1954 Volume 22 Issue 4 Pages 217-222
1. Studies were conducted to clarify the ecological characters of spinach in relation to its favorable growing temperature range, flower stalk differentiation and development. Two varieties, Virofley and Japanese Spine, were successively sown at the different altitudes during summer season. They were also grown under controlled temperature and photoperiod.
2. It was found that the most favorable temperature range was 15-20°C. for spinach vegetative growth.
3. Flower stalk differentiated when daylength summation after emergene had reached 450-500 hours, though there were slight variations in relation to variety and sex.
4. Seed stalk did not developed if photoperiod was less than 12 hours after flower cluster had differentiated.
5. Consequently, the critical time after which summer-sown spinach does not develop seed stalk, is logically middle August at the hilly region of Nagano Prefecture (N 36°). But practically, summer spinach may be sown after middle July without serious losses due to premature seed stalk development.