Maize vegetation period length depending on climate conditions and sowing date

The corn vegetation length, which is genetically determined, is greatly influenced by the external environmental factors, especially temperature. To determine the length of individual phenophases, as well as the entire vegetation period, sums of heat units and the number of days are used. The experiment was carried out in fields in the South of Serbia (surroundings of Leskovac), at 430 01′ 476“ north latitude and 21° 56′ 126“ east longitude, and 225 m above sea level. The experiment was set up according to a random block system in three repetitions. The following maize hybrids were included in the experiment: ZP 434, NS 4023, ZP 555, NS 5051, ZP 666, NS 6030, which were sown in two periods: the beginning and the end of April. The length of the growing season was measured based on the number of days and the sum of the effective heat units (SET). The results of the research show that the length of the maize vegetation is directly dependent on the climatic conditions of the year (temperature) and the hybrids. The average length of the growing season from emergence to full maturity ranged from 127 to 129 days when hybrids of FAO ripening group 400 were in question, from 137-142 days for FAO ripening group 500, and 146-148 days for hybrids of FAO group 600. In the same period, the sum of effective temperatures was 1162-1187°C when hybrids FAO ripening group 400 were in question, 1263-1318°C for hybrids FAO ripening group 500, that is, from 1350-1366°C for hybrids FAO ripening group 600. The period from physiological to full maturity was 28-37 days, depending on the FAO ripening group, and the sum of effective temperatures was 249-316°C. The hybrid ZP 434 had the shortest vegetation period, while the hybrid NS 6030 had the longest one.