Assessing the phytosociological characteristics of weed complex in okra field under different control strategies

Abstract

Weed diversity is crucial for supporting ecological services, but weed control methods significantly influence weed species dominance and diversity. The present study was conducted in southwestern Nigeria’s rainforest-savanna transitional agroecological zone during the 2017 and 2018 rainy seasons. Different weed management techniques were assessed, including applying cyanide-сontaining cassava effluent (CE@3WAS), pendimethalin (P), and hoe weeding (HW@3WAS), as well as repeated applications of HW and CE (HW@3&5WAS, CE@3&5WAS), and integrated approaches (P + CE@5WAS, P + HW@5WAS, CE@3WAS + HW@5WAS). A control treatment, where the weeds were left unmanaged, was also included. The experiment followed a randomized complete block design with three replications. Weed samples were collected using 25 cm x 25 cm quadrats placed randomly along the plot diagonals. Weed diversity was assessed using the ShannonWiener index and descriptive statistics. Results indicated that the control methods influenced weed species composition. Specifically, the presence of broad-leaf weeds was prominent in the P + HW@5WAS (2017) and P + CE@5WAS (2018) treatments, while grasses dominated in the weedy check (2017) and HW@3WAS (2018), suggesting that these strategies favour specific morphological groups of the weeds. Weed diversity decreased across various management practices, with the rankings in ascending order: CE@3&5WAP, CE@3WAP, P+CE@5WAS, CE@3WAP + HW@5WAP, P + HW@5WAP, Pendimethalin, HW@3WAP, and HW@3&5WAP. These findings underscore the importance of selecting weed management strategies based on weed ecological significance. Integrated weed management emerged as a more ecologically sustainable approach for okra fields compared to sole herbicide application or manual weeding.