Weed species composition under different coffee (Coffea arabica L.)
production systems, altitude and soil conditions in Ethiopia
Abstract
A weed population survey was carried out to assess the influence of the
coffee production system, altitude gradients and physicochemical
characteristics of the soil on weed species composition and distribution
in the major coffee-growing belt of Ethiopia. A total of 168 coffee
fields were assessed using a quadrat count (0.5 m x 0.5 m) in a
systematic sampling technique. The result revealed that a total of 98
weed taxa belonging to 35 families were recorded. Asteraceae and Poaceae
were the most abundant families. The most frequent weed species,
regardless of the production systems, altitude and soil types, were
Oplismenus hirtellus, Galinsoga parviflora, Achyranthes bidentata,
Impatiens balfourii, Bidens pilosa and Commelina benghalensis, with a
frequency of > 40%. The density of weed species was varied
(ranged from 0.04 to 95.29 plants 0.25m-2) and the highest abundance
value (95.25 plants per 0.25m2) was recorded by O. hirtellus. Similarity
indices of the 16 districts were ranging from 8.33% to 72.73% and that
of the 4 coffee production systems and 3 altitudinal gradients were also
ranged from 7.14% to 49.49% and 41.76% to 68.75%, respectively.
According to canonical correspondence analysis (CCA) and the
Kruskal-Wallis test, coffee production systems, altitude and
physicochemical properties of soil were the main explanatory variables
influencing weed species distribution and composition. Therefore, it is
concluded that the measured variables significant account for variation
in the composition and distribution of weed species in coffee fields of
Ethiopia and coffee producers should take into account those variables
to manage weeds of coffee.