长期干旱环境对柑橘生长及养分吸收和相关生理的影响

Effect of perennial drought environments on Citrus tangerina Hort. cv. "Chuanju" growth, nutrient absorption and physiology

  • 摘要: 为了揭示长期干旱环境下柑橘生长及养分吸收和相关生理响应的特点, 探索长期干旱对柑橘的不良影响, 以红橘(Citrus tangerina Hort. cv. "Chuanju")为材料, 以有灌溉条件为对照,在贵州北盘江喀斯特河谷长期自然干旱环境下连续4年观察和取样分析测定红橘的物候期, 新梢和果实生长发育状况, 叶片寿命, 果实及叶片N、P、K、Ca、Mg、Fe、Cu、Zn、B等元素的含量, 分析果实生理病害与干旱及元素含量的关系; 测定与抗旱相关的形态、组织解剖及生理特征, 研究红橘对长期干旱的生理响应与适应长期干旱的关系。结果表明: 长期干旱环境下红橘新梢生长、开花及生理落果物候期明显推迟, 果实成熟期提早, 叶寿命缩短; 新梢短而细且数量及叶片数减少, 枯死严重; 叶片革质化程度加重, 叶片变小变厚, 新梢叶缺N、Zn、Fe、B等症状明显; 果实的鲜重、干物质质量、水分含量、种子数、果汁含量减少, 春梢叶中N、P、K、Ca、Mg、Fe、Cu、Zn、B及果实的N、P、Ca、Fe、B素的含量明显降低, 果皮流胶和汁胞粒化程度加重, 品质下降; 叶片的栅栏组织增厚, 海绵组织变薄, 组织紧密度和气孔密度增大, 气孔变小,组织疏松度降低; 在周年中叶片的脯氨酸及可溶性糖含量增加, 临界水分饱和亏增大, 失水速率及相对含水量和叶水势变小, Pn及Tr明显降低, 夏季的WUE明显提高。红橘适应长期抗旱的能力强。在长期干旱的环境中红橘的生长节律、植株及叶片形态和寿命、叶片厚度及组织结构、气孔密度与大小、叶片的临界水分饱和亏、失水速率、相对含水量、叶水势及脯氨酸和可溶性糖含量、光合速率与蒸腾速率都发生了有利于抵御长期干旱的特异性变化。长期干旱是导致红橘树冠枝梢大量枯死、果实发育缓慢变小、种子败育、果皮流胶及汁胞粒化和果实及叶片中营养元素含量减少的主要原因。

     

    Abstract: The objective of this paper was to study the specifics of Citrus tangerina Hort. cv. "Chuanju" in terms of growth, nutrient absorption and related physiological responses to perennial drought environments using annual irrigations as the control. The main aim of the study was to reveal any adverse impacts of perennial drought on citrus. The phenological phases, new shoot/fruit growth conditions, leaf life spans, and N, P, K, Ca, Mg, Fe, Cu, Zn and B contents of spring-shoot leaves/fruits were measured in four successive years. The relationships among physiological diseases, droughts and nutrient uptakes were researched into along with morphological characteristics, organizational structures and drought-resistance physiology. Also the relationships between physiological response and the adaptability to perennial drought were discussed. The results showed that under perennial drought environments, growth, flowering and fruit-dropping periods clearly delayed while fruit maturity period advanced. Leaf life span shortened; shoots became shorter, thinner and the amounts of shoots and leaves dropped while leaf withering worsened. The degree of leaf leathery increased and so leaves became smaller and thicker. Deficiency symptoms caused by elements such as N, Zn, Fe, B, etc became very distinct. Fresh weight, dry-matter weight, water content, seed amount, juice content and N, P, K, Ca, Mg, Fe, Cu, Zn and B contents in spring shoot leaves obviously dropped along with those of N, P, Ca, Fe and B in fruits. The degrees of fruit gummosis and juice sac granulation worsened such that fruit quality fell drastically. Leaf palisade tissues thickened while spongy tissues thinned out. CTR (tissue tense ration) and stomata density increased as stomata and SR (tissue soothing ratio) got smaller. The contents of proline, soluble sugar and water saturation deficiency in leaves increased. Dehydration rate, relative water content and leaf water potential dwindled. Then while Pn and Tr clearly dropped, WUE drastically improved in summer. The study showed that C. tangerina Hort. cv. "Chuanju" had strong ability to adapt to perennial droughts. Under perennial drought environments, C. tangerina Hort. cv. "Chuanju" adopted specific adjustments to resist adverse environments. Such adjustments involved in growth regularities, plant/leaf shapes and life spans, leaf thicknesses and structures, stomata densities and sizes, leaf water saturation deficiencies, dehydration rates and relative water contents, leaf water potentials, proline/soluble sugar contents, Pn/Tr. Perennial droughts were the main causes of canopy shoot deaths, slow fruit developments, seed abortions, seedcase gummoses, juice sac granulations and decreased element contents of fruits/spring shoot leaves.

     

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