Growth of theobroma cacao seedlings in the presence of Digitaria Insularis weeds

Abstract

An experiment to evaluate the growth of Theobroma cacao L. seedlings in the presence of Digitaria
insularis (L.) Mez ex Ekman was conducted at the Cocoa Research Institute of Ghana in 2008. Hybrid
cocoa and D. insularis seeds were sown in soil-filled polythene bags measuring 25 cm x 37.5 cm. One
cocoa seedling and 0, 1, 2, 3, or 4 D. Insularis seedlings (equivalent to 0, 20, 40, 60 or 80 seedlings m-2 )
were maintained in each polythene bag 3 weeks after sowing. The D. Insularis seedlings were either
slashed at 5 cm above the soil level at intervals of 6 or 10 weeks or not slashed during the entire period of
the trial. The experiment was laid out as 5 x 3 factorial with 6 replicates. The growth of the cocoa
seedlings was significantly reduced (P≤ 0.05) in the presence of D. Insularis seedlings at 23 weeks after
sowing. Stomatal conductance, rates of transpiration and photosynthesis were lower in cocoa grown
without D. insularis than those grown with D. insularis. Leaving D. insularis unslashed or slashing at 10
weeks intervals, adversely affected the growth of the cocoa seedlings. Slashing D. insularis at 6 weeks
intervals could not completely eliminate the competitive effects of the weed on the cocoa seedlings,
suggesting that clean weeding close to the soil level is important in ensuring good growth of young
cocoa among D. insularis weeds.