Studies on the growth and productivity of maize for whole-plant silage in the north-marginal area, Nemuro district in Hokkaido.

Abstract

The object of this report is to clarify the dry-matter accumulation habits during the early vegetative growth period and to investigate the effect of the early growth on yield and quality of maize for whole-plant silage in the north-marginal area in Japan (where accumulated temperature from May to September is 2200°C.). Experiments were conducted for 6 years (1978∼'83), based on the same design. Wase-homare (an eary hybrid) was planted on three dates from mid-May to early-June in 1978∼'82 and late-May in 1983. The dry-matter weight in each organ was measured at the 4th-, 7th-, and 11th-leaf fully developed stages, and dry-matter yields were measured at harvesting date. The results obtained were as follows : 1. Root dry weight growth rate in each growth period from emergence to the 11th-leaf stage showed highly positive correlations with leaf expansion rate and top growth rate (TGR)(Table 1). 2. TGR during the period from emergence to the 4th-leaf stage showed highly positive correlations with daily maximum temperature and sunshine hours, but was not correlated with solar radiation (Table 2). 3. TGR in each growth period from emergence to the 7th-leaf stage showed a highly positive correlation with LAI. TGR during the period from the 7th-leaf stage to the 11th-leaf stage showed highly positive correlations with both of LAI and NAR (Table 3). 4. TGR during the period from emergence to the 4th-leaf stage showed highly positive correlations with ear DM yield, total DM yield and percentage of dry-matter in whole-crop, but was not correlated with stover DM yield (Fig. 4). 5. Thus it was concluded that the early growth is of great significance on the growth and development of ears which are essential for stable and high yield, and high quality of maize for whole-plant silage under severe conditions in the north-marginal area.