| Summary: | 博士 === 國立中興大學 === 園藝學系所 === 96 === Since colored sweet pepper has high economic value, it without the habit of heat-tolerance can not be year-round cultured in Taiwan. The purposes of this study were to select and evaluate the heat-tolerance of color sweet pepper, providing for the heat-tolerance breeding program. First, a total of 57 colored sweet pepper genotypes collected from homeland and abroad had been used as materials in this study. Among them, 24 genotypes were selected based on vigor growing, high fruiting rate, better fruit color and fruit type, and high seed amount by field evaluating in summer and autumn trials 2004. Eight genotypes had then been selected on account of better economic values, good horticultural properties and high heat-tolerance potentiality by field evaluating in summer and autumn trials 2005. They included four genotypes of bell pepper and four genotypes of non-bell pepper. Data obtained from summer trials showed that the averaged fruit weight of selected four bell pepper genotypes (‘KC104’, ‘C00947’, ‘C01336’ and ‘RB102’) was from 54 to 68 g, and the averaged fruit number per plant was from 4 to 7 fruits. Among them, ‘KC104’ had the highest fruit yield in summer trial, particularly. ‘C00947’ with the medium-sized fruit and having a least fruit weight difference of 19.7% performed as more stable genotype than others in the summer and autumn trials. Data obtained from summer trials also showed that the fruit number per plant of selected four non-bell pepper, i.e. paprika pepper, (‘C02410’, ‘C00611A’, ‘C02080’ and ‘C03338B’) was from 9 to 14 fruits per plant and the fruit weight was from 30 to 38 g. The fruit weight difference (%) between summer and autumn trials was from 17.39% to 62.00%. ‘C02410’ with a weight difference of 17.39% performed more stable in the summer and autumn trials.
Assessment of the genetic diversity by molecular markers is useful for their systematic and high efficiency for crop breeding program. There were 36 genotypes of Capsicum, including 34 genotypes of sweet pepper and 2 genotypes of chili pepper which were conducted by random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and simple sequence repeat (SSR) to estimate pair wise genetic similarity. The result showed 302 RAPD fragments were generated from 12 primers, and 233 with polymorphism (77.2%). For ISSR analysis, 160 fragments were obtained from 10 primers, and 142 with polymorphism (88.8%). For SSR assay, 61 alleles were generated and the polymorphic index content (PIC) 0.569. Furthermore, a combination of RAPD and ISSR markers assessed the cluster analysis of UPGMA, showed the relationships among groups following the fruit shapes. While combined all of the RAPD, ISSR and SSR markers also reveled the groups generally cluster together with similar fruit sharps even the high yield genotypes in summer would be distinguished too. Combining these three marker systems and assessed principle component analysis (PCA) that resulted as well as the UPGMA analysis, besides the higher yield genotypes in summer could be distinguished clearly. These results suggest that a combination of different kinds of markers can generate sufficient polymorphism to assess genetic variation even within closely related species.
For evaluating the photosynthesis efficiency of color sweet pepper under heat stress, using 12 genotypes of colored sweet pepper selected in the field, including 6 genotypes of bell-pepper and 3 of paprika pepper that might have heat-tolerance potentiality; two additional genotypes of bell-pepper performed a little worse in summer test and one commercial variety, were examined to evaluate the efficiency of photosynthesis and heat–tolerance of colored sweet pepper utilizing the chlorophyll fluorescence assessment. Under environment temperature of 27/22℃, the experimental results showed ‘C02080 ’and ‘RB102’ had higher performance of photosynthesis efficiency among 12 genotypes of colored sweet pepper which evaluated by chlorophyll fluorescence parameters of Fo (minimal of fluorescence) and Fv/Fm (Maximal quantum efficiency of PSⅡ photochemistry). For treatment of high-temperature circumstance (D/N: 33/22℃) from flower differentiation stage to anthesis (42~62 DAS), fluorescence parameters of Fm (maximal of fluorescence), Fo and Fv/Fm could be used as good parameters to evaluate the photosynthesis efficiency among the tested genotypes, and the results showed ‘C02080’ and ‘C00611A’ with the better performance. While under treatment of 33/22℃ and evaluated by Fm parameter, the best performance was ‘C01184’. The parameters of chlorophyll fluorescence assessment under temperature of 27/22℃ and 33/22℃ may respond to the behavior of the colored sweet pepper when growing under high-temperature circumstance. Screened genotype of ‘C02080’ with vigor growing and having heat-tolerance potentiality in the field also appeared with the best photosynthesis efficiency by the chlorophyll fluorescence analysis.
High temperature would cause flowers and fruits drop in sweet pepper. In order to assess the heat tolerance behavior of different genotypes of the colored sweet peppers, 12 genotypes, including 6 bell-pepper genotypes and 3 of paprika pepper that have been screened in the field and might have heat-tolerance potentiality, had been investigated under high temperature (33 degrees Centigrade) with an aim to evaluate the influence of pollen vigor in vitro and under another high temperatures (33/27oC) within the reproduction growth period to evaluate the performances of pollination ability of pollen and fertilization ability of pistil. Furthermore, the result of the experiments indicated that high temperature (33oC) obviously reduced the pollen germination rates of tested colored sweet peppers. Except for ‘Chocolate Miniature Bell’, ‘C02080’, ‘C05464A’, and ‘Beauty Star’, the pollen germination percentages of other tested genotypes were all lower than 5%. In addition, the influence of the high temperatures (33/27 ℃) on the growth of pollen tubes was observed by the fluorescent microscope. High temperatures obviously reduced the pollination ability and pollen tube growth, but the fertilizing ability of pistil was not influenced. The tendency of the fruiting habits and the fruit quantity of tested genotypes under high temperatures were the same as the performances of pollen germination rates and the growing behavior of pollen tubes under the same condition. The assessment results of pollen vigor and pollinating under high temperatures revealed ‘Chocolate Miniature Bell’, ‘C02080’, and‘C00947’ should belong to the genotype with better heat-tolerance; however, ‘C02080 ’was the best among them.
After generalized assessment of study results described above, the heat tolerance performance of paprika type of colored sweet pepper was better than the bell colored sweet pepper. Experimental results showed that ‘C02080’ (paprika type) performed best in the photosynthesis efficiency, pollinating behaving, and pollination results under the high temperature circumstances; however, the bell colored sweet pepper with good at fruit shape and having large diversified cultivars was relatively popular by the market. Through assessment data of RAPD (random amplified polymorphism DNA), ISSR (inter-simple sequence repeat), and SSR (simple sequence repeat) approved that genetic diversity of the bell colored sweet pepper was indeed high. For example, the fruit weigh differed relatively large between 14g to153 g. Finally, compared with the pollen vigor or photosynthesis efficiency under high temperature circumstances, ‘C00947’ with the medium-sized fruit (64 g) performed better than others genotype, but second to ‘C02080’. All of results revealed that ‘C02080’ and ‘C00947’ both were the most superior colored sweet pepper genotype with heat tolerance abilities. These also revealed that the performances of pollen germination under high temperature in vitro, and photosynthesis efficiency from earlier flowers differentiation stage to beginning of anthesis could be used as useful tools for assessment of heat tolerance evaluation for colored sweet pepper.
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