【作者】 徐凯；

【导师】 张上隆；

【作者基本信息】 浙江大学 ， 果树学， 2005， 博士

【摘要】 草莓是我国最重要浆果之一,产量和栽培面积在浆果中仅次于葡萄2003年我国草莓面积已达8.2万公顷,产量133.8万t,均居世界首位。浙江是我国草莓的主产地之一,2003年浙江草莓栽培面积已超过0.6万公顷,产量超过12万t。随着我国加入WTO,草莓将面临着市场国际化的激烈竞争,优质草莓生产迫在眉睫。人工补光、CO₂施肥以及合理供氮已成为草莓保护地栽培的重要技术措施。但草莓生产中仍存在下列问题:①光抑制问题:由于草莓为耐荫作物,在露地栽培中其叶片在强光下容易遭受光抑制和光氧化损伤,常导致越夏植株死亡;②供氮水平的调控问题:在高氮条件下易引起植株徒长、座果率下降和果实品质降低。而低氮影响植株生长、叶片黄化,进而影响光合作用,导致抗性减弱和产量品质下降;③CO₂供应问题:目前我国草莓栽培常在设施环境下进行,在封闭性强的设施中空气流通不畅,常导致设施内部CO₂供应不足而影响光合作用,进而影响产量和品质;④光不足与光质问题:设施栽培中,光通过玻璃和塑料棚膜后使设施内的光强与光质均发生改变,这些变化特别是光质变化对草莓生长与结果的影响程度尚无明确认识。 上述问题前人曾有过局部研究,但在机理上缺乏深入探讨,为此本研究以丰香草莓为试材,拟通过对草莓叶片光合作用的光抑制特性和强光保护机理,氮素水平对草莓叶片光合作用的富CO₂响应机理,CO₂加富和氮素水平互作对草莓叶片光保护系统的影响,D1蛋白周转在草莓叶片光保护中的作用机理,光质对草莓叶片光合作用和叶绿素荧光的影响,和光质对草莓生长发育与果实品质的影响机理等六个方面进行研究,以期为解决草莓生产中常见问题提供理论依据,主要结果如下: 1) 用便携式调制叶绿素荧光仪和光合仪研究了强光下草莓叶片荧光参数及表观量子效率的变化。结果表明,Fm、Fv/Fm、PS Ⅱ无活性反应中心数量和Q_A的还原速率在强光下降低,在暗恢复时升高;而PS Ⅱ反应中心非还原性Q_B的比例在强光下增加,在暗恢复时降低。上述荧光参数的变化幅度均以强光胁迫或暗恢复的前10 min最大。强光下Φ_PSII、ETR和qP先升高后降低,但qN先大幅度降低,然后小幅回升。强光处理4 h后,丰香和宝交早生的表观量子效率（AQY）分别降低了20.9%和37.5%;qE（能量依赖的非光化学猝灭）为NPQ（非光化学猝灭）的最主要成分。强光胁迫下丰香的Fo、Fm、Fv/Fm、Φ_PSII、ETR和AQY的变化幅度均明显比宝交早生小。DTT处理后,草莓叶片的Fm和Fv/Fm明显降低,Fo显著升高。上述结果可推测,依赖叶黄素循环和类囊体膜质子梯度两种非辐射能量耗散在草莓更多还原

【Abstract】 Strawberry is one of the most important baccate fruits in China. Its yield and cultivated area reached to 1338 thousands tons and 82 thousands hectares respectively in 2003, which ranked the first in the world. With the yield and cultivated area of strawberry exceeded 120 thousands tons and 6 thousands hectares respectively in 2003, Zhejiang province is one of the largest growing districts in china. After entry of China into WTO, our domestic strawberry market will surely face the competition from abroad. Therefore, the breeding and production of high quality strawberry fruit is urgent.The supplement of CO2 and light are two important cultural practices commonly used in strawberry culture under-glass.The photosynthetic response to CO2 can also depend on N supply, which is poorly known in strawberry. Growth, morphogenesis, photosynthesis, metabolism, and gene expression of plants are all regulated by light quality. Chromatic plastic film and light conversion film has been applied in protected cultivation, and plastic films with different light quality may serve as a non-chemical approach regulating growth and thermoperiodic responses of plants. A few studies showed that light quality affected growth and yield of strawberry, but little is known about its effects on photosynthesis and chlorophyll fluorescence in strawberry leaves, and fruit quality. So it is beneficial to scientific regulating growth and fruiting for strawberry protected cultivation to study on those effects and the interactions between CO2 and N supply on photosynthesis.Strawberry is thought to be a shade adapted plant. Leaves of strawberry plants grown in open field suffer from photoinhibition and photooxidative damage which may result in death in high light that usually occurs during the summer, which mechanism is still unknown. Therefore, it is needed to understand how high irradiation influences its photosynthesis.To clarify the mechanism of photoinhibition and responses of growth and fruiting to light quality, we studied the following physiological aspects (1) Response of photosynthesis to high light and its mechanism in strawberry leaves. (2) Effects of three levels of nitrogen nutrition on photochemistry and photoinhibition of photosynthesis in strawberry leaves growth in elevated CO2. (3) Effects of three levels of nitrogen