The effects of weather, seed rate and cultivar on lodging and yield in winter wheat

摘要: Winter wheat cultivars Apollo, Hornet, Longbow and Norman were each sown at 50, 100, 200, 400, 800 1600 seeds/m 2 in a field experiment conducted Northern Ireland over the 1989/90 crop year. No growth regulators applied received 178 kgN/ha top-dressing spring. Hourly rainfall, windspeed wind direction data recorded lodging was visually assessed from end of May to harvest. Lodging first occurred seed-rate plots as ears emerging early June then progressively increased 800, 400 200 during June, July August. did not occur suddenly but took several hours, with stems lying an angle before completely. Stem buckling or breakage appear be principal form structural failure. The longest strawed cultivar, Longbow, lodged most severely. shorter-strawed also badly contrast Hornet which had similar straw length. taller than produced more per square metre other cultivars, least tended lean c. 30° vertical. within 24 h periods rainfall which, many cases, coincided windspeeds height averaging > 25 km/h occasionally 50 km/h. following when exceed 16 grain yield negatively correlated average ear emergence harvest, there being 1 t/ha decline for 10% increase area lodged. 100 yielded 10 little no lodging. seed rate attributed effect rather associated fall number grains/ear 1000-grain weight 56 53·5 g lowest 15 42·7 highest, respectively. A comparison plants unlodged rates, subsequently indicated that higher rate, less fresh unit area, basal internodes smaller diameters, fewer support roots stem, lower root dry stem.