Abstract:
The mechanisms which control the biomass yield and quality o f Napier-CIone 13
(Pennisetum purpureum) when grown near and under canopies were investigated in a
simulated pot experiment. Napier-CIone 13 was established in galvanized containers (2
plants/ 0.28m2 container) filled with normal soil (150 kg), treated with poultry litter (PL),
goat manure (GM) or spent tea leaves (STL), at the rate o f 50kg N/ha/cut. Each manure
type i.e. PL, STL and GM was pre analyzed and applied at a rate o f 335.7g, 76.38g and
103.5g respectively per container to provide a rate o f 50kg N ha'1. Plants were grown
either in full sunlight (FL), or two levels o f shading, namely, near the canopy with a
reduction o f 40% full light (NC) and under the canopy with a reduction o f 90% full light
(UC) imposed by shade cloth. Nine treatments were replicated 3 times, and arranged in a
randomized complete block design.
Plant height, stem diameter, leaf area and root biomass yield (g/plant) were highest 2)
when grown NC as compared with plants grown in FL which increased the rate o f tillering
and the number o f leaves. Deep shade UC caused significant decrease in all the above
parameters. Poultry manure responded (P<0.05) positively in increasing above
parameters over STL or GM. The increase in ion biomass yield (BMY) was affected
(P<0.05) by the level o f shading with more than two fold increase in full sunlight as
compared to the deepest shade level. The difference in BMY between FL and NC was
around 25%). PL responded similarly in increasing BMY over STL or GM. Deep shade UC
augmented shoot nitrogen (N) concentration (P<0.001) over NC or FL. Poultry manure
had a significant (P<0.05) effect on shoot N concentration over STL or GM as well.
The results o f the simulated shade conditions on the yield and nutritive value o f Clone 13
suggested that there would be an increase in N content but the biomass yield was marginal.
Vice versa was observed under FL due to the dilution effect o f N as a result o f increasing
biomass yield. Interaction o f shade and soil fertility especially by the application o f
poultry manure near the canopy substantially enhanced the yield and quality o f Napier CIone 13. Therefore, it could be suggested that the grass yield and quality near the
canopies could be easily boosted by adding organic manures.
