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Effects of Planting Density and Harvesting Time on Productivity of Natural Sweetener Plant ( Stevia rebaudiana Bertoni.) in Larache Region, Morocco

2017; Volume: 7; Issue: 4 Linguagem: Inglês

2163-260X

Abderrahmane Benhmimou, Mohammed Ibriz, Chaouki Al Faïz, Fatima Gaboun, Ahmed Douaik, Fatima Zahra Amchra, Abdelkarim Khiraoui, Mounira Lage,

Botanical Research and Applications

Stevia (Stevia rebaudiana Bertoni) has achieved economic importance due to the different natural steviol glycosides (SG) which are obtained from its leaves which are many times sweeter than sugarcane and sugarbeet. The produvtivity of stevia depends on many agronomical factors such as planting density. A field experiment was conducted from 10th May to 23rd October 2014 in a sandy soil under irrigated conditions to study the effect of plant spacing D1 (70 cm x 30 cm), D2 (70 cm x 20 cm), and D3 (70 cm x 10 cm) on growth, yield, and quality of stevia. Spacing significantly affected plant height, stem diameter, fresh biomass yield, fresh and dry leaf yield, stevioside (STV), rebaudioside A (Reb A), and total SG yield in all the harvests. Higher plant height (79.67 cm) and stem diameter (6.73 mm) were obtained in the wider spacing D1 as compared to closer spacing D3 (65.00 cm and 6.09 mm, respectively) in first harvest (95 days after transplanting). While, highest fresh biomass, dry leaf and total SG yields (cumulative of two harvests) were obtained with D3 (37.23, 4.95, and 0.69 t ha-1, respectively). SG contents were not significantly affected by planting density. However, higher STV and total SG contents were obtained with closer plant spacing D3 (11.27 and 17.20%, respectively) in the first harvest. At the second harvest (72 days after first harvest) significantly lower dry leaf and SG yields were obtained in all the 3 planting densities. The study revealed that under Larache, Moroccan conditions, the higher dry leaf yield and better quality of stevia were obtained in the narrow spacing when plants were harvested during summer season.