【作者】 艾希珍；

【导师】 邢禹贤；

【作者基本信息】 山东农业大学 ， 蔬菜学， 2003， 博士

【摘要】 研究了日光温室主要生态因子的变化规律，不同时期黄瓜叶片的生长发育速度，叶片发育过程中光合特性及光化学效率的变化，不同叶位叶片的需光特性和种植密度对需光特性的影响。探讨了弱光下日光温室黄瓜对光能的利用及光合效率调节，并对弱光下长期亚适温和短期低温对黄瓜光合机构的影响机理进行了比较分析。主要结果如下:1．11月至翌年5月，本试验结构类型和保温设施日光温室内的光量子通量密度（PFD）变化范围为110-1068μmol·m-2·s-1（晴天），中午透光率高于早晨和下午。不同季节室内气温(Ta)变化范围很大，白天为10～35℃，夜间8～27℃。地温(Ts)变化范围13～27.5℃，相对湿度(RH)43～91%。日光温室内PFD、Ta、Ts均以1月份最低，11月和3月其次，5月最高，RH相反。白天的PFD、Ta、Ts先升后降，而RH和CO2浓度则先降后升，峰值和谷值多出现在12:00～14:00。夜间最低气温一般出现在4:00～6:00。有机肥施用量对日光温室内CO2浓度有重要影响，在有机肥充足的情况下基本能够满足黄瓜生长对CO2的需要。　2．10～11月黄瓜叶片的生长发育速度最快，叶面积最大，12～1月的生长发育最慢，叶面积最小。一般叶片展出20d左右时光合速率（Pn）达到最大值，其增长速度大于叶片展开速度。叶片展开过程中，气孔与非气孔因素同时存在，对Pn都有一定影响；而在叶片衰老过程中光合功能的衰退主要取决于非气孔限制。3．各时期展出叶的光饱和点和补偿点多随叶片展开时间的延长而降低。表观量子效率（AQY）、羧化效率（CE）、叶绿体色素含量的变化均与叶片Pn的变化趋势相似；叶片初展时光化学效率多随叶龄的增大有较明显增加，衰老过程中，PSⅡ最大光化学效率<WP=9>（Fv/Fm）和实际光化学效率（фPSⅡ）的降低速度明显小于Pn。叶龄越大，叶片用于光化学反应的光能比例越大，而用于热耗散的光能越少。在黄瓜整个生长发育过程中，光合作用暗反应是决定黄瓜光合速率高低的关键因素。4．日光温室黄瓜叶片的Pn和羧化效率（CE）以中上位叶的较高，基部弱光和CE降低是导致下位叶Pn降低的主要原因。光合作用饱和光强也以中位叶最高，但光补偿点多随叶位的下降而降低，AQY、Fv/Fm和ΦPSⅡ日均值多随叶位的下降而增大。不同叶位叶片Pn的日变化规律基本相同，均呈单峰曲线型，高峰出现在12:00左右。Fv/Fm和ΦPSⅡ日变化与Pn相反，即上午逐渐减小，12:00以后逐步增加，变化幅度多随叶位的下降而减小。叶绿体数目、大小、基粒数和基粒片层数均以基部叶为最大或最多，上数第1叶的较小或较少。表明叶片初展时叶绿体发育不健全是Pn较低的原因之一，基部叶片对弱光环境有较强的适应和调节能力。单个细胞的平均淀粉粒数和淀粉粒大小以第1叶最多或最大，第4叶最少也最小。说明初展叶和基部叶的物质运输能力均较弱。5．随着种植密度的增加，植株各层次叶片的PFD逐渐降低，尤其是中下部叶片降低幅度较大。下位叶的Pn及饱和光强多随种植密度的增加而降低。在本试验肥力条件下，中密度处理的产量最高，高密度处理的其次，低密度处理的最低。 6．在测定范围内，日光温室盆栽黄瓜的光响应曲线高度、光饱和点、光（CO2）饱和时的最大光合速率（Amax）和AQY均随CO2浓度的增加而增加，而光补偿点则随着CO2浓度的增加而减小。CO2响应曲线和CE随着PFD的增加而增加，AQY和光化学效率则随PFD的增加而减小。7．功能叶的光饱和点和Amax显著高于老叶，说明老叶光合机构的暗反应效率明显下降；CO2饱和时老叶的Pn显著低于功能叶，但其CO2饱和点并未明显降低，表明光系统的吸能转能能力虽然有所减弱，但不是光合功能衰退的主要原因，与暗反应有关过程的衰退是黄瓜老叶Pn降低的主要原因。8．对黄瓜植株进行30%和70%的遮光处理后，其功能叶片的Pn、光合能力（A350）、CE、光合作用光饱和点和补偿点均降低，暗适应下初始荧光（Fo）、Fv/Fm、ΦPSⅡ及光化学猝灭（qP）都有所增加，而非光化学猝灭（qN）呈下降趋势。9.弱光下黄瓜叶片的叶绿素及类胡萝卜素含量降低，但Chla和Chl a/b的下降幅度显著大于Chlb，即Chl b的相对含量增加。叶绿体数目及淀粉粒数目成比例减少，叶绿体和淀粉粒减小，叶绿体内基粒数和单个基粒中的片层数明显增加。这都有利于叶片有效地捕获有限的光能，提高光能利用率。<WP=10>10．对黄瓜幼苗进行长期弱光亚适温（T1）和短期弱光低温（T2）处理后，其生长速度和光合功能均显著下降。其中T1的Pn、CE、AQY降低幅度较小，但光合功能恢复较慢；而T2的Pn、CE、AQY降低幅度较大，条件改善后，光合功能可在短期内恢复正常。T1的Fv/Fm和ФPSⅡ降低幅度小且恢复快；而T2降低幅度大，恢复速度也较慢。说明长期弱光亚适温可能主要影响暗反应过程；而短期弱光低温条件下光合功能下降的主要原因是光反应活性降低。弱光亚适温条件下Pn的降低与气孔开度减小显著相关；而短期弱光低温下Pn降低的主要原因是叶肉因素。T1、T2处理的叶绿体类囊体垛叠程度均增大，T1表现尤其明显；长期弱光亚适温下合成和积累的碳水化合物明显减少，而短期弱光低温下黄瓜幼苗基本停止生长，物质运输严重受阻。更多还原

