EFFECTS OF TEMPERATURE AND IRRADIANCE LEVEL ON CARBOHYDRATE CONTENT AND KEEPING QUALITY OF CHRISTMAS BEGONIA (BEGONIA X CHEIMANTHA-EVERETT)

The carbohydrate content and keeping quality of Christmas begonia were determined in a factorial experiment in which the plants were subjected to irradiance levels of 15, 30 and 60-mu-mol m-2 s-1 and to temperature levels of 15, 18 and 21-degrees-C for the last pan of the growing period. This period lasted from 11 to 24 days depending on irradiance level and temperature. The contents of sucrose, glucose and starch were determined at the marketing stage. The keeping quality of the plants was determined after 3 weeks in a simulated interior climate. Increase in temperature and irradiance level both enhanced the development of flowers during the later part of the growing period. The temperature,did not have any effect on plant quality at the marketing stage nor on the carbohydrate content, but high temperature caused an increase in flower stem height after 3 weeks in interior climate. Increase in irradiance level caused a significant increase in the content of starch at the marketing stage. Percent increase in new flowers during the interior holding period was highly correlated with the contents of sucrose and starch in the inflorescences and with the content of starch in the leaves. A large starch pool in the inflorescences and in the leaves at the marketing stage reduced the abscission rate during the interior holding period.