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Made available in DSpace on 2020-12-12T02:29:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Eucalyptus harvests generate residues that remain on the soil and affect the efficacy of preemergent herbicides in the following planting cycle. The objective of this work was to evaluate the dynamics of flumioxazin, sulfentrazone, and isoxaflutole herbicides applied on different amounts and compositions of eucalyptus harvest residues subjected to different rainfall depths; and evaluate the weed control effectiveness of these herbicides when applied under these conditions. A LC–MS/MS system was used for the evaluations and the results showed that a cumulative rainfall of 50 mm was sufficient for the maximum removal of herbicides from the eucalyptus residues, regardless of the residue composition. The amount of the flumioxazin, sulfentrazone, and isoxaflutole herbicides that reached the soil was lower in the treatment with the highest amount of eucalyptus harvest residue used (40 Mg ha−1). The greatest amount of herbicide reaching the soil was found with the use of 15 Mg ha−1 of residues without presence of bark. The highest amount of residue used (40 Mg ha−1) reduced the control of Brachiaria decumbens by sulfentrazone and isoxaflutole. The control of Commelina benghalensis was inefficient (> 80%) in the treatment with 15 Mg ha−1 of residues without barks, regardless of the herbicide. Sulfentrazone controlled Ipomoea grandifolia (> 90%) under the evaluated residue conditions. Spermacoce latifolia and Sida rhombifolia were controlled by all herbicides in the evaluated residue conditions. Isoxaflutole controlled Panicum maximum in all residue conditions. The choice between the herbicides depends on the residue condition, rainfall regime, and weed species to be controlled. School of Agriculture of the São Paulo State University (Unesp), Av. Universitária, 3780 - Altos do Paraíso, Fazenda Experimental Lageado School of Agriculture of the São Paulo State University (Unesp), Av. Universitária, 3780 - Altos do Paraíso, Fazenda Experimental Lageado

Made available in DSpace on 2019-10-06T15:19:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-09-01 Susceptibility to chlorimuron varies according to soybean genotype. STS® (sulfonylurea-tolerant soybean) presents a high tolerance to some sulfonylureas; this feature is determined by semi-dominants alleles, Als1 and Als2. Experiments were conducted in the field for four seasons with two cultivars for season to evaluate the selectivity of chlorimuron rates in post-emergency (V4) of glyphosate-tolerant and sulfonylurea-tolerant soybean. Data analysis made it possible to infer that there was no significant effect on the productivity of the cultivars when they received application in post-emergency, of chlorimuron at the doses used (0, 15, 30, 45, 60, 75, and 90 g ai ha-1). The maximum recommended rate for non-STS cultivars of chlorimuron is 20 g ai ha-1, or 4.5 times less than the maximum rate employed in this study. The soybean cultivars CD 250 RR/STS, CD 236 RR/STS, CD 2630 RR/STS, and BMX Turbo RR/STS were tolerant to the application, in post-emergency (V4) of the herbicide chlorimuron, until the rate of 90 g ai ha-1. Department of Agronomic Sciences Federal University of Paraná (UFPR) Palotina Campus Department of Crop Science University of São Paulo (USP) “Luiz de Queiroz” College of Agriculture (ESALQ) Faculty of Agronomic Sciences São Paulo State University (UNESP) Faculty of Agronomic Sciences São Paulo State University (UNESP)

Made available in DSpace on 2019-10-03T18:19:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-01. Added 1 bitstream(s) on 2019-10-09T18:33:21Z : No. of bitstreams: 1 S0100-204X2018000800909.pdf: 458835 bytes, checksum: b4658d73c9c98102ddd084f2d5fb09ae (MD5) Universidade Federal do Parana The objective of this work was to evaluate the effect of winter cover crop species on the agronomic performance of soybean (Glycine max) cropped in succession, under a no-tillage system. The study was conducted during three crop seasons (2011/2012, 2012/2013, and 2013/2014), with the following cover crops: white oat (Avena sativa), black oat (Avena strigosa), ryegrass (Lolium multiflorum), vetch (Vicia sativa), forage radish (Raphanus sativus), the intercrop black oat + forage radish, and wheat (Triticum aestivum) as the standard management. Forage radish and the intercrop black oat + forage radish provided greater soil cover rates after 30 days of planting, as well as dry matter production in the three crop seasons. After 45 and 90 days from desiccation, however, white oat and ryegrass showed the highest soil cover rate. Black oat and the intercrop black oat + forage radish provided higher soybean yield than the standard management with wheat, in the 2012/2013 and 2013/2014 crop seasons. Winter cover crops can significantly affect soybean yield in succession, and black oat and the intercrop black oat + forage radish stand out for this purpose. Univ Estadual Paulista, Fac Ciencia Agron, Campus Botucatu,Ave Univ 3-780, BR-18610034 Botucatu, SP, Brazil Univ Fed Parana, Setor Palotina, Rua Pioneiro 2-153, BR-85950000 Palotina, PR, Brazil Univ Estadual Paulista, Fac Ciencia Agron, Campus Botucatu,Ave Univ 3-780, BR-18610034 Botucatu, SP, Brazil

