【作者】 韩霜；

【导师】 陈立松；

【作者基本信息】 福建农林大学 ， 果树学， 2007， 硕士

【摘要】 每隔一天用含0、2.5、5、10和25μmol／L硼的营养液浇盆栽（基质为砂）雪柑[Citrus sinensis（L.）Osbeck]实生苗，14周后调查缺硼对柑橘生长、根系形态结构、矿质营养、光合作用、光合酶、碳水化合物和活性氧代谢的影响。1缺硼对柑橘实生苗生长及营养元素含量的影响除0μmol／L处理外，其他处理的柑橘实生苗均生长正常，不显示任何缺硼症状，叶片B含量也处于适宜范围。基于此，本试验把0μmol／L处理称为缺硼处理，其他处理均称为不缺硼处理。缺硼处理后9周柑橘实生苗出现缺硼症状，初期表现为新梢顶端生长点枯死，幼叶出现水渍状黄斑，叶片卷曲：后期叶增厚黄化，叶脉肿大、破裂和栓化，叶畸形，表现出典型的缺硼症状。缺硼柑橘根尖膨大，表面凹凸不平，细胞、组织结构变形，龟裂严重。因为缺硼对地上部生长的影响比对根系生长的影响大，故缺硼实生苗有较大的根冠比。缺硼降低柑橘叶片B、K、Ca和P含量，但对根系K、Ca和P含量的影响较小。缺硼并不影响柑橘根、茎和叶Mg元素含量。因为缺硼降低柑橘叶片N含量，而对C含量影响不大，故缺硼叶片有较高的C／N比。2缺硼对柑橘叶片光合作用的影响缺硼叶片有较低的Chla、Chlb、Chl、Car含量和Chla／b比显著下降，较高的Car／Chl比；较低的光合速率、气孔导度和光合酶（Rubisco，GAPDH和叶绿体基质FBPase）活性，较高的胞间CO₂浓度；较高的葡萄糖、果糖和淀粉含量，较低的蔗糖含量。总之，缺硼下柑橘叶片光合作用可能受到已糖（葡萄糖、果糖）和淀粉过度积累引发的反馈调节。3缺硼对柑橘叶片活性氧代谢的影响缺硼下，柑橘片超氧阴离子和H₂O₂产生速率，单位叶面积表示的APX、MDAR、GR、POD和SOD活性及单位Chl表示的AsA和GSH含量均显著增加，而单位叶面积表示的DHAR和CAT活性显著下降。与不缺硼叶片相比，缺硼叶片有显著增加的MDA含量和电解质渗漏。总之，缺硼下虽然柑橘叶片抗氧化系统被上调，但并不足以保护叶片在强光下免遭光氧化伤害。更多还原

【Abstract】 Citrus （Citrus sinensis （L.） Osbeck） seedlings grown in pots containing sand were fertigated for 14 weeks with nutrient solution at a B concentration of 0, 2.5, 5, 10, or 25μmol/L every other day. Effects of boron deficiency growth, root morphology and structure, mineral nutrition, photosynthesis, photosynthetic enzymes, carbohydrates, and active oxygen metabolism were investigated in this study.1 Effects of B deficiency on growth and contents of nutrient elements in citrus seedlingsAll growth was normal in appearance and did not differ very much among different treatments except that 0μmol/L B treated trees showed visible symptoms of B deficiency. Also, leaf B levels were in the normal range except for the plants without supplying B. Based on these results, plants without supplying B and those treated with 2, 5, 10, or 25μmol/L B every other day are considered as B-deficient plants and B-sufficient ones, respectively. Boron deficiency symptoms in the shoots firstly appeared at the apex and in the actively growing leaves 9 weeks after B treatment. Boron deficiency symptoms included dieback of terminal growth, yellow, water-soaked spots in young leaves and deformation of these leaves, thickening and yellowing of mature and aging leaves, enlargement, splitting, and corking of leaf veins. Boron deficiency symptoms in roots included enlargement of tips, deformation of cells and tissues, unevenness and crack of surfaces. Because leaf and stem dry weights decreased to a larger extent than root dry weight in response to B deficiency, root/shoot ratio was greater in B-deficient plants than in B-sufficient ones.Boron deficiency decreased B, K, Ca, and P contents of citrus leaves, but had less effect on K, Ca, and P contents of roots. Boron deficiency did not affect Mg content of citrus roots, stems, and leaves. Because B deficiency decreased N content of citrus leaves and had little effect on their C content, C/N ratio was higher in B-deficient leaves than in B-sufficient leaves.2 Effects of B deficiency on photosynthesis in citrus leaves Contents of Chl a, Chl b, Chl, and Car, and Chl a/b ratio were higher in B-deficient leaves than in B-sufficient ones, whereas Car/Chl ratio was higher in B-deficient leaves than in B-sufficient ones. Boron-deficient leaves had decreased CO₂ assimilation, stomatal conductance, and activities of photosynthetic enzymes （Rubisco, GAPDH, stromal FBPase）, but increased intercellular CO₂ concentration compared with B-sufficient ones. Boron-deficient leaves had increased hexoses （glucose, fructose） and starch contents, but decreased sucrose content compared with B-sufficient ones. It is consluded that CO₂ assimilation may have been feedback-regulated by the excessive accumulation of hexoses （glucose, fructose） and starch in B-deficient leaves.3 Effects of B deficiency on active oxygen species metabolism in citrus leavesBoron-deficient leaves had increased superoxide anion and H₂O₂ profuction rates, APX, MDAR, GR, POD, and SOD activities expressed on a leaf basis, and AsA and GSH contents expressed on a leaf Chl, whereas leaf-area based activities of MDAR and CAT activities were lower in B-deficient leaves than in B-sufficient ones. Compared with B-sufficient leaves, B-deficient leaves had higher MDA content and electrolye leakage. In conclusion, although antioxidant systems are up-regulated in B-deficient citrus leaves, this up-regulation can not provide enough protection to B-deficient leaves against photooxidative damage under hight light.更多还原