Abstract
The objective of the present study was to determine the proper seeding time of different types of quinoa varieties for a high grain yield in the climatic conditions of Southern Kanto District of Japan. The effects of day length and average daily temperature during the period following the flowering time on the grain growth was investigated in growth cabinets. The grain growth of the Valley type variety was severely suppressed under the long-day condition, while in the Sea-level type variety higher daily temperature promoted the grain growth. It was hypothesized, therefore, that the Valley type variety should be sown in summer to fit the grain filling period to the short-day season, and also that the Sea-level type variety should be sown in spring, to fit the grain-filling period to the high-temperature season in summer. To confirm these hypotheses, we sowed two types of quinoa varieties on the field in different seasons. The maximum yield was gained in the Sea-level type variety sown in March to May, followed by the Valley type variety sown in July. In the present study, proper seeding time for different types of quinoa varieties were well estimated by the experiment in which day length and temperature were artificially controlled in a growth cabinet.
