Períodos de interferência de erva-quente (Spermacoce atifolia) no crescimento inicial de eucalipto (Eucalyptus grandis)

The buttonweed (Spermacoce latifolia) is becoming a plant among the most current infesting eucalypts plantation in State of São Paulo due to the continual use of same herbicides and control methods. Owing this, this work aimed to evaluate the effects of periods of company and control of S. Iatifolia on the initial growth of Eucalyptus grandis, planted in winter and summer. Only one seedling of Eucalyptus was planted in amianthus cement box and submitted for crescent periods of company and control of S. Iatifolia (0, 20, 60 and 80 days in competition or not). The densities of plants of S. Iatifolia were 4 and 16 plants per m 2 (under winner and summer conditions). The experimental period was 100 days after the planting (DAP). The experimental design for both experiments was the completely randomized blocks (CRB) with ten treatments and four replicates. The results of plant high, stem diameter, dries weights and leaf area showed that the before interference period (BIP), whole period of prevention for interference (WPPI) and critical period of prevention for interference (CPPI) were 40, 60, and 60 DAR, respectively, under winner conditions. Under summer conditions, the WPPI and CPPI were 20, 80 and 20 to 80 DAR.

Risk prediction for weed infestation using classification rules

This paper proposes a fuzzy classification system for the risk of infestation by weeds in agricultural zones considering the variability of weeds. The inputs of the system are features of the infestation extracted from estimated maps by kriging for the weed seed production and weed coverage, and from the competitiveness, inferred from narrow and broad-leaved weeds. Furthermore, a Bayesian network classifier is used to extract rules from data which are compared to the fuzzy rule set obtained on the base of specialist knowledge. Results for the risk inference in a maize crop field are presented and evaluated by the estimated yield loss. © 2009 IEEE.

Influéncia da adubação nitrogenada sobre a interferéncia de plantas daninhas em feijoeiro1

The competition between weeds and bean plants, especially because of nutrients in the environment, is extremely important to minimize potential losses of crop productivity. Thus, the aim of this work was to evaluate the effects of using nitrogen fertilization on the timing and extent of the period before interference (PAI), total period of interference (PTPI) and the critical period of interference control (PCPI) in bean cultivar 'Ruby'. The seeds were sown in the conventional system and the trial was conducted in two areas at the same time, in which the nitrogen fertilization was performed only in one of them. Each area received 14 treatments consisting of two groups: first, the crop was free of interference of weeds from emergence to 10, 20, 30, 40, 50, 60 and 70 days; and the second: the crop remained free of interference from sowing to the same periods described above. The experimental design was randomized blocks with four replications. Raphanus raphanistrum showed greater relative importance in the two areas, mainly due to the accumulation of dry mass, followed by Amaranthus deflexus. There was no difference in diversity and evenness of weed populations in response to the fertilization. In the area without N PAI occurred 18 days after emergence (DAE), and up to 24 DAE PTPI, resulting in PCPI 18 to 24 DAE, this area had 58% of reduction in crop yield. In the area where with nitrogen fertilization, PAI occurred at 38 DAE and PTPI occurred at 19 DAE. In this area there was 56% of reduction in crop yield. The nitrogen fertilization increased crop productivity and favored competitiveness in relation to weeds.

Indices of competition and bio-agroeconomic efficiency of lettuce and tomato intercrops in greenhouses

Intercropping is a cropping system for the production of greenhouse vegetables. It uses space more efficiently, thus reducing the cost of production. Intercropping tomato and lettuce has not been studied, but knowledge of the competitive and agroeconomic indices of these vegetables can help in the management of the intercropping system. The objectives of this study were to assess, through biological and agroeconomic indices, the competition between species and the profitability of intercropping tomato and lettuce at different times of transplantation over two growing seasons (autumn-winter and summer-winter) in greenhouse conditions. In autumn-winter, two experiments were conducted with a randomised complete-block design and five replicates. Tomato and lettuce were the main crops in the individual experiments. Treatments were arranged in a factorial of two cropping systems (intercropping and individual crops) with four transplants of the secondary crop (0, 10, 20 and 30 days after) plus an additional treatment (individual main crop). These two experiments were repeated in summer-winter. Tomato was the dominant crop regardless of transplant order. Intercropping systems established with transplants of both species on the same day had higher values of indices of competition and bio-agroeconomic efficiency than systems with longer periods of transplants between main and secondary crops. The intercropping of lettuce and tomato in greenhouses, regardless of transplant time or order, had bio-agroeconomic advantages over individual crops. The transplantation of tomato after lettuce is recommended for greater profitability.

