Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100045
F. Frandoloso, L. Galon, G. Concenço, E. Rossetto, F. Bianchessi, C. O. Santin, C. T. Forte
ABSTRACT: The objective of this work was to evaluate the interference and to determine the level of economic damage (NDE) of the weed when infesting the corn crop. Treatments were composed by corn densities (2.60, 3.10, 3.65, 4.00 and 4.80 plants m-1) and 10 Alexandergrass populations for each crop seeding density. The population of plants, leaf area, soil cover and shoot dry mass of Alexandergrass were evaluated as indicator of infestation. Shoot dry mass of Alexandergrass presents better adjustment to the model of rectangular hyperbole, and losses of grain yield due to interference of the weed were satisfactorily estimated by this model. Corn sowing densities of 2.60; 3.10 and 3.65 plants m-1 in average, were more competitive of all evaluated variables in the presence of Alexandergrass. Corn densities of 2.60; 3.10 and 3.65 plants m-1 increase the level of economic damage, justifying the adoption of control measures of Alexandergrass when in higher populations. NDE values ranged from 1.58 to 9.37 plants m-2 at the densities of 4.00 and 4.80 maize plants m-1, which were less competitive with Alexandergrass.
{"title":"Interference and Level of Economic Damage of Alexandergrass on Corn","authors":"F. Frandoloso, L. Galon, G. Concenço, E. Rossetto, F. Bianchessi, C. O. Santin, C. T. Forte","doi":"10.1590/s0100-83582020380100045","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100045","url":null,"abstract":"ABSTRACT: The objective of this work was to evaluate the interference and to determine the level of economic damage (NDE) of the weed when infesting the corn crop. Treatments were composed by corn densities (2.60, 3.10, 3.65, 4.00 and 4.80 plants m-1) and 10 Alexandergrass populations for each crop seeding density. The population of plants, leaf area, soil cover and shoot dry mass of Alexandergrass were evaluated as indicator of infestation. Shoot dry mass of Alexandergrass presents better adjustment to the model of rectangular hyperbole, and losses of grain yield due to interference of the weed were satisfactorily estimated by this model. Corn sowing densities of 2.60; 3.10 and 3.65 plants m-1 in average, were more competitive of all evaluated variables in the presence of Alexandergrass. Corn densities of 2.60; 3.10 and 3.65 plants m-1 increase the level of economic damage, justifying the adoption of control measures of Alexandergrass when in higher populations. NDE values ranged from 1.58 to 9.37 plants m-2 at the densities of 4.00 and 4.80 maize plants m-1, which were less competitive with Alexandergrass.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100047
J. L. Pereira, R. R. Pereira, G. A. Resende-Silva, A. Jakelaitis, A. Silva, M. Picanço
This study aims to evaluate the impact of glyphosate-resistant soybean and its management with glyphosate on the canopy arthropod community. We study the direct impact of the insertion of the resistance gene and the indirect impact of management practices, specifically herbicide application. To do this, we use the following treatments: non-GM and GM soybean with mechanical weed control and GM soybean with one and three applications of glyphosate. Arthropods in the crop canopy were sampled over time in all treatments. The incorporation of the glyphosate resistance gene did not affect the richness and abundance of arthropods in the plant canopy. Glyphosate application reduced the richness of predators and chewing and sucking phytophagous arthropods in treatments with three herbicide applications. In the second season, total arthropod density was the lowest in transgenic soybean with three glyphosate applications. The density of Cerotoma arcuatus, a chewing phytophagous arthropod, followed similar trends, while both glyphosate treatments (one or three applications) reduced the densities of the predator Solenopsis sp. and the detritivore Hypogastrura sp. Meanwhile, the densities of the sucking phytophagous arthropods Bemisia tabaci, Caliothrips brasiliensis, and Tetranychus sp. were the highest in transgenic soybean with three glyphosate applications.
