Defense mechanism of leaves to environmental stress in fruit trees

1. 以几种落叶果树为试验对象，研究了不同施氮量对叶片和根系无结构碳水化合物积累的影响。叶片叶绿素含量、可溶性总糖含量、叶片和根系氮含量随施氮量的增加而增加，而叶片淀粉含量与施氮量成反比。随着叶片含氮量的增加，叶绿体中RuBisCO的积累和RuBisCO特异性抗体的免疫反应程度增加。N-O树叶片中的RuBisCO被限制在叶绿体的外围，因为叶绿体内积累了大量的淀粉粒。研究了不同施氮量对几种落叶果树日晒成熟叶片叶绿素荧光的影响。光抑制程度通过监测有效叶绿素荧光与最大叶绿素荧光的比值（Fv/Fm）来确定。氮肥的施用对各种属的Fv/Fm均有影响。缺氮叶片的这一比例一直较低。研究了芒果膨大叶片解剖生理特征的变化，以确定与叶龄相关的光合活性控制因素。用DAPI染色未成熟幼叶时，在相同的叶肉组织中，一些叶绿体发出红色荧光，另一些发出黄色荧光。叶片冲水后气孔未迅速分化。当叶片达到28.6 cm2时，气孔保护细胞全部出现。与幼嫩、未成熟叶相比，绿叶和成熟叶的RuBisCO含量较高。根据单位叶面积的耗氧量和可变叶绿素荧光与最大叶绿素荧光的比值（Fv/Fm）估算，未成熟叶片的光合活性始终低于成熟叶片。少

1. The effects of different amounts of nitrogen, applied in the soil, on the accumulation of no*tructural carbohydrate in leaves and roots were determined in several deciduous fruit trees. Leaf chlorophyll content, total soluble sugar, and nitrogen content of leaves and roots increased with increased application of nitrogen, whereas starch content of leaves was inversely proportional to the amount of nitrogen administered.2. The accumulation of RuBisCO and the extent of immunoreaction with RuBisCO-specific antibodies increased in chloroplasts with increases in the nitrogen content of leaves. RuBisCO in The leaves of N-O trees was restricted to the periphery of chloroplasts because large starch grains had accumulated within the chloroplasts.3. The effects of the application of different amounts of nitrogen fertilizer on the chlorophyll fluorescence were examined in mature sun-exposed leaves of several deciduous fruit trees. The extent of photoinhibition was determined by monitoring the … More ratio of valuable to maximum chlorophyll fluorescence (Fv/Fm). In each species, Fv/Fm was affected by the application of nitrogen fertilizer. The ratio was consistently low in nitrogen-deficient leaves.4. Changes in anatomical and physiological features of expanding leaves of mango trees were examined to identify the factors that control photosynthetic activity related to leaf age. When immature young leaves were stained with DAPI, some chioroplasts fluoresced red and others fluoresced a yellowish color in the same mesophyll tissues. Stomata did not differentiated in the leaves soon after flushing. When leaves reached a leaf size, 28.6 cm2, guard cells of stomata appeared all at once. Compared with young immature leaves, green and mature leaves contained higher concentration of RuBisCO.Photosynthetic activity, estimated in terms of the amount of oxygen evolved per unit leaf area and the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) , were consistently lower in young immaturte leaves than in mature leaves. Less