| Summary: | 博士 === 國立中興大學 === 園藝學系 === 91 === The research work made use of the current available pineapple (Ananas comosus (L.) Merr.) varieties in Taiwan for the investigation of the characteristics of pineapple plants, capacity of photosynthesis, mineral nutrient content of leaves and its relations with fruit qualities. It was our hope to utilize the related characters as criteria for selecting the desirable hybrid at an early stage of seedling growth and as index for improving the efficiency of plant breeding. In the mean time, RAPD was employed to estimate the genetic similarities among clones and varieties as well as to search for a reliable marker for the selection of hybridized seedlings.
The qualities of pineapple fruits vary with years, seasons and climatic conditions. Results of fruit-quality analyses of different varieties were comparable with those of pineapple-hybridized seedlings line comparative experiments conducted at the Chia-Yi Agricultural Experiment Station.
The characteristics of plant such as leaf numbers, total fresh weights, total leaf areas and total fresh weights of the above ground portion were found to be irrelevant to the fruit qualities. The relationships between the leaf angle and fruit sugar-acid ratio or between the length of the longest leaf and titratable acid of the fruit was insignificant.
The maximum quantum yield and effective quantum yield of pineapple varied among cultivars: highest in Tainung No.13 but lower in Tainung No.19, Tainung No.6 and Pernambuco. Chlorophyll contents also varied among different varieties. The total chlorophyll content related with neither maximum quantum yield nor effective quantum yield, which in turn had no effect on fruit quality. No significant correlation between total chlorophyll content and fruit quality was found. Sugar content tended to increase with increasing chlorophyll concentration, so was the sugar acid ratio（TSS/TA）.
The titratable acid of leaves before sunrise was to a certain degree of proportional to the effective quantum yield but with no relations with maximum quantum yield. The titratable acid before sunset was affected neither by the effective quantum yield nor by the maximum quantum yield. The differences in the amount of titratable acids before sunrise and after sunset had no influence upon fruit qualities.
Nutrient elements concentrations of leaves differed among varieties ; nitrogen concentration correlated with total chlorophyll content while magnesium did not. Leaf nitrogen and phosphorus had no effect on fruit quality whereas potassium had negative correlation with fruit sugars and titratable acids. No consistent relationship was found between potassium and fruit sugar-acid ratio.
Leaf calcium showed a significant negative correlation with titratable acids and a positive correlation with sugar-acid ratio but not with fruit sugars. No meaningful relationship was found between magnesium and fruit quality.
RAPD Analysis was used to assay the 7 clones of Smooth Cayenne. Results indicated that bands of DNA obtained were almost identical. In a separate experiment, RAPD was applied to test 11 varieties with same primer, and bands separated could be classified into several clusters. This proves that RAPD can be adopted to identify different varieties of pineapple.
RAPD was also used to map the dendrogram of Tainung No.4 to No. 19, that a family tree could be constructed. Besides, RAPD on the 2,000 bp position of OP P10 primer revealed that Clone 3607 had lost a distinct band. The finding was taken to mean that it resulted in the gene expression of piping leaf characteristic of Clone 3607.
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