【作者】 胡利明；

【导师】 夏仁学；

【作者基本信息】 华中农业大学 ， 果树学， 2007， 博士

【摘要】 光合作用是果树最重要的生理过程之一，果树干物质的90％-95％来源于光合作用的产物，通过光合作用形成的碳水化合物是果树产量，果实品质形成的主要物质基础。植物C₄光合代谢途径比C₃光合代谢途径有更高的光合效率和水分利用效率，尤其在逆境条件下，如高温、干旱或强光条件下。柑橘为亚热带常绿果树，光合速率远低于落叶果树，有一定的耐荫性，忌夏季高温和高光强。改善柑橘栽培条件是提高柑橘光合效率的有效方法；同时，作为典型的C₃植物，增加柑橘体内C₄光合代谢途径的表达，则更有利于提高柑橘光合效率。本文研究了不同栽培条件下不同种类的柑橘光合特性，以及柑橘各类绿色器官C₄途径的关键酶活性，主要内容和结果如下：1大棚栽培条件下不同砧木对温州蜜柑光合特性的影响。以体细胞杂种红橘+枳（Citrus reticuiata+Poncirus trifoliata）、Troyer枳橙（C．sinensis×P．trifoliata）、Swingle枳柚（C．paradisi×P．trifoliata）和枳（P．trifoliata）作砧木的‘国庆4号’温州蜜柑（C．unshiu cv．Guoqing No．4）幼树为试材，在塑料大棚盆栽条件下研究了4种砧木对幼树光合特性的影响，结果表明：不同砧木上的温州蜜柑幼树的Pn日变化规律相似，均表现出双峰曲线，主峰出现在上午10∶00，次峰出现在13∶00以后；综合Pn、Tr、WUE、CE和AQY等可以看出Troyer枳橙砧幼树光合效率最弱，枳砧幼树最强，红橘+枳和Swingle枳柚介于两者之间；比叶重、可溶性蛋白质和光合色素含量等生理指标结果显示，枳砧表现最优光合特性，其他3种砧木差异不明显；在大棚条件下Pn与Gs、RH和Tr呈正相关，与Ci呈负相关。2田间条件下温州蜜柑的光合特性。以枳作砧木的‘国庆4号’温州蜜柑为试材，对外围叶片和内膛叶片的光合作用进行了系统研究。结果表明，6-10月，外围春梢叶片Pn日变化规律呈双峰曲线，首峰出现在上午9∶00，次峰出现在下午14∶00-15∶00，次峰值小于首峰值。11月为单峰曲线，最大值出现在上午10∶00。内膛叶Pn的日变化规律在8月为单峰曲线，最大值出现在中午12∶00，6、7、9-11月则为锯齿型曲线。外围叶的Pn显著高于内膛叶，均存在明显的季节变化规律，且趋势一致，6月最高，日变化最高值和平均值分别为8.8和4.2μmol m^-2 s^-1；7月下降，8-9月上升，并在9月再次出现高峰，之后随着气温下降，Pn下降至11月的最低值，分别为2.55和1.65μmol m^-2 s^-1。7月AQY日变化进程为中午降低型，而CE为单峰曲线型，中午达到最高值。通过对不同叶位、结果枝与营养枝叶片光合特性测定分析结果表明：枝条中上部叶片的Pn高于其它节位叶片，结果枝叶片的光合特性强于营养枝。相关分析结果说明，田间条件下，影响温州蜜柑Pn的主要因子是PAR，Ta，Gs，Ci，和VPD。3柑橘绿色组织中C₄循环途径关键酶活性。以‘HB柚’（C．grandis cv．HiradoBuntan），‘红肉脐橙’（C．sinensis cv．Cara Cara）和‘国庆4号’温州蜜柑为试材，检测了叶片不同生育期和不同绿色组织（果皮、嫩茎和叶脉）的C₄途径酶的活性。结果表明：柑橘叶片在不同的发育时期均存在不同活性强度的C₄途径酶。PEPC活性呈先下降后上升的趋势，最大值出现在4月20日；PPDK的活性变化规律则相反，先上升后下降，5月1日最大；NADP-ME活性则整体呈下降趋势，全年中，‘HB柚’的NADP-ME活性显著高于‘国庆4号’温州蜜柑和‘红肉脐橙’；3个柑橘品种的NADP-MDH活性总体呈下降趋势。柑橘果皮，嫩茎和叶脉的C₄途径酶活性显著高于叶片，但低于C₄植物玉米或与其相当。不同组织中PEPC和NADP-ME活性大小顺序为果皮＞叶脉＞嫩茎＞叶，PPDK活性为嫩茎＞果皮＞叶片＞叶脉，NADP-MDH活性为叶脉＞嫩茎＞果皮＞叶。这些结果说明，柑橘体内可能存在有限C₄微循环，尤其是非叶组织中的高C₄途径酶活性不容忽视。4不同类型柑橘品种的光合特性。以田间栽培条件下的‘能晚’（C．Sinensis cv．Lanelate）（橙类）、‘星路比’（C．paradisi cv．Star Ruby）（葡萄柚类）、‘日辉’（C．reticulata×C．grandis cv．Sunburst）（杂柑类）和‘江西无核’（C．reticulata cv．Jiangxiseedless Ponkan）（宽皮柑橘类）为试材，研究比较了不同类型柑橘品种的光合特性。结果表明：晴天和多云天气条件下，均以‘江西无核’Pn最高，分别为8.8和7.6μmolm^-2 s^-1，‘能晚’最低，分别为和5.4和5.2μmol m^-2 s^-1，‘星路比’和‘日辉’介于二者之间；阴天条件下各类柑橘之间Pn差异不明显。晴天条件下，除‘能晚’的Pn日变化规律呈单峰曲线型以外，其它3个品种的Pn日变化规律均呈双峰曲线型，有轻度“午休”现象。多云天气条件下，除‘能晚’表现为单峰曲线外，其它3个品种的Pn日变化进程均表现为锯齿型。阴天天气条件下，4个柑橘品种的Pn日变化规律模式均为单峰曲线，最大值出现在上午11∶00。4个柑橘品种的光补偿点为2.7-10.2μmol m^-2s^-1，光饱和点为1088-1139μmol m^-2 s^-1，暗呼吸速率为0.0104-0.3313μmol m^-2 s^-1，AQY为0.023-0.0405，CO₂补偿点为64.3-69.0μmol mol^-1，CO₂饱和点为788-142lμmolmol^-1，光合速率为5.8-10.4μmol m^-2 s^-1，光呼吸速率为0.90-1.01μmol m^-2 s^-1，羧化速率为0.0139-0.0172，光合最适温度为26.4℃-30.4℃。由以上结果得出：柑橘具有明显的C₃植物的光合特征。另外，在柑橘体内也能检测到低活性的C₄途径酶（PEPC，PPDK，NADP-ME，NADP-MDH），说明在柑橘体内可能存在有限的C₄循环途径。更多还原

【Abstract】 Photosynthesis is the most valuable physiology reaction for fruit trees; almost 90％-95％dry material is formed through photosynthesis. Carbohydrogen came from photosynthesis is the basic material to form quality and quantity in fruit. The C₄ pathway photosynthesis is more efficiency than C₃ pathway, especially under stressful conditions, such as high temperature, drought and high photosynthetic active radiation（PAR）. Citrus, as a evergreen fruit tree grown in semi-tropical, possessing a far lower net photosynthetic rate （Pn） than hardwood fruit tree and is shade tolerance. It is well known that exposing citrus trees to high temperatures and high PAR in summer could lead to reductions in Pn. Improving cultivation level is a good method