Four introduced forage rape (Brassica napus) cultivars, 'Akela', 'Ramon', 'Sparta', and 'Velox' and a leading rapeseed cultivar, 'Hallayuchae' were grown at nitrogen (N) rates of 0, 100, 250, 300, 350, and 400 kg/ha to (i) select forage rape cultivars adapted best to Cheju area, and (ii) determine the optimum N rate for the best cultivars. Days from seeding to flowering across the cultivars increased 190 to 195 days as N rate increased from 0 to 400 kg/ha. Average days to flowering of six cultivars ranged from 182 to 198 days. Plant height increased as N rate increased up to 300 kg/ha and then decreased with a further increase in N rate and ranged from 159 to 174 cm among the cultivars. The optimum N rate for the greatest dry matter yield of five cultivars ranged from 222 to 258 kg/ha. Sparta showed the greatest dry matter yield (35.79 Mg/ha), followed by Akela, Hallayuchae, Velox, and Ramon. As N rate increased, crude protein content linearly increased but crude fiber content declined curvilinearly. Akela and Sparta had higher protein content than the other cultivars did. The forage cultivars had lower crude fiber content than the oilseed cultivar Hallayuchae did. Our results demonstrated that Sparta was best adapted to Cheju area and the optimum N rate for Sparta was about 220kg/ha.

Four introduced forage rape cultivars 'Akela', 'Ramon', 'Sparta', and 'Velox' and a leading rapeseed cultivar Hall-ayuchae were seeded on 1 October 1994 on 20-cm rows at seeding rates of 3, 5, 7, 10, 13, and IS kg/ha to select the best adapted forage rape cultivars and to determine the optimum seeding rate in the Cheju area. Days to flowering of each cultivar was not significantly affected by seeding rate. Average plant height increased from 151 to 164 cm as seeding rate increased from 3 to 10 kg/ha and then decreased to 156 cm at 15 kg/ha. Stem diameter linearly decreased with increasing seeding rate. The optimum seeding rate for the greatest dry matter and protein yields of five cultivars ranged from 10.7 to 11.8 and 10.8 to 14.4 kg/ha, respectively. Dry matter yields of five cultivars ranged from 7.72 and 22.01 Mg/ha. Sparta produced the greatest dry matter yield, followed by Akela, Ramon, Hallayuchae, and Velox. Crude protein yields of five cultivars ranged from 0.29 to 1.08 Mg/ha. Sparta produced the greatest crude protein yield, followed by Akela, Ramon, Velox, and Hallayuchae. As seeding rate increased, crude protein content linearly increased but crude fiber content linearly decreased. The forage cultivars had higher crude protein and lower crude fiber than the oilseed cultivar Hallayuchae. Our results demonstrate that Sparta was the best adapted cultivar to Cheju area and the optimum seeding rate for Sparta was about 10 kg/ha.

Two determinate soybean cultivars, 'Baegunkong' and 'Namhaekong', were planted on 8 Jone, 23 June, and 8 July 1996 at Cheju at planting densities of 33, 43, 53, 63 plants per m2 to determine the optimum planting density of double crop soybean for recently recommended cultivars in Cheju area at various planting dates. The plant height, and the diameter and node number of main stems decreased as planting was delayed. The plant height increased but the stem diameter and node number decreased with increasing planting density. Pod number per plant was greater for Namhaekong than for Baegunkong and was not affected by planting date. Pod number per plant decreased but pod numbers per ~textrmm2 increased with increasing planting density. The number of seeds per pod was greater at the two later plantings and fewer at the highest planting density. 100-seed weight decreased with delaying planting. The seed weight was lighter at the highest planting density for Baegunkong but there was no difference for Namhaekong among the planting densities. The seed yield of Baegunkong was greater for 23 June and 8 July plantings (2,280 and 2,420 kg/ha) than for 8 June planting (1,450 kg/ha) while that of Namhaekong was greatest at 23 June planting (2,690 kg/ha) compared with 8 June and 8 July plantings (1,890 and 2,080 kg/ha). Across the planting dates and cultivars, seed yield increased from 1,860 to 2,290kg/ha as the planting density increased from 33 to 53 plants/~textrmm2 and then leveled off with a further increase in planting density.