2016 Volume 85 Issue 4 Pages 385-390
An effective fertilizer system is required to achieve high and stable grain protein levels in the wheat cultivar “ChikushiW2” for Chinese noodles. In this study, we examined the fertilizer nitrogen utilization rate (FNU), grain nitrogen content, nitrogen contribution ratio (NCR) of nitrogen fertilizer, and nitrogen fertility using 15N-labeled ammonium sulfate in “ChikushiW2” to determine the nitrogen kinetics in wheat plants. At the early-ripening stage, nitrogen was distributed within the range 78-83% in foliage and 17-22% in grain. Nitrogen translocated from foliage to grain during the middle-ripening stage, with a final grain accumulation of 87-89% of the nitrogen at the late-ripening stage. FNU of the basal dressing was the lowest at 15-20%, increasing to 37-56% for the topdressing at tillering stage with annual variation, and highest at 67-74% for the topdressing at the panicle formation stage and the topdressing at full heading. NCR in the grain nitrogen content was lowest at 4-7% for basal dressing, 10-14% for the topdressing at the tillering stage and topdressing at the panicle formation stage, 24-30% for the topdressing at full heading, and highest at 41-49% for nitrogen fertility. These results indicate that reducing the quantity of low FNU basal dressing, reducing the variable FNU on the topdressing at the tillering stage, and adjusting the timing and quantity of fertilizer application on the high-FNU topdressing at the panicle formation stage, may be effective in enhancing and stabilizing the grain protein content.
