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-The repetitive use of iodosulfuron for the control of weeds in winter cereals in the south of Brazil has favored the emergence of resistant Raphanus sativus biotypes. The objective of this study was to evaluate: the response of Raphanus sativus biotypes susceptible and resistant to different dosages of iodosulfuron; the control of biotypes with alternative registered herbicides for the control of the species in crops of wheat, corn and soybean; and the existence of cross-resistance of the biotypes. Thus, four experiments were done in a greenhouse, with a completely randomized design and four replicates. The experimental units were composed of vases with a volumetric capacity of 0.75 L filled with substrate, containing a plant each. For the dose-response curve, three biotypes (factor A) and nine doses of the iodosulfuron herbicide (factor B) were used. For the alternative control, the recommendation was herbicides in pre or postemergence of the crops, and the crossedresistance was evaluated by using herbicides that inhibit the ALS enzyme of different chemical groups. The analyzed variables were control and shoot dry matter. GR 50 of the susceptible biotype (B 1 ) was 0.11 g a.i. ha -1 , whereas GR 50 of resistant biotypes (B 4 and B 13 ) was 102.9 and 86.8 g a.i. ha -1 of the iodosulfuron herbicide, respectively. The resistant biotypes presented crossed resistance to herbicides that inhibit the ALS enzyme, where the control can be efficient with the use of herbicides with different action mechanisms. Keywords:Raphanus sativus, dose-response, acetolactate synthase, weed. RESUMO -O uso repetido do herbicida iodosulfurom para controle de plantas daninhas em cereais de inverno no Sul do Brasil favoreceu o surgimento de biótipos de Palavras-chave:Raphanus sativus, dose-resposta, acetolactato sintase, planta daninha.

-Plants compete for resources present below and above the soil surface. The objective of this work was to separate the individual effects of the competition for resources between soybean and corn as competitor plants. The experiment was conducted in a greenhouse, in 2014/2015. The treatments consisted of soybean cultivars (TEC 5718 and TEC 6029) in competition conditions with corn (no competition, competition for soil resources, competition for solar radiation and total competition). The variables evaluated were plant height at 7, 14, 21, 28, 35 and 42 days after emergence (DAE), stem/culm diameter, leaf area, shoot dry mass, root dry mass and the chlorophyll index, at 42 (DAE). The competition for soil resources between soybean and corn is pronounced, being that short cultivars with determinate growth habit, such as TEC 5718, invest more in root biomass, specific leaf area and leaf area ratio when in competition. The soybean cultivars do not suppress corn, but allow it to benefit when associated to its root system, increasing the shoot and root dry mass, leaf area and chlorophyll index.Keywords: Glycine max, Zea mays, water, competitiveness, solar radiation, competitor plant. de plantas, aos 7, 14, 21, 28, 35 RESUMO -As plantas competem por recursos presentes abaixo e acima da superfície do solo. O objetivo deste trabalho foi separar os efeitos individuais da competição por recursos entre a soja e o milho como planta competidora. O experimento foi conduzido em casa de vegetação, em 2014/15. Os tratamentos consistiram de cultivares de soja (TEC 5718 e TEC 6029) sob condições de competição com milho (ausência de competição, competição por recursos do solo, competição por radiação solar e competição total). As variáveis avaliadas foram estatura

The global temperature to rise 0.3 to 4.8 oC to century. Supra-optimal temperatures can affect plants at different organizational levels, causing morphological, physiological, biochemical and gene expression alterations. Rice, weedy rice, and barnyardgrass may to response differently when subjected to supra-optimal temperatures. Thus, the aimed at determining the physiological response and expression of the genes APX2, HSP24.15 e HSP71.10 in rice, weedy rice, and barnyardgrass when in to supra-optimal temperatures. A greenhouse experiment was conducted in randomized complete desing with four repetitions, with a factorial combination of temperature x plantas, where: factor A consisted of two temperatures (25 oC and 40 oC); and factor B of three plants [rice (Oryza sativa cv. Puitá INTA-CL), weedy rice (Oryza spp.), and barnyardgrass (Echinochloa spp.)]. The 40 oC temperature, in general, caused a reduction in the photosynthesis parameters and in the protein content, and increased the oxidative stress in C3 plants; no damage was observed in the C4 plant subjected to this temperature. In response to the supra-optimal temperatures, rice and weedy rice increased of APX and SOD activity and the expression of OsAPX2, OsHSP24.15 and OsHSP71.10 genes. Barnyardgrass exposed to supra-optimal temperature do not modify the activity of its antioxidant system and increased the OsHSP71.10 gene expression.

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