不同光质对‘春美’桃光合特性和果实品质的影响

Effects of light quality on photosynthetic characteristics and fruit quality of 'Chunmei' peach

【目的】研究不同光质对桃树叶片光合特性和果实品质的影响。【方法】以露地‘春美’桃为试验材料,分别对试验树罩红、蓝、绿、白4种不同颜色的薄膜,测定透过薄膜的光质、叶绿素含量、光合特性和果实品质。【结果】绿膜处理的叶绿素含量最高,白膜处理下最低。红膜和白膜处理的净光合速率显著高于蓝膜和绿膜。蓝膜的叶绿素荧光中F0、Fm和Fv/Fm参数最高,白膜最低。同时白膜处理下果实着色最好,绿膜处理下的可溶性糖含量最高,红膜处理下的可滴定酸含量最高,蓝膜处理下的可溶性蛋白含量最高,白膜处理下的维生素C含量最高。【结论】白膜处理果实着色最好,绿膜可提高果实可溶性糖含量。

[ Objective ]Photosynthesis is the most important chemical reaction on the earth, providing food for all living organisms. Light is the driving force of photosynthesis. Light quality regulates plant growth, photosynthesis, morphogenesis, metabolism and gene expression. The effects of light quality on photosynthetic characteristics, fluorescence characteristics and fruit quality of peach （Prunus persiea L.） were studied in plants grown under films of different colors in order to select films that promote fruit growth and fruit quality. [ Methods ] Five-year-old ＇Chunmei＇ peach trees grown in an open field in Baoding were se- lected as the experimental materials. Red, blue, green and white films with a thickness of 0.15 mm were tested. The colored films were laid on the stent, covering the entire trees with room for growth. Filters were set in the films 40 cm from the ground to promote air circulation and to prevent vapor condensation inside the films. The treatments started from one week after fruit set and continued until fruit ripened, when the covering films were removed. Light transmittance of the films was measured. Leaf chlorophyll content, photosynthetic characteristics and chlorophyll fluorescence were measured after 30 days of treatment. The ap- pearance and intrinsic quality of ripe fruit were determined. The experimental data were processed and an- alyzed statistically using Microsoft Excel and DPS7.05. [ Results ] The light through the white film had the highest light gray values at various wavelengths. The peak light gray value of light through the red film appeared between 580-620 nm corresponding to the orange light. The light through the blue film had a peak gray value at 450-490 nm, corresponding to the blue light. Green film generated a light with a peak light gray value at 520-580 nm, which is the green light. Chlorophyll a, chlorophyll b and chlorophyll a＋b contents changed consistently and were in a descending order of green film〉 blue film〉 red film〉 white film.Chlorophyll contents under the green film were significantly higher than under the white film and red film. Those under the blue film were significantly higher than under the white film. The chlorophyll a, chlorophyll b and total chlorophyll contents in the blue film treatment were 9.65%, 16.83% and 9.75% higher than in the white film treatment, respectively. The ratio of chlorophyll a/b in red film treatment was significantly lower than in the other treatments. The ratio was in the order of white film〉 green film〉 blue film〉 red film. Net photosynthetic rate in the red film and the white film treatments was significantly higher than that in the blue film treatment. In the red film treatment, net photosynthetic rate was 72.51% higher than that in the blue film treatment. The stomatal conductance in the red film treatment was significantly higher than that in the other film treatments, and it was the lowest in the blue film treatment. The stomatal conductance in the red film treatment was 53.53% higher than that in the blue film treatment. Intercellular carbon dioxide was not significantly different between treatments, but was highest in the blue film treatment. The transpiration rate under white film was significantly higher than that in other treatments, and the red film treatment was the lowest. The white film treatment had a transpiration rate which was 42.57% higher than that in the red film treatment. The change trends of Fo, F,n and Fv/Fn, were the same among different color film covering. The values under the blue film were the highest, followed by the green film and red film, and the white film treatment had the lowest values. Fo, Fm and Fv/Fm in the blue film treatment was 8.39%, 10.87% and 1.6% higher than those in the white film treatment, respectively. The qP in the white film and the red film treatments was significantly higher than that in the blue film treatment. Y （NPQ） and Y （NO） were highest under the treatment of blue film. Y （NPQ） was lowest in the white film treatment, and Y （NO） was lowest in the red film treatment. Y （ II ） was significantly higher in the red film treatment than in the blue film treatment, which had the lowest value. There were significant differences in excursion coefficient α- 1 between PS Ⅱ and PS I, and the open degree of PS II reaction center was higher in the blue film and the green film treatments than in the other treatments. β/α-1 was smaller under the red and white films, and more of the excitation energy was transferred to PSI . Fruit weight in different treatments was between 187.6-194.3 g, and there was no significant difference among the treat- ments. There were significant differences in fruit coloration among different treatments. The color area of fruit treated by the white film was 93.75%. It was 84.38%, 75% and 50% in fruit under the red, the green and the blue films, respectively. The content of total soluble sugars in the fruit was in the order of green film〉 white film〉 red film〉 blue film. It was significantly higher in the green film treatment than in the other treatments. The blue film treatment was significantly lower than the other treatments. The green film treatment had a soluble sugar content which was 8.8% higher than the blue film treatment. The content of titratable acids in mature fruit was in a descending order of red film〉 blue film〉 green film〉 white film. It was significantly higher in the red film treatment than in the other treatments, and in the red film treatment, it was 35% higher than that in the white film treatment. There was no significant difference between the treatments in sugar/acid ratio. [Conclusion] Comprehensively, in the white film treatment, fruit coloration was the best, and the green film covering can improve the soluble sugar content of the fruit.