通过盆栽试验研究了不同供钾水平下水稻各叶位的含钾量变化.结果表明,水稻含钾量随生育期的推进逐渐下降,下降幅度达69％ ～ 75％.水稻含钾量与生育期和土壤供钾水平有关:分蘖期不同叶位的鞘、叶含钾量由上至下大幅下降,鞘与叶的含量钾比值均大于1,且比值随叶片含钾量的增加而上升.拔节期钾素水平由低至高,叶位间鞘、叶含钾量由上至下降低的趋势减弱；鞘与叶含钾量比值为0.26～ 1.49,且随叶片含钾量的增加而增加.齐穗期,低钾水平下,叶位间鞘、叶含钾量由上至下降低,高钾水平则相反；鞘叶含钾量比值为0.36～ 1.33.成熟期,秸秆的含钾量范围为2.8 ～ 22.9 g/kg,随钾素水平增加而增加；籽粒的含钾量约为5.0 g/kg.综合不同时期含钾量变化规律可以看出,水稻分蘖期上部叶是钾素优先积累的部位,而叶鞘更是钾奢侈吸收储存的部位；齐穗期以后,钾奢侈吸收主要是积累到了中下部叶和叶鞘中.由于水稻植株钾含量因不同生育期、不同部位而变化很大,根据植株钾含量来进行营养诊断需要考虑取样时期、取样部位,而鞘、叶钾含量比值可能有较好的指示作用.%Pot culture experiment was carried out to investigate the effect of soil K level on K contents in various parts of rice plants.The results showed that K content of rice plant reduced gradually during whole growth period.As compared with tillering stage,K content office plant decreased by about 69％-75％ at maturity stage.Both growing stage and soil K level were the key factors affecting K content of rice plant.At tillering stage,K content of leaf and sheath reduced significantly from top leaf to lower leaves.The ratios of the sheath K content to the corresponding leaf K content were all higher than 1,and the ratios increased accordingly as leaf K content increased.At jointing stage,the similar trend of K content among leaves was also observed as compared with that of tillering stage,but the decrement of K content from top leaf to lower leaves became smaller,and K content ratios of sheath to leaf also reduced,which ranged from 0.26 to 1.49.At full heading stage,K content of upper leave and sheaths was higher than that of lower leave or sheaths when K supply in soil was lower,but K content of lower leave was higher that that of upper leaves when soil K supply was higher.At maturity stage,K content of rice stalk ranged from 2.8 to 22.9 g/kg as the soil K supply increased,while K content office seeds remained about 5.0 g/kg.The above results indicated that rice K was preferentially accumulated in upper leaves at tillering stage,and the sheath is the reserve for luxury K uptake,while the lower leave and sheaths were the reserve for luxury K uptake after full heading stage.As rice K content varied greatly among different growing stages and different organs,it's important to choose the right stage and fight organ for rice K status diagnoses.The ratios of sheath K content to corresponding leaf K content is possible a good index for rice K status diagnoses.
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