With the possibility of using ammonium glufosinate in corn, studies on its association with other herbicides are essential. The aim of this study was to assess weed control and herbicide selectivity in association with ammonium glufosinate in corn containing the pat and cp4-epsps genes. The experiment was carried out under field conditions in two sites in a randomized block design with four replications. Treatments consisted of ammonium glufosinate, glyphosate, ammonium glufosinate + glyphosate, ammonium glufosinate + nicosulfuron, ammonium glufosinate + atrazine, ammonium glufosinate + tembotrione, ammonium glufosinate + mesotrione, ammonium glufosinate + carfentrazone ethyl, ammonium glufosinate + bentazon, ammonium glufosinate + 2,4-D, control without weeding, and hand-weeded control. Visual assessments were performed regarding damage, electron transport rate in photosystem II (ETR), ammonia quantification, height, and grain yield of corn plants, as well as weed control at both sites. The application of ammonium glufosinate and its associations did not provide a reduction in productivity when compared to the hand-weeded control. Some treatments presented higher levels of visual damage and ammonia accumulation, but without a yield reduction. Therefore, herbicide mixture with ammonium glufosinate may be an alternative to weed control without damaging corn crop, which presents in its genetic constitution the cp4-epsps and pat genes. RESUMO: Com a possibilidade do uso de amônio-glufosinate no milho, são fundamentais estudos com associações desse herbicida junto a outros. O objetivo do presente trabalho foi avaliar o controle de plantas daninhas e a seletividade de herbicidas em associação ao amônio-glufosinate em milho contendo os genes pat e cp4-epsps. O experimento foi realizado em campo em duas localidades, dispostos em blocos ao acaso com quatro repetições. Os tratamentos foram: amônio-glufosinate; glyphosate; amônio-glufosinate + glyphosate; amônio-glufosinate + nicosulfuron; amônio-glufosinate + atrazine; amônio-glufosinate + tembotrione; amônio-glufosinate + mesotrione; amônio-glufosinate + carfentrazone ethyl; amônio-glufosinate + bentazon; amônio-glufosinate + 2,4-D; e testemunha sem capina e testemunha capinada. Foram feitas realizadas avaliações visuais de injúria, fluxo de transporte de elétrons do fotossistema II (ETR), quantificação de amônia, altura e rendimento de grãos das plantas de milho, além de controle das plantas daninhas em ambos os locais. A adoção da aplicação de glufosinate e suas associações não proporcionou redução de produtividade quando comparada à testemunha capinada; alguns tratamentos apresentaram maiores níveis de injúria visual e acúmulo de amônia, porém sem redução de produtividade. Portanto, a mistura de herbicidas com o amônio-glufosinate pode ser uma alternativa para o controle de plantas daninhas, sem causar danos à cultura do milho, que apresenta na sua constituição genética os genes cp4-epsps e pat.

Phosphinothricin acetyltransferase ( pat) gene confers resistance to glufosinate by transforming this herbicide into N-acetyl-l-glufosinate (NAG). The pat gene was inserted in six maize hybrids (Herculex, Agrisure TL, Herculex Yieldgard, Leptra, Viptera 3, Power Core) as a selectable marker, and its expression was evaluated by qPCR in comparison with the maize glufosinate-susceptible cultivar VTPRO. In addition, the levels of NAG, glufosinate degradation, ammonia accumulation, electron transport rate (ETR), visual injury, and biomass were also investigated. The VTPRO, Herculex, Agrisure, and Viptera showed lower pat gene expression, and consequently lower NAG contents and glufosinate degradation, as well as reduced ETR and biomass accumulation. In contrast, greater ammonia accumulation and higher visual injury were observed. The ranking of pat gene expression was LeptraPower CoreHerculex Yieldgard ≫ HerculexAgrisure TL = Viptera 3VTPRO. This gene expression was proportional to the glufosinate resistance level observed in each maize hybrid.

