根分泌物及其在植物营养中的作用 Ⅱ.锌营养状况对禾本科植物根分泌物的影响

ROOT EXUDATES AND THEIR ROLE IN PLANT NUTRITION Ⅱ.EFFECT OF ZINC NUTRITIONAL STATUS ON THE ROOT EXUDATES OF GRAMINACEOUS PLANT SPECIES

研究了在控制条件下,锌营养状况对禾本科植物根系分泌低分子量有机物质及其分泌物对活化难溶性锌和铁的能力的影响。缺锌虽然导致玉米、小麦和大麦根系分泌氨基酸、糖类化合物和酚类化合物增多,但这一变化与它们对难溶性锌和铁的活化作用无关。禾本科植物氨基酸、糖类化合物和酚类化合物的分泌率随着苗龄和缺锌程度的增加而减少,同时也随生长介质中锌浓度的增加而降低。但是,禾本科植物根分泌物对难溶性锌和铁的活化能力不同于双子叶植物。缺锌小麦的根分泌物不仅可以活化石灰性土壤中的难溶性锌,而且可以活化新沉淀的难溶性铁。与对照植物相比较,其活化能力增加了13～14倍。缺锌导致根系分泌锌和铁的活化物质在植物营养方面有重要意义。

In various graminaceous plant species(wheat,barly and maize) grown in nutrient solutions the effect of the zinc nutritional status on exuda- tion of low moleculare organic compounds(amino acids,sugars and phenolics) and the role of these root exudates in mobilization of zinc and iron were studi- ed.In all plants zinc deficiency increased root exudation of amino acids,sugars and phenolics.The root exudates of zinc deficient wheat plants mobilized not only zinc from a calcareous soil(luvisol),but also iron from freshly precipita- ted Fe(Ⅲ)-hydroxide.These results demostrate the possible importances of the root.exudates in the zinc or/and iron acquisition of the graminaceous plant species.