. The maximum percentage of germination with 99%, 97%, and 95% belong to seed coating with potassium chloride, calcium chloride, and weeding in Shiroudi cultivar, respectively. The highest germination rate could be observed in potassium and calcium chloride seed coating treatments and weeding. The lowest density of broadleaf weeds with 0.91 plants m-2 is obtained in Shiroudi cultivar and by managing the seeds coating of this cultivar with calcium chloride. The highest seedling length and weight vigor indices are obtained with 3559 and 137 in Shiroudi cultivar under weeding management, respectively. Results show that seed coating improves the seed yield of rice cultivars.

This experiment was conducted to evaluate the effects of the pre planting herbicides including Trifluralin (Treflan 48% EC) and Ethalfluralin (Sonalan 33. 3% EC), pre emergence herbicides including Oxadiazon (Ronstar 25% EC, 12% SL), Simazine (Princep 4L) and Prometryn (Gasagard 80% WP) and post emergence herbicide including Linuron (Afalon 50% WP, 45% SL) on weed control and yield, yield components, seed yield, essence yield and essence efficiency of cumin in a randomized complete block design with three replications. Five dominant weed species i. e. Chenopodium album, Fumaria officinalis, Polygonum avicular, Hordeum murinum and Triticum aestivum were identified. Results showed that effect of the herbicides on density and dry weight of each and total weed species were significant. In this study, all herbicides significantly decreased total weed density compared to weedy check. The order of reduction in total weed density was hand weeding> Ethalfluralin> Oxadiazon> Trifluralin= Linuron= Simazine> Prometryn. The highest and lowest total dry weight of weeds were obtained in weedy check and hand weeding, respectively. Among various herbicides treatments, Ethalfluralin and Oxadiazon had the inhibitoriest effects on the total dry weight of weeds in comparison with weedy check (97. 40 and 84. 31% respectively). The results also showed that there were significant differences among various herbicide treatments on cumin density, number of umbrella per plant, number of seed per umbrella, 1000- seed weight, seed yield, and essence yield and efficiency. The highest and lowest seed and essence yield were obtained in hand weeding and weedy check, respectively. After weeding treatment, Ethalfluralin application had the highest seed yield and essence yield.

