Etude des principaux facteurs de la production de l'armoise annuelle (Artemisia Annua L.) sur le domaine de l'organisation "Le Relais - Sénégal" à Yendane (région de Thies, Sénégal) : Effet de la densité et de la fertilisation

Abstract

Three tests were conducted with the « Apollo » variety of Mediplant company during the dry season of 2016-2017 in the horticultural domain of « Le Relais - Sénégal » in Yendane-Terokh in order to optimize leaf and stem production of sweet wormwood (Artemisia annua L.). All tests were conducted under sprinkle irrigation; allowing a 50 % gain of yield harvest in comparison with the 2016 yield under drip irrigation. The first test aimed to determine the most suitable plant density with two cuts (most efficient cutting frequency identified in 2016). An additional intermediary cut increased production by 25 % regarding the single cut production, while remaining at an interesting proportion of leaves and stems. The 20 000 plants/ha density distinguished itself from the others by a better production per hectare and by the lowest cost price. Moreover, this density with the spatial system of 1 m x 0,5 m, induced a decrease of Rhizoctonia genus pathogenic fungus which appeared during the trial. The second test aimed to determine the best mineral fertilisation formula and dose adapted to local conditions by testing the effect nitrogen, potassium and phosphorus substraction from the complete fertilizer. Results put in evidence a potassium deficiency in the farm soil and a lack of synergic effect linked to the presence of sulphur in some fertilizer applied. Nitrogen remains the decisive element for plant growth and yield per hectare. An input greater than 29 kg N/ha improved yield and explains the interest for the actual optimal mineral treatment consisting in 47,3 kg N/ha, 4,2 kg P2O5/ha et 8,3 kg K2O/ha. No significant differences were observed between organic treatments and the mineral control fertilizer. The third test aimed to determine the most adapted organic fertilization taking into account its cost and availability in the area. No significant differences were observed in terms of yield between the 6 modalities of poultry or cow-horse manure based organic fertilizer. The cost-effective solution was to input 3 handfuls of cow-horse compost 30, 60 and 90 days after transplantation. From a practical point of view, the 20 000 plant/ha density option, under sprinkler irrigation, with the additional intermediary cut approximately 3 months after transplantation and the input of 47,3 kg N/ha, 4,2 kg P2O5/ha et 8,3 kg K2O/ha was identified as the best crop management technique for the moment being for sweet wormwood production in dry season (transplantation in December – final harvest in the end of May). This technological itinerary enabled a raw material yield for infusion and capsule production of about 8 tons/ha, and a cost price around 0,70 EUR (460 FCFA) per kg with a 50%-50% mix ratio of dried leaves and stems.