Responses to Nitrogen Fertilizer Application at Regrowing Stage of High-Yielding Cultivar of Winter Triticale in Comparison with Those of Wheat and Rye in Hokkaido

Abstract

The efficiency of nitrogen fertilization (the increase of grain yield (G) per unit nitrogen fertilizer (FN) applied at the regrowing stage, ΔG/ΔFN) of high yielding winter triticale cultivar 'Presto' was analyzed in comparison with that of Japanese wheat cultivar 'Hokushin' and Polish rye cultivar 'Warko' in the field from 1997 to 2000. In each of the 4 years G and ΔG/ΔFN of triticale were higher than those of wheat and rye. The differences in ΔG/ΔFN among the three crops were due to the differences in mean leaf area index (MLAI) during the grain filling period. The differences in MLAI between triticale and wheat were attributed to the differences in the leaf blade dry-weight per unit nitrogen uptake (ΔLW/ΔN) at the milk-ripe stage. On the other hand, the differences in MLAI between triticale and rye were due to the differences in the nitrogen allocation to the leaf blade at the milk-ripe stage, which resulted from the differences in the nitrogen concentration of the leaf blade per unit nitrogen uptake (ΔLNC/ΔN). The results indicated that high yields of new winter triticale cultivars were due to a combination of the high efficiency of nitrogen uptake for leaf expansion, which is the characteristic of rye, and the high nitrogen allocation to the leaf blade during the grain filling period, which is the characteristic of wheat.