Abstract

JARMA, Alfredo; RENGIFO, Teresita  and  ARAMENDIZ-TATIS, Hermes. Physiology of stevia (Stevia rebaudiana) regarding radiation near the Colombian Caribbean coast.: II. Growth analysis. Agron. colomb. [online]. 2006, vol.24, n.1, pp.38-47. ISSN 0120-9965.

Stevia rebaudiana Bertoni is a plant which produces a variety of high-potency, low-calorie sweetener in its leaf tissue. Its sweetening potential is considered to be 300 times greater than sucrose. Stevia sweeteners are used in food products in a number countries including Japan, Brazil and China and, more recently, in Colombia. The research was carried out from July 2002 to April 2003 in the Universidad de Córdoba’s Agricultural Sciences’ fields in Montería, Colombia. The study was aimed at evaluating the effect of four levels of incident radiation on Stevia rebaudiana growth in the Sinu river valley’s climatic conditions. A completely random design used incident radiation levels (19%, 24%, 56% and 100%) and stevia genotypes (‘Morita 1’ and ‘Morita 2’) as factors. The most important results indicated that ‘Morita 2’ exposed to 100% incident radiation presented the highest absolute growth rate (AGR); this could possibly be attributed to this variety’s genetic advantage allowing it to carry out greater photosynthesis. Relative growth rate (RGR) was high in both genotypes at the beginning of the cycle (the first 60 days following transplant) for shady levels (19% and 24%); once this stage was finished, the high radiation produced greater increases RGR. ‘Morita 2’, exposed to 100% incident radiation, presented the greatest net assimilation rate (NAR), suggesting greater efficiency in daily biomass production for each square centimeter of leaf surface per day.

Keywords : incident radiation; shade; growth index; dry matter.

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