Efeito da época e local de semeadura na interferência das plantas daninhas na cultura do amendoim

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos de períodos de interferência na comunidade infestante e na produtividade da beterraba

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variações nos níveis de elementos minerais após aplicações de 2,4-D em progênies de Eucalyptus grandis

Pós-graduação em Ciência Florestal - FCA

Interferência de Digitaria insularis em Coffea arabica e respostas destas espécies ao glyphosate

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Crescimento de Brachiaria plantaginea e Raphanus raphanistrum em convivência com híbridos de milho submetidos a períodos de controle das plantas daninhas

The objective of this experiment was to evaluate the effects of corn hybrid cultivation and weed control periods on the population and growth of the weeds B. plantaginea and R. raphanistrum. The trial was set at Universidade Estadual the São Paulo (UNESP), Botucatu Campus, São Paulo - Brazil. A completely randomized block design with four replications was used. The treatments were arranged in a factorial scheme with four corn hybrids (C701, DINA170, XL678, and C125) and four manual weed control periods [a. 15 days after emergence (DAE); b. 15 and 30 DAE; c. 15, 30 and 45 DAE, and d. weedy]. The hybrids DINA170 and C125 significantly decreased the density of B. plantaginea. The hybrids C701, DINA170 and XL678 affected the growth of the plants, but they did not affect the emergence of new plants of R. raphanistrum. Hand-hoeing at 15 DAE decreased the dry matter weight of the weeds B. lantaginea and R. raphanistrum by 93.1%, 95.4% and 89.2%, respectively, at harvest of the four hybrids.

Alterações morfoanatômicas foliares da cana-de-açúcar na fase de estabelecimento em condições de matocompetição

Aiming at the assessment of the production parameters and leaf tissues morph anatomical possible changes of the sugar cane RB 86 7515 variety in its establishment phase in the conditions of weed competition, a study over vases has been accomplished in the city of Dracena, São Paulo State, from April to June, 2010, at Universidade Estadual Paulista Júlio de Mesquita Filho. The species Brachiaria brizantha e Brachiaria decumbens, which are regarded as invaders, were used. It was also used the Completely Randomized Design with seven treatments and five repetitions, totalizing 35 lots or vases. The treatments ranged according to the number of Brachiaria brizantha and Brachiaria decumbens seeds, as it follows: T1 - no occurrence of weed competition; T2 - low occurrence of weed competition with Brachiaria brizantha; T3 - medium occurrence of weed competition with Brachiaria brizantha; T4 - high occurrence of weed competition with Brachiaria brizantha; T5 - low occurrence of weed competition with Brachiaria decumbens; T6 - medium occurrence of weed competition with Brachiaria decumbens, and T7 - high occurrence of weed competition with Brachiaria decumbens. There was an evaluation over the following issues after 60 days of the sugar cane plantation and the invading plants: the weight of the total dry matter of the plants, the thickness of the upper surface epidermis or adaxial, the thickness of the lower surface or abaxial, the thickness of the mesophill, the thickness of the limbo, the diameter of the xylematic vessels and the diameter of the phloem vessels. The weed competition of the species Brachiaria brizantha e Brachiaria decumbens, which are considered as invaders, provoked some reduction of the morph anatomical characteristics and of the sugar cane production. In general, the Brachiaria decumbens was the species which mostly influenced the leaf thickness of the sugar cane in negative aspects.

Épocas e extensões do período de convivência das plantas daninhas interferindo na produtividade da cultura do milho (Zea mays)

Q field experiment was carried out at the Gralha Azul Experimental Farm/PUCPR, in the municipality of Fazenda Rio Grande-PR, to evaluate the effect of different times and coexistence extension periods of weeds interfering in corn yield. The experiment was arranged in a complete randomized complete block design and the treatments in a 4x5+2 factorial, with four replications. The treatments were as follows: four initial weed control periods (0-0, 0-7, 0-14 and 0-21 DAE) and five restarted weed control periods until the harvest (28, 42, 56, 70 and 84 DAE) and two checks, weedy and weed-free. The experiment was carried out under a no-till system. The period prior to weed interference (PBWI), the start of the critical period of weed interference (CPWI) and the infesting community were evaluated. When the initial weed control period was 0-0 day, the PPWI was at 9 DAE of corn; however, with increasing initial weed control periods (0-7, 0-14 and 0-21 DAE) the period prior to weed interference inncreased in relation to 0-0 day of the initial weed control, evidencing the existence of PPWI-S of 17, 24 and 28 DAE of corn, respectively. Thus CPWI initiates at the end of PPWI-S, the period when weed control is indispensable to prevent a significant reduction in corn yield. Coexistance with the weeds throughout the crop cycle reduced yield in 15%, compared to the weed-free check. Nine species of seven botanical families were assessed in the infesting community. Reduced density and dry mass were verified in the weeds that coexisted with corn, compared to those that grew without it, thus evidencing a suppressive effect of corn over the infesting plants.