nutrition on xanthophyll cycle and the antioxidant system in strawberry leaves growth in elevated CO2. (4) Response of Dl turnover to high light in strawberry leaves. (5) Effect of light quality on photosynthesis and chlorophyll fluorescence in strawberry leaves. (6) Effect of light quality on photosynthesis and chlorophyll fluorescence in strawberry leaves. The results were summarized below.1) PAM-2000 portable chlorophyll fluorometer and HCM-1000 photosynthesis measurement system were used to measure the apparent quantum efficiency(AQY), initial fluorescence (Fo), maximal photochemical efficiency of PSII (Fv/Fm), maximal fluorescence(Fm), photochemical quenching(qP), non-photochemical quenching(qN),actual quantum yield of PS II electron transport (Opsn), electron transport rate (ETR), amount of inactive PS II reaction centers (Fi-Fo) , rate of Qa reduction, proportion of Qe-non-reducing PS II reaction centers[(Fi-Fo)/ ( Fp-F ) ], and energy-dependent quenching (qE), photoinhibitory quenching (ql) and state-transition quenching (qT) of non-photochemical quenching in strawberry leaves. The results showed that Fv/Fm, Fm, Fi-Fo and the rate of Qa reduction decreased in strong light and increased during subsequent dark recovery, but (Fi-Fo) / (Fp-Fo) increased in strong light and decreased during subsequent dark recovery. They changed drastically within the first 10 minutes in strong light or in subsequent darkness. In the strong light, Opsh , ETR and qP increased first, and then decreased, but qN decreased drastically first, and then increased slightly. ’Toyonoka’ showed less changes in strong light than ’Houkouwase’ in Fo, Fv/Fm, Fm, ETR, Opsn and AQY. After treated with DTT, Fv/Fm and Fm were lower , but Fo was much higher than control.2) Biochemically based models of C3 photosynthesis was used to study effects of threelevels of nitrogen nutrition (12 mM, 4 mM, 0.4 mM) on acclimation of photosynthesis to elevated CO2 (700 ulT1) in strawberry leaves. The results showed that strawberry grown in 12 mM nitrogen, all of Pn, maximal carboxylation efficiency (Vc. raax), maximal linear electron flow through photosystemll (Jmax), electron flow to the photosynthetic carbon reduction cycle (Jc) and qP was significantly higher in plants grown and measured at elevated CO2 than for plants grown and measured at ambient CO2. This was due to a significant increase in Jc exceeding any suppression of electron flow to the photorespiratory carbon oxidation cycle (Jo). This increase in photochemistry with decreased non-photochemistry(qN or NPQ) at elevated CO2 alleviated photoinhibition at high light. For plants grown at 4 mM and 0.4 mM nitrogen, all of Pn , Vc, max, Jc and qP was significantly lower in plants grown and measured at elevated CO2 than for plants grown and measured at ambient CO2. Consistent with decreased photochemistry and increased non-photochemistry(qN or NPQ), for leaves grown at at 4 mM and 0.4 mM nitrogen, the photoinhibition was aggravated at elevated CO2. Elevated CO2 suppressed Jo leaves grown at 12 mM , 4 mM and 0.4 mM nitrogen. The results above suggested that deficient nitrogen( 4 mM and 0.4 mM )nitrogen elevated CO2 resulted in an acclimatory decrease of photosynthesis in leaves grown elevated CO2.3) Both the xanthophyll cycle pool size and the conversion of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) at noon increased with decreasing N supply.As N supply decreased, activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), Guaiacol