Relationship Between Light Quality And Growth And Development And Light Utilization Characteristics In Ginger

Ginger was native to the tropical rain forest region and planted by shading. In recent years, the growth period was prolonged and production was increased by planting in the small arch shed covering with plastic film. More than 90 percent dry matter making of production roots in photosynthesis that is affected by light, so the fore-researcher studied the relationship between light quantity and photosynthesis in ginger mainly. Therefore, the effects of light quality on photosynthesis in ginger was not studied. Using two methods that shading with color film in the field and indoor lamp-house, this paper studied on the relationship between light quality on growth and development and light utilization characteristics in ginger and created the new cultivating technology that merged the traditional shading and protection planting. The main results were as follows:1. Compared with the traditional shading, covering with color films not only changed the light quality environment remarkably, but also increased the air or earth temperature and shortened the ermerging seedling time. Furthermore, covering color film not only reduced the light intensity but also reduced the air or earth temperature by ventilating after ginger seedling emerged.2. The plants treated by color films or traditional shading growed better than that of cultivating bareness, and the effects of different colored film was different. The plants under blue film were higher in height and with thinner stem and lesser shoot, compared with those shaded with other color films. The red film induced biomass was more than that of traditional shading, but that was less than that of white or green film. The white film induced the plant was thicker, but lesser shoot or biomass than that of green film. The plant under green film was more in shoot and higher in production than those of other treatments. In parallel, the yield of green, white, red or blue film at harvesting stag were 3560.6, 3362.8, 3194.3 or 2901.2 kg·666.7 m-2, which was 37.7%, 30.0%, 23.5%, and 12.2% higher than that bareness, respectively, was 18.5%, 12.0%, 6.3%, and -3.4% higher than that traditional shading.The effects was different between the treatment of indoor light quality and covering with color films in the field, white or red light induced the greatest biomass, followed by blue and green light in turn, and white or blue light induced the better seedling quality.3. Chlorophyll content of different color film was different. Blue or green film induced the greatest chlorophyll content in functional leaves and young leaves, followed by shanding with white film, and red film. Furthermore, chlorophyll content of old leaves growing under blue film decreased rapidly.White or red light induced the greatest chlorophyll content, was 3.01, and 2.94 mg·g-1FW respectively, green light induced the least, only was 2.17 mg·g-1FW.4. In the whole growth period, green film induced the greatest photosynthetic rate, followed by shading with white, red or blue film. In parallel, at seedling stage the light saturation point(LSP), the maximum photosynthetic rate, carboxylation efficiency(CE) and maximum RuBP regeneration rate under green film-shading was the highest than that of other treatments. Although there was no difference in LSP between blue film and green film, blue film induced the greatest photorespiration(Pr) and Pr/Pn which reduced the net photosynthetic rate. Uncovering at vigorous growth, although there was no difference in the LSP among different treatments, the maximum photosynthetic rate and maximum RuBP regeneration rate under green film-shading was 5.8%, 9.3%, 16.3% and 4.6%,11.9%,17.0% higher than under white, red, and blue film-shading, respectively.5. Covering with color film remarkably affected light energy utilization and distribution characteristics. Though the diurnal variation of chlorophyll fluorescence in leaves of different treatments was similar, the maximal photochemical efficiency (Fv/Fm), the efficiency of excitation energy capture by open PSII reaction centers (Fv′/Fm′), quantum yield of PSII (ΦPSII), photochemical quenching coefficient(qP) and photochemical reflectance index (PRI) of leaves treated with green film was the highest, followed by blue, white or red film in turn. In contrast, green, blue, white or red film induced the relative deviation from full balance between two photosystems (β/α-1) and nonphotochemical quenching (NPQ) increased in turn. Increasing the ratio of green light in light quality could reduce the photoinhibition, make the correspondence of transferring electron between PSI and PSII well, decrease heat dissipation of excitation