Translocation of phosphorus-32 into wilting and healthy fruits of cacao (Theobroma Cacao)

Summary

The uptake of phosphorus into young cacao fruits (cherelles) was studied by applying 1.0 mC of P-32 to tins of soil in which young cacao trees were growing. The radiation from the fruits was measured daily with a shielded end-window G-M tube until the fruit wilted. While the fruit remained healthy accumulation of P-32 was linear and uptake continued for about three days after the fruit stopped growing (the first sign of wilting); uptake of P-32 then ceased. An increase in the count rate as the fruit became flaccid was attributed to reduced self-absorption due to loss of water.

The distribution of the radio-active phosphorus in the seeds and pericarp was investigated and comparative analyses of phosphate in wilting and healthy fruits are presented.

The results provide additional evidence for the hypothesis that cherelle wilt is analogous to a fruit-thinning mechanism.