IntroductionBroad bean (Vicia faba, L.) is grown and consumed principally in developing countries in Latin America, Africa, and Asia. Farmers often consider weeds to be the major biological constraint to growing legume crops successfully. Chemical control of weeds became widespread in the world because it brings about rapid and desirable control of weeds; and today chemical weed control is one of the most popular methods of controlling weeds. Weed interference in dry bean can reduce seed yield as much as 83%. There is limited number of post emergence herbicides available for broad bean production. More research is needed to identify POST herbicides that provide broadleaves weed control in broad beans. The objectives of this study were to evaluate the efficacy of some broadleaved herbicides applied POST at the proposed manufacturer’s recommended rate and to assess broad bean yield response to these herbicides since no information is available in the literature on these chemicals.
Materials & MethodsField experiment was conducted in 2011-2012 at the Shoushtar Branch, Islamic Azad University, Iran (320 3´ N, 480 50´ E). The experiment was performed in randomized complete block design with four replications. Treatment consisted of 1) Basagran (bentazon) SL 48% 1.5 Lha-1 Haloxyfop-R-methyl (super gallant) EC 10.8% 0.6 Lha-1 2) Bentazon SL 48% 1.5 Lha-1 Sethoxydim (nabo-S) OEC 12.5% 1.5 Lha-1 3) Bentazon SL 48% 1.5 Lha-1 Fenoxaprop-p-ethyl (whip super) EC 12% 0.7 Lha-1 4) Imazthapyr(pursuit) SL 10% 0.6 Lha-1 5) Pursuit SL 10% 0.4 applied POST, with two control plots weed-free and weed-infested throughout the crop cycle, respectively. Plots were maintained weed free by cultivation and hand hoeing as required to eliminate the confounding effect of weed interference. Bean shoot dry weight was determined by cutting plants at the soil surface from 1m of row per plot. Plants were dried at 75 0C to constant moisture and then weighed. Broad bean height was measured for 10 plants in each plot 5 WAT and averaged. Broad bean was considered mature when 90% of the pods in the untreated control had turned from green to a golden color. Beans were harvested from each plot, weight and seed moisture content were recorded, and seed yields were adjusted to 13% moisture. Data were analyzed as an RCBD using PROC MIXED in SAS 9.2. The comparison of means was conducted by Duncan method at 1 and 5% probability level.
Results & DiscussionHerbicide treatments applied to broad bean resulted in significant (P ≤ 0.05) reduction in weed biomass and density relative to the untreated control (Table1, 2). The blend of Bentazon㚆S and Pursuit with the dose of 0.6 Lha-1 has been more successful in the control of weed than other treatments, and has decreased the weed biomass by over %98.7 in compare to weedy check. Other studies have found that 50 g ai ha-1 of imazethapyr (pursuit) applied post emergence will provide season-long control of broad leaf weed in pinto beans. There was no statistical difference in weed control between pursuit applied alone or tank-mixed of Bentazon with Nobo-S (Table 3). The least level of control were observed in blend of Bentazon娘 super and pursuit with the dose of 0.4 Lha-1(Table 4). Weed management practitioners must adjust pursuit herbicide doses based on weed species composition. Among experimental treatments there was a significant difference in terms of impact on the density of weed (Table 1). Mean comparison of treatments showed that pursuit with the dose of 0.6 Lha-1 decreased the density of weed by 66.2%. Seed yield was equal in all POST herbicide treatments, and there was no statistical difference in seed yield among herbicide treatments. The lowest and highest seed yield recorded 2403 and 2545 kg ha−1 in tank-mixed of Bentazon䫪 gallant and pursuit with the dose of 0.6 Lha-1, respectively (Table 4). In the weedy treatment seed yield was 1494.9 kg ha−1, and on hoeing treatment it was 3239 kg ha−1 (Table 4). Because the highest yield of herbicide treatments was only 78% of the hoeing treatment, it is likely that more efficient weed management programs can be developed. Higher seed yield in herbicide treated plots in compare to weedy check, may be an outcome of efficient weed control achieved there. These results are in conformation with those of some researchers who reported that herbicides offer sizeable increase in crop productivity corresponding to their weed control spectrum.
ConclusionsIt is concluded that the most effective herbicide treatment was pursuit with the dose of 0.6 Lha-1, which provided maximum reduction in total weed dry matter. However, all herbicide treatments increased broad bean biological and seed yield as compared with the weedy check.

In order to investigate the effect of codacide adjuvant on the efficacy of clodinafop propargyl and tribenuron methyl, a field experiment was carried out on wheat at the Iranian Research Institute of Plant Protection in Alborz province during 2013-2014 growing season. Treatments included tribenuron methyl at three doses (10.5, 12.75 and 15 g a.i. ha-1), tribenuron methyl at three doses (10.5, 12.75 and 15 g a.i. ha-1) 0.25% V/V codacide, clodinafop propargyl at three doses (0.048, 0.064 and 0.08 L a.i. ha-1), clodinafop propargyl at three doses (0.048, 0.064 and 0.08 L a.i. ha-1) 0.25% V/V codacide, and weed-free control. Herbicides were sprayed at tillering stage of wheat. Results showed that clodinafop propargyl at 0.08 L a.i. ha-1 performed better regarding grass weed control and application of codacide adjuvant with this herbicide increased its efficacy. Application of tribenuron methyl (12.75 g a.i. ha-1) codacide resulted in highest reductions in broad-leaved weed density and dry matter (95% and 93%, respectively), which was not significantly different with weed-free control. Wheat biological yield (3275 kg ha-1), grain yield (2200 kg ha-1) and the number of fertile spikelets/spike (6.26) were 22, 40 and 13% higher than the weed-infested control, respectively. The lowest yield among herbicide treatments belonged to tribenuron methyl (10.5 g a.i. ha-1) with harvest index of 34.04% and 36.50 fertile spikelets/spike.

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.

