THE IDENTIFICATION OF EARLINESS CLASSES IN SWEET CORN CULTIVARS WITH THE SUMS OF EFFECTIVE TEMPERATURES

摘要

At present there is no system classifying the cultivars of the sweet corn subspecies according to their earliness. The length of the vegetation period is determined with the number of vegetation days. It ranges from 70 to 110 days and it largely depends on the course of environmental conditions. This study attempts to classify sweet corn cultivars with the Sums of Effective Temperatures. Apart from that, the aim of the study was to present the dependence between the course of temperature, total radiation, atmospheric precipitation and the length of the vegetation period. The Sums of Effective Temperatures which were calculated from sowing to the stage of lactic ripeness were found to be useful for the classification of sweet corn cultivars. The distribution into the classes of earliness was the most equal for the threshold temperature of 6°C. The length of sweet corn vegetation was found to be directly proportional to atmospheric precipitation and total radiation, but it was inversely proportionalto temperature. Temperature had the most significant influence on the length of vegetation.