Made available in DSpace on 2019-10-03T18:19:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01. Added 1 bitstream(s) on 2019-10-09T18:33:21Z : No. of bitstreams: 1 S0100-83582018000100306.pdf: 1030366 bytes, checksum: 0a20f2f4f94286c88fdd366df1b1a081 (MD5) This study aimed at evaluating the agronomic performance of Intacta RR2 soybean submitted to the application of glyphosate doses in post-emergence. For this, two experiments were conducted in two locations (Palotina and Marechal Candido Rondon - Parana state). Applications were carried out with increasing rates of glyphosate (0, 720, 1,440, 2,160, 2,880, 3,600, 4,320 g a.e. ha(-1)), constituting seven treatments with an experimental design in randomized blocks with four replications, totaling 28 plots for each location. The cultivar used for both experiments was Monsoy 6210 Intacta RR2 IPRO (TM). The analyzed variables were phytotoxicity at 3, 7,14, 21 and 28 DAA, A-B and total chlorophyll index, final height, number of pods, 100-seed weight, and yield. A regression analysis was used. There was a positive behavior of the linear regression for phytotoxicity and a negative one for final height, number of pods, A-B and total chlorophyll index, and yield in the city of Palotina. In Marechal Candido Rondon, there were adjustments of the positive linear regressions for phytotoxicity, and negative linear regressions for chlorophyll index, final height, number of pods and yield. Results show that the glyphosate increase from the dose 1,440 g a.e. ha(-1) in the studied cultivar damaged the agronomic performance of the culture. UNESP, Botucatu, SP, Brazil Univ Fed Parana, Palotina, PR, Brazil UNESP, Botucatu, SP, Brazil

The effectiveness of a new product has a great importance to weed control, especially those that are difficult to control or resistant to, such as the sumatran fleabane (Conyza sumatrensis). The objective of this research was to evaluate the control of C. sumatrensis at different growth stages, using halauxifen-methyl in combination with other herbicides. The experimental design used was a randomized blocks in a 3x10 factorial scheme, with four replications. The plants of C. sumatrensis were evaluated at different growth: stage 1: plants with 8 leaves; Stage 2: plants with 19 leaves and stage 3: plants with 45 leaves fully expanded. The herbicides used were the association of glyphosate with the herbicides 2,4-D at 806, 943 and 1,209 g a.e. ha-1, halauxifen-methyl + diclosulam at 5.06 g a.e. ha-1 + 25.52 g a.i. ha-1 and 6.32 g a.e. ha-1 + 31.87 g a.i. ha-1, halauxifen-methyl + 2,4-D at 5.00 + 783 g a.e. ha-1 and 6,0 + 940 g a.e. ha-1 and halauxifen-methyl at 5.0 and 6.0 g a.e. ha-1 and untreated, totaling 10 treatments. The herbicides demonstrated satisfactory control of the plants in Stage 1 at 50 DAA, with the exception of the glyphosate + 2,4-D treatment at the lowest rate. However for Stages 2 and 3 the halauxifen-methyl + diclosulam in both rates, provided superior controls in relation to the other treatments. The control of sumatran fleabane was facilitated when their management occurs in the early stages of development, however independent of the development stage, the best controls obtained were with the treatment containing glyphosate + halauxifen-methyl + diclosulam at 1,440 g a.e. ha-1 + 6.32 g a.e. ha-1 + 31.87 g a.i. ha-1. Thus, combinations of herbicides containing halauxifen-methyl are another option to control C. sumatrensis in agricultural systems. RESUMO: A confirmação da efetividade de novos produtos é de grande importância para o controle de plantas daninhas, principalmente aquelas de difícil controle ou resistentes, como o caso da buva (Conyza sumatrensis). O objetivo deste trabalho foi avaliar o controle de C. sumatrensis em diferentes estádios de desenvolvimento, utilizando-se halauxifen-methyl em associação com outros princípios ativos de herbicidas. O delineamento experimental utilizado foi de blocos ao acaso, em esquema fatorial 3x10, com quatro repetições. As plantas de C. sumatrensis foram divididas em três estádios de desenvolvimento: estádio 1: plantas com 8 folhas, estádio 2: plantas com 19 folhas e estádio 3: plantas com 45 folhas totalmente expandidas. Os tratamentos consistiram da associação de glyphosate (1.440 g ha-1) com os herbicidas 2,4-D a 806, 943 e 1.209 g e.a. ha-1, halauxifen-methyl + diclosulam at 5,06 g e.a. ha-1 + 25,52 g i.a. ha-1 and 6,32 g e.a. ha-1 + 31,87 g i.a. ha-1, halauxifen-methyl + 2,4-D at 5,00 + 783 g e.a. ha-1 and 6,0 + 940 g e.a. ha-1 and halauxifen-methyl at 5.0 and 6.0 g e.a. ha-1, além de testemunha sem aplicação, totalizando 10 tratamentos. Os herbicidas apresentaram controle satisfatório das plantas de buva no estádio 1 aos 50 DAA, com exceção do tratamento glyphosate + 2,4-D, na dose mais baixa. Contudo, para os estádios 2 e 3 o halauxifen-methyl + diclosulam, em ambas as doses, proporcionou controles superiores em relação aos demais tratamentos. O controle de C. sumatrensis foi facilitado quando manejado em estádios iniciais de desenvolvimento; entretanto, independentemente do estádio de desenvolvimento, os melhores controles foram com o tratamento contendo glyphosate + halauxifen-methyl + diclosulam a 1.440 g e.a. ha-1 + 6.32 g e.a. ha-1 + 31.87 g i.a. ha-1. Assim, as associações de herbicidas contendo halauxifen-methyl são mais uma opção para o manejo de C. sumatrensis nos sistemas agrícolas.