In order to study the effect of rimsulfuron application time and dose on weed control and potato tuber yield, a field experiment was carried out in Ardabil during 2014. Treatments included different rates of rimsulfuron (0, 5, 10, 20, 30, 40 and 50 g ai ha-1), and rimsulfuron application time at different potato growing stages (potato emergence, stolon initiation and potato tuber bulking). A weed free treatment was also considered as control for evaluating potato yield components. Results showed that application of 50 g ai ha-1 rimsulfuron reduced weed biomass by 94.6 %. Which was not statistically different from 30 and 40 g ai ha-1. Among rimsulfuron application times, potato emergence produced maximum percent reduction of weed biomass. On the other hand, application of 50 g ai ha-1 at potato emergence stage caused the highest mean weight of potato tuber, tuber per plant and total tuber yield. There was no significant difference between 20, 30 and 40 g ai ha-1. Visual assessment results showed that rimsulfuron had minimum harm in potatoes which was negligible.

In order to determine the critical period of weed control(CPWC) in Corn(Zea mays L.), an experiment was carried out in a randomized complete blocks design with 14 treatments and three replications during 2013 growing season in the Nahavand climatic conditions. Two series of the treatments including weed-free and weed-infested were applied in the regular time distances of 10, 20, 30, 40, 50 and 60 days after Corn emergence. Two check treatments including full and no control of weed during the whole season were also included. The nonlinear models kind of Logistic and Gompertz were applied to determine the start and end of critical period of weed control respectively. Major weed species were field bindweed(Convolvulus arvensis L.), red root pigweed(Amaranthus retroflexus L.), pigweed(Amaranthus blitoides L.) and lambsquarters(Chenopodium album L.) with greater biomass and size. The results showed that periods of weed- free and weed- infested differently affected the dry weight and number of weeds in all treatments. The critical periods of weed control in Corn by accepting a 5% acceptable yield loss, it is necessary to control weeds in a period between 14-47 days after planting or 117- 566 growth degree day(4-12 leaf stage) and by accepting a 10% acceptable yield loss it is necessary to control weeds in a period between 23-36 days after planting or 220- 419 growth degree day(6-10 leaf stage).

In order to determine the critical periods of weed control in dry bean, an experiment was conducted in 2011 at Agricultural and Natural Research Center of Hamadan, Iran. The experiment was a randomized complete blocks design with 12 treatments and 3 replications. Treatments were divided into two groups. The first group included weed interference periods until 10, 20, 30, 40 and 50 days after emergence of dry bean. The second group included weed control periods until aforementioned periods. Control plots consisted of two treatments that kept weed free and weed infested throughout the growing season. The planted bean cultivar was Naz, which is a creeping cultivar. Seeds were hand-planted in June 2011. Results showed that among the weeds, the maximum importance value of weed (IVW) was related to lamb's quarters and red-root amaranth (36.66 and 30.11%, respectively). Increase in duration of weed-infested periods caused an ascending trend for dry weight of weeds, while their density increased at first and decreased when it reached at maximum point. Taking 5% and 10% acceptable yield loss for dry beans, the critical period of weed control was determined as 20 to 68 days after emergence (equivalent to V2 to R1 stages) and from 22 to 55 days after emergence (equivalent to V2 to V6 stages), respectively. Therefore, weeds of dry bean must be controlled in these periods.

In order to determine the critical period of weed control in Thyme (Thymus vulgaris)، an experiment was carried out in a randomized complete blocks design with 18 treatments and three replications in 2008-2009 at the research field of the medicinal plants departments، Shahed University، Tehran، Iran. Two series of the treatments including weed-free and weed-infested were applied in the regular time distances of 15، 30، 45، 60، 75، 90، 105 and 120 days right after the beginning of thyme growth at spring. Two check treatments including full and no control of weed during the whole season were also included. The nonlinear models kind of logistic and Weibull were applied to determine the start and end of critical period of weed control respectively. Major weed species were field bindweed (Convolvulus arvensis)، flixweed (Descurainia sophia)، mon groundsel (Senecio vulgaris) and prickly lettuce (Lactuca scariola) with greater biomass and size. The results showed that periods of weed- free and weed- infested significantly affected the dry weight and number of weeds in all treatments. Considering 5% and 10% of the acceptable yield loss in the models، critical periods of weed control were between 41-90 days and 54-76 days for fresh weight، 12-94 days and 29-78 days for dry weights، and 20-105 days and 30-86 days for essence yield after the beginning of growth at spring.