螯合-缓冲营养液中不同磷锌配比对小麦苗期磷-锌关系的影响
Effect of varying combination of P and Zn in chelater-buffered solution on P-Zn interaction in wheat seedling
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摘要: 采用螯合-缓冲营养液培养方法对小麦进行了苗期培养试验, 在3个磷水平(0、0.6 mmol·L-1、3.0 mmol·L-1)和3个锌水平(0、3 μmol·L-1、30 μmol·L-1)的完全组合下对小麦苗期的磷-锌关系进行了研究, 以期为提高小麦籽粒锌的生物有效性提供理论依据。结果表明, 与正常磷锌供应比较, 磷锌的缺乏与过量均不利于小麦生长, 缺磷比过量供磷的抑制程度更大, 而过量供锌比缺锌的影响更为强烈, 缺磷和过量供锌主要影响小麦幼苗的分蘖和地上部干物质的积累。过量供磷时, 小麦根部存在明显的磷-锌拮抗, 抑制了根部对锌的吸收, 但磷的供应却提高了锌在小麦植株体内向地上部的转运; 缺锌时, 小麦叶片会积累大量磷, 而供锌后则会抑制磷在小麦植株体内向地上部的转运。在小麦苗期, 磷、锌均处于正常水平时其交互作用有利于锌的吸收和向地上部转运, 但抑制了磷向叶部的转运。此外, 磷、锌的缺乏均降低了叶绿素SPAD值, 而磷的正常供应和锌的供应促进了叶绿素的合成。缺磷胁迫时小麦叶片的SOD和POD活性较高, 而CAT活性较低; 锌缺乏和过量时叶片SOD活性较低, 而缺锌时POD和CAT活性较高, 供锌后二者活性降低。总之, 磷-锌拮抗作用主要发生在小麦根部, 但在其他器官内也会发生; 且不仅在二者配比不合理时发生, 即使在配比合理时也会发生。Abstract: A nutrient solution experiment with chelater-buffered solution was conducted to investigate the interactions of Zn and P nutrients in wheat seedlings. Zn rates were supplied at three levels of deficient (0 μmol·L-1), normal (3 μmol·L-1) and excess (30 μmol·L-1), while P was supplied at 0 mmol·L-1 (insufficiency), 0.6 mmol·L-1 (normal) and 3.0 mmol·L-1 (excess). The results show that wheat seedling growth slows under deficient or excess P and Zn. Growth retardation is greater under deficient P than under excess P, and under excess Zn than under deficient Zn. The effects of deficient P and excess Zn mainly embody at tillering and shoot biomass accumulation. An obvious antagonism exists in wheat seedling roots under excessive P supply, resulting in decreased Zn content of roots. However, Zn translocation rate to shoots increases under normal and excess P dose. Large amounts of P accumulate in wheat leaf under Zn deficiency. The rate of P translocation to shoots decreases with increasing supply of Zn. Under normal P and Zn supply, P-Zn interaction benefits Zn absorption and translocation. It, however, inhibits P translocation to leaves.While chlorophyll SPAD decreases under deficient P and Zn dose, it increases under normal P and Zn supply. Wheat leaf SOD and POD activity is high while CAT activity is low under deficient P. SOD activity is low under both deficient and excess Zn. The activities of POD and CAT are high under deficient Zn, which decrease with increasing Zn dose. The study shows distinct antagonism between Zn and P in the root system, which might be the case for the other part of the wheat crop. The antagonism does not only occur under abnormal supplies of P and Zn, but also under balanced P and Zn doses.