적산온도를 활용한 중북부지역 찰옥수수 적정파종기 설정

Determination of Adaptable Sowing Dates of Waxy Corn Using Growing Degree Days in the Central Northern Area of Korea

It is important to determine sowing date as it decisively affects the quality as well as quantity of waxy corn. In the central northern area of Korea, optimum sowing date of waxy corn is May and requires about 20-26 reproductive growth days from silking date to harvest. We determined adaptable sowing date of waxy corn varieties using growing degree days (GDDs), especially in the central northern area. Earlier sowing required many more emergence days owing to the low temperature. All waxy corn varieties required about 16~22 emergence days when sown in April. Otherwise, less than 15 emergence days were needed for sowing from May to August. Sowing dates to maximize ear yield of waxy corns were different depending on the eco-types of corn varieties as well as GDDs during the growth period. Early maturity type Mibaek2’ showed the highest ear yield at the May 15th sowing date. Middle maturity ‘Iimichal’ and late maturity ‘Chalok4’ showed the highest ear yield at the May 25th and June 5th sowing dates, respectively. GDDs of 26 days after silking was an index to determine the highest yield sowing date of ‘Mibaek2’. The total GDDs from sowing to harvest and to silking were other indexes to determine the highest yield sowing date of ‘Ilmichal’ and ‘Chalok4’, respectively. Generally, it required about 2,400°C GDDs from sowing date to maturity and at least 65 days of silking date from sowing to obtain about 1,200kg of ear yield of waxy corn in the central northern area of the Korean peninsula. The results of the study will be helpful for corn farmhouses to determine optimum sowing date of waxy corn in the central northern area of Korea.