【Abstract】 Changes of the ecological factors in solar-greenhouse, and the growing and developing speed of cucumber leaves at different stages were studied. The characteristics of photosynthesis and photochemical efficiency throughout their ontogenetic periods, the characteristics of photosynthesis in different position leaves and the effect of plant density on photosynthesis, the solar energy utilization and the regulation of photosynthetic efficiency under low light density, the effect machenism of suboptimal temperature for long time and low temperature for short time under low light density on photosynthetic apparatus were also analyzed. The main results are as follows:　1. From November to next May, the photon flux density (PFD) in solar-greenhouse changed from 110 to 1068μmol·m-2·s-1 in sunny day. The air temperature (Ta) was 10～35℃ in daytime, and 8～27℃ in night. Soil temperature (Ts) was 12～28℃. Air relative humidity (RH) was 43～ 91% in general. The PFD, Ta, and Ts in solar-greenhouse were observed to be the lowest in Jan, second in Nov and Mar, and hightest in May. In sunny day, the PFD, Ta, Ts curves of diurnal variation showed single-peak which appeared at 12:00 a.m.～14:00 p.m.While the RH and CO2 concentration changed contrarily. The lowest Ta in night appeared at 4:00～6:00 a.m. The quantity of organic fertilizer had great influence on CO2 concentration in solar-greenhous. If sufficient organic fertilizer is applicated, the CO2 in<WP=12>solar-greenhouse could meet the demands of cucumber’s growth.2. Leaves unfolded in Oct-Nov developed quickly, and had the largest leaf area. While those in Des-Feb developed slowly and the leaf area were the least. The photosynthetic rate(Pn) came to the largest on 20 days after leaves unfolded, and their increasing rate were greater than that of leaf area. During leaves coming out, stomatal and non-stomal factors existed simultaneously, and they all affected pn. The decline of photosynthetic founction maily depended on the non-stomatal limitation in the course of senescene. 3. The light saturation point and compensation point decreased as leaves unfolded. The apparent quantum yield (AQY), carboxylation efficiency (CE), and pigment content were　all samilar to Pn in changing trend. During early days of leaves unfolding, the photochemical efficiency increased as leaves grew. In the course of the senescene, the decreasing rate of Fv/Fm and фPSⅡ were less than that of Pn remarkably. The older the leaves, the larger light energy proportion were used for photochemical action, while the less for thermal energy dissipation. The process of CO2 assimilation was the primary determinant of photosynthetic ability throughout growth and development of cucumber leaves. 4.The Pn and CE of mid-position leaves were the highest. Low light density and CE were the major reasons for decreasement of Pn of lower-position leaves. The saturation light of the mid-position leaves were also the highest, while the photocompensation points of the upper, middle and lower position leaves decreased as leaf-position descended. The AQY, Maximal PSⅡ efficiency (Fv/Fm) and Actual photochemical efficiency of PSⅡ(ΦPSⅡ) of most leaves enhanced as leaf-positon descended.　 Pn curves of diurnal variation in different position leaves showed single-peak which appeared at 12:00 a.m., but the Fv/Fm and ΦPSⅡ changed contrarily，the variation extent mostly decreased as leaf position descended. The diurnal variation range of Fv/Fm and ΦPSⅡ in Jan. was less than that of in Nov.obviousy.The number of chloroplast, grana and lamella in lower position leaves were maximum, and their size of chloroplast were the largest. While those of 1st leaves were less. These indicated that unperfect chloroplast structure was one of the reasons for Pn decreased in upper positon leaves, and the lower position leaves had strong adaptive and regulative capicity to weak light envionment. The number of starch grain in 1st leaves were maximum, and those of<WP=13>size were the largest, while those of 4th leaves更多还原