Made available in DSpace on 2019-10-04T12:42:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-07-01. Added 1 bitstream(s) on 2021-07-15T15:04:58Z : No. of bitstreams: 1 S0104-77602018000300162.pdf: 1031369 bytes, checksum: c2d0028d11d2931b8803f6af7d1f78dc (MD5) Eucalyptus stands out in the Brazilian silvicultural sector as the most planted tree species for commercial purposes thus, practices that facilitate management and improve wood quality are increasingly required. Although artificial mechanical pruning has been used for this crop, the use of herbicides for pruning can be more practical, rapid and have lower costs. Thus, the objective of this work was to evaluate the use of glufosinate ammonium in the chemical pruning of eucalyptus plants. Eucalyptus seedlings were transplanted into 10-L pots filled with soil and substrate and subjected to the treatments (mechanical pruning, chemical pruning, and no pruning) 90 days after transplanting. Lateral branches were cut with pruning shears for the mechanical pruning. Glufosinate ammonium (500 g a.i. ha(-1)) was applied to the sides of the plants for the chemical pruning, simulating a fieldplanting row (3.5 x 2.0 meters), using a CO2-pressurized sprayer; the untreated branches were covered with plastic bags to avoid receiving the herbicide. The percentage of artificial pruning used was 60% of the vertical height of the eucalyptus plants. Glufosinate, glutamate, and ammonia contents, electron transport rate, percentage of pruning, plant height, number of leaves, and dry matter mass of the plants were evaluated. The application of glufosinate ammonium defoliate the treated branches and did not affect significantly the parts of the plants that did not receive the herbicide regarding the evaluated compounds, and growth of the plants, denoting that glufosinate ammonium can be used for chemical pruning of eucalyptus plants. Sao Paulo State Univ, Botucatu, SP, Brazil Bayer Environm Sci, Botucatu, SP, Brazil Sao Paulo State Univ, Botucatu, SP, Brazil

Made available in DSpace on 2018-12-11T16:51:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-04-01 Universidade Federal do Paraná For optimum yield, it is necessary to incorporate a good weed control into the system. This study aimed to determine the effects of a post-emergent application of different herbicides (individually and combined) on corn presenting cp4-epsps and pat genes. Field studies were conducted on the corn hybrid 2B810 with the cp4-epsps and pat genes in the agricultural years 2012/13 and 2013/14 and included 8 treatments with isolated and combined application of glyphosate, glufosinate-ammonium, and atrazine. The variables evaluated were chlorophyll type a and b, total chlorophyll index, stem diameter, height of the cob insertion, prolificacy index, first height, second height, yield, and volume of 100 grains. The combination of all three herbicides hindered the yield of corn cultures. This practice therefore requires caution when applied to weed management. The combination of two herbicides did not affect the final height or yield and may be a useful method of weed management in future. São Paulo State University (Unesp) School of Agriculture Federal University of Paraná - Agronomy Department Luiz de Queiroz College of Agriculture University of São Paulo São Paulo State University (Unesp) School of Agriculture

