甘蔗幼苗对难溶性磷的吸收及其根系对低磷胁迫的响应

Absorption of poorly soluble phosphorus by sugarcane seedlings and its response to low phosphorus stress

为明确甘蔗适应低磷胁迫的生理生化机制,挖掘甘蔗对磷素的利用潜力,揭示甘蔗对低磷胁迫适应的可能机制,该研究以ROC22和ROC10两个甘蔗品种为材料,采用水培和土培的方法研究了甘蔗幼苗对难溶性磷的吸收及其在低磷胁迫下根构型和根系的生理反应。结果表明:(1)培养在以难溶性磷(Ca-P和Al-P)为磷源的培养液中的甘蔗的叶片数、地上部干重、生物量较缺磷(-P)处理显著增加,与对照(+P)的相当,甘蔗总磷积累量也显著提高,达到对照(+P)处理磷积累量的30%~77%。(2)在低磷条件下,甘蔗幼苗的根系有向土壤深层分布的趋势,根的总体积增大、最长根长变长、浅根系分布增多。(3)甘蔗幼苗在低磷环境下,根际环境明显酸化,且根系分泌物能溶解难溶性的铝磷,植株体内酸性磷酸酶的活性也明显增强。以上表明甘蔗幼苗有较强的吸收利用难溶性磷的能力,而低磷条件下根系数量增加、主根的向地性、浅根系分布增多、根际酸化以及植株体内酸性磷酸酶活性的增强可能是甘蔗幼苗适应缺磷环境的重要机制。

In order to make clear the physiological and biochemical mechanism of sugarcane adapting to low phosphorus stress,to tap the potential of sugarcane self-phosphorus,and to reveal the possible mechanisms of sugarcane adaptation to low phosphorus stress,the absorption of insoluble phosphorus in sugarcane seedlings,the physiological responses to root and root architecture under low phosphorus stress by hydroponic and pot-culture were studied,by using two sugarcane varieties ROC22 and ROC10 as materials.The results were as follows:(1)The number of leaves,the dry weight of the shoots and the biomass of sugarcane in the culture medium with insoluble phosphorus(Ca-P and Al-P)as phospho-rus source,were significantly increased compared with those treated with phosphorus deficiency(-P).Moreover,compared with the control(+P),the total phosphorus accumulation of sugarcane also increased significantly,reaching 30%-77%of the phosphorus accumulation in the control(+P)treatment.(2)Under the condition of low phosphorus,the roots of sugarcane seedlings tended to distribute in deep soil,the total volume of roots increased,the longest root length became longer,and the distribution of shallow roots increased.(3)Under the low phosphorus environment,the sugarcane seedlings were obviously acidified in the rhizosphere environment,and the root exudates could dissolve the inso-luble aluminum phosphorus,and the activity of acid phosphatase in the plants was also significantly enhanced.The above results indicate that sugarcane seedlings have strong ability to absorb and use insoluble phosphorus,while roots increase under low phosphorus conditions,the roots of the main roots and the distribution of shallow roots increase,the acidification of the rhizosphere and the enhancement of acid phosphatase activity in the plants,which may be an important me-chanism for sugarcane seedlings to adapt to the phosphorus deficiency environment.