{"title":"Glyphosate Impact on Arthropods Associated to Roundup Ready and Conventional Soybean (Glycine max L.)","authors":"J. L. Pereira, R. R. Pereira, G. A. Resende-Silva, A. Jakelaitis, A. Silva, M. Picanço","doi":"10.1590/s0100-83582020380100047","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100047","url":null,"abstract":"This study aims to evaluate the impact of glyphosate-resistant soybean and its management with glyphosate on the canopy arthropod community. We study the direct impact of the insertion of the resistance gene and the indirect impact of management practices, specifically herbicide application. To do this, we use the following treatments: non-GM and GM soybean with mechanical weed control and GM soybean with one and three applications of glyphosate. Arthropods in the crop canopy were sampled over time in all treatments. The incorporation of the glyphosate resistance gene did not affect the richness and abundance of arthropods in the plant canopy. Glyphosate application reduced the richness of predators and chewing and sucking phytophagous arthropods in treatments with three herbicide applications. In the second season, total arthropod density was the lowest in transgenic soybean with three glyphosate applications. The density of Cerotoma arcuatus, a chewing phytophagous arthropod, followed similar trends, while both glyphosate treatments (one or three applications) reduced the densities of the predator Solenopsis sp. and the detritivore Hypogastrura sp. Meanwhile, the densities of the sucking phytophagous arthropods Bemisia tabaci, Caliothrips brasiliensis, and Tetranychus sp. were the highest in transgenic soybean with three glyphosate applications.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100092
Saulo F. B. Campos, João P. A.R. Cunha, Heli H.T. Assunção, Thales C. Alves, César H.S. Zandonadi, Ernane M.Lemes
Background: The use of electrostatic spray has the potential to optimize pesticide applications; however, further studies are required to verify its effectiveness. Objective: The objective of this work was to evaluate the electrostatic application system for the chemical control of weeds with glyphosate and adjuvant in different carrier volumes. Methods: The physicochemical properties of the spray solution, charge/mass relations, spray deposition on weeds, losses to the soil, effectiveness of weed control, and spray drift were evaluated. The field experiment was designed to have randomized blocks with four replications in a 2x2x2+2 factorial: the presence or not of electrostatic spray; with and without adjuvant (soybean lecithin + propionic acid); two carrier volumes (50 and 90 L ha-1); a control without applications and a conventional spray rate (150 L ha-1) for additional treatments. The study was performed in duplicate. Results: The electrostatic system energized the droplets during the application of glyphosate and adjuvant; however, this did not influence the deposition on the weeds, the losses to the soil, and the drift. The adjuvant improved the effectiveness of weed control in various situations, changed the spray solution properties, and reduced the losses due to drift. Conclusions: The adjuvant used proved to be an important tool in application technology. The effectiveness of weed control, in general, was not influenced by the electrostatic system.
