Perspectives on the Biology of Heliotropium curassayicum in the Deltaic Mediterranean Coast of Egypt PDF

Keywords

Egypt, biology, mediterranean

Abstract

Heliotropium curassavicum L. (Boraginaceae) has become a serious polycarpic weed infesting many agricultural fields in the newly reclaimed salt affected lands in the Deltaic Mediterranean coast of Egypt. Floristic composition of its plant communities, seed germination, phytomass allocation, adventitious root buds, cell division and karyotype analysis, and pollen fertility were investigated. The following results were obtained: (1) The poor adaptation of its associated wild plants and the strong selection pressure in the Deltaic agro-ecosystems supported the dominance of H. curassavicum as a weed. (2) Persistence of intermittent seed germination and seedling establishment in open areas increases the chance of its spreading. (3) Synchronized pattern of dry phytomass allocation and phenological events through different stages of the life cycle. (4) Ability to produce adventitious root buds allow for the plant's perennation and wide spreading. (5) Chromosomal abnormalities during the cell division included lagging chromosomes, chromatin bridge, stickiness, mis-orientation and asynchrony. These abnormalities and the reduced pollen fertility made the species shifts its sexual reproduction to vegetative propagation by adventitious root buds.