Effect of drought/irrigation on proximate composition and carbohydrate content of two enset [Ensete ventricosum (Welw.) Cheesman] clones

Abstract

Enset [Ensete ventricosum (Welw.) Cheesman] is an important root crop serving as a carbohydrate rich food source in Ethiopia. Perennial crops, like enset, are often exposed to recurrent dry periods which could greatly affect their growth, physiology and yield. The effect of induced drought/irrigation on the proximate composition and carbohydrate content of harvestable plant parts (pseudostem and corm) of two field grown enset clones (Ameratye and Yesherakinkye) was investigated. Proximate analysis showed that extended drought significantly (P £0.05) reduced crude protein, ash content, potassium and phosphorus contents of enset pseudostem and corm of the two clones. On the other hand, crude fibber content and calcium levels were significantly higher in droughted groups than irrigated ones. There were no significant treatment effects on crude fat content and /or magnesium levels. Moreover, drought resulted in a significant increase in the level of soluble sugars and a decline in starch content of plant parts in both clones. Droughted plants accumulated 2–4 fold more soluble sugars than irrigated groups while the latter group gained 14–23% more starch. There was no significant difference between the two clones for the parameters considered. Low nutrient content of droughted plants could be the result of reduced nutrient uptake and assimilation caused by low soil water content and limited energy source (carbon skeleton). The observed increase in soluble sugars could be an indication of osmotic adjustment mechanisms in droughted enset plants. On the other hand, the decline in starch content could be due to reduced carbon assimilation and/or starch degradation.