Evaluation of two contrasting cassava canopy structures on weed flora composition in a rainforest zone of Nigeria.

Abstract

The impact of weed competition on crop growth is a universal concern to farmers. This study was conducted in 2010 at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife to evaluate the impact of cassava canopy on weed diversity and identify shade-tolerant weed species in response to varying canopy structure at Obafemi Awolowo University Teaching and Research Farm, Ile-Ife ecological zone. The treatments consist of hand-weeded, herbicidal treatment, and unweeded checks in the main plot. The sub-plots constituted the cassava cultivars (TMS 30572 and TME 1) laid out in a randomized complete block with a split-plot arrangement in three replications. Fifteen weed species survived under the shade of TMS 30572 where two families were monocots while four families were dicots. However, twenty weed species were recorded where TME 1 was cultivated of which two families were monocots while five families were dicots. TMS 30572 suppressed weeds by 20% when compared to TME 1. In conclusion, TME 30572 is recommended for cultivation in this agroecology to obtain a maximum benefit on cassava production. The study designed was a randomized complete block with a split-plot arrangement laid in three replications. The weed control treatments (hand-weeded, herbicidal treatment, and unweeded check) constituted the main plot while cassava cultivars (TMS 30572 and TME 1) were the sub-plots. The cassava cultivars planted at 1m × 1m have 12 rows per sub-plot with 288 plant density and 576 per plot which amounted to 5,184 per location. The weed floras collected were from the fallow vegetation before land preparation and during the study. Quadrat of 1 m × 1 m was randomly thrown before land preparation, two times at 5 m intervals along transects that were 5 m apart, given a total of 40 samples for each location. Weed species found within each quadrat were harvested and identified using Akobundu and Agyakwa, (1987). Weed density was determined by counting the harvested weed stands at monthly intervals.