不同钾效率基因型香蕉根际钾营养与根系特性研究

摘要

为探讨不同钾效率基因型香蕉根际钾营养与根系特性,在水培和低钾土培条件下,分析了不同钾效率(高效基因型包括广粉、牛角蕉2个品种,低效基因型包括天宝蕉和黎母山野生蕉2个品种)基因型香蕉(Musa spp.)根际与非根际土壤的速效钾、缓效钾与全钾质量分数的变化,以及根系主要分泌物、根际微生物数量、根系CEC和根系H+分泌量的变化.结果显示,香蕉根际土壤的缓效钾和速效钾质量分数明显高于非根际土,并且于根际形成了钾的相对富集区域,4个品种香蕉的根际土的速效钾和缓效钾质量分数是非根际土壤的1.9~3.9倍.在根际钾的富集能力方面,钾高效基因型显著高于低效基因型,钾高效基因型根际土壤的速效钾和缓效钾质量分数均比低效基因型高出27.35%以上.但是,香蕉非根际土壤的全钾质量分数却高于根际土壤.钾高效型香蕉的根系分泌能力和根际微生物数量都显著高于低效基因型,钾高效基因型根系游离氨基酸与可溶性糖的分泌量与低效基因型相差0.62~2.09倍;真菌、细菌和放线菌的数量方面,高效基因型均与低效基因型相差1倍以上,但基因型内各品种间差异却不显著.钾高效基因型根系H+分泌量与根系CEC显著高于低效基因型,H+分泌量前者是后者的1.57~1.82倍,根系CEC前者是后者的1.69~2.57倍.根系H+分泌量、根系CEC与植株含钾量之间呈显著正相关;根际土速效钾和缓效钾分别与根际微生物数量、根系 CEC、根系氢质子分泌量、各根系分泌物指标呈显著正相关关系,相关系数达0.95以上.%To investigate the potassium (K) nutrition in rhizospheres and the characteristics of roots for different K-efficiency genotypes of banana(Musa spp.),we analyzed the changes in contents of three K species,namely the readily available K,slowly available K, and total K (TK) in the rhizospheres and non-rhizospheres from these genotypes in a soil with K deficient and in the aquaculture with different K contents. We also investigated the quantities of microorganisms in the rhizospheres, the rates of important root exudates and H+secretion, and the rhizosphere caption exchange capacity (CEC). Four banana genotypes used in this study were high-efficiency genotype (Guangfen and Niujiaojiao) and low-efficiency genotype (Tianbaojiao and Limushanyeshengjiao). Results showed that the contents of readily available and non-exchangeable K in the soil from the rhizospheres were higher than that from the non-rhizospheres, and an area of relatively K enrichment was formed in the rhizospheres. Our results further revealed that the contents of readily available and non-exchangeable K in the rhizospheres from the four bananas genotypes were 1.9~3.9 times higher than that in the non-rhizospheres. The ability of K accumulation from the high-efficiency genotype was more than 27.35% higher than that from the low-efficiency genotype, and the difference was statistically significant. In contrast, the content of TK in the soil from the non-rhizosphere was higher than that from the rhizosphere, and the increasing extent of TK in the non-rhizosphere for the high-efficiency genotype was higher than for the low-efficiency genotype. Furthermore, the amounts of microorganisms and the rate of root exudates from the high-efficiency genotype were significantly higher than that from the low-efficiency genotype. The secretions of free amino acids and total soluble sugar from the high-efficiency genotype were 0.62~2.09 times higher than that from the low-efficiency genotypes. The amounts of fungi, bacteria and actinomycetes from the high-efficiency genotypes were more than one time larger than that from the low-efficiency genotype although the differences were not statistically significant among the species of the same genotype. The CEC and rate of H+secretion in the rhizospheres from the high-efficiency genotype were, respectively, 1.69~2.57 times and 1.57~1.82 times higher than that from the low-efficiency genotype. Correlation analysis showed that the H+secretion and CEC in the rhizosphere were significantly correlated with banana K content. The amounts of microorganisms, root exudates, H+secretion and CEC in the rhizospheres were significantly correlated with the contents of available and non-exchangeable K in the soil rhizosphere at α=0.05.