Investigation of Yielding Ability of Wheat Cultivars for Early-Sowing Cultivation in Yamaguchi

The spring-type cultivar (Triticum aestivum L.) is usually sown in November. However, the sowing time is sometimes delayed considerably because of much rain in October, and the seed bed does not become suitably dry for sowing due to cold temperature. To find a solution to this problem, we compared the yielding ability of wheat sown early (early-sown group) with wheat sown at the standard date (standard group) in Yamaguchi. The grain yield for nine cultivars averaged for three growing seasons, 1999/2000, 2001/2002 and 2002/2003 was 230 gm-2 in the early-sown group, and significantly lower than that in the standard group (334 gm-2). The spike number and grain number per spike were lower in the early-sown group than in the standard group. Akitakko, Iwainodaichi, Airakomugi had a higher grain yield, and Akitakko had a higher spikelet number per spike and higher grain number per spike than the other cultivars when sown earlier. Iwainodaichi showed higher spike number when sown earlier. Airakomugi showed higher grain number per spike and grain weight when sown earlier. Akitakko was the only cultivar that showed a higher grain yield by early sowing.