Made available in DSpace on 2018-11-26T16:05:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01. Added 1 bitstream(s) on 2021-07-15T14:31:39Z : No. of bitstreams: 1 S0100-83582018000100275.pdf: 753405 bytes, checksum: 5e4cd96c5a90b6deb2a82ebc3eef18e8 (MD5) The goal of this study was to compare the efficacy of different weed management through a burndown application followed by sequential applications of herbicides to control Conyza spp. Thus, four field experiments were conducted, two in the western region of Parana state (E1 and E2), one in Jatai, Goias state (E3) and another one in Ibiruba, Rio Grande do Sul state (E4). Conyza spp. in this area had a height ranging between 25 and 60 cm. Treatments were arranged in a randomized block design with four replications. The primary herbicide treatments were 2,4-D + glyphosate + diclosulam, chlorimuron-ethyl + glyphosate + 2,4-D, and four doses of diclosulam + halauxifen-methyl + glyphosate. These treatments were applied singly or in sequential applications, made 10 days before the application of ammonium glufosinate, paraquat or saflufenacil. In all experiments, results showed efficient (90%) control of treatments containing diclosulam + halauxifen-methyl in combination with glyphosate on day 35 DAA, regardless of sequential applications. Applications of 2,4-D + glyphosate + diclosulam or chlorimuron-ethyl + glyphosate + 2,4-D were not effective against Conyza spp. at E1 and E2 locations, possibly due to the greater weed size (50 to 60 cm) at these sites. However, the same treatments were effective at E3 and E4 locations, where weeds were smaller. Diclosulam + halauxifen-methyl + glyphosate associated with ammonium glufosinate, paraquat or saflufenacil in sequential applications, proved to be an important tool to manage Conyza spp. at different growth stages. Dow AgroSci Ind Ltda, Sao Paulo, SP, Brazil Univ Estadual Paulista, Botucatu, SP, Brazil Univ Estadual Paulista, Botucatu, SP, Brazil

The Roundup Ready (RR) soybean was developed for weed control with the use of glyphosate. Some herbicide combinations with glyphosate has been used in weed control and some effects of this practice may be undesirable in the agronomic performance of RR soybean. The present study evaluated the agronomic performance of RR2 intact soybean applied with associations between herbicides and glyphosate at post-emergence, in two experiments conducted in two municipalities in the state of Paraná, Palotina and Marechal Cândido Rondon. This experiment consisted of seven treatments in a randomized block design with four replications, totaling 28 plots for each municipality. The cultivar used in both experiments was Monsoy 6210 Intact RR2 IPROTM. The variables analyzed were: phytotoxicity at 3, 7, 14, 21 and 28 days after application, chlorophyll A, B and total chlorophyll, final height, number of pods, 100 seed weight and yield. Data were analyzed by analysis of variance and Tukey’s test at 5%. There were differences between treatments for phytotoxicity in both locations and differences in yield (Palotina) and final height (Marechal Cândido Rondon). From the data it is understood that some associations of certain herbicides such as lactofen, chlorimuron-ethyl in the glyphosate can potentiating effect cause phytotoxicity and even reduction in productivity. RESUMO: A soja Roundup Ready (RR) foi desenvolvida para controle de plantas daninhas com a utilização do herbicida glyphosate. Algumas associações de herbicidas com o glyphosate vêm sendo usadas no controle de plantas daninhas, e alguns efeitos dessa prática podem ser indesejados no desempenho agronômico da soja RR. O presente trabalho objetivou avaliar o desempenho agronômico da soja intacta RR2 submetida a associações de herbicidas com o glyphosate, em pós-emergência. Para isso, foram realizados dois experimentos em duas localidades (Palotina - PR e Marechal Cândido Rondon - PR). Esses experimentos contiveram sete tratamentos com delineamento em blocos ao acaso com quatro repetições. O cultivar utilizado em ambas as localidades foi o Monsoy 6210 Intacta RR2 IPROTM. As variáveis analisadas foram fitotoxicidade aos 3, 7, 14, 21 e 28 dias após aplicação, índice de clorofila A, B e total, altura final, número de vagens, massa de 100 sementes e produtividade. Foi feita a análise de variância e utilizado o teste de média de Tukey a 5%. Houve diferença entre os tratamentos para fitotoxicidade em ambas as localidades e diferença na produtividade (Palotina) e altura final (Marechal Cândido Rondon). A partir dos resultados, conclui-se que algumas associações de determinados herbicidas, como chlorimuron-ethyl e lactofen, na presença do glyphosate podem provocar efeito potencializador de fitotoxicidade e até mesmo na redução na produtividade.

