Effects of Sowing Time on the Seed Yield of Quinoa (Chenopodium quinoa Willd) in South Kanto, Japan
The objective of the present study was to determine the optimum sowing time of three quinoa ecotypes (Altipllano, sea level, and valley) for high seed yields in south Kanto, Japan. Pot experiments were conducted in the experimental field at Nihon University during 2011, 2012, 2013, and 2014. In this experiment, the following quinoa varieties were used NL-6, Baer Cajon and Cauquenes (sea-level type), Amarilla de Marangani, Blanca de Junin, CICA-127, ECU-420, ECU-525, Ingapirica, and Narino (valley type), 94R and Isluga (Altiplano type). The quinoa seeds were sown on March 29, June 17 and September 22, 2011; March 27, June 17 and August 28, 2012; March 26, June 15 and 5 September 5, 2013; and March 27, June 17 and August 28, 2014. When the sea-level type and Altiplano type seeds were sowed from March to September, the seeds could be gained in all sowing plots. However, the seed weights of all varieties were the highest in the sowing plots of March. And the seed weights in the sowing plot of March were significantly higher than that in the other sowing plots. The sea-level type and Altiplano type quinoa had almost the same seed growth reaction for day length and day temperature. Thus, to gain a high seed yield of the sea-level and Altiplano type quinoa, March was the optimum sowing time in south Kanto, Japan. When the valley-type seeds were sowed from March to June, the seeds could not be gained, except in 2012. In 2012, the seed weights and seed numbers in sowing plots of March and June were significantly lower than those in the sowing plot of September. Thus, to obtain a high seed yield of the valley type quinoa, the optimum sowing time in south Kanto, Japan was from August to September.