Estudo fitossociológico e interferência das plantas daninhas na nutrição e produtividade do quiabeiro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Período anterior da interferência das plantas daninhas no amendoim em resposta a densidade de plantas e espaçamentos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Períodos de interferência de plantas daninhas em algodoeiro cultivares BRS Safira e BRS Verde

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Impact of the timing and duration of weed control on the establishment of a rubber tree plantation

A produção da seringueira é reduzida pelas plantas daninhas que competem por recursos ambientais; portanto, a época e duração do controle de plantas daninhas influencia a interferência das plantas daninhas. Os objetivos deste estudo foram: avaliar o crescimento de plantas de seringueira (Hevea brasiliensis), determinar o período crítico para controle das plantas daninhas e avaliar a recuperação do crescimento das seringueiras que conviveram com plantas daninhas por diferentes períodos de tempo após o plantio. Dois grupos de tratamentos foram estabelecidos em condições de campo, no primeiro ano de investigação: um grupo conteve períodos crescentes de infestação de plantas daninhas, enquanto o outro conteve períodos crescentes de controle das plantas daninhas, também incluindo uma testemunha livre de plantas daninhas e uma testemunha com infestação total de plantas daninhas. No segundo ano da investigação, as plantas daninhas foram totalmente controladas. Urochloa decumbens foi a planta daninha dominante (mais de 90% de cobertura). O crescimento da cultura foi grandemente reduzido devido à interferência de plantas daninhas. A altura de plantas decresceu mais rapidamente que qualquer outra característica. Altura de planta, massa seca de folhas e área foliar decresceram em 99%, 97% e 96%, respectivamente, e foram as características mais reduzidas. A altura de plantas também se recuperou mais rapidamente que qualquer outra característica quando o período de controle das plantas daninhas foi entendido. Contudo, a massa seca do caule aumentou em 750%, fazendo desta a característica mais recuperada. O período crítico para o controle de plantas daninhas foi entre 4 e 9½ meses após o plantio, no primeiro ano; contudo, as seringueiras mostraram expressiva recuperação do crescimento quando as plantas daninhas foram controladas ao longo do segundo ano.

Comparação entre métodos para determinar o período anterior à interferência de plantas daninhas em feijoeiros com distintos tipos de hábitos de crescimento

Beans grain productivity may be reduced by up to 80% and, therefore, knowing the proper time to control weeds becomes fundamental, his research was conducted in order to determine the period prior to interference (PPI) on bean cultivars of different types'plant growth through distinct approaches: arbitrary level of 5% productivity loss; tolerance level (TL), and the Weed Period Prior to Economic Loss (WEEPPEL). Experimental treatments were constituted of ten periods of coexistence, periods of the crop with the weeds: 0-7; 0-14; 0-21; 0-28; 0-35; 0-42; 0-49; 0-56; 0-97 (harvesting) days after emergency (DAE), and a control plot, weed free for the entire period. The experimental design was of the Random Block Design, with four replications. PPI was obtained in all of the different approaches, and the bean plant type II with indeterminate growth had the lowest times of coexistence.

Interação entre Sorgo Sacarino e plantas daninhas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Food Competition in a Semi-Free-Ranging Cebus apella Group

The competitive regime faced by individuals is fundamental to modelling the evolution of social organization. In this paper, we assess the relative importance of contest and scramble food competition on the social dynamics of a provisioned semi-free-ranging Cebus apella group (n=18). Individuals competed directly for provisioned and clumped foods. Effects of indirect competition were apparent with individuals foraging in different areas and with increased group dispersion during periods of low food abundance. We suggest that both forms of competition can act simultaneously and to some extent synergistically in their influence on social dynamics; the combination of social and ecological opportunities for competition and how those opportunities are exploited both influence the nature of the relationships within social groups of primates and underlie the evolved social structure. Copyright (c) 2008 S. Karger AG, Basel

