Abstract

BARACALDO A., Adriana del P.; IBAGUE O., Alejandra  and  FLOREZ R., Víctor J.. Rates and indexes of standard carnation cv. Nelson grown in soil and substrates to second harvest peak. Agron. colomb. [online]. 2010, vol.28, n.2, pp.209-217. ISSN 0120-9965.

Because of sanitary problems, Colombian carnation growers have adopted soilless cropping systems, which make use of burnt rice husk substrates. Hence, the objective of the present research study, conducted in the SENA facilities at the multisectorial center of the municipality of Mosquera, was the evaluation of a series of growth parameters of the second harvest peak of standard carnation cv. Nelson grown on soil and on the following substrates (treatments): 100% burnt rice husks, 65% burnt rice husks plus 35% coconut fiber, and 35% burnt rice husks plus 65% coconut fiber. By means of destructive sampling we measured foliar area and dry mass by plant organs. Based these data, we modeled the growth curves of the crop, and calculated the following parameters: leaf weight ratio, leaf area index, specific leaf area, relative growth rate, net assimilation rate and crop growth rate. Leaves dry mass was significantly higher in the soil treatment than in the 100% burnt rice husks one. Total dry mass data indicate that the former treatment determines a lower and later absolute growth rate, from which a low assimilate export can be inferred. These same plants also showed lower specific leaf area, indicating they have thicker leaves. The behavior of the relative growth, net assimilation and crop growth rates reveals that the substrate grown plants tend to export more assimilates to the flower bud than those grown on soil.

Keywords : organic substrates; soilless culture; dry mass allocation; cut flower.