Effect of shading and nitrogen application on yield, grain size distribution and concentrations of nitrogen and water soluble carbohydrates in malting spring barley (Hordeum vulgare L.).

摘要

In field trials in 1991 and 1993 in Wageningen, Netherlands, barley cv. Prisma was given no shading (S1) or shading from tillering to the start of stem elongation (S2), from the start of stem elongation to heading (S3) or from heading to the end ofgrain filling (S4), and no N fertilizer or 90 kg N/ha at sowing minus soil N content alone or with 60 kg N at the flag leaf stage. Compared with S1, total grain yield was 5% lower in S2, 35% lower in S3 and 45% lower in S4. S2 and S3 significantly reduced the concentration of water soluble carbohydrates in plant organs and increased the N concentration, but in general these concentrations returned to the values of the control after the shading period. S3 significantly reduced the number of grains m-2, mainly because there were 35% fewer grains per spike. This treatment resulted in a mean grain weight 14% above that of the control in 1991, probably as a result of the cold, wet spring and warm, dry summer, while in 1993 the spring was warm and dry and the summer was cool and wet. S4 reduced mean grain weight by 40% in 1991 and by 25% in 1993 and shifted the median of the size distribution towards smaller grains in both years. It also increased the N concentration in the grains, resulting in unacceptablyhigh protein concentrations (14-21%) for malting quality. Higher rates of N fertilizer increased LAI, total dry matter production and grain N concentration. N had a positive effect in establishing yield potential because it increased grain number per unit area; however, it did not improve assimilate supply during grain filling, and hence grain number and mean grain weight were negatively correlated. Only in 1993 did N increase grain yield. It is concluded that shading during the growing period and highrates of N fertilizer adversely affect the quality (in terms of grain size, size distribution and grain N concentration) of malting barley.