Competition for neuronal resources: how hallucinations make themselves heard

BACKGROUND: Hallucinations are perceptions in the absence of a corresponding external sensory stimulus. However, during auditory verbal hallucinations, activation of the primary auditory cortex has been described. AIMS: The objective of this study was to investigate whether this activation of the auditory cortex contributes essentially to the character of hallucinations and attributes them to alien sources, or whether the auditory activation is a sign of increased general auditory attention to external sounds. METHOD: The responsiveness of the auditory cortex was investigated by auditory evoked potentials (N100) during the simultaneous occurrence of hallucinations and external stimuli. Evoked potentials were computed separately for periods with and without hallucinations; N100 power, topography and brain electrical sources were analysed. RESULTS: Hallucinations lowered the N100 amplitudes and changed the topography, presumably due to a reduced left temporal responsivity. CONCLUSIONS: This finding indicates competition between auditory stimuli and hallucinations for physiological resources in the primary auditory cortex. The abnormal activation of the primary auditory cortex may thus be a constituent of auditory hallucinations.

Compensatory growth in moose and its relationship to sex, longevity, intraspecific competition, and senescence

Individual life history theory is largely focused on understanding the extent to which various phenotypes of an organism are adaptive and whether they represent life history trade-offs. Compensatory growth (CG) is increasingly appreciated as a phenotype of interest to evolutionary ecologists. CG or catch-up growth involves the ability of an organism to grow at a faster-than-normal rate following periods of under-nutrition once conditions subsequently improve. Here, I examine CG in a population of moose (Alces alces) living on Isle Royale, a remote island in Lake Superior, North America. I gained insights about CG from measurements of skeletal remains of 841 moose born throughout a 52-year period. In particular, I compared the length of the metatarsal bone (ML) with several skull measurements. While ML is an index of growth while the moose is in utero and during the first year or two of life, a moose skull continues to grow until a moose is approximately 5 years of age. Because of these differences, the strength of correlation between ML and skull measurements, for a group of moose (say female moose) is an indication of that group’s capacity for CG. Using this logic, I conducted analyses whose results suggest that the capacity for CG did not differ between sexes, between individuals born during periods of high and low population densities, or between individuals exhibiting signs of senescence and those that do not. The analysis did however suggest that long-lived individuals had a greater capacity for CG than short-lived individuals. These results suggest that CG in moose is an adaptive trait and might not be associated with life history trade-offs.

Choosing the Path of Austerity: How Policy Coalitions Shape Welfare-policy Choices in Periods of Fiscal Consolidation

In general, fiscal adjustments are associated with significant reductions in social spending. Hence, the welfare state is not spared from austerity. Because the welfare state is still central to party competition, this is electorally risky. The paper addresses the following questions: Do left parties differ from their centrist and rightist competitors in the design of austerity measures? And does government type has an impact on the extent to which austerity policies rely on social spending cuts? By comparing 17 OECD countries between 1982 and 2009 we show that if governments embark on a path to austerity, their ideology does not have a significant effect on the magnitude of welfare state retrenchment. However, if major opposition parties and interest groups rally against social spending cuts, a broad pro-reform coalition is a crucial precondition for large fiscal consolidation programs to rely on substantial cuts to social security.

Ball possession effectiveness in men's and women's elite basketball according to situational variables in different game periods

The aim of the present study was to identify the importance of floorball tactical variables to predict ball possession effectiveness, when controlling quality of opposition and game periods. The sample was composed by 1500 ball possessions, corresponding to 14 games randomly selected from the International Championships played during 2008 and 2010 (World Championship, Four nations tournament and classificatory phases for World Championship) by teams from different competition levels (HIGH, INTERMEDIATE and LOW). The effects of the predictor variables on successful ball possessions according to the three game contexts (HIGH vs. HIGH; HIGH vs. LOW; LOW vs. LOW games) were analyzed using Binomial Logistic Regressions. The results showed no interaction with the game period. In HIGH vs. HIGH games, quality of opposition showed an association with ball possession effectiveness with ending zone, offensive system, possession duration, height of shooting and defensive pressures previous to the shot. In HIGH vs. LOW games the important factors were the starting zone, possession duration, defensive pressure previous to the last pass and to the shot, technique of shooting and the number players involved in each ball possession. Finally, in LOW vs. LOW games, the results emphasized the importance of starting and ending zones, the number of passes used and the technique of shooting. In conclusion, elite floorball performance is mainly affected by quality of opposition showing different game patterns in each context that should be considered by coaches when preparing practices and competitions.