Abstract
In Citrus natsudaidai HAYATA cv. Kawanoamanatsudaidai, fruits in the shade of trees begin to color prior to ones in the sunshine, where the rind of sunny side of fruits exposed to sunlight is delayed intensively in coloring and retains green. There were some difference in chlorophyll content of the rind between the sunny side and the shady side of fruits. But, chlorophyll content of the rind of the sunny side, one of which was changed from the shady side at certain time of the experiment, decreased later than that of the shady side did. When immature green fruits were covered with cheese-cloths which reduced transmittance of light in various degrees, the area of the green surface of the rind was retained as much as the shade was intensive, whereas, measuring the rind temperature, the covered treatments that the green color was much preserved caused to raise the rind temperature.
Most effective period of the shading on coloring was for Oct. 7 to Nov. 17 in regard to the green area retained, but the shading at early November was most inhibitory. Carotenoid contents increased as the shading was delayed.
When harvested fruits were storaged at 33, 26, 20°C and room temperature, separately, 26°C was greatest effect on coloring but 33°C was very inhibitory. Preservation of green in the rind was exhibited by gibberellin treatment, but other plant growth regulators such as kinetin were not effective.
