Edaphic and Climatic Factors Affecting Phenology of Naturally Growing Calotropis procera in Semi-arid Regions of Kenya

Abstract

Background and Objective: Cultivating Calotropis procera for fiber supply to the textile industry can improve the livelihoods of communities in arid and semi-arid regions. This study determined edaphic and climatic factors affecting phenological traits of C. procera in the semi-arid regions of Kenya. Materials and Methods: Repeated measure research design was used with multistage sampling technique to monitor activity indices, number of flowers and fruits and phenophase intensities. Climatic and edaphic factors of study sites were also monitored. Data was analyzed using linear, Poisson log linear regression based on Generalized Estimation Equation (GEE) and Mixed Analysis of Variance (ANOVA). Results: High Soil Organic Carbon (OC) content (3%) and exchangeable Na (112.5 ppm) at (0-20) cm soil depth were recorded in Tharaka. High mean monthly rainfall (160.37 mm) was recorded in Makueni. Flowering activity indices in (June-August, 2018) were 64.97% and 69.6% in Tharaka and Makueni, respectively . Available P, average monthly rainfall and temperature had significant association with flowering and fruiting activity indices (p<0.05). The mean number of flowers and fruits per stem were significantly associated with soil available P, exchangeable Na and OC content (p<0.05). Though edaphic factors were not significantly associated with phenophase intensities of C. procera, average monthly rainfall and temperature were positively and negatively associated with phenophase intensities, respectively . Conclusion: Available P, exchangeable Na, available K and OC content noticeably affect phenological traits of naturally growing C. procera. Rains and temperatures are critical climatic factors affecting phenological traits of C. procera.