Made available in DSpace on 2022-04-28T19:06:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-03-01 Allelochemicals are important and innovative tools for weed control as they neither harm the environment nor increase weed management costs. The secondary metabolites can be extracted by water or soaking and later applied in soil or leaves. This study evaluated the leaf extracts of Cymbopogon citratus, affecting germination of Bidens pilosa and B. subalternans seeds. Two trials were conducted in germination chambers. The completely randomized design was employed in both trials with 5 replications. Trial one was arranged in a 2×3 double factorial design, with two periods of leave collection (morning and afternoon); and three extract preparations (aqueous extract by maceration, aqueous extract by infusion and control with distilled water). Trial two was set up in a 2×2×5 triple factorial design, with two extracts (aqueous extract by maceration, aqueous extract by infusion); two time of day collection (morning and afternoon) and five extracts concentrations (0; 25; 50; 75 and 100%). The means were compared by F and Tukey's test (p ≤ 0.05). To evaluate extracts concentrations a regression analysis was run. The results showed that the aqueous extract by maceration of C. citratus decreased germination and germination speed of Bidens pilosa and Bidens subalternans more than the aqueous extract by infusion, for both species. The concentrations interfered, inversely and proportionally, decreasing germination and germination speed. The germination of beggarticks was affected by the extracts of C. citratus, suggesting further studies for this plant. Faculty of Agronomic Sciences Sao Paulo State University Faculty of Agronomic Sciences Sao Paulo State University

The planting of RR2 Intacta soybeans by farmers has been expanding strongly. However, some visual injuries have been noted after glyphosate application. The aim of this study was to evaluate the influence of glyphosate application on chlorophyll, photosynthesis and water use of four Intacta RR2 soybean cultivars. The experiment was conducted in a greenhouse, in a randomized block design with a 3 × 4 factorial scheme, consisting of three glyphosate rates and four soybean cultivars. The glyphosate formula used was isopropylamine salt + potassium salt. The parameters analyzed were phytotoxicity at 7, 14, 21 and 28 days after application, and total chlorophyll index at 0, 3, 7, 14, 21, 28, 35, 42 and 49 days after application. Furthermore, 40 days after application, the net CO2 assimilation rate (A), transpiration rate (E), stomatal conductance (G), and internal CO2 concentration (Ci) were evaluated as well. The water-use efficiency (WUE) and carboxylation efficiency were calculated. The data were submitted to analysis of variance and compared by the Tukey’s test (p ≤ 0.05), followed by regression analysis. The phytotoxicity influence could be seen until 21 days after application, in which Monsoy 6210 IPRO cultivar was the most injured. The increasing doses promoted a reduction of the chlorophyll level up to 35 days after application in Monsoy 6410 IPRO. The cultivars tested here showed similar chlorophyll index values. On the 3rd, 7th and 14th DAA (Fig. 5a–c), there was a significant linear decline in the chlorophyll index with rising glyphosate dose for all four cultivars. The chlorophyll index cultivars were not influenced by the doses on the 42nd and 49th DAA. There was no difference in water use and carboxylation efficiency. The parameters A, E and A/Ci showed a positive correlation as the doses increased, while Ci declined, in both cultivars. The application of glyphosate on these soybean cultivars causes different injuries according to the sensitivity. In general, RR2 soybeans have the ability to recover from visual intoxication injuries and reestablish the normal chlorophyll production and photosynthetic parameters after glyphosate application.

