水稻不同基因型吸收利用土壤钾素的差异

利用特制的淹水培养装置,选取耐低钾和缺钾敏感的两个水稻基因型,研究它们吸收利用土壤钾素的差异.结果表明,在低钾条件下,耐性基因型辐简稻地上部生长未受明显抑制,而根干重略有增大.供钾充足时,根际及近根土壤中4种形态钾的亏缺程度都是缺钾敏感基因型81394大于耐低钾基因型辐简稻,这与81394生物量大,需钾量大的遗传特性有关.缺钾条件下,辐简稻距根2 mm内根际土壤易交换态速效钾和可交换态速效钾的平均亏缺率分别为96%和84%,而81394分别为93.7%和66%;在辐简稻近根10 mm土壤中,两形态钾亏缺率仍为83%和84%,而81394分别减小至53%和44%.易释放态缓效钾在两基因型间差异不显著.辐简稻距根3 mm内根际土壤难释放态缓效钾的平均亏缺率为56.6%,显著高于81394.研究发现,辐简稻根际土壤pH的降低程度大于81394,这可能是辐简稻根系适应低钾胁迫分泌更多质子的结果及促进难释放态缓效钾向速效态钾转化的原因.

Studies on the differences in uptake and utilization of soil potassium between different rice genotypes

The differences between uptake and utilization of soil K by two lowland rice genotypes differed in the tolerance to low K were studied by rhizobox cultivation. The results showed that the growth of aerial part of Fujiandao, a rice genotype tolerant to low K, was not obviously affected by low K stress, but the dry root weight was a little promoted. When K supply was adequate, the depletion ratios of all soil K fractions in the rhizosphere of 81394, a genotype sensitive to low K, were more serious than those in the rhizophere of Fujiandao, which may be the result of rice genetic characteristics. Under low-K stress,the depletion ratios of the readily-available K and the exchangeable K in the rhizosphere (<2 mm) of Fujiandao were 96% and 84%, respectively, while it was 93.7% and 66%, respectively, in that of 81394. The depletion ratios of two K form in the soil at 10 mm from root surface of Fujiandao was still as high as 83% and 84%, respectively, but it was decreased to 53% and 44%, respectively, in 81394. There was no significant difference of readily-released K content between the rhizophere of Fujiandao and 81394. The average depletion ratio of slowly-released K in the rhizophere (<3 mm) of Fujiandao was 56.6%, which was significantly higher than that of 81394, 41.7%. More visible descending of soil pH in the rhizosphere of Fujiandao was found compared to that of 81394, which should be the result of the more proton secretion adapting to low-K stress, and the reason of reletively more rapid transformation of slowly-released K into available K promoted in the rhizosphere of Fujiandao than those of 81394.