背景:静电喷雾具有优化农药施用的潜力;然而，需要进一步的研究来验证其有效性。目的:评价不同载体体积下草甘膦和佐剂的静电施用体系对杂草的化学防治效果。方法:对喷雾溶液的理化性质、电荷/质量关系、喷雾在杂草上的沉积、对土壤的损失、防杂草效果和喷雾漂移进行评价。田间试验设计为随机分组，在2x2x2+2的阶乘中有4个重复:静电喷雾的存在与否;添加和不添加佐剂(大豆卵磷脂+丙酸);两个载体体积(50和90 L ha-1);一种是无应用的对照，另一种是常规喷雾量(150 L ha-1)。这项研究是重复进行的。结果:在草甘膦和佐剂的施用过程中，静电系统对液滴进行了通电;但是，这对杂草的沉积、土壤的损失和漂移没有影响。该助剂提高了各种情况下的除草效果，改变了喷雾溶液的性能，减少了因漂移造成的损失。结论:所使用的佐剂是应用技术的重要工具。除草效果一般不受静电系统的影响。
{"title":"Efficacy of glyphosate applied using an electrostatic sprayer as affected by adjuvant and carrier volumes","authors":"Saulo F. B. Campos, João P. A.R. Cunha, Heli H.T. Assunção, Thales C. Alves, César H.S. Zandonadi, Ernane M.Lemes","doi":"10.1590/s0100-83582020380100092","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100092","url":null,"abstract":"Background: The use of electrostatic spray has the potential to optimize pesticide applications; however, further studies are required to verify its effectiveness. Objective: The objective of this work was to evaluate the electrostatic application system for the chemical control of weeds with glyphosate and adjuvant in different carrier volumes. Methods: The physicochemical properties of the spray solution, charge/mass relations, spray deposition on weeds, losses to the soil, effectiveness of weed control, and spray drift were evaluated. The field experiment was designed to have randomized blocks with four replications in a 2x2x2+2 factorial: the presence or not of electrostatic spray; with and without adjuvant (soybean lecithin + propionic acid); two carrier volumes (50 and 90 L ha-1); a control without applications and a conventional spray rate (150 L ha-1) for additional treatments. The study was performed in duplicate. Results: The electrostatic system energized the droplets during the application of glyphosate and adjuvant; however, this did not influence the deposition on the weeds, the losses to the soil, and the drift. The adjuvant improved the effectiveness of weed control in various situations, changed the spray solution properties, and reduced the losses due to drift. Conclusions: The adjuvant used proved to be an important tool in application technology. The effectiveness of weed control, in general, was not influenced by the electrostatic system.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67279789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100030
Y. Abdullah, M. S. Baloch, A. Shah, M. M. Hashim, M. A. Nadim, G. Ullah, A. Khan, M. Shahzad
ABSTRACT: The present study was to assess the additive effects of cuscuta (akasbel) aqueous extract alone and in combination with full and reduced doses of commercially available weedicides against weeds in wheat crop during the year 2016-2017. The study was conducted in a randomized complete block design (RCBD) with 3 replications. The results showed that hand weeding and use of weedicides Allymax and Axial (full and half recommended doses) significantly controlled all prevailing weeds and increased yield and yield contributing parameters over the weedy check/control and sole application of cuscuta aqueous extract. Hand weeding and Allymax (full dose) showed minimum weed population, relative density, fresh and dry weed biomass and higher leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), plant height, 1000 grain weight and grain yield while net assimilation rate (NAR), chlorophyll content, number of tillers, spike length, grains spike-1 and biological yield were maximum only in hand weeding. These findings suggest that in order to attain highest wheat yield, the field should be kept free from weeds by hand weeding (if labour is not a limiting factor) or use recommended dose of weedicide Allymax for efficient weed management in wheat.
