Seed germination and vegetative propagation of bush tea (athrixia phylicoides)

Abstract

Bush tea (Athrixia phylicoides) is an herbaceous plant of the Asteraceae family used throughout history as medicinal herbal tea by the people of South Africa. Many studies stated that the plant has an ability to be commercialized as a medicinal herbal tea. But vegetative propagation of this type of plant by stem cutting, survival ability of the rooted cuttings, response to different hormone concentrations and the requirement of the seeds for germination has not been studied. In this investigation, different features aimed at effective propagation of bush tea were studied. These comprised: cutting position (apical vs. basal), media (pine bark vs. sand), hormone (Seradix No. 2), season (summer, autumn, winter and spring), transplanting survival of rooted apical and basal cuttings, response of basal cuttings to three hormone concentration levels (Seradix No. 1, 2 and 3) and light and temperature requirement for bush tea seed germination. In vegetative propagation, apical cuttings rooted to higher percentage and produced high root number as well as longer roots than basal cuttings. Pine bark improved the number of roots developed but had no effect on rooting percentage as well as root length. Application of rooting hormone (Seradix No. 2) increased root numbers but not rooting percentage or root length. Rooting of cuttings was improved when propagated in autumn (longer roots) and spring (more number of roots) than in summer or winter. There was higher survival percentage (67.5%), high root number as well as longer roots from apical cuttings than from basal cuttings (50%) two months after transplanting. Propagation in pine bark with hormone application increased root number after transplanting. Application of hormone also improved root and shoot length after transplanting. Apical cuttings propagated in pine bark with hormone developed more number of roots. Cuttings propagated in sand with hormone and in pine bark without hormone also produced longer shoots after transplanting. Regarding response of basal cuttings to hormone concentration, high number of roots was produced in pine bark with Seradix No. 2 at 10 days after planting (DAP) but at 15 DAP more roots were produced in pine bark with Seradix No. 1. With sand, more roots were produced with Seradix No. 3 than Seradix No. 1 and 2. Number of roots were also higher with 0.3% IBA concentration (Seradix No. 2) and 0.1% IBA concentration (Seradix No. 1). Similarly, cuttings with lower IBA concentration (0.1%, Seradix No. 1) rooted to higher percentage followed with 0.3% IBA concentration (Seradix No. 2). Germination percentage of bush tea seeds differed with the temperature treatments and the highest was 75.5% at 20 and 25°C followed by 15°C with 64.5% and low percentage at 30 and 10°C with 36 and 47% respectively. There was a high germination percentage in constant temperatures than alternate temperatures and in continuous light than alternate light: dark or continuous dark. Germination percentage was also higher in continuous light at constant temperatures than with alternated light: dark with constant temperatures. In addition, there was more differences in germination percentage with variation in light exposure than variation in temperatures. At low temperature (10°C), longer time was required to start germination and germination rate was high at 20°C continuous light and low at 30:30°C alternate light: dark. Based on this investigation, better vegetative propagation and survival of bush tea can be attained from apical cuttings with Seradix No. 2 but basal cuttings rooted better with Seradix No. 1 in pine bark. Seeds germinated to higher percentage and rate at 20°C constant temperature and continuous light.