energy, enhance the light energy utilization efficiency. Uncovering at vigorous growth stage, there was remarkably difference in light energy utilization, green film induced the greatest light utilizing efficiency when the photoinhibition was strong, followed by that of white, red and blue film.6. Covering with color film remarkably affected the pigment content, photosynthetic rate and light utilization in ginger leaves of different age.Chlorophyll content reached the maximum when it was 30 days leaf unfolding, and that under blue or green film-shading was the highest, red was the lowest. After it was 30 days leaf unfolding, blue film induced droping extent of chlorophyll content was remarkably higher than that of other treatments. When it was 20 days leaf unfolding, white, blue or green film induced the carotenoid content reached the maximum, while it was 30 days, red film got to the maximum.When it was 20 days leaf unfolding, photosynthetic rate in ginger leaves reached the maximum, which growing under green film-shading was 6.6%, 11.5%, and 17.9% higher than that under white, red, or blue film-shading, respectively. The carboxylation efficiency's change pattern in different shading treatments was similar to that of photosynthetic rate, and that reached the maximum when it was 20 days leaf unfolding. While growing under green film was the higest, followed by white, red, or blue film in turn. In contrast, red film induced the apparent quantum yield of photosynthesis(AQY) was the highest, white or green film was the lowest.When it was 5 days leaf unfolding, the Fv/Fm approached the maximum, and it was remaining higher value from 10 to 50 days leaf unfolding. In parallel, when it was 10 days leaf unfolding, Fv′/Fm′,ΦPSⅡ, or qP approached the maximum. Furthermore, Fv/Fm, Fv′/Fm′,ΦPSⅡ, or qP growing under blue film-shading was higher than that of other treatments when it was 1 days leaf unfolding. When Fv/Fm, Fv′/Fm′,ΦPSⅡ, or qP reached the maximum, which treated with green film was the highest, followed by blue, white or red film in turn.7. The LSP, the maximum photosynthetic rate, carboxylation efficiency(CE) and maximum RuBP regeneration rate under white light was the highest, followed by blue, red, or green light in turn. There was no difference in Fv/Fm between different treatment, but Fv′/Fm′orΦPSⅡunder white or blue light was the highest, the green light was the lowest. When ginger seedlings were transferred to sunlight, the leaves of different treatment appeared seriously photoinhibition. Compared with the Fv/Fm at 7:00, Fv/Fm of white, green, red or blue light at 17:00 decreased by 20.4%, 42.0%, 30.7%, or 22.5%, respectively. The diurnal variation of Pn appeared one-peak-type, and the peak was at 9:00. White light induced the highest Pn, being 7.9 mol·m-2·s-1, followed by blue, red, or green light in order from high to low.8. O2-·production rate of different treatment reached the maximum at noon. Green film induced the lowest O2-·production rate than that of white, red or blue film, in which there was no difference. In contrast, SOD or APX activity under blue film-shading was the highest, followed by white, red or green film in turn at 13:00. In parallel, MDA content and electrolytic leakage reached the maximum at 13:00, those under green film was the lowest than that of others. There was no difference between white, red and blue film.O2-·production rate of young leaves and functional leaves was lower than that of old leaves, and that under green film-shading was lower than that of other treatments. Blue film induced the highest MDA content and electrolytic leakage of old leaves than the green, white or red film.9. Light quality affected the stomatic characteristics in ginger leaves. The upper cuticle stomatic density, stomatic width and stomatal aperture width under green film was the highest than those of others. No matter covering with film at seedling stage or uncovering at vigorous growth, green film induced the thicker leaves, stronger palisade tissue, and PTT/STT, while blue film induced the thinner leaves and palisade tissue.There was no difference in leaf thickness between white and red light which was thicker than that of blue light and green light. Although blue light induced the thinner palisade tissue than white or red light, induced the PTT/STT was 15.9%,19.9%,14.2% higher than white, red, and green light, respectively. The number of chloroplast in each cell, chloroplast size, number of starch grains in each cholroplast, number of grana in each chloroplast, number of amella in each grana under green light was lower than that of others. Blue light induced the highest number of grana in each chloroplast, number of amella in each grana than that of white, red and green light.