{"title":"Weed Management in Wheat by Cuscuta Alone and in Combination with Commercial Weedicides Allymax and Axial","authors":"Y. Abdullah, M. S. Baloch, A. Shah, M. M. Hashim, M. A. Nadim, G. Ullah, A. Khan, M. Shahzad","doi":"10.1590/s0100-83582020380100030","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100030","url":null,"abstract":"ABSTRACT: The present study was to assess the additive effects of cuscuta (akasbel) aqueous extract alone and in combination with full and reduced doses of commercially available weedicides against weeds in wheat crop during the year 2016-2017. The study was conducted in a randomized complete block design (RCBD) with 3 replications. The results showed that hand weeding and use of weedicides Allymax and Axial (full and half recommended doses) significantly controlled all prevailing weeds and increased yield and yield contributing parameters over the weedy check/control and sole application of cuscuta aqueous extract. Hand weeding and Allymax (full dose) showed minimum weed population, relative density, fresh and dry weed biomass and higher leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), plant height, 1000 grain weight and grain yield while net assimilation rate (NAR), chlorophyll content, number of tillers, spike length, grains spike-1 and biological yield were maximum only in hand weeding. These findings suggest that in order to attain highest wheat yield, the field should be kept free from weeds by hand weeding (if labour is not a limiting factor) or use recommended dose of weedicide Allymax for efficient weed management in wheat.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100064
Muhammad N. Zahoor, M. Nadeem, J. Iqbal, Muhammad F. Shahzad, T. Islam, Hussan A. Begum, Mohammad S. Baloch, Ayat Ullah
Background: Plant-derived compounds are alternatives of synthetic insecticides in sustainable agriculture. Objective: This study investigated the phytotoxic effect of higher concentrations (2, 4, 8 and 16%) of four plants extracts (Azadirachta indica, Mentha arvensis, D. stramonium and Citrus limonium) on cotton plants. Methods: Each concentration was replicated four times to check the phytotoxic effect (CO2-in, CO2-out, H2O-in, H2O-out and photosynthesis absorption rate (PAR) in randomized complete block design. Data was recorded after 12, 24, 48 and 72 hours of spray with the help of Photosynthetic CL 340 meter. Results: The results showed that CO2-in was more affected by the D. stramonium (131.65±0.38) at 8% concentration. The overall progress showed that C. limonium was more affected the CO2-in of cotton crop. CO2-out was less affected by the C. limonium (117.83±1.46) at 4% concentration than M. arvensis (116.99±1.25) at 8% concentration and D. stramonium (115.77±0.74) at 16% concentration, but was more affected by the A. indica (118.15±0.71) at 4%. H2O-in was more affected by the C. limonium (0.39±0.05) than D. stramonium, A. indica and M. arvensis at 16% concentration. H2O-out of cotton was least affected by the D. stramonium (7.63±0.01) at 2% and more affected by the C. limonium (1.56±0.15) at 16% concentration. PAR was more affected by the A. indica (931.47±8.39) at 4% concentration and least affected by the M. arvensis (1499.7±9.94) at 8% concentration. Conclusions: Different dosages of various botanicals influenced the opening and closing of stomata and photosynthesis of cotton plants.
{"title":"Phytotoxic effect of plant extracts on physiology of cotton (Gossypium hirsutum L.) plants","authors":"Muhammad N. Zahoor, M. Nadeem, J. Iqbal, Muhammad F. Shahzad, T. Islam, Hussan A. Begum, Mohammad S. Baloch, Ayat Ullah","doi":"10.1590/s0100-83582020380100064","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100064","url":null,"abstract":"Background: Plant-derived compounds are alternatives of synthetic insecticides in sustainable agriculture. Objective: This study investigated the phytotoxic effect of higher concentrations (2, 4, 8 and 16%) of four plants extracts (Azadirachta indica, Mentha arvensis, D. stramonium and Citrus limonium) on cotton plants. Methods: Each concentration was replicated four times to check the phytotoxic effect (CO2-in, CO2-out, H2O-in, H2O-out and photosynthesis absorption rate (PAR) in randomized complete block design. Data was recorded after 12, 24, 48 and 72 hours of spray with the help of Photosynthetic CL 340 meter. Results: The results showed that CO2-in was more affected by the D. stramonium (131.65±0.38) at 8% concentration. The overall progress showed that C. limonium was more affected the CO2-in of cotton crop. CO2-out was less affected by the C. limonium (117.83±1.46) at 4% concentration than M. arvensis (116.99±1.25) at 8% concentration and D. stramonium (115.77±0.74) at 16% concentration, but was more affected by the A. indica (118.15±0.71) at 4%. H2O-in was more affected by the C. limonium (0.39±0.05) than D. stramonium, A. indica and M. arvensis at 16% concentration. H2O-out of cotton was least affected by the D. stramonium (7.63±0.01) at 2% and more affected by the C. limonium (1.56±0.15) at 16% concentration. PAR was more affected by the A. indica (931.47±8.39) at 4% concentration and least affected by the M. arvensis (1499.7±9.94) at 8% concentration. Conclusions: Different dosages of various botanicals influenced the opening and closing of stomata and photosynthesis of cotton plants.