Abstract

LAZO, José Vicente  and  ASCENCIO, Jocelyne. Interference between Phaseolus vulgaris L. and Amaranthus dubius Mart.: Functional plant growth analysis in a replacement series model. Bioagro [online]. 2016, vol.28, n.3, pp.151-162. ISSN 1316-3361.

Amaranthus dubius is a common weed in crops of Phaseolus vulgaris in the central and western states of Venezuela. To evaluate the effect of interference on the growth of both species growing under different relative proportions in a replacement series model, the functional plant growth analysis methodology was used. The experiment was conducted under greenhouse conditions, in a completely random arrangement with nine consecutive samplings performed at five-day intervals. Five combinations of relative proportions were used (4:0, 1:3, 2:2, 3:1 and 0:4) with a total density of four plants per experimental unit, consisting of a light opaque container filled to a depth of 18 cm with sandy loam and surface area of 254 cm². At each harvest shoot dry weight and total leaf area of both species were measured. The natural logarithms of these variables were used to calculate for each relative proportion, the instantaneous values ​​of relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), leaf weight ratio (LWR) and specific leaf area (SLA). The leaf area duration (LAD) was calculated by the classic method. The results showed that intrinsic competitive success of P. vulgaris on A. dubius was mainly due to its higher LAD, higher seed size, and higher rate of emergence and seedling development, while the RGR was not a good indicator of the competitiveness ability of the species.

Keywords : Competition weed-crop; net assimilation rate; relative growth rate; substitutive model.

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