Weed herbicide resistance has been a challenge in agriculture. The objective of this study was to detect sourgrass (Digitaria insularis (L.) Fedde) glyphosate-resistant plants and to evaluate the growth and polymorphism rate between the resistant and susceptible biotypes, as a subsidy for the integrated management of species. An experiment was conducted primarily for the detection of weed resistance using increasing doses of glyphosate to generate a dose-response curve. Then, an experiment consisting of eight treatments (destructives analysis of growth) and five replications was conducted to characterize and compare the phenological stages of each biotype. In addition to visual assessments, the dry weight and leaf area, absolute and relative growth rates, net assimilation rate and leaf area ratio of plants were determined. Finally, polymorphism among biotypes was determined using inter simple sequence repeat molecular markers. A resistant factor of 3.12 was found among the biotypes. The resistant biotype grew faster and was more robust than the susceptible biotype, arriving first to flowering. The resistant biotype was better adapted to light interception. The 25 inter simple sequence repeat molecular markers analysis showed a polymorphism rate of 56.6% among the analyzed biotypes.

RESUMO:A cultura do eucalipto expandiu-se para a região Centro-Oeste do País, áreas onde antes havia pastagens, sobretudo de Brachiaria decumbens (capim-braquiária), passando essa a se constituir a principal planta daninha. O presente trabalho objetivou avaliar a eficácia haloxifope-p-metílico no controle de B. decumbens infestando mudas de eucalipto (Eucalyptus urograndis) e sua seletividade para a cultura. Para tanto, montouse um experimento com três situações: eucalipto plantado isoladamente, eucalipto em convivência com a espécie B. decumbens e B. decumbens plantada isoladamente. Aos 67 dias após o plantio das mudas foi feita a aplicação do haloxifope-p-metílico nas doses de 0; 48 e 96 g . i . a . ha ), proporcionou um bom controle da planta daninha. O herbicida, nas doses testadas, foi seletivo à cultura do eucalipto e a convivência entre eucalipto e B. decumbens resultou em interferência negativa para ambas as espécies. HALOXYFOP-P-METHYL IN THE CONTROL OF BRACHIARIA DECUMBENS IN EUCALYPTUSABSTRACT: : Eucalyptus plantations in Brazil expanded to the Midwest region of the country in areas previously occupied by pastures, especially of Brachiaria decumbens (signal grass), making it the main weed in eucalyptus plantation. This work aimed to evaluate the efficiency of haloxyfop-P-methyl to control B. decumbens infesting eucalyptus seedlings. This experiment was set up in three situations: monoculture eucalyptus, eucalyptus in coexistence with B. decumbens and the weed cultivated alone. Haloxyfop-p-methyl was applied 67 days after plating the seedlings at doses of 0; 48 and 96 g . i . a . ha ) of haloxyfop-p-methyl provided good weed control. The herbicide, at the tested doses, was selective for eucalyptus and the relationship between eucalyptus and B. decumbens resulted in negative interference for both species.

Weed interference is one of the main factors responsible for reducing the productivity of the peanut crop. Among weed control methods, the chemical is considered one of the main tools, however, the herbicides registered for this crop are scarce. The objective of this study was to evaluate the selectivity of herbicides applied in post-emergence in Runner peanut cultivars. For this, an experiment was performed in an 11x5 factorial scheme, meaning 10 herbicides plus one control (without herbicide) and five peanut cultivars, with four replicates. Visual evaluations of phytointoxication were carried out at 7, 14 and 21 days after application of the herbicides. At the end of the experiment, was determined the dry mass of aboveground and root parts. ) have potential to be used for all the peanut cultivars studied. Herbicides hexazinone (2.50 kg ha-1), amicarbazone (2.00 kg ha ) must not be indicated, at these doses, for post-emergence spraying in the evaluated cultivars. The genotypes do not react equally to certain products, therefore, there is a need for further studies the at field conditions to attest the responses obtained in the present study and verify that the yield potential is not affected.