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67279029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100044
S. Banaras, A. Javaid, A. Shoaib
ABSTRACT: Urdbean [Vigna mungo (L.) Hepper] is an important leguminous crop whose production is severely affected by charcoal rot disease caused by Macrophomina phaseolina. This study was undertaken to seek an environmental friendly alternative to synthetic fungicides for management of this disease. Dry biomass of an allelopathic weed Sonchus oleraceous L. was used to combat the menace. Fumigated sandy loam pot soil, pre-inoculated with M. phaseolina, was amended with different doses of dry biomass of the weed ranging from 0.5% to 3%. Application of 2% weed biomass completely controlled the disease. Soil inoculation with M. phaseolina inoculation (positive control) reduced shoot dry weight and grain yield of urdbean by 59% and 91%, respectively, over negative control. Application of different doses of soil amendment in pathogen inoculated soil enhanced shoot dry weight and grain yield of urdbean by 107-307% and 438-7400%, respectively, over positive control. The highest positive effect on growth and yield of uedbean in M. phaseolina contaminated soil was recorded due to 2.5% amendment. M. phaseolina inoculation significantly enhanced peroxidase (POX) and phenyl alanine ammonia lyase (PAL) activities. However, application of different doses of S. oleraceous biomass to the soil gradually decreased activities of these enzymes. The present study concludes that application of 2.5% dry biomass of S. oleraceous can completely control charcoal rot of urdbean and significantly enhance crop growth and yield.
{"title":"Non-Chemical Control of Charcoal Rot of Urdbean by Sonchus oleraceous Application","authors":"S. Banaras, A. Javaid, A. Shoaib","doi":"10.1590/s0100-83582020380100044","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100044","url":null,"abstract":"ABSTRACT: Urdbean [Vigna mungo (L.) Hepper] is an important leguminous crop whose production is severely affected by charcoal rot disease caused by Macrophomina phaseolina. This study was undertaken to seek an environmental friendly alternative to synthetic fungicides for management of this disease. Dry biomass of an allelopathic weed Sonchus oleraceous L. was used to combat the menace. Fumigated sandy loam pot soil, pre-inoculated with M. phaseolina, was amended with different doses of dry biomass of the weed ranging from 0.5% to 3%. Application of 2% weed biomass completely controlled the disease. Soil inoculation with M. phaseolina inoculation (positive control) reduced shoot dry weight and grain yield of urdbean by 59% and 91%, respectively, over negative control. Application of different doses of soil amendment in pathogen inoculated soil enhanced shoot dry weight and grain yield of urdbean by 107-307% and 438-7400%, respectively, over positive control. The highest positive effect on growth and yield of uedbean in M. phaseolina contaminated soil was recorded due to 2.5% amendment. M. phaseolina inoculation significantly enhanced peroxidase (POX) and phenyl alanine ammonia lyase (PAL) activities. However, application of different doses of S. oleraceous biomass to the soil gradually decreased activities of these enzymes. The present study concludes that application of 2.5% dry biomass of S. oleraceous can completely control charcoal rot of urdbean and significantly enhance crop growth and yield.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"17 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100055
Bruno M. Silva, Renan R. Zandoná, Roberto C. A. Neto, Jonathan Torchelsen, D. Agostinetto
