Effects of Planting Dates and Mulch Types on the Growth, Yield and Chemical Properties of Waxy Corn Crosses $Sonjajang{\times}KNU-7$ and $Asan{\times}KNU-7$

The growth, yield and chemical properties of waxy corn $Sonjajang{\times}KNU-7$ and $Asan{\times}KNU-7$ planted in different dates and mulch types in a converted paddy field was investigated. Experiment was carried out in a randomized complete block design in a split split-plot arrangement with four replications. Planting dates (D) [May 16 (D1, early), June 1 (D2, middle), June 6 (D3, late)] represented main plots, plastic mulch (M) [(BM, black mulch; TM, transparent mulch)] for subplots while waxy corn crosses [$Sonjajang{\times}KNU-7$ (‘Sonja’) and $Asan{\times}KNU-7$ (‘Asan’)] for sub-subplots. Results showed that D had a significant effect on growth characters except emergence, ear quality except ear diameter, and yield whereas M showed significant effect on growth characters only. Superior growth and ear quality performance were recorded in D1 and BM. In terms of crosses, ‘Sonja’ had better growth performance than ‘Asan’ regardless of D and M, but performed better at D1 and BM. Highest yield was obtained in D1 for BM (2,131 kg $10a^{-1}$) and TM (1,655 kg $10a^{-1}$) but no significant difference in the yield across V was recorded. In terms of starch and sugar contents, a decreasing trend was observed from D1 to D3 regardless of M and V.