Tropentag, September 10 - 12, 2025, Bonn "Reconciling land system changes with planetary health"

Performance of amaranth (Amaranthus dubius) and African nightshade (Solanum spp.) under varying shade net levels in Kilifi County, Kenya

¹Pwani University, Dept. of Crop Sciences, Kenya
²Pwani University, Dept. of Biological Sciences, Kenya
³Pwani University, Community Development, Kenya
⁴Gaston Berger University, Faculty of agricultural sciences, Senegal
⁵Humboldt Universität zu Berlin, Center for Rural Development (SLE), Germany

Abstract

Vegetable production in Kenya's coastal region is increasingly challenged by high ambient temperatures and elevated evaporation rates, resulting in reduced crop yields. Agroforestry systems have the potential to enhance productivity and income generation in such environments; however, identifying shade tolerance in nutritionally dense crops such as vegetables is crucial to maximizing their performance and contribution to nutrition security. A study was conducted in Pwani University farm to assess the performance of two indigenous vegetable species, amaranth (Amaranthus dubius Mart. ex Thell.) and African nightshade (Solanum spp.), under four different shading intensities. A randomised complete block design was used, with the shade net levels 0%, 35%, 55%, and 75% assigned to main plots and vegetable species to subplots, and replicated three times. Data on total biomass (TB; including the roots), above-ground fresh weight (FW), and plant height (PH) were collected from six tagged plants of each crop type at crop maturity. Data were subjected to analysis of variance, followed by Tukey HSD test. For amaranth, shading level had a significant (p < 0.001) effect on all three measured variables. Highest values were obtained for the 55% shading level and lowest for 0% shading (mean TB 252 g versus 83 g, FW 114 g versus 51 g and PH 38 cm versus 19 cm, respectively). In African nightshade, shading level also significantly (p < 0.001) influenced all three variables with highest and lowest values recorded at 55% and 0%, respectively (mean TB 89 g versus 30 g, FW 57 g versus 19 g and PH 18 cm versus 10 cm). The study showed that both amaranth and African nightshade performed best under the shade levels of 55% and using such shade nets could be an important climate-smart adaptation strategy to enhance productivity and resilience of vegetable farms in coastal Kenya. In addition, the two tested vegetables can potentially grow well under tree canopies of similar intermediate shade levels and thus have a potential for integration into vegetable agroforestry systems.

Keywords: Adaptation, agroforestry, climate change, indigenous vegetables, shading

Contact Address: Mathew Mumo, Pwani University, Dept. of Crop Sciences, 195-80108, 00200 Kilifi, Kenya, e-mail: mattmumoyahoo.com