ABUNDANCE AND ALLELOPATHIC EFFECT OF Parthenium hysterophorus ON CROPS OF SOUTH-WESTERN REGION OF BANGLADESH

Abstract

Periodical weed surveys were conducted during 2020-21 at Jashore, Jhenaidah, Chuadanga, Meherpur, and Khustia of Bangladesh to observe the severity of parthenium and to identify how many crops were affected by this weed. Parthenium weed was identified using the visual method, and quadrates were used to determine the number of parthenium weeds. The densest infestations of parthenium weed were found along roadsides, in fallow land, grasslands, and in fields of various crops. Only one species of parthenium which affected rice, maize, lentil, chickpea, field pea, jute, cotton, mustard, sesame, groundnut, tomato, pointed gourd, brinjal, bean, okra, onion, garlic, turmeric, chili, ginger, potato, banana, sugarcane, napiergrass, marigold, etc. The highest (29.67 plants m -2 ) abundance of parthenium weed occurred at border areas due to the proximity to routes connecting Bangladesh and India. Among 27 Upazilla studied sites, the relative density was highest at Sarsha, Jashore (33.5%) followed by Damurhuda, Chuadanga (29.8%). The allelopathic activity of P. hysterophorus was examined against the seed growth of twenty crop species including major cereals, pulses, oilseeds, spices, fiber, and vegetables. 5% aqueous leaf extract was used to investigate the allelopathic activity of P. hysterophorus to seeds and pregerminated

seeds (radicle protruded by at least 1 mm) of test species. The following three parameters were used in allelopathic screening methodologies (a) germination percentage (%), (b) radicle length (cm), and (c) plumule length (cm). Results of Petri dishes experiment had shown a complete failure of germination (0%) due to the treatment in sesame, jute, pumpkin, red amaranth, chili, radish, and tomato. Among the cereals, wheat had the greatest reduction in radicle and plumule length (96% and 94%, respectively) compared to the respective control. Therefore, an integrated parthenium management approach is urgently needed to control the spread of this invasive weed.