Eficácia de herbicidas no controle pós-emergente de Sisyrinchium micranthumCav. e Agrostis sp. Abstract -This work aimed to evaluate the effectiveness of herbicides applied during postemergence on weed control in onion crop that recently have infested the onion crop areas in Monte Alto city, São Paulo state, Brazil. Fourteen herbicides, either alone or in mixture, were tested to control Sisyrinchium micranthum Cav. and an unidentified specie of the genus Agrostis. The herbicides used were: flumioxazin, bentazon + ioxynil + oxyfluorfen, fluazifop-p-butyl, fluazifop-p-butil + ioxynil, fluazifop-p-butil + oxyfluorfen, paraquat + oxyfluorfen, paraquat + fluazifop-p-butil + oxyfluorfen, metribuzin, sethoxydim, clethodim + fenoxaprop-p-ethyl, oxadiazon, trifluralin, and oxyfluorfen. Herbicide efficacy was evaluated at 5, 10, 15, 20, 25 and 30 days after herbicide spraying. The herbicides paraquat + oxyfluorfen, paraquat + fluazifop-pbutyl + metribuzin and oxyfluorfen showed good efficacy for Agrostis until 30 DAS and the herbicides bentazon + ioxynil + oxyfluorfen and paraquat + oxyfluorfen was considered satisfactory for S.micranthum.

Entre os fatores ambientais, a deficiência hídrica tem efeito em diversosprocessos morfológicos e fisiológicos das plantas, podendo afetar ocrescimento e o desenvolvimento das culturas, refletindo na produtividade.Diante disso, objetivou-se avaliar as características fisiológicas de genótiposde amendoim submetidos à deficiência hídrica. Realizou-se um experimentoem blocos inteiramente casualizados, com os tratamentos dispostos emesquema fatorial 12 × 2, tendo como tratamentos 12 genótipos e duascondições hídricas, em cinco repetições. Para avaliar o efeito do estresse, aos25 dias após a emergência (DAE), as plantas de amendoim permaneceramsob deficiência hídrica por quatro dias, enquanto as testemunhas forammantidas a 70% da capacidade de campo. Aos 29 DAE, foram realizadas asavaliações de fotossíntese, transpiração, teor relativo de água, teor de ceraepicuticular e massa seca das plantas. A taxa fotossintética foi menor paratodos os genótipos sob deficiência hídrica, exceto para a linhagem 870, quedemonstrou maior tolerância à seca. Para a transpiração, as cultivares RunnerIAC 886, IAC OL3, IAC OL4 e as linhagens 573, 599, 870 não foram afetadospela deficiência hídrica. Entre os genótipos, há variação na quantidade deceras epicuticulares sob condições hídricas. Com relação ao comportamentoanatomofisiológico dos genótipos, concluiu-se que as linhagens 573 e 870são altamente tolerantes à deficiência hídrica, as cultivares IAC OL3, IAC OL4,Runner IAC 886 e as linhagens 599 e 967 são moderadamente tolerantes eIAC 503, IAC 505 e IAC Tatu-ST e as linhagens 322 e 506 são mais sensíveisao estresse hídrico durante a fase de florescimento.

Among the factors that may influence the germination process of seeds, water deficiency is considered the most important. The present study aims to evaluate the physiological response of peanut genotypes to water deficiency. The experiment was conducted in a completely randomized design with four replications in a 12 x 7 factorial scheme with 12 peanut genotypes and seven polyethylene glycol 6000 concentrations corresponding to osmotic potentials of 0.00; -0.10; -0.20; -0.40; -0.60; -0.80 and -1.00 MPa. The data were submitted to analysis of variance and Tukey's test at a 5% probability level and, when significant, to analysis of variance adjusted to a quadratic polynomial curve. The germination percentage, seed vigor evaluated by the speed germination index, mean germination time, root length and root dry matter of some genotypes were affected by the osmotic potentials. Among the genotypes, there is a differential response related to the water deficiency level. In relation to the physiological response of the seeds, the lineages 506, 599, and 870 and the cultivar IAC Tatu-ST have a higher tolerance of water deficit. The peanut genotypes begin to suffer the effects of water deficiency at the osmotic potential of -0.4 MPa.

The aim of this study was to evaluate the weed populations of sweet sorghum hybrid CVSW 81198 and its interference capacity in increasing periods with and without weeding. Two experiments were carried out, one during the summer and another during the autumn in the municipality of Jaboticabal, São Paulo state, Brazil. For each experiment, two treatment groups were established: one consisting of increasing periods without weeding and another of increasing periods with weeding. Periods were 0, 4, 7, 14, 21, 28, 35, 42 and 56 days after emergence (DAE) in the summer experiment and 0, 4, 7, 14, 21, 28, 35, 42, 49, 56, 63 and 100 DAE in the autumn experiment. Phytosociological studies of the weed community were carried out in each treatment, with emphasis on the importance index of each weed population. Under the experimental conditions, Amaranthus spp. and Alternanthera tenella were the most important species in the weed community of sweet sorghum grown during summer and autumn, respectively. With the natural infestation of the weed community, sorghum hybrid CVSW 81198 did not suffer interference in crop development and stem productivity even without weeding throughout the crop cycle.

No abstract