Abstract
In order to develop a high-yielding culture method for wheat we examined the effects of a higher top to basal nitrogen dressing ratio (HTBD) on the growth and yield of the new lodging tolerant variety “Satonosora” for two years. The reduced basal dressing accompanied with increased top dressing, increased the leaf area index (LAI) after jointing stage, and maintained a high net assimilation rate (NAR) during the late ripening period resulting in increased dry matter production. On the other hand, smaller stem number due to reduced basal dressing and plentiful nitrogen top dressing at the jointing stage were considered to alleviate competition of assimilate and nitrogen among stems and improved stem survival rate, resulting in both larger panicle number and panicle size. High NAR during the late ripening period might also increase the 1000 grain weight. As a result of the increased dry matter production and yield components, a HTBD increased the yield of wheat by 15 - 50%. On the other hand, some problems hindering practical use were clarified; delay of maturation, decline in the apparent quality, excess grain protein content, and acceleration of soil acidification.
