缺铁胁迫柑橘砧木幼苗的光合特性和叶绿体超微结构

【目的】通过研究枳壳与枳橙砧木在缺铁和正常铁浓度处理下的反应，重点揭示两种柑橘砧木光合特性、叶绿体超微结构等对铁敏感性的差异。【方法】以柑橘的枳壳砧木和枳橙砧木实生苗为试验材料，设置缺铁 (–Fe，0 μmol/L) 和正常铁 (+Fe，37.3 μmol/L) 2个处理进行营养液培养，测定了缺铁胁迫对两种砧木苗期铁元素含量与积累量、光合色素含量、叶片糖含量的影响，并进行了叶绿体超微结构的电镜扫描。【结果】缺铁胁迫显著降低了两种砧木铁元素含量与积累量、叶片光合色素含量，且枳橙砧木光合色素含量下降幅度较大。与对照相比，缺铁后枳壳砧木叶片的糖类物质含量降低，且达到显著差异水平；而枳橙砧木叶片可溶性糖、蔗糖含量显著升高，淀粉和果糖含量显著下降。另外，缺铁胁迫条件下，两种柑橘砧木片层结构模糊，嗜饿体数目增加。并且，缺铁后枳壳砧木叶绿体长度、厚度比对照分别降低了22.1%、26.4%，枳橙砧木则分别下降了55.1%、40.4%。【结论】缺铁胁迫下，枳橙砧木幼苗的铁元素含量和积累量、叶片光合色素含量、叶绿体超微结构等均比枳壳砧木受到较大影响，表明枳橙砧木比枳壳砧木对铁营养缺乏更加敏感。

Photosynthetic characteristics and chloroplast ultrastructure of citrus rootstocks under iron deficiency stress

Objectives]Response of photosynthetic characteristics and chloroplast ultrastructure of different Fe sensitivity citrus rootstocks to different iron (Fe) treatments was studied.Methods]A hydroponic experiment was carried out with -Fe (0 μmol/L) and +Fe (37.3 μmol/L), and citrange and trifoliate orange rootstocks were selected as research materials. The contents of Fe, photosynthetic pigment and carbohydrates and chloroplast ultrastructure of samples were analyzed.Results]The results showed that Fe deficiency significantly decreased the contents and accumulation of Fe, photosynthetic pigment contents in both rootstocks, and the photosynthetic pigment content in citrange rootstock was decreased in a larger extent. The iron deficiency significantly decreased carbohydrates contents in leaves of trifoliate orange, and the contents of total soluble sugar and glucose in leaves of citrange were significantly increased under Fe-deficiency, however, the contents of fructose and starch in leaves of citrange were significantly decreased with no Fe supply. Lamellae structure in chloroplast became fuzzy, and the numbers of plastoglobulus were increased without the Fe application. Compared with the Fe-sufficiency treatment,the chloroplast length and the chloroplast thickness of trifoliate were decreased by 22.1% and 26.4%, and those of the citrange orange were decreased by 55.1% and 40.4%.Conclusions]The content and accumulation of iron, the content of photosynthetic pigment and the ultrastructure of chloroplast of citrange rootstocks were more sensitive to Fe deficiency.