Biochemical Requirements for Seed Germination and Shoot Development of Witchweed (Striga asiatica)

Germination of witchweed [Striga asiatica (L.) Kuntze] seeds was induced by treating air-dry seeds with kinetin (6-furfuryl-aminopurine) at 1.16 × 10−4 M and 2.32 × 10−4 M without subjecting the seeds to the conventional preconditioning procedures. Rudimentary shoot development of the seedlings also was promoted. Tissue culture techniques were used also to study growth regulator and nutritional requirements for witchweed seedling development. Seedlings with normal leaves and stems were obtained under aseptic conditions in synthetic media at pH 5.4 in the absence of a host plant when cultured in the presence of kinetin, indole-3-acetic acid (IAA), sucrose, casein hydrolysate and mineral salts. No shoot development occurred in the absence of kinetin or zeatin [6-(trans-4-hydroxy-3-methylbut-2-enylamino)purine]. Shoot development was more advanced if IAA or gibberellic acid (GA3) was used in combination with the cytokinins. Witchweed seedlings are dependent on a host plant not only for their nutrition, but also for plant hormones such as a cytokinin required for the promotion of shoot development.