Influence of Growth Substrate in Rooting Ability of Pyrethrum (Chrysanthemum cinerariifolium) Stem Cuttings

Abstract

Pyrethrum (Chrysanthemum cinerariifolium) is an important cash crop valued for its natural insecticidal properties. Kenya’s production, once the world's highest, declined due to policy and market challenges but rebounded to 1,680 tons in 2023, supported by government and private sector interventions This study evaluated the rooting performance of pyrethrum (Chrysanthemum cinerariifolium) stem cuttings across different growth substrates and auxin hormone treatments to optimize propagation protocols for seedling production. Four substrates (soil, soil:sand, manure:sand, cocopeat:sand) and two indole-3-butyric acid (IBA) formulations (0.6% powder and 4.5% solution) were tested using a split plot design. Results showed that the cocopeat:sand substrate combined with 0.6% IBA powder produced the highest rooting frequency, root number, and length. No rooting occurred without hormone treatments. The study recommends using cocopeat:sand with IBA powder for efficient large-scale pyrethrum propagation under controlled conditions. This protocol supports sustainable seedling production and future breeding efforts for this important natural insecticide crop.