富钾基因型籽粒苋主要根系分泌物及其对土壤矿物态钾的活化作用

通过试验，研究了2种供K水平对籽粒苋(Amaranthus spp.)富K基因型和一般基因型根系分泌物含量变化的影响，以及在低K胁迫时3个生长期两类基因型主要根系分泌物含量的变化特点，模拟了籽粒苋根系分泌物对土壤矿物态钾的活化作用.结果表明,籽粒苋根系分泌物中可溶性糖、氨基酸和有机酸含量随供K水平的升高而降低，且富K基因型根系分泌物中3种物质的分泌量始终大于一般基因型；在正常供K条件下，两基因型根系分泌能力相近，但在低K处理时，前者显著高于后者，差异显著；在2种供K水平下，根系有机酸分泌量在3种分泌物中占绝对优势，分别是可溶性糖和氨基酸分泌量的几十倍和几百倍.籽粒苋生长到50 d时，一般基因型根系可溶性糖、氨基酸和有机酸的分泌量较40 d时迅速降低.富K基因型根系分泌物中可溶性糖、氨基酸和有机酸含量在3个生长时期均大于一般基因型，且随着生长时间的延长，两基因型间可溶性糖、氨基酸和有机酸含量的差异明显增大.两类基因型在3个生长时期均以分泌有机酸为主，其占总分泌量的93%以上.籽粒苋根系分泌物处理后的土壤速效钾含量均高于清水对照处理，富K基因型在低K胁迫时的根系分泌物对土壤K的活化作用明显大于一般基因型.

Root exudates of potassium-enrichment genotype grain amaranth and their activation on soil mineral potassium

With solution culture experiment,this paper studied the effects of two potassium supply levels on the root exudates content and its dynamics of two grain amaranth genotypes(potassium-enrichment K12 and ordinary M9),and the activation of root exudates on soil mineral potassium.The results showed that the root exudation rates of soluble sugar,amino acids and organic acids of these two genotypes were decreased with increasing potassium supply level,which was higher in K12 than in M9.The root exudation capability of the two genotypes was similar under normal potassium supply level,while that of K12 was significant higher than M9 under low potassium supply level.Organic acid was the main root exudate under two potassium supply levels,which was several decuples or hundreds times as much as that of soluble sugar and amino acids.Compared with those at the fortieth day,the exudation rates of soluble sugar,amino acids and organic acids at the fiftieth day decreased rapidly in M9,while decreased slowly in K12.At three growth phases,the contents of soluble sugar,amino acid and organic acid were higher in the root exudate of K12 than in that of M9,and the difference of the two genotypes became significant with time extended.The content of organic acid in root exudate was accounted for >93% in the two genotypes at three growth phases.Soil available potassium content after treated by the root exudates of grain amaranth was higher than that treated by pure water.Under low potassium stress,the content of soil available potassium treated by the root exudates of K12 was higher than that treated by those of M9.