施用磷、钙对红壤上胡枝子生长和矿质元素含量的影响

采用红壤土培试验,研究了施用P、Ca对耐Al性不同的两个胡枝子品种的生长和矿质元素含量的影响.结果表明,单独 +P处理显著增加了耐Al 品种根和地上部生物量,而对Al敏感品种无影响;单独 +Ca处理显著促进了Al敏感品种根部的生长,而对耐Al品种的生长无影响;+P+Ca处理显著增加了两个品种根和地上部生物量.耐性品种地上部Al含量显著低于敏感品种,而根部Al含量无显著差异.两个品种体内P含量在 +P处理时耐性品种显著高于敏感品种,其他处理品种间无显著差异.整体上,胡枝子体内Ca、K、Mn和Mg含量耐性品种大于敏感品种,Fe含量反之.结果表明,低P胁迫是酸性土壤上耐Al胡枝子品种生长的主要限制因子,增施P肥效果明显,而对于Al敏感品种,Al毒是其生长的首要限制因子,只有施用石灰后对其加P,生物量才能提高.耐性品种根部有阻碍Al 向地上部运输的机制,而这种机制与体内P含量较高有着直接或间接的关系.另外,推测耐Al胡枝子品种对其他养分的吸收利用能力也较强.

Effects of Phosphorus or Lime Applications on Growth and Mineral Compositions of Two Lespedeza Species

Soil culture experiment was employed to explore the effects of phosphorus or lime applications on biomass and mineral compositions in two lespedeza species different in Al sensitivity. The results showed that +P treatment could increase the biomass of Al-tolerant species, but not for that of Al-sensitive species. +Ca treatment could augment the root biomass of Al-sensitive species, but not for that of Al-tolerant species. Biomass were enhanced by +P+Ca treatment in both species. Al content in shoots of Al-tolerant species was much lower than that of Al-sensitive species, and no difference in Al content of roots was found. P content in shoots of Al-tolerant species was higher than that in Al-sensitive species only with +P treatment. Contents of Ca, K, Mn and Mg in Al-tolerant species were higher than those in Al-sensitive species, Fe content was contrary. The results suggested that the main limit factor for Al-tolerant species was P deficiency in acid soil. However, Al toxicity was the primary limit factor for Al-sensitive species. Al-tolerant species had some mechanisms to prevent Al transport from roots to shoots, and such tolerant mechanisms could be related with the higher content of P in plants. In addition, Al-tolerant species had the stronger ability to uptake Ca, K, Mg, Mn than Al-sensitive species.