Yield, Quality and Water Consumption of Stevia rebaudiana Bertoni Grown under Different Irrigation Regimes in Southern Italy

Abstract

Stevia rebaudiana Bertoni is a herbaceous perennial plant originating in the north-east of Paraguay. Its leaves contain low-calorie sweetening agents that can be used as a natural alternative to artificial sweeteners. The leaves are consumed in special human diets and for the treatment of various diseases. The aim of the present work is to study water consumption, yield potential and quality characteristics of this species under different irrigation levels in southern Italy. The field work was carried out in 2006-2007. Irrigation treatments consisted of a control (T100), irrigated with 100% restitution of water consumption and two treatments that received a water depth of 33% (T33) and 66% (T66) of treatment T100. Watering volume was estimated to replenish the soil profile to field capacity for a depth of 0.40 m. The crop was harvested twice a year, and agronomic performance as well as the major cation and glycoside contents (stevioside and rebaudioside A) were evaluated. Overall, the crop coefficients were similar between the two years, although in each year the second growing period showed higher values due to the higher evaporative demand of this period. Interactions of years with irrigation treatments and harvest time were not significant either for yield or yield components. In both cuts the T100 treatments achieved 40% higher leaf dry yield than T33, while T66 showed intermediate values. The harvest index and water use efficiency showed no differences between the two cuts for the same treatments, while the values of both indices decreased with the increase in irrigation regime. Stevioside, rebaudioside A and cation content in the leaves were unaffected by irrigation regime. In order to develop the field cultivation of this species, field experiments are required to prepare a cultivation protocol as well as a genetic improvement program to develop varieties that better respond to the local environment.

Necesidades hídricas de estevia calculadas con el coeficiente del cultivo

“…En promedio, los Kc variaron entre 0,55 y 1,36, donde los mayores valores se presentaron en la etapa de madurez. Los resultados obtenidos estuvieron por debajo de los reportados por otros autores, cuyos valores hallados estuvieron entre 1,16 y 1,45 (Fronza y Folegatti, 2003) y entre 0,85 y 1,14 en condiciones mediterráneas (Lavini et al, 2008). No obstante, fueron más altos que los reportados por González et al (2002) en Paraguay, en cultivos sembrados sobre 3 cm de mulch de bagazo de caña, cuyos valores estuvieron entre 0,25 y 0,82.…”

“…Diversos valores de Kc han sido reportados para estevia, cuyos valores varían entre 0,25 y 1,16 en etapas iniciales y entre 0,59 y 1,45 en etapas de madurez (González et al, 2002;Fronza y Folegatti, 2003;Lavini et al, 2008;Daza et al, 2015b;Reis et al, 2015;Villafañe et al, 2016). Algunos autores han investigado el cálculo de láminas de riego para estevia con base en el potencial matricial, metodología que resulta muy particular a cada suelo.…”

“…Estos porcentajes recomendados varían desde el 100% hasta el 60% (Lavini et al, 2008;Karimi et al, 2015), para obtener buenos resultados agronómicos.…”

Efecto del potencial mátrico del suelo en el crecimiento del cultivo de estevia (Stevia rebaudiana Bert.)

“…Según estos investigadores, el alto IAF está justificado por los días largos, la alta radiación solar y la ubicación del área del experimento (43ºN), cerca de la máxi-ma radiación incidente para la temporada en la que llevaron a cabo su estudio. Lavini et al (2008) reportan en estevia un IAF de 2,7 para las plantas mantenidas a capacidad de campo, presentando esta variable diferencias significativas entre tratamientos; estos resultados los explican conforme al alto contenido de agua en el suelo del cultivo durante los primeros periodos de crecimiento como consecuencia de la alta precipitación, situación meteorológica distinta en el presente estudio en el que los volúmenes de agua contenidos por el suelo se debieron principalmente a las láminas de riego aplicado.…”

Characterization of Stevia rebaudiana Bertoni Accessions Cultived in Southern Brazil

“…The precipitation is also a limiting factor for stevia and according to Lavini et al (2008) precipitation below 200 mm impairs productivity, directly affecting the production of stevia biomass. In spite of this, dry leaf yield of accessions 4, 9 and 12 were higher than those found by Andolfi et al (2006), Fronza and Folegatti (2003), González et al (2007), Lima Filho et al (2004), Megeji et al (2005), Pal et al (2013Pal et al ( , 2015, and Serfaty et al (2013).…”