The effects of vesicular-arbuscular mycorrhizae inoculation on the growth of cacao seedlings (Theobroma cacao var. Ocumare 60) grown for 5 months in a nursery were studied. The effects of introduced VAM fungi ( Glomus occultum, Acaulospora appendicula, Glomus manihotis, Acaulospora morrowae and Scutellospora pellucida) in soils treated with copper oxychloride or methyl bromide, were compared with the indigenous VAM and with their respective non-inoculated controls.
Cacao seedlings responded well to indigenous VAM fungi, which included Scutellospora calospora as the dominant species, inducing increases significant in height, dry weight and foliar uptake of P, Cu and Zn in relation to the sterile control. G. occultum and A. appendicula increased the height of cacao seedlings but to an extent not yet statistically significant through the duration of the experiment. S. pellucida and A. appendicula doubled the phosphorus uptake of cacao seedlings. The methyl bromide sterilization induced the lowest Cu and Zn uptake in the cacao seedlings but this effect was ameliorated with VAM inoculation. Manifest deficiency symptoms were not observed in the treatments.
Copper oxychloride treatment depressed growth to the same level as the sterile control although its residual effects did not kill VAM. It could change the competitive relations among the VAM species and in this case seemed to affect adversely the more efficient native fungi.
The influence of the presence and long permanence of large cotyledons in cacao on the results obtained is discussed.
This study assessed the response of Theobroma cacao var. Ocumare 60 to inoculations with VA mycorrhiza (Glomus occulturn, Acaulospora appendicula, Glomus manihotis, Scutellospora