to improve Pn for citrus; at the same time, as a typical C₃ plant, improving C₄ pathway photosynthesis in citrus will increase Pn more quickly. We studied the photosynthesis of different kinds of citrus planted in different environment and the C₄ pathway enzymes in different citrus’ green tissue, the main contents and results are as follow:1, Effects of different rootstocks on Satsuma Mandarin in photosynthesis under greenhouse condition. It was conducted with Guoqing No.4 Satsuma Mandarin three-year-old young tree whose rootstocks were Trifoliate [P. trifoliata], sexual hybrid Troyer Citrange[C. sinensis×P, trifoliata], Swingle Citrumelo[C. paradisi×P. trifoliata] and somatic hybrid Red tangerine+Trifoliate [C. reticuiata+P. trifoliata]. Studyed on the effects of rootstocks on the Pn through potted experiment in the green house, Results showed that: The diurnal variation of Pn in young tree with different rootstocks was seminar and presented bimodal carve; the first peak occurred at 10: 00, the second peak occurred after 13: 00 and the value was lower than the first one. With the analysis of Pn, transpiration rate（Tr）, water use efficiency（WUE）, apparent quantum yield（AQY） and carboxylation efficiency（CE）, the results were the young tree--Troyer Citrange had a weaker photosynthesis, Trifoliate’s photosynthesis was the best, red Tangerin+Trifoliate and Swingle Citrumelo was between the above two; Trifoliate had a higher physiological value in soluble protein, specific leaf weight and photosynthetic pigment; the other three didn’t have remarkable difference. Under protected condition, Pn had obvious positive relationship with stomatal conductance（Gs）、Tr and relative humidity（RH）, Pn had obvious negative relationship with intercellular CO₂ concentration（Ci）.2, Photosynthesis of Satsuma Mandarin under nature condition. The photosynthesis of sunlit and shaded leaves in ’Guoqing No.4’ Satsuma Mandarin whose rootstocks were Trifoliate was studied under nature condition. The results showed that, the diurnal variation of Pn in sunlit leaves from June to October presented bimodal curve, the first peak occurred at 9: 00, the second peak occurred at 14: 00-15: 00 and the value was lower than the first one. The diurnal variation of Pn present one peak curve in November and the maximum value occurred at 10: 00. In August, the diurnal variation of Pn showed one peak curve with the most value at 12: 00 and presented indention curve in June, July and from September to November. The sunlit leave showed higher Pn than shaded leaves. The sunlit and shaded leaves presented the similar seasonal variation, the maximum occurred at June, it were 8.8 and 4.2μmol m^-2 s^-1 respectively, and decreased in July, then increased from August to September and came to the second maximum value in September. After that, with a progressive decline in temperature, Pn decreased quickly and came to the minimum value in November, it were 2.55 and 1.65μmol m^-2 s^-1. In July, diurnal variation of AQY presented a midday depression pattern and CE showed one peak curve. The Pn at middle leaves was higher than at based and apical ones. After studied the photosynthetic of different types of shoot, the fruit-beating shoot have a better photosynthetic than nutritive shoot. Analysis all results, the main factors effected Pn of Satsuma Mandarin under nature condition