缺磷胁迫对黑籽南瓜幼苗根系生长和根系分泌物的影响

采用营养液培养方法,以1/2单位日本园试配方为基本营养液,在温室内培养黑籽南瓜(Cucurbita ficifolia B.)幼苗,测定正常供磷处理和缺磷胁迫下黑籽南瓜幼苗在根系生长、根系形态和根系分泌物等方面的差异,以期为南瓜磷高效种质创新和耐低磷机制研究提供理论依据.结果表明,缺磷胁迫后21 d,黑籽南瓜幼苗地上部生物量显著降低,根系生物量与正常供磷处理相比没有明显差异,根冠比增大;总根长和根表面积显著增加,根数、根横径和根体积与正常供磷处理相比没有明显的差异;根系吸磷量和磷转运率下降,根系吸磷量占总吸磷量的百分数增加,根系磷利用效率显著增高.总根长和根表面积增加可能与其磷吸收效率密切相关,是黑籽南瓜幼苗对缺磷胁迫的适应性变化.与正常供磷处理相比,缺磷胁迫后21 d,黑籽南瓜幼苗根系分泌的化合物种类组成类似,主要由酚类、芳香烃类、酯类、胺类、烯烃类和烷烃类化合物组成.但缺磷胁迫后根系分泌物中的化学成分多于正常供磷处理,邻苯二甲酸二(1丁基2异丁基)酯等8种化合物是缺磷胁迫下黑籽南瓜根系分泌物的特有成分.缺磷胁迫后黑籽南瓜的自毒作用增强.

Effect of Phosphorus Deficiency on Root Growth and Root Exudates of Cucurbita ficifolia B.

To probe into the morphological and physiological responses of Cucurbita ficifolia B.in response to phos-phorus deficiency, the biomass, root morphological characters, P absorption characters and root exudates were determined by using nutrient solution approach in greenhouse.Based on the studies, we expected to lay some theoretical foundations for the improvements of P efficiency and provide materials for such studies.The results showed that on the 21st days after phosphorus deficiency,the shoot biomass of C.ficifolia was significant decreased,root/shoot ratio,root lengths and root surface areas increased, no significant differences were found in root biomass, root tips, root average diameter and root vol-ume between phosphorus deficiency and normal phosphorus status.P uptake rate and P reallocation rate decreased,root P uptake/plant P uptake ratio and P utilization rate increased. The results demonstrated that root lengths and root surface ar-eas increased might be responsible for the efficient P acquisition in C. ficifolia in the phosphorus deficiency environment. On the 21st days after phosphorus deficiency, root exudates of C .ficifolia contained similar chemical compounds as those of normal phosphorus status,which were mainly phenol,aromatic,ester,amine,olefin and alkanes.The components of root exudates of C. ficifolia under phosphorus deficiency were more than that in normal phosphorus status.The autotoxicosis of C.ficifolia was enhanced in phosphorus deficiency.