Effects of Seeding Date and Polyethylene Film Mulching on the Yield Potential and Agronomic Characteristics of Proso Millet (Panicum miliaceum L.) in Miryang, Korea

This study was carried out to identify the optimum seeding dates for selecting a double-cropping system and to assess the effect of polyethylene film mulching on the yield of Proso millet. Seeds of the varieties Hwanggeumgijang and Ibaegchal were sown in Miryang on five different dates: 1st (May 25), 2nd (June 15), 3rd (June 25), 4th (July 5), and 5th (July 15), with and without polyvinyl mulching. The varieties have different characteristics, for example, Hwanggeumgijang is an early-maturing type and more sensitive to temperature, whereas Ibaegchal is a medium-maturing type and more sensitive to the duration for which it is exposed to sunlight. Late-sown Hwanggeumgijang had a short heading date from seeding and required a low accumulated temperature. It also had a shorter period of heading, a shorter culm length and a shorter diameter of stem. In contrast, it had had a higher number of ears per m2 although similar ear length and similar 1000-grain weight. The yield potential of Hwanggeumgijang was found to decrease at a late seeding date. In particular, it significantly decreased at the seeding date of July 15. In the case of cultivation with polyvinyl mulching, the period of heading was shorter by 2 - 4 days and the yield potential was increased by approximately 12 - 32%. The length and diameter of culm in Ibaegchal were slowly decreased, but the length of ear, the 1000-grain weight and the yield potential were similar for all seeding dates (except July 15) and cultivation with and without mulching. When sown late, the length and diameter of the culm of Ibaegchal very rapidly decreased by the July 15 seeding date. The protein content of Ibaegchal was higher but the amlyose content of Ibaechal was lower compared to Hwanggeumgijang. At late seeding dates, the protein contents of the two varieties increased but the amylose contents were similar.