and the lack of selective herbicides registered for birdsfoot trefoil crops affect their development and limit their productivity. Objective: This study aimed to evaluate selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops. Methods: Experiments were carried out in a greenhouse and on a field, in both vegetative and reproductive development stages of birdsfoot trefoil crops. Treatments were composed of post-emergent herbicides recommended for soybean, corn and garlic cultivation. Phytotoxicity (PHYTO), plant height (HEI), shoot dry matter (SDM) and root dry matter (RDM) were evaluated. Data were submitted to the analysis of variance and when means were significant, they were compared by the Duncan’s Test (p≤0.05). In order to determine post-emergent herbicides which were selective to the crop, those that provided PHYTO below or equal to 15% were recommended, since they did not significantly interfere with morphological variables HEI, SDM and RDM, by comparison with the control. Results: Unlike results found in the vegetative stage, birdsfoot trefoil plants were more tolerant to phytotoxic effects of herbicides imazethapyr, chlorimuron-ethyl, cloransulam-methyl and fomesafen in the reproductive stage. The variables were negatively affected by the herbicides bentazon, glyphosate and carfentrazone-ethyl, with PHYTO higher than 40% at 20 days after treatment in
{"title":"Selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops","authors":"Bruno M. Silva, Renan R. Zandoná, Roberto C. A. Neto, Jonathan Torchelsen, D. Agostinetto","doi":"10.1590/s0100-83582020380100055","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100055","url":null,"abstract":"and the lack of selective herbicides registered for birdsfoot trefoil crops affect their development and limit their productivity. Objective: This study aimed to evaluate selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops. Methods: Experiments were carried out in a greenhouse and on a field, in both vegetative and reproductive development stages of birdsfoot trefoil crops. Treatments were composed of post-emergent herbicides recommended for soybean, corn and garlic cultivation. Phytotoxicity (PHYTO), plant height (HEI), shoot dry matter (SDM) and root dry matter (RDM) were evaluated. Data were submitted to the analysis of variance and when means were significant, they were compared by the Duncan’s Test (p≤0.05). In order to determine post-emergent herbicides which were selective to the crop, those that provided PHYTO below or equal to 15% were recommended, since they did not significantly interfere with morphological variables HEI, SDM and RDM, by comparison with the control. Results: Unlike results found in the vegetative stage, birdsfoot trefoil plants were more tolerant to phytotoxic effects of herbicides imazethapyr, chlorimuron-ethyl, cloransulam-methyl and fomesafen in the reproductive stage. The variables were negatively affected by the herbicides bentazon, glyphosate and carfentrazone-ethyl, with PHYTO higher than 40% at 20 days after treatment in","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"4 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100049
H. Dong, Y. Ma, H. Wu, W. Jiang, X. Ma
ABSTRACT: Solanum nigrum L. (black nightshade), an annual to short-lived perennial weed, has become a problem weed in farming systems in central China. Laboratory and greenhouse experiments were conducted to examine the influence of various abiotic factors on seed germination of black nightshade to develop effective weed control programs. Seeds germinated at a range of constant temperatures from 15 to 30 oC, but no germination occurred at temperatures below 10 oC or above 35 oC. Seeds also germinated at alternating temperature regimes from 15/5 to 40/30 oC, with maximum germination (> 93.5%) at the alternating temperatures of 25/15 and 30/20 oC. Germination decreased as osmotic potential became more negative, and no germination was observed at ≤ -0.8 MPa. Moreover, germination was reduced by saline and alkaline stresses and no germination occurred at ≥ 200 mM NaCl or ≥ 150 mM NaHCO3 concentrations. Seed germination was not significantly affected by pH values from 5 to 10. Seedling emergence was significantly affected by burial depth with maximum emergence (93.1%) at 1 cm depth.