peroxidase (G-POD) and dehydroascorbate reductase (DHAR) on a Chi basis increased, and O2 generated rate and contents of H2O2 and Malondialdehyde (MDA) on a Chi basis also increased , but activitie of catalase (CAT) decreased with decreasing N supply. There were significant interactions between CO2 and N supply onxanthophyll cycle and the antioxidant system in strawberry leaves. For plants grown at 12 mM nitrogen, all of xanthophyll cycle pool size, activities of SOD, APX, G-POD and DHAR decreased at elevated CO2, and O2 generated rate and contents of H2O2 and MDA also decreased at elevated CO2, but plants grown at 4 mM and 0.4 mM nitrogen were on the contrary at elevated CO2.4) Responses of Dl turnover to high light in strawberry leaves were studied with Western-blotting. The results showed that Dl content in ’Toyonoka’ leaves grown at high light for one week (4 hours/day) changed inapparently, but that in ’Houkouwase’ increased significantly. Shortage in nitrogen supply facilitated degradation of Dl protein in photosystem II reaction center in high light , Dl content in ’Toyonoka’ leaves grown at 4 mM and 0.4 mM nitrogen were lower than that in 12 mM at high light for one week (4 hours/day) significantly.5 )Studies on the photosynthetic characteristics of strawberry(Fragaria^ananassa Duch cv. ’Toyonoka’) leaves under identical light intensity(55-57% natural light) and different light quality showed that chlorophyll contents, maximal photochemical efficiency of PSII (Fv/Fm), Fm/Fo, amount of inactive PS II reaction centers (Fi-Fo) and rate of QA reduction were correlated with red/blue ratios positively, but chlorophyll (a/b) ratios were correlated with red/blue ratios negatively. Carotenoid contents were in the order: blue film >green film> red film, white film and yellow film, which were correlated with red/far-red ratios negatively.The apparent quantum efficiency(AQY), photo-respiratory rate (Pr) and carboxylation efficiency(CE) also were strongly affected by light quality. The photosynthetic rate (Pn) of strawberry leaves under green film was significantly lower than that of all other film treatments.5) Studies on the photosynthetic characteristics of strawberry (Fragariaxananassa Duch cv.’Toyonoka’) leaves under identical light intensity(55-57% natural light) and different light quality showed that chlorophyll contents, maximal photochemical efficiency of PSII (Fv/Fm), Fm/Fo, amount of inactive PS II reaction centers (Fi-Fo) and rate of QA reduction were correlated with red/blue ratios positively, but chlorophyll (a/b) ratios were correlated with red/blue ratios negatively. Carotenoid contents were in the order: blue film >green film> red film, white film and yellow film, which were correlated with red/far-red ratios negatively.The apparent quantum efficiency(AQY), photo -respiratory rate (Pr) and carboxylation efficiency(CE) also were strongly affected by light quality. The photosynthetic rate (Pn) of strawberry leaves under green film was significantly lower than that of all other film treatments.6) The influence of different light quality on plant growth and fruiting of ’Toyonoka’ strawberry {Fragaria^ananassa Duch.) were studied. The optimum light quality for leaf and petiole growth was green film, red film was in the next place, and the last was bule film. The proportion of total plant dry biomass allocated to fruits, crowns and roots under blue film was the greatest, the next was red film, and the last was green更多还原