Abstract

JARMA O, Alfredo; CARRANZA G, Carlos  and  CLAVIJO P, Jairo. Light capture and use by plants of stevia (Stevia rebaudiana Bert.) in the Colombian Caribbean. Agron. colomb. [online]. 2010, vol.28, n.1, pp.37-46. ISSN 0120-9965.

The capture and efficient use of solar radiation in stevia, a noncaloric sweetener producing species, is a fundamental aspect of its cultivation in the hot neotropical regions of Colombia. Notwithstanding, works dealing with this aspect are currently scarce. On these grounds, the present research study sought to determine the effect of photosynthetically active radiation (PAR) on the biomass production of stevia genotypes Morita 1 (M1) and Morita 2 (M2), at planting densities of 25.00, 12.50 and 6.25 plants/m2. The experiment was conducted in the municipality of Monteria (Cordoba, Colombia), during the dry seasons of 2007 and 2008 (E1 and E2). In both occasions, a completely randomized block design with a 2 x 3 factorial arrangement was applied. A mathematical model calculated calculated the cumulative daily rate of dry matter (DM) production for leaves and stem (simulated with Euler's integration method), using light use efficiency (LUE), PAR and its intercepted-by-the-canopy fraction (FLINT) as inputs. During E1, the dry mass record was 3 MJ m^-2 day^-1 larger than that of E2; and the foliar area index (FAI) (3.12±0.02) was almost three times that of E2. As a consequence, the highest value of the light extinction coefficient (k= 0.21) was recorded in the 25 M2 plants/m2 experiment during E1. This same season allowed the highest LUE values (2.04 g MJ PAR), as well as the largest record of DM distribution to the leaves, which raised up to 60% in the case of M2.

Keywords : dry matter distribution; simulation models; photosynthetically active radiation; sweetness.

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