Effects of weed density and species diversity on cassava (Manihot esculenta Crantz) Yield in Zambia
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Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sokoine University of Agriculture
Abstract
Cassava (Manihot esculenta Crantz) is one of the important crops in the world for food
and income security. Cassava production is challenged by weeds as they reduce yield to
100%. Effective weed management in cassava production depend determination of weed
species diversity and determination of Critical Period for Weed Removal (CPWR). A
study was conducted in Zambia, to document weed species diversity in cassava growing
areas of Chongwe and Kaoma districts in Zambia, determine the critical period for weed
removal in three cassava varieties (Nalumino, Mweru and Chila) commonly grown and
estimate yield losses caused by weeds on cassava farms in the two districts. Farmer survey
was done to get farmers experience in weed management. The experiment was established
whereby, two weeding regimes were applied; weed free (WF) and weed infested (WI).
Sampling of weeds for density, species diversity and yield components was done within
the period of 21 days until 168 Days After Planting (DAP). Weed species diversity index
in Kaoma was 2.12 and Chongwe was 3.487 (Shannon diversity index) Forty weed
species in Chongwe and 33 in Kaoma were identified. Findings reveal that CPWR was
between 42 and 105DAP. Cassava root yield 6 months after planting in weed free plots
was significantly higher than in weed infested treatments. All varieties were affected by
weeds, and under un controlled weed condition the loss of 99.9% was recorded.
Therefore, keeping the crop weed free during the first four months of growth is important
for all varieties in order to reduce significant yield penalty. Additionally, further studies on
weed seed bank and herbicide screening is important to postulate appropriate weed
management and reduce drudgery respectively.
Description
MSc. Dissertation 2018
Keywords
Weed removal, Weed management, Cassava weeds, Cassava yield loss, Weed species diversity