摘要:龙葵(Solanum nigrum L.)是一种一年生到短生的多年生杂草，已成为中国中部地区农业系统中的问题杂草。通过室内和温室试验，研究了各种非生物因素对茄属植物种子萌发的影响，以制定有效的杂草防治方案。种子在15 ~ 30℃的恒温范围内萌发，但在低于10℃或高于35℃的温度下不萌发。在15/5 ~ 40/30℃的交替温度下，种子也能萌发，在25/15和30/20℃的交替温度下，种子的最高发芽率为93.5%。渗透压越负，种子萌发率越低，≤-0.8 MPa时未萌发。此外，盐和碱胁迫降低了种子的萌发，≥200 mM NaCl和≥150 mM NaHCO3浓度均不萌发。pH值5 ~ 10对种子萌发无显著影响。埋深对苗木出苗率有显著影响，埋深1 cm时出苗率最高(93.1%)。
{"title":"Germination of Solanum nigrum L. (Black Nightshade) in Response to Different Abiotic Factors","authors":"H. Dong, Y. Ma, H. Wu, W. Jiang, X. Ma","doi":"10.1590/s0100-83582020380100049","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100049","url":null,"abstract":"ABSTRACT: Solanum nigrum L. (black nightshade), an annual to short-lived perennial weed, has become a problem weed in farming systems in central China. Laboratory and greenhouse experiments were conducted to examine the influence of various abiotic factors on seed germination of black nightshade to develop effective weed control programs. Seeds germinated at a range of constant temperatures from 15 to 30 oC, but no germination occurred at temperatures below 10 oC or above 35 oC. Seeds also germinated at alternating temperature regimes from 15/5 to 40/30 oC, with maximum germination (> 93.5%) at the alternating temperatures of 25/15 and 30/20 oC. Germination decreased as osmotic potential became more negative, and no germination was observed at ≤ -0.8 MPa. Moreover, germination was reduced by saline and alkaline stresses and no germination occurred at ≥ 200 mM NaCl or ≥ 150 mM NaHCO3 concentrations. Seed germination was not significantly affected by pH values from 5 to 10. Seedling emergence was significantly affected by burial depth with maximum emergence (93.1%) at 1 cm depth.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"35 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100086
Carlos E. Schaedler, Célio U.M. Taborda, Francisco A.P. Goulart, Diego M. Chiapinotto, P. J. Pinho
Background: Weedy rice belongs to the same taxon as irrigated rice (Oryza sativa L.), and is the main weed of the crop. However, it exhibits different traits that produce greater competitive capacity using solar radiation. In competition for light, plants invest in photoassimilates for the shoots and can reduce their root development. Objectives: The objective of this work is to evaluate the initial growth of weedy and cultivated rice roots in response to light competition. Methods: The experiment was conducted in a greenhouse (hydroponic system), using a completely randomized design, arranged in a 2x2x6 factorial scheme, with five replications. Factor A consisted of the weedy rice biotype Q35B and the rice cultivar IRGA 424; factor B of light competition conditions (presence or absence of 75 weedy rice plants); and factor C of assessment time. At 0, 7, 14, 21, 28 and 35 days after transplanting, samples were taken from each experimental unity to measure the root area, perimeter, length, number of tips, and root dry weight (RDW), and shoot dry weight (SDW). Results: Competition for light reduced the area, perimeter, length, number of root tips, reduced the RDW and the SDW of both, the weedy rice biotype and crop rice. However, regardless of the competitive condition, the weedy rice showed a higher area, perimeter, initial growth, number of tips, RDW and SDW than that of cultivated rice. Conclusion: Weedy rice exhibits greater competitive capacity using the resources beneath the soil.
