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引起橡胶树停止排胶主要有两种不同症状:(1)割面干涸(TPD),一种过度采胶引起的可恢复性生理反应;(2)树皮坏死(BN),一种从芽接部位韧皮部扩展的不可恢复的病症。目前树皮坏死在世界各国橡胶种植园都有发生,其危害程度取决于种植品种、树龄和种植地点。通过对大量种植园的调查,目前澄清了橡胶树树皮综合病症多态的各种争议。虽然对以前和近来的病原分析还不能下定论,但环境因素确实与树皮坏死有关。对一些开割树位的流行规律研究表明,早期病树发生的位置不是随机的,其主要发生在靠近沼泽、胶园道路、边行、原推土机过道、树桩残余地和斜坡缓冲地等区域。树皮坏死的发生与土壤的化学因素没有显著的相关性,但是土壤物理测定(如土壤紧实度)表明,树皮坏死树较差的根系与土壤较高的紧实度有关。此外,在砧木与芽片接合处首先观察到树皮坏死的早期症状。用PMS压力计测定的大量生理生态学对照数据表明,树皮坏死树内有水分胁迫。这些结果意味着患病树树干同其根系的维管联系处于非理想状态。因此,同土壤紧实度相关的土壤有效水分的减少、不能满足旱季水分需求的脆弱根系、被扰乱的树液流动和土壤水分循环等因素的共同作用,被认为是在芽接区产生树皮坏死的主要外部诱因,坏死随后向上扩展到割面。此外,细胞及分子生物学研究表明,橡胶树内在失调是导致树皮坏死迅速扩展的原因。在这些胁迫的作用下,胶树芽接部位的细胞破裂,释放出极具扩散性的高浓度氰化物。这种韧皮部内氰化物的产生和分解作用的不平衡将毒害邻近细胞。多学科的交叉研究为多因素胁迫诱导的这种生理病害提出了一个新的、完整的模型。
There are two main symptoms that cause the rubber tree to stop gum removal: (1) TPD, a recoverable physiological response caused by over-sealant; (2) bark necrosis (BN) Unrecoverable condition of phloem extension. At present, bark necrosis occurs in rubber plantations in various countries in the world. The extent of the damage depends on the species, age and location of planting. Through surveys of large numbers of plantations, various controversies have been clarified about the polymorphism of the bark of rubber trees. Although the previous and recent pathogen analysis can not be conclusive, environmental factors are indeed related to bark necrosis. The epidemiological study of some tree-cutting positions showed that the location of the early diseased tree was not random. The main occurrence occurred in areas near swamps, rubber-paved roads, sidewalks, former bulldozer aisles, stump remnants and slope buffers. The occurrence of bark necrosis was not significantly correlated with soil chemical factors, but soil physical measurements such as soil compaction showed that the poor root system of necrotic tree was associated with higher soil compaction. In addition, the early symptoms of bark necrosis were first observed at the junction of rootstock and shoots. Numerous ecophysiological control data measured with a PMS manometer indicate that there is water stress in the bark necrotic tree. These results mean that the diseased tree trunk is in a non-ideal relationship with its root system. Therefore, the reduction of soil available moisture associated with soil compaction, the fragile roots that do not meet the moisture requirements of the dry season, the disturbed flow of sap and the cycling of soil moisture are all considered to result in bark necrosis in the bud junction zone The main external cause, necrosis then extends upward to the cut surface. In addition, cellular and molecular biology studies have shown that imbalance in the rubber tree is responsible for the rapid expansion of bark necrosis. Under the action of these stresses, the cells in the budding junctions of the gum tree are broken, releasing a highly diffusible cyanide. This phloem cyanide production and decomposition of the imbalance will poison adjacent cells. Multidisciplinary cross-fertilization studies have proposed a new and complete model for this physiological disease induced by multi-factor stress.