土壤中有毒物质对宿根甘蔗苗期黄化的效应研究

The Effect Study of Some Soil Toxic Substance on Yellowing Disease of Perennial Sugarcane Seedlings

为探明宿根甘蔗(Saccharum officinarum L.)发生黄化的原因,遏制黄化现象的蔓延,对宿根甘蔗苗期发生黄化较严重的产地进行实地调查,并采样分析各产地宿根正常苗种植地、宿根黄化苗种植地和新植蔗苗种植地的甘蔗根系、叶片与土壤的各项生理生化指标。结果表明,宿根黄化苗种植地的土壤酚酸含量高于宿根正常苗种植地和新植蔗苗种植地,宿根甘蔗黄化苗的根系细胞严重受损,根系细胞膜透性显著高于宿根甘蔗正常苗和新植蔗苗,根系活力弱;叶片活性铁含量、硝酸还原酶活性和叶绿素含量则低于正常苗和新植苗。说明长期连作导致土壤酚酸类有毒物质大量积累,甘蔗根系中毒,根系受损细胞膜透性增大,大量内容物外渗,死亡的根细胞残体和根系分泌物又加速有毒物质的积累;而植株吸收过量的锰和铝后,降低了甘蔗叶片的硝酸还原酶活性,抑制了甘蔗正常的氮代谢;植株发育不良对新根的萌发和生长也不利,造成植株体内铁锰比例失衡,阻碍宿根甘蔗对铁的吸收与活化,最终宿根甘蔗幼苗因缺铁而出现黄化。

In order to explore the reasons for etiolation of perennial sugarcane（Saccharum officinarum L.） seedings and curb it spreading, four regions where the etiolation phenomenon is serious were investigated; then soil, leaves and roots samples were collected from normal fields,etiolated fields and newly planting fields of sugarcane to analyze their physiological and biochemical indicators. Results showed that the soil phenolic acids content in etiolated fields was higher than in normal fields and new planting fields;the roots of etiolated perennial sugarcane seedlings were damaged seriously; and roots membrane permeability was higher than normal and new planting sugarcane seedlings; roots system vitality of etiolated seedlings was weak;and activate Fe content,nitrate reductase activity and chlorophyll content in leaves was lower than normal and new planting seedlings.Continuous cropping for a long time led to phenolic acids accumulation,which infected roots system, so that the membrane permeability of roots system increased, lots of contents exuded. The dead root cells and root secretion could accelerate accumulation of toxic substances. Once the plants absorbed excess Mn and Al,it could reduced the nitrate reductase activity and inhibit nitrogen metabolism of sugarcane.The germination and growth of new roots were depressed due to the plants＇ poor development. The proportion of Fe and Mn was imbalanced in the plants, which hindered the sugarcane form absorbing and activating Fe. At last, the perennial sugarcane young soot went to etiolate for short of Fe.