Effects of AM fungi on potassium absorption of flue-cured tobacco LI Dengwu, Photosynthesis and transpiration in relation to ion accumulation in Vitex trifolia under varied light intensity Potassium Accumulation and Root Physiological Characteristics of Potassium-Enriched Flue-Cured Tobacco Genotvpes Effects of phosphorus and potassium fertilization on potassium accumulation and utilization efficiency of relay-cropping soybean