In the period from maximum tillering stage to full panicle stage, plant takes up large amount of K which occupied 1/3-1/在最大分蘖期到齐穗期，植株吸收大量钾，占整个生育期吸收全部钾的1/3~1/2，但随着植株干物质迅速增加，植株含钾量下降到2.5%，换言之，稀释作用造成植株含钾量降低。