Eficácia de herbicidas aplicados em pré-plantio incorporado na cultura da cana-de-açúcar

Pós-graduação em Agronomia - FEIS

Even-sowing pattern strategies for a low-input agricultural system in forage maize

The objective of this study was to verify the effectiveness of new patterns of sowing and to achieve a low-input organic system in two different environments (northern and southern Europe). The study was motivated by the hypothesis that more even sowing patterns (triangular and square) would significantly enhance the growth and yield of forage maize under widely varying conditions, compared with traditional mechanised rectangular seed patterns. An experiment was conducted in Madrid and duplicated in Copenhagen during 2010. A random block design was used with a 2 × 2 factorial arrangement based on two seed-sowing patterns: traditional (rectangular) and new (even) and two weed-management conditions (herbicide use and a low-input system). In both weed-management conditions and locations, the production of aerial maize biomass was greater for the new square seed patterns. In addition, the new pattern showed a greater effectiveness in the control of weeds, both at the initial crop stages (36 and 33% fewer weeds m-2 at the 4- and 8-leaf stages, respectively, in the Copenhagen field experiment) and at the final stage. The final weed biomass for the new pattern was 568 kg ha-1 lower for the Copenhagen experiment and 277 kg ha-1 lower in Madrid field experiments. In the light of these results, the new pattern could potentially reduce the use of herbicides. The results of the experiments support the hypothesis formulated at the beginning of this study that even-sowing patterns would be relatively favourable for the growth and yield of the maize crop. In the near future, new machinery could be used to achieve new seed patterns for the optimisation of biomass yield under low-input systems. This approach is effective because it promotes natural crop-weed competition.

EFEITOS DE DIFERENTES TIPOS DE CONTROLE DE PLANTAS INFESTANTES SOBRE A MIRMECOFAUNA EM Eucalyptus grandis

Este estudo teve como objetivo avaliar os efeitos de diferentes tipos de controle de plantas infestantes sobre a mirmecofauna em um plantio inicial de Eucalyptus grandis . Para tanto, em março de 2011 foi realizado o início da implantação da cultura, em uma área localizada no município de Santa Maria - RS. Os seis tratamentos constituíram-se em controle químico total de plantas infestantes, na linha e na entrelinha de plantio, com glifosato (T1); controle químico total de plantas infestantes, na linha de plantio, com glifosato (T2); controle químico de monocotiledôneas na linha e entrelinha de plantio, com setoxidim (T3); controle químico de dicotiledôneas na linha e entrelinha de plantio, com bentazona (T4); controle químico total de plantas infestantes em faixa de um metro paralela à linha de plantio, com glifosato, e de um metro na parte central da entrelinha, sem controle (T5); e testemunha, sem controle de plantas infestantes (T6). O levantamento da mirmecofauna foi realizado no período de um ano utilizando-se três métodos de coleta: isca atrativa, armadilha de solo e funil de Berlese, com seis repetições por tratamento, em cada data de coleta. Nesse período foram coletadas 46.675 formigas, distribuídas em 37 espécies, não sendo verificada diferença significativa entre o total de espécimens coletados. Na área do tratamento constituído pelo controle de plantas infestantes somente na linha de plantio verificou-se eficiência amostral de 99,0% e Sobs = 35. Entre os índices de Diversidade de Shannon (H’), destacou-se o valor encontrado para a área do tratamento T2 (H’= 1,34) em detrimento dos valores das áreas nas quais foram instalados os tratamentos T1 (H’= 1,25) e T5 (H’= 1,23). Havendo assim, uma maior coexistência de espécies de formigas entre as áreas com estrutura florística menos alterada e entre as áreas mais simplificadas. Não tendo sido verificada correlação significativa (r = 0,0463) entre a riqueza de espécies de formigas coletadas e o número de plantas infestantes encontradas ao final do experimento. Assim, conclui-se que os efeitos indiretos da ação dos herbicidas afetam mais a composição local de espécies de formigas do que sua riqueza.

