Effect of Genetic and Altitude Differences on Stomata Characters as Resistance Indicators to Vascular Streak-Dieback （VSD） in COCOA （Theobroma cacao L.）

Preliminary research results indicated that the stomata is one important trait that can be used as an indicator of resistance to vascular streak dieback （VSD） disease. The influence of genotype and environment on the stomatal characters is expected to provide information for specificlocations （habitats） suitable for planting cocoa in particular to avoid VSD attack. The research was conducted at KendengLembu, PTPNXII, East Java. Experimental design used a splitplot design testing： location （altitude） and genotype factors. The location factors, distinguished on the basis of the altitude, were labelled highlands and lowlands. The genotype factors consisted of three clones with different levels of resistance to VSD diseases： PA 191 （tolerant）, BL 703 and GC 29 （susceptible）. The cocoa clones observed were top grafted onto locally available rootstock seedling and planted in 2006-2007. The maintenance of the plants was conducted in accordance with the standards of cocoa cultivation in the PTPN XII. Parameters measured were leaf stomata traits at different positions of the leaf （tip, middle and base）. Characters observed were the number of stomata, opening width of stomata, and diameter of the stomata. The results of the research showed that PA 191 in the lowlands had the lowest number, diameter and opening width of stomata. In contrast, GC 29 in the lowlands showed the highest number of stomata PA 191 and BL 703 in the highlands had a number, diameter and openings width of stomata that was relatively low compared with GC 29. However, the characters of the stomata （number, diameter and openings width of stomata） of the three genotypes in the highland showed a smaller value in each case than in the lowlands. The severity level of VSD attack was greater in the lowlands than in the highlands and PA 191 showed the lowest level of VSD attack at both altitudes.

Research on Leaf Anatomical Structure of Psammosilene tunicoides Populations under Water-limited Conditions

[Objective] This study aimed to investigate the leaf anatomical structures of P. tunicoides populations under water-limited conditions. [Method] 2-year-old seedlings of herbaceous perennial P. tunicoides that was introduced into the experi- mental field were selected as the research objects. Under the well-watered and wa- ter-limited conditions, we conducted the comparative observation of leaf anatomical structure and stomatal characteristics of two populations by using paraffin slice method and imprinting method. [Result] The result showed that the upper cuticle of P. tunicoides leaves were thickened, the palisade tissue/spongy tissue ratio, vascular bundle diameter and number of xylem vessels in main vein had increased, the stomatal opening became smaller and the stomatal density had increased in winter- spring drought period under water-limited conditions. The plasticity of above traits could be regarded as the important indicators for detecting the responses of P. tunicoides populations to water-limited conditions. Meanwhile, variation amplitudes of these indicators were different among populations. Leaf anatomical structure and stomatal characteristics in Lijiang Axi population under water-limited conditions varied significantly, which might cause the stronger adaptability of this population to drought conditions. [Conclusion] This research provided a reference for the selection of drought-resistant P. tunicoides germplasm and exploration of the adaptive differentia- tion of P. tunicoides populations under natural drought conditions.