ALLELOPATHIC EFFECT OF RHAZYA STRICTA PLANT RESIDUE ON RAPHANUS SATIVUS (RADISH)

Abstract

      This study was designed to investigate the allelopathic potential of Rhazya stricta on Raphanus sativus using laboratory bioassay and greenhouse pot experiment. In laboratory bioassay, aqueous extract of R. stricta showed inhibitory effect on R. sativus seedling growth particularly at the high concentrations. The germination percentages were not significantly affected. Results in greenhouse pot experiment showed that the residue of R. stricta showed inhibitory effect on root length, dry weight and root to shoot length ratio of R. sativus especially at the high concentrations at different ages. The Rhazya residue showed positive effects on the photosynthetic pigments of R. sativus particularly on the carotenoids and chlorophyll a/b ratio at different ages. A significant increase in nitrogen content of R. sativus including total amount of free amino acid, soluble and insoluble nitrogen and crude protein was prominent at the early growth stage especially at the high concentrations. The Rhazya residue inhibited the contents of soluble nitrogen of R. sativus in the late growth stage. The results of RAPD-DNA profiles showed significant effect of Rhazya residue on R. sativus plant from where variation in band intensity, disappearance of bands, and appearance of new PCR product.