{"title":"Rice root growth and development in competition with weedy rice","authors":"Carlos E. Schaedler, Célio U.M. Taborda, Francisco A.P. Goulart, Diego M. Chiapinotto, P. J. Pinho","doi":"10.1590/s0100-83582020380100086","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100086","url":null,"abstract":"Background: Weedy rice belongs to the same taxon as irrigated rice (Oryza sativa L.), and is the main weed of the crop. However, it exhibits different traits that produce greater competitive capacity using solar radiation. In competition for light, plants invest in photoassimilates for the shoots and can reduce their root development. Objectives: The objective of this work is to evaluate the initial growth of weedy and cultivated rice roots in response to light competition. Methods: The experiment was conducted in a greenhouse (hydroponic system), using a completely randomized design, arranged in a 2x2x6 factorial scheme, with five replications. Factor A consisted of the weedy rice biotype Q35B and the rice cultivar IRGA 424; factor B of light competition conditions (presence or absence of 75 weedy rice plants); and factor C of assessment time. At 0, 7, 14, 21, 28 and 35 days after transplanting, samples were taken from each experimental unity to measure the root area, perimeter, length, number of tips, and root dry weight (RDW), and shoot dry weight (SDW). Results: Competition for light reduced the area, perimeter, length, number of root tips, reduced the RDW and the SDW of both, the weedy rice biotype and crop rice. However, regardless of the competitive condition, the weedy rice showed a higher area, perimeter, initial growth, number of tips, RDW and SDW than that of cultivated rice. Conclusion: Weedy rice exhibits greater competitive capacity using the resources beneath the soil.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67280071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100010
A. Rehman, R. Qamar, M. Safdar, H. Javeed, M. Shehzad, M. Ali, M. Asif, Z. H. Tarar, A. Ahmed, M. Jamil
ABSTRACT: Weed-induced yield loss in wheat crop is a great threat to food security in Pakistan. A comprehensive understanding of weed-crop competition is very important to develop sustainable and cost-effective weed management. For this purpose, two-year field studies were conducted to determine the effect of different blessed milkthistle densities on the phenology and yield of wheat crop in a rice-wheat cropping scheme in Sargodha, Pakistan during 2013-2014 and 2014-2015. The experiment comprised seven treatments: control (weed free), weedy check (weedy without any control) and blessed milkthistle densities of 5, 10, 15, 20 and 25 plants m-2. In response to increasing weed density, a gradual reduction in yield and yield-related traits of wheat was noted. Compared to the weed-free control, a significant reduction in number of productive tillers m-2 (20% and 18%), plant height (15% and 18%), spike length (19% and 26%), number of grains spike-1 (23% and 26%), 1000 grain weight (28% and 28%), grain (29% and 30%) and biological (20% and 24%) yields of wheat occurred at and beyond blessed milkthistle density of 5 plants m-2 during 2013-2014 and 2014-2015 respectively. It can be concluded that blessed milkthistle weed must be controlled if its population density reaches 5 plants m-2 in order to avoid significant grain yield losses in wheat.
{"title":"Understanding the Competitive Effects of Blessed Milkthistle Densities on Wheat","authors":"A. Rehman, R. Qamar, M. Safdar, H. Javeed, M. Shehzad, M. Ali, M. Asif, Z. H. Tarar, A. Ahmed, M. Jamil","doi":"10.1590/s0100-83582020380100010","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100010","url":null,"abstract":"ABSTRACT: Weed-induced yield loss in wheat crop is a great threat to food security in Pakistan. A comprehensive understanding of weed-crop competition is very important to develop sustainable and cost-effective weed management. For this purpose, two-year field studies were conducted to determine the effect of different blessed milkthistle densities on the phenology and yield of wheat crop in a rice-wheat cropping scheme in Sargodha, Pakistan during 2013-2014 and 2014-2015. The experiment comprised seven treatments: control (weed free), weedy check (weedy without any control) and blessed milkthistle densities of 5, 10, 15, 20 and 25 plants m-2. In response to increasing weed density, a gradual reduction in yield and yield-related traits of wheat was noted. Compared to the weed-free control, a significant reduction in number of productive tillers m-2 (20% and 18%), plant height (15% and 18%), spike length (19% and 26%), number of grains spike-1 (23% and 26%), 1000 grain weight (28% and 28%), grain (29% and 30%) and biological (20% and 24%) yields of wheat occurred at and beyond blessed milkthistle density of 5 plants m-2 during 2013-2014 and 2014-2015 respectively. It can be concluded that blessed milkthistle weed must be controlled if its population density reaches 5 plants m-2 in order to avoid significant grain yield losses in wheat.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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