Agronomic-productive characteristics of two genotypes of Stevia rebaudiana in Central Italy [Toscana]
2006
Andolfi, L. | Macchia, M. | Ceccarini, L.
Stevia rebaudiana Bertoni produces a variety of high-potency low caloric sweeteners in its leaf tissues. The aim of this work was to evaluate the productive potential of two different Stevia rebaudiana genotypes and the characteristics of the production of the plant obtained through different cultivation methods, in Central Italy. For several years (1992-2000), agronomic trials on Stevia rebaudiana cultivated in the littoral area near Pisa (Italy) were carried out. In 1992, two different genotypes of Stevia (B1 and B2) transplanted in silt-loam soil, in 1996 other plants from B2 genotype, produced by vegetative process (micropropagation), were transplanted in the same field. In the period 1992-1999 the production of leaves from both genotypes increased since the third year and the ratio leaf-aerial plant, after the peak in the third year, tended to decrease. Excepting the first year (1997), no statistically significant differences between the two propagation methods, related to leaf production, were observed. The amount of leaves produced from a single harvest was lower than the one resulting from two cuttings and the micropropagated plants produced a larger amount of leaves compared to the ones from cutting. The leaf-stem ratio is an interesting morphological and production character of the plant. Stevia rebaudiana appears particularly suited for the cultivation in environments of Central Italy. A particular positive aspect to be considered in these regions is that Stevia can be grown successfully as pluriennial species because crop survival over the Winter is high. The results obtained show that this species is economically profitable until the 5th or 6th year of cultivation. At our latitudes, it is also necessary to establish a program of genetic improvement in order to develop earlier varieties that can guarantee an optimum qualitative and quantitative seed production
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