Abstract
For the purpose of determining yield curve in early sowing of Italian ryegrass presupposing year round utilization of soiling crops, it was sown three times (early September, late September, and late October). 1. The cutting periods extended from 20 to 40 days in principle and frequent cuttings were made with these periods. 2. For plotting yield curve, the methods of least squares was applied. 3. In average total yield, the maximum yield was gained by one cutting made from middle or late April to middle May in each sowing. 4. In average total yield by two cuttings, the maximum yield was gained when the first cut was made in growth progressing stage in and after middle March in each sowing. 5. Concerning yield curve by frequent cutting gaining the highest average total yield in each sowing, following formula was shown. 1) Sowing in early September A. In four cuttings, the first cut was made from Nov. 30 to Jan. 14, the 2nd cut from Feb. 28 to March 15, the 3rd cut from April 25 to May 25 and the 4th from June to June 15. First cut: y=-0.35x^2+2.21x+2.41 (0≦x≦3, 1x=15 days) 2nd cut: y=0.05x+3.35 (0≦x≦3, 1x=5 days) ?3rd cut: y=1.23x+13.33 (0≦x≦3, 1x=10 days) 4th cut: y=-1.14x+6.11 (0≦x≦3, 1x=3 days) Where y: yield per 3.3m^2 x: days after first cutting date Same hereafter B. In three cuttings, the first cut was made from Nov. 30 to Jan. 14, the 2nd cut from March 29 to April 25 and 3rd cut from May 18 to June 5. First cut: same as that of A above 2nd cut: y=0.79x+10.04 (0≦x≦3, 1x=9 days) 3rd cut: y=-1.325x^2+3.965x+11.365 (0≦x≦3, 1x=6 days) 2) Sowing in late September A. In four cuttings, the first cut was made from Dec. 15 to Feb. 28, the 2nd cut from March 8 to March 28, the 3rd cut from April 26 to May 21 and the 4th cut from June 10 to June 15. First cut: y=0.486x+3.285 (0≦x≦5, 1x=15 days) 2nd cut: y=-0.06x^2-0.07x+3.225 (0≦x≦5, 1x=4 days) 3rd cut: y=1.506x+9.52 (0≦x≦5, 1x=5 days) 4th cut: y=-0.6x+4.17 (0≦x≦5, 1x=1 days) B. In three cuttings, the first cut was made from Dec. 15 to Feb. 28, 2nd cut from March 30 to April 29 and 3rd cut from May 18 to June 12. First cut: same as that of A 2nd cut: y=0.977x+10.024 (0≦x≦5, 1x=6 days) 3rd cut: y=-1.1x+14.6 (0≦x≦5, 1x=5 days) C. In two cuttings, the first cut was made from March 30 to May 1 and the 2nd cut from May 17 to June 18. First cut: y=3.84x+11.58 (0≦x≦4, 1x=8 days) 2nd cut: y=-2.18x+12.16 (0≦x≦4, 1x=8 days) 3) Sowing in October A. In three cuttings, the first cut was made from March 18 to March 30, the 2nd cut from April 30 to May 20 and the 3rd cut from June 4 to June 12. First cut: y=0.8x+6.98 (0≦x≦4, 1x=3 days) 2nd cut: y=1.04x+8.22 (0≦x≦4, 1x=5 days) 3rd cut: y=0.06x+2.24 (0≦x≦4, 1x≦2 days) B. In two cuttings, the first cut was made from April 10 to May 10 and the 2nd cut from May 21 to June 5. First cut: y=3.7x+14.85 (0≦x≦3, 1x=10 days) 2nd cut: y=-1.48x+9.57 (0≦x≦4, 1x=5 days)
