Research briefs: nutrient uptake in poinsettia changes during different stages of growth

摘要

We all know that applying excess amounts of fertilizer and water through top irrigation can lead to leaching of nutrients into the ground water and streams. During the past decade different researchers have studied various fertility aspects of poinsettia. Yelanich and Biernbaum 1994 at Michigan State University showed that marketable poinsettias could be produced using reduced nitrogen application rates by simply reducing the leaching fraction to 15%. Argo and Biernbaum 1995 showed that poinsettias irrigated overhead for the first 58 days with 392 ppm N and 331 ppm K, provided ample nutrients in the top 2.5 cm so that by leaching, sufficient nutrients could be supplied to meet the needs of the crop for the remainder of the production period. Nutrient requirements change and rates of uptake change during different stages of growth. In 1991, Jim Tsujita at the University of Guelph showed how nutrient uptake changed in rose shoots depending on the stage of growth, with uptake increasing as shoots rapidly elongate but decreasing as flower buds develop.