Growth and nutrient uptake among three wetland plant species occurring in Lake Victoria basin in Kenya.

Abstract

Nutrient enrichment is one of the most serious threats to wetland ecosystems. Information is lacking, particularly concerning the response of wetland plants species in Kenya in regard to nutrient enrichment of wetlands. Understanding the mechanisms and adaptations that allow only certain species to thrive in the potentially stressful wetland environment requires the study of the biology of these plants. This study was carried out to investigate the growth and nutrient uptake among some selected wetland plant species in Lake Victoria basin, Kenya. Seedlings of Cyperas esculentus L., Aframomum angustifolium (Sonn.) and Phragmites australis (Cav.) Trin. Ex Steudel) were grown outdoors in pots. The pots were arranged in a completely randomised design under out-door conditions in the Botanic garden at Maseno University. Plants were provided with four nutrient dosage levels of 0 mg [no fertiliser added], 50 mg, 100 mg, 150 mg fertilizer [N: P: K, 10:26:10] per pot and replicated five times. The plants were irrigated daily with tap water for eight weeks. Data on growth which included shoot height, stem diameter, leaf number per plant, leaf area, leaf width, leaf length, shoot and root weights were determined. Leaf N and P was also determined. The data were analysed by analysis of variance (ANOVA) in SAS statistical package. Nutrient availability treatments significantly (P ≤ 0.05) influenced the growth and biochemical parameters investigated. Cyperas esculentus and A. angustifolium had higher rate of biomass accumulation as evidenced by increase in shoot and root weights compared to P. australis. Root-shoot ratios reduced with increasing nutrient concentration in C. esculentus and A. angustifolium, while that of P. australis increased up to 100mg treatment, then slightly reduced at 150mg treatment. Phragmites australis had significantly higher foliar P and N content than the other two species with increasing nutrient availability. There were significant interactions between nutrient treatments and species in most of the parameters measured. We recommend Phragmites australis as a better agroforestry plant species for reclaiming wetland areas.