Effects of Timing of Supplemental Nitrogen Application on Lodging Resistance and Yield of Wheat(<i>Triticum aestivum</i> L.)

要旨

To assess the effects of timing of nitrogen supplemental application on and grain yield, and lodging resistance considering culm strength, we conducted a field study using the Japanese noodle wheat (Triticum aestivum L.) cultivars Ayahikari and Iwainodaichi. Supplemental nitrogen at the rate of 80 kg/ha was applied at three different Zadoks growth stages, GS30 (ear at 1 cm), GS32 (2nd node detectable), and GS39 (flag leaf ligule just visible). Grain yield increased significantly by the application of the supplemental nitrogen at GS30 and GS32. Maximum tiller number increased at GS30, whereas the percentage of productive culms significantly increased at GS32. Grain number per spikelet and grain number per spike significantly increased at GS30 and GS32. Chlorophyll content (SPAD value) of the flag leaf at late maturity increased at GS39. The 1000-grain weight, however, was not significantly affected by any treatment. Further, supplemental nitrogen application increased the moment of the aerial part at GS30, GS32, and GS39, but decreased the bending moment at breaking of the basal internode at GS30 and GS32. As a result, the lodging index significantly increased by supplemental nitrogen at GS30 and GS32. These findings suggest that supplemental nitrogen between GS30 and GS32 has sizeable positive effects on wheat yield but decreased resistance to lodging.

主題