Potencial competitivo de cultivares de trigo em função do tempo de emergência

Abstract

RESUMO -Características morfofisiológicas de cultivares de trigo definem a sua capacidade em competir com plantas daninhas pelos recursos do meio. Objetivou-se com este trabalho quantificar variações no tempo de emergência, crescimento e desenvolvimento inicial de cultivares de trigo com diferentes ciclos e estatura de plantas. O experimento foi conduzido no ano de 2006 em casa de vegetação da Universidade Federal de Pelotas, em delineamento completamente casualizado com cinco repetições. Os tratamentos foram compostos por sete cultivares de trigo -BRS Guatambu, BRS Tarumã, BRS Timbaúva, BRS Camboatá, BRS Buriti, CD 105 e BRS Camboim -e duas plantas daninhas: nabo e azevém. O tempo de emergência dos cultivares e o das plantas daninhas foram avaliados até os dez dias após a semeadura. Aos 10, 20 e 35 dias após a emergência (DAE), foi determinada a estatura das plantas de trigo e, aos 20 e 35 DAE, o estádio de desenvolvimento. Aos 35 DAE foi determinada a área foliar e a matéria seca das partes aérea e radicular, sendo os dados submetidos à análise de variância e as médias comparadas pelo teste de Duncan. Entre as características avaliadas nos cultivares de trigo, a duração do ciclo e a estatura da planta não influenciaram o tempo de emergência; os cultivares BRS Guatambu, BRS Timbaúva e BRS Camboim foram os que apresentaram maior potencial competitivo no início do ciclo, e o BRS Tarumã, o que apresentou as menores médias para as variáveis morfológicas.Palavras-chave: Triticum aestivum, genótipos, planta daninha, ciclo de desenvolvimento.ABSTRACT -Morphophysiological characteristics of wheat cultivars define their capacity to compete naturally with weed plants. The objective of this study was to quantify variations in emergence time, growth and initial development of wheat cultivars with different cycles and plant heights. This greenhouse experiment was arranged in a completely randomized experimental design, with three replications at the Universidade Federal de Pelotas, in 2006. Treatments consisted of seven wheat cultivars; BRS Guatambu; BRS Tarumã; BRS Timbaúva; BRS Camboatá; BRS Buriti; CD 105; BRS Camboim, and two weed plants, turnip and Italian ryegrass. Emergence time of the cultivars and weed plants was evaluated up to 10 days after sowing. Plant height was determined at 10, 20 and 35 days after emergence (DAE) and development stage at 20 and 35 DAE. Leaf area was measured at 35 DAE as well as dry matter of the aerial parts and roots, with data being submitted to analysis of variance and means compared by the Duncan test. Among the characteristics of the wheat cultivars evaluated, cycle duration and plant height did not affect emergence time with cultivars BRS Guatambu, BRS Timbaúva and BRS Camboim, presenting the highest competitive potential at the beginning of the cycle and BRS Tarumãt showing the lowest means for the morphological variables.

Seed vigor, antioxidant metabolism and initial growth characteristics of red rice seedlings under different light intensities

“…The low number of tillers, in the early ontogeny of the plant, can be explained by greater carbon investment for the growth of the main stem. This process can be reflected in the delay in generating tillers, a fact that contributes to a reduction of the competitiveness of the genotype (Rigoli et al 2009). The number of tillers varies from genotype to genotype, is determined by hormonal balance, and may be dependent on the light available to the plant (Valerio et al 2009).…”

Perspectives for using light quality knowledge as an advanced ecophysiological weed management tool

“…Several studies have found differences among crop genotypes in relation to weed interference (Fischer et al, 1997;Bianchi et al, 2006;Fleck et al, 2006;Murphy et al, 2008;Rigoli et al, 2009). Variability of specific morphological traits has been correlated with the interspecific competition in these studies.…”

Weed Interference Periods in Early Wheat in the Midwest of Paraná

“…Consequently, taller plants show greater competitiveness against weeds because they have more advantage in light interception (Rigoli et al, 2009). …”

“…In addition, the morphological characteristics of cultivated species are also important, since rapid initial growth of crops, high leaf area index, high interception of photosynthetically active radiation and dry matter production favor the competitive ability of crops (Haefele et al, 2004;Bianchi et al, 2006;Rigoli et al, 2009).…”