影响菜豆体内铁再利用效率的因素及其机理

本文在人工气候室中，用营养液培养方法，并结合同位素示踪技术研究了铁的供应状况，两种形态氮素（ＮＯ＾－３－Ｎ和ＮＨ＾＋４－Ｎ）及叶处遮光对菜豆体内铁再利用效率的影响，并对其有关机理进行了深入的研究。结果表明，铁的缺乏有利于累积在根和初生叶中的铁身新生组织中转移，铁的再利用效率明显提高。无论有缺铁还供铁条件下，ＮＨ＾＋４－Ｎ的供应使得菜豆新叶中活性铁含量、新叶叶绿素含量及体内铁的再利用效率都明显高于Ｎ

FACTORS AFFECTING REUTILIZATION EFFICIENCY OF IRON IN BEAN PLANTS AND THEIR MECHANISM

The effects of iron supply, nitrogen forms (N0₃^-N and NH₄⁺-N) and primary-leaves-shading on reutilization efficiency of Fe in bean plants and their mechanism were studied in nutrient solutions under controlled conditions. The 59 Fe isotopic method was also used to identify the iron reutilization efficiency. The results showed that Fe deficiency could enhance Fe translocation to young leaves from roots and primary-leaves, thus increasing Fe reutilization efficiency. The plants added with NH₄⁺-N had a much higher content of active Fe, more chlorophyll in young leaves and high Fe reutilization efficiency, much better ultrastructure chloroplast than those fed with N0₃^-N, and these were true both in Fe-sufficient and deficient treatments. No chlorosis occurred in young leaves of bean plants fed with NH₄⁺-N under Fe-deficient condition. More active Fe and 6 percent enhancement in Fe reutilization efficiency were found in the primary-leaves-shading treatment, which improved Fe nutrition in young leaves of Fe-deficient plants fed with N0₃^-N. All these results demonstrated that both NH₄⁺-N and primary-leaves-shading had a beneficial effect on mcreasing Fe reutilization efficiency, improving Fe nutrition in young leaves and depressing chlorosis symptom in bean plants.