Yield and Quality affected by Light Deficiency and Growth Promotion of Strawberry (Fragaria × ananassa Duchesne) by LED and Titanium Dioxide

다국어 초록 (Multilingual Abstract)

A strawberry is very important horticultural crop to enhance income of farmers in South Korea. "Daewang" of octoploid strawberry (Fragaria × ananassa Duchesne) is cultivated on many farmers of South Korea because to have a good fruit characteristics such as shape, size, aroma and hardness. Cultivation of high quality strawberry fruit, is needed a good environmental conditions as light, nutrient, soil and carbon dioxide. However, the elevation of the earth's temperature due to the carbon dioxide produced by the ever increasing use of fossil fuels, has led to serious global warming problems. The abnormal climate changes in the Korean peninsula are believed to have resulted in part from the rapid melting of the Arctic glaciers, which has been accelerated by global warming. The abnormal weather due to global warming is apparent that the frequent occurrence of cloudy days during the winter and early spring season constitutes one of the primary causes depresses the photosynthetic efficiencies of crops. Especially, a strawberry is cultivated during the winter and spring season reduced insolation conditions. Recent reduced a strawberry yield and diminished a fruit qualities are occurred with deficient insolation. This studies were carried out to investigate extent of strawberry damages under deficient insolation and to consider a countermeasure from those damages.
Firstly, the experiment was conducted to investigate damage of strawberry growth and yield under deficient insolation conditions by using 40% and 70% shading curtains. Control was non-shading treatment. When strawberry plants were subjected to shading treatments, their photosynthesis and fruit yields were found to significantly depressed. Although mineral element and organic acid contents of strawberry fruits were not affected by shading treatments, total nitrogen (T-N) of the stems and roots were noticeably reduced. Furthermore, the study found that shading treatments of strawberry plants also resulted in reductions of sugar contents and total phenolics of fruits. In parallel with these observations, shading treatments were also found to depress antioxidant activities of fruits as measured with 2,2’-diphenyl- 1-picrylhydrazyl (DPPH) assay.
Secondly, the study was carried out to confirm the effect of LED to improve strawberry yield and fruit quality under season of deficient insolation as the winter and early spring. A strawberry was planted and grown in two separated places as a growth chamber and a plastic greenhouse. It was noted that leaves of plants cultivated in the growth chamber under LED showed an elevated levels of chlorophylls than those cultivated in the plastic greenhouse. In contrary, yield of fruits were increased the strawberry plants that had been cultivated in the plastic greenhouse compared with in the growth chamber. Moreover, harvested strawberries in the plastic greenhouse were improvement of organic acid contents than those in the growth chamber. When the effects of different LED were examined, a remarkably higher production of fruits was achieved in the plastic greenhouse when the illumination was supplemented with either blue LED or overlapped LED made of blue and red wavelengths. Furthermore, it was also noted that higher accumulation of organic acids and phytochemicals such as phenolic compounds was observed in the fruits that had been cultivated in the plastic greenhouse when the illumination was supplemented with either red LED or mixed blue and red LEDs.
Finally, the study was performed to confirm the effect of TiO2 solution in promoting growth of strawberry plants in a greenhouse when they suffer from insufficient solar radiation conditions during the winter season. TiO2 treatments were found to promote fruit yield as well as fruit hardness of strawberry. TiO2 treatments were also effective in raising the DPPH antioxidant activity and the glucose contents of fruits. Furthermore, amounts of photosynthetic pigments as chlorophyll a and b were found to increase when leaves of strawberry were treated with TiO2. In contrary, TiO2 solutions resulted in inhibited growth of petioles. Moreover, total phenolic compounds of fruits were also found to be decreased as a result of TiO2 treatments.
Those results of the studies can estimation to decrease yield and fruit qualities when strawberry plants will be grown under deficient insolation condition. Also, it was confirmed that the effects of LED and TiO2 solution be used for cultivation countermeasure of strawberry under deficient insolation condition.

목차 (Table of Contents)

• PARTⅠ: Yield Loss and Quality Degradation of Strawberry Fruits Cultivated under Deficient Insolation Conditions by Shading . 1
• Abstract . 1
• 1.1 Introduction . 3
• 1.2 Materials and Methods . 6
• 1.3 Results 13
• 1.4 Discussion . 25
• 1.5 References . 30
• PARTⅡ: Effects of Light Emitting Diode on the Production of Strawberry during Cultivation in a Plastic Greenhouse and in a Growth Chamber. 35
• Abstract . 35
• 2.1 Introduction . 37
• 2.2 Materials and Methods . 41
• 2.3 Results . 54
• 2.4 Discussion 67
• 2.5 References 72
• PARTⅢ: Effects of Foliar Fertilization containing Titanium Dioxide on Growth, Yield and Quality of Strawberry during Cultivation . 77
• Abstract . 77
• 3.1 Introduction . 79
• 3.2 Materials and Methods . 82
• 3.3 Results . 88
• 3.4 Discussion 98
• 3.5 References 103
• ABSTRACT IN KOREAN . 108