A, The PHYTOREGULATORY EFFECTS OF AQUEOUS EXTRACTS OF CARTHAMUS TINCTORIUS L. ON EMERGENCE AND SEEDLING GROWTH OF ECHINOCHLOA CRUSS-GALLI L.: AN OBNOXIOUS ENVIRONMENTAL WEED

Abstract

ABSTRACT Crops exude allelochemicals that have ability either to promote or inhibit seed germination and seedling growth of surrounding crops and weeds and this situation is known as allelopathy. Laboratory experiment was performed to determine the suppressive or simulative influence of aqueous extracts of Carthamus tinctorius L. flowers, leaves and stem at different concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) on environmental weed Echinochloa cruss-galli L. Results revealed that 8% concentration of aqueous extracts of all tested parts of C. tinctorius was most phytostaic against germination as well growth of E. cruss-galli. Maximum mean emergence time (5.60 days), minimum emergence index (1.87), time to 50% emergence (6.17 days), minimum shoot (5.82 cm) and root length (1.91 cm) were recorded with the application leaf extract at 8% concentration. The E. cruss-galli emergence percentage (53.33%) and seedling fresh weight (15.35 g) was minimum when treated with 8% aqueous extract of C. tinctorius fruit extract. The lower concentration of all the studied extracts showed a hermetic response and stimulated the root, shoot and seedling fresh weight of E. cruss-galli. The aqueous extracts inhibitory effect was of order leaf > fruit > stem. This study leads to conclusion that 8% or higher concentration of C. tinctorius leaf aqueous extract may be exploited to biologically suppress the establishment of E. cruss-galli. Hermetic response may affect the manifestation of primary and secondary sequence in biological process and this phenomenon must be considered in the development of natural herbicides keeping focus on toxic dose responses. Keywords: Allelopathy, emergence, seedling growth, inhibitory, extracts-concentrations. INTRODUCTION