Periods of weed interference in chicory cultivars development in indirect sowing system

Chicory (Cichorium intybus L.) is an important broadleaves vegetable, consumed in salads and recognized by nutritional, pharmacological properties and its low calorie value. With the objective of assessing weeds interference periods over chicory crop in indirect sowing, two experiments were carried out at Garça County, São Paulo State, by using “Folhas Amarelas - Radiche” and “Folha Larga” cultivars and spacing of 0.25×0.25 m. Treatments consisted of checks with and without weeds and infestation control periods, so that crop was maintained in presence or absence of coexistence with weeds until 7, 14, 21, 28 and 35 days after seedlings transplant (DAST). Results demonstrated that “Folhas amarelas - Radiche” and “Folha Larga” chicory cultivars transplanted on winter, allowed occurrence of initial period of cohabitation with weeds (6 and 5 IPCW) greater than final period (14 and 9 FPCW), conferring, respectively, the establishment of critical periods for weed control (CPWC) in intervals of 6th to 14th and 5th to 9th days after crop transplant. Medium reduction of yield in function of weeds interference during the whole crop cycle was about 52.0% and 54.4%, respectively, for “Folhas amarelas - Radiche” and “Folha Larga” cultivars. It is important to mention that these results indicated the real need for conducting early weed control in chicory crop cultivation, even when carried out in indirect sowing system, as well as it characterizes the importance of a greater number of regional information to successfully consolidate management alternatives, less costly and more efficient in order to guarantee superior yields.

The combined effect of biological control with plant competition on the management of parthenium weed (Parthenium hysterophorus l.)

Parthenium hysterophorus L., (Asteraceae) commonly known as parthenium weed, is a highly invasive plant that has become a problematic weed of pasture lands in Australia and many other countries around the world. For the management of this weed, an integrated approach comprising biological control and plant competition strategies was tested in southern central Queensland. Two competitive pasture plant species (butterfly pea and buffel grass), selected for their high competitive ability, worked successfully with the biological control agent (Epiblema strenuana Walker) to synergistically reduce the biomass of parthenium weed, by between 62 and 69%. In the presence of biological control agent, the corresponding biomass of competitive plants, butterfly pea and buffel grass increased in comparison to when the biological control agent had been excluded, by 15 and 35%, respectively. This suggests that biological control and competitive plants can complement one another to bring about improved management of parthenium weed in Australia. Further, this approach may be adopted in countries where some of the biological control agents are already present including South Africa, Ethiopia, India, Pakistan and Nepal.

Weed interference on maize (Zea mays) under no tillage system

A field trial was carried out in Brazil in March 2002 with the aim to evaluate the effects of different timing and extension of weedy period on maize productivity. The hybrid Pioneer 30K75 was sowed under 7 t ha(-1) mulching promoted by glyphosate spraying. The treatments were divided in two groups: In the first group, weeds were maintained since the maize sowing until different periods in the crop cycle: 0, 14, 28, 42, 56, 70, and 150 days (harvesting time). In the second group, the maize crop was kept weed free for the same periods of the first group. Weed control was done through hand hoeing. A complete randomized blocks experimental design with five replications was used for plots distribution in the field. Nonlinear regression model was used to study the effects of weedy or weedfree periods on maize productivity. Weed community included 13 families and 31 species. Asteraceae, Poaceae, and Euphorbiaceae were the most abundant families. Results showed that under no tillage condition with 7 t ha-1 mulching at sowing time, the maize crop could cohabit with weed community for 54 days without any yield lost. on the other hand, if the crop was kept weed free for 27 days, the weed interference was not enable to reduce maize production. According to these results one weed control measure between 27 and 54 days after crop emergence could be enough to avoid any reduction in maize productivity.

Critical periods of weed control in naturally green colored cotton BRS Verde

Cotton with naturally colored fiber is increasing as a commercial crop due specially to its textile processing with reduced environmental impact, as dying is not necessary. The critical period of weed control and the weed community were studied in a field with the naturally green colored fiber cv. BRS Verde cultivated in Missao Velha, Brazil. Without weed control during all the cycle, a reduction of 82.9% in yield was observed. The critical period of weed control was between 31 and 74 days after emergence for a reduction of 5% in yield. The weed community was composed of 21 species, with higher relative importance and dominance of monocotyledonous species. The beginning of the critical period was found to be more influential on yield than the ending. Thus, defining the right moment to start weed control can be more important to yield than determining the moment to cease it. (C) 2011 Elsevier B.V. All rights reserved.

Weed interference on coffee fruit production during a four-year investigation after planting

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)