Yield response of stevia (Stevia rebaudiana Bertoni) to the salinity of irrigation water

• Stevia yield decreased above 2 dS m−1 of irrigation water (ECw), until 1st harvest.
• At 2nd harvest, yield reduction was observed when ECw exceeded 0.3 dS m−1.
• Stevia may be grown in semiarid and saline regions, if there is only one harvest.
• To obtain two or more harvests only fresh water should be used.

Stevia (Stevia rebaudiana Bertoni) is a relatively unknown crop in Europe, with great potential as a natural sweeteners source. Stevia has a high content of sweeteners, which are up to 150 times sweeter than sugar, but virtually with no calories. Stevia can be cultivated as an irrigated summer crop in Europe, being suitable to be cultivated in semiarid climates and coastal areas, like the Mediterranean region, which are characterized by the low quality of the irrigation water. Here, we studied the growth development and the yield response of stevia to the salinity of the irrigation water in a Mediterranean region (Algarve, Portugal). It was shown that yield was reduced when electrical conductivity of the irrigation water was higher than 2 dS m−1, during the growth period until the 1st harvest. Later, between the 1st and 2nd harvests, yield reduction began when the electrical conductivity of the irrigation water was greater than 0.3 dS m−1. Hence, it was concluded that stevia is suitable to be grown in semiarid and saline regions, if there is only one harvest; to obtain two or more harvests only fresh water with low electrical conductivity should be used. Moreover, it was shown that stevia crop tolerance to salinity was greater than the one of the sugar cane, and crop sensitivity to salinity was lower in stevia than in the conventional sugar crops.