The benefits of glyphosate tolerant crops technology are well-known, and its acceptance by farmers is undeniable. However, results of recent research indicate that, in some situations, glyphosate applied to herbicide-tolerant soybean crops may have phytotoxic effects affecting nutritional balance, photosynthesis and others biochemical process in plants. Despite the increasing information available on this subject, there are still scientific and technical issues that need to be clarified. Therefore, the present study aimed to assess the impact of applying different rates, management systems, and formulations of glyphosate to glyphosate-tolerant soybean trough different regions of Brazil in different environmental conditions. Two experiments were conducted over two crop seasons. A 2 × 2 × 5 (formulations × stage of application × doses) factorial design was used in each of them, for a total of 20 treatments with four replications. The study assessed a series of variables related to agronomic performance such as total chlorophyll and yield. The results suggest some problems associated with post-emergent use of glyphosate in tolerant soybean crop as 5% total yield reduction even without phytotoxicity symptoms dependent of season. There was not found any formulation interaction with yield decrease.

O objetivo do trabalho foi avaliar a seletividade dos herbicidas chlorimuron-ethyl, metsulfuron-methyl e nicosulfuron, aplicados em soja RR/STS. O experimento I constituiu-se da aplicação de doses (0, 15, 30, 45 e 60 g i. a. ha-1) de chlorimuron-ethyl. Para o experimento II foram aplicadas doses (0; 1,8; 3,6; 5,4 e 7,2 g i. a. ha-1) de metsulfuron-methyl. Para o experimento III foram aplicadas doses (0, 50, 100, 150 e 200 g i. a. ha-1) de nicosulfuron. Foi empregado delineamento experimental em blocos casualizados, com quatro repetições. Foram avaliadas: altura de plantas, número de vagens por planta, clorofila A, B e total, condutividade, vigor e germinação das sementes, produtividade e massa de mil sementes. Os dados foram submetidos à análise de regressão. De maneira geral, as variáveis analisadas não sofreram influência pela aplicação dos herbicidas. O cultivar de soja CD 250 RR/STS apresentou-se tolerante aos herbicidas chlorimuron-ethyl, metsulfuron-methyl e nicosulfuron.

Some desiccation techniques for harvesting wheat may affect seed quality. The objective of this study was to evaluate the effect of different desiccant herbicides applied to the wheat crop and their effects on the production and seed quality. The experiment was conducted with cultivar COODETEC 150 (CD 150) in two sites in Palotina (Paraná state, Brazil) with a randomized block design consisting of 7 treatments (desiccation herbicides) and 4 replications. Desiccation was realized when 50% of the plants were in stage 80 with seeds in powdery or mass consistency. The variables analyzed were percentage of moisture content after harvest, Yield, hectoliter weight, mass of 100 seeds, vigor, germination, fresh mass of seedlings, dry mass of seedlings and root length. The herbicides carfentrazone-ethyl and clethodim were the ones that promoted greatest reduction in vigor. The herbicide paraquat caused reduction in seedling length. There was a reduction in the mass of 100 seeds for glufosinate-ammonium, clethodim, diquat and carfentrazone-ethyl. Glufosinate-ammonium, paraquat, glyphosate, clethodim and diquat caused reduction in yield. Desiccation of Cultivar CD 150 at stage 80 is not recommended, since plant Yield and physiological seed parameters were adversely affected by herbicides. Resumo: Algumas técnicas de manejo da cultura do trigo, como a dessecação pré-colheita podem afetar a produtividade e a qualidade fisiológica das sementes. O objetivo deste estudo foi avaliar o efeito de diferentes herbicidas dessecantes aplicados na cultura do trigo e seus efeitos sobre a produtividade e a qualidade das sementes. O experimento foi conduzido com a cultivar COODETEC 150 (CD 150), em dois ambientes de produção localizados no Município de Palotina - PR, sob o delineamento experimental de blocos casualisados, constituído de 7 tratamentos (herbicidas na dessecação) com 4 repetições. A dessecação foi realizada quando 50% das plantas apresentavam-se no estádio 80 com as sementes de consistência farinácea ou de massa. As variáveis analisadas foram umidade após a colheita, produtividade de sementes, peso hectolitro, massa de 100 sementes, germinação e vigor. Os herbicidas carfentrazone-ethyl e clethodim reduziram o vigor das sementes produzidas, e o herbicida paraquat reduziu o comprimento de plântulas. Ocorreu redução na massa de 100 sementes para o amônio - glufosinate, clethodim, diquat e carfentrazone-ethyl. O amônio - glufosinate, paraquat, glyphosate, clethodim e diquat reduziram a produtividade. A dessecação de plantas da cultivar CD 150 no estádio 80 não é recomendada, em decorrências dos efeitos negativos dos herbicidas nos parâmetros produtivos e fisiológicos das sementes de trigo.