A Study on the Effec t of Soil Amendments and Environmental Conditions of Stevia rebaudiana in Urban Soils of Buenos Aires, Argentina

Abstract

The leaves of wild Stevia plants contain several different natural glycoside compounds responsible for producing the sweet taste sensation. It is used as a sweetener, and has some important properties as regulation of sugar level in blood, and other medical issues. The objective of this work is to study the effects of different soil amendments and the location of the culture, inside or outside a greenhouse, on Stevia rebaudiana growth and final dry weight, at an urban soil. A complete randomized design with 4 replications was used. The effect of two factors on Stevia growth were evaluated: the application with organic amendments and the location, at field and at greenhouse conditions. Amendments treatments were control, liquid vermicompost, compost and vermicompost. The height and diameter of Stevia plants were measured at T2 (vegetative state) and T3 (flowering, ) and final plant dry weight was also weighed at T3. Inside the greenhouse Stevia plants had a higher development, measured by height and diameter growth and by final dry weight accumulation, due to higher temperatures and drip irrigation. Solid amendments, compost and vermicompost, presented higher values of the measured parameters, height, diameter and dry matter, with statistically significant differences from the control and liquid vermicompost; values of these latter treatments did not differ statistically from each other. Differences in diameter growth were more closely related to final dry weight than height growth, which suggests that diameter is a suitable variable to use as an early indicator of growth conditions. In this trial Stevia adapted to existing conditions of the urban soil, slightly acid, non saline and well supplied in organic matter, and completed its cycle properly, with good potential as an organic grown crop.