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 th...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.展开更多
文摘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.
