Evaluation of Productivity and Adaptability of Sorgo-Type Sorghum (Sorghum bicolor Moench) ‘Tarzan’ in Northern and Eastern Hokkaido

Abstract

Field experiments with sorgo-type sorghum (Sorghum bicolor Moench) ‘Tarzan’ were conducted for two years (2018-2019) to evaluate its productivity and adaptability in northern and eastern Hokkaido, which are colder throughout the year than other areas in Hokkaido. Considering changes of dry matter yields and dry matter ratios of sorghum ‘Tarzan’ in these areas, the optimal planting time was ascertained as the period from May to early June. Regional and annual variations of productivity were found among the field experiments, which suggested that differences in the effective cumulative temperature based on 14°C during June-August influenced ’Tarzan’ productivity. The effective cumulative temperatures based on 12°C, at which the dry matter ratio reaches 25% and 30%, were 652°C and 705°C, respectively, for ‘Tarzan’. Maps of the estimated harvest times based on these effective cumulative temperatures showed that the dry matter ratio could be 30% in the flat area of Kamikawa in northern Hokkaido and 25% in the central of Tokachi in eastern Hokkaido. Therefore, these areas might be suitable for cultivation.