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.