is PAR, Ta, Gs and VPD.3, Activity of C₄ pathway enzymes in different tissues of citrus. Hirado Buntan pummelo（C. grandis cv. Hirado Buntan）, Cara cara navel orange（C. sinensis cv. Cara Cara） and Guoqing No.4 Satsuma Mandarin were used as experimental material. The activity of C₄ pathway enzymes in citrus leaf at different time in different tissues, such as pericarp, fresh shoot and vein, were been assayed. The results showed that: There were C₄ pathway enzymes activities at different time in leaf. The activity of PEPC declined at first and then increased and the maximum value occured in April 20; The activity of PPDK increased firstly and then declined, the maximum value occurred in May 1; The activity of NADP-ME declined all the time, Hirado Buntan pummelo showed significant higher NADP-ME activity than Cara cara navel orange and Guoqing No.4 Satsuma Mandarin all the time; The activity of NADP-MDH declined all the time too. The activity of C₄ pathway key enzyme in pericarp, stem and fresh shoot were significant higher than in citrus leaf and lower or equals to in maize leaf. From higher to lower, the activity of PEPC and NADP-ME in different tisse was in pericarp, stem, fresh shoot and leaf, activity of PPDK was fresh shoot, pericarp, leaf and stem, activity of NADP-MDH was stem, fresh shoot, pericarp and leaf. It implied there be a C₄ pathway photosynthesis in citrus, especially in pericarp, stem and fresh shoot, the high activity of C₄ enzymes were very important.4, Photosynthesis in different kinds of citrus（cultivar）. The photosynthesis of Lanelate navel orange（C. Sinensis cv. Lanelate）, Star Ruby Grapefuit（C. Paradisi cv. Star Ruby）, Sunburst tangelo（C. Reticulata×C. Grandis cv. Sunburst） and Jiangxi seedless Pnkan（C. Reticulata cv. Jiangxi seedless Ponkan） under nature condition were studied. The results showed that: in sunny and cloudy day, Jiangxi seedless Pnkan had the maximum Pn value, it were 8.8 and 7.6μmol m^-2 s^-1, and Lanelate navel orange had the minimum Pn value, it were 5.4 and 5.2μmol m^-2 s^-1, Star Ruby and Sunburst tangelo were between the above two; In overcast day, Pn among four kinds of citrus didn’t show obvious difference. In sunny day, diurnal variation of Pn presented one peak curve in Lanelate navel orange and two peak curves in others, presented light "midday depression". In cloudy day, diurnal variation of Pn showed one peak curves in Lanelate navel orange and indention curve in others. In overcast day, all citrus presented one peak curve in diurnal variation of Pn and the maximum value occurred at 11: 00. Light compensation point in four kinds of citrus were 2.7-10.2μmol m^-2 s^-1, light saturation point were 1088-1139μmol m^-2 s^-1, dark respiration rate were 0.0104-0.3313μmol m^-2 s^-1, AQY were 0.023-0.0405, CO₂ compensation point were 64.3-69μmol m^-2 s^-1, CO₂ saturation point were 788-1421μmol m^-2 s^-1, photosynthetic capacity were 5.8-10.4μmol m^-2 s^-1, photorespiratory rate were 0.90-1.01μmol m^-2 s^-1, CE were 0.0139-0.0172 and the best temperature for Pn were 26.4℃-30.4℃. From those results, we can concluded that citrus possessed obvious characteristic of C₃ pathway photosynthesis, at the same time, we also found very lower activity of C₄ pathway enzymes （PEPC, PPDK, NADP-ME, NADP-MDH）, it implied there maybe exists a limited C₄-microcycle photosynthesis in citrus.更多还原