【作者】 刘旭；

【导师】 廖明安；

【作者基本信息】 四川农业大学 ， 果树学， 2008， 博士

【摘要】 梨属于蔷薇科（Resaceae）梨亚科（Pomoideae）梨属（Pyrus）植物。我国是世界梨的主要原产地和栽培地之一,已有3000多年的栽培历史。目前,对梨果实采前生理即生长发育过程的系统研究较少,特别是针对我国南方梨在生长发育期间处于高温、高湿和光、热、水充裕的气候条件下其果实生长发育及其内部机理研究甚少,多集中在与果实品质相关的指标,或局限于某一类激素和某一种酶的变化,没有全面、系统的综合研究其各种内部因素的平衡关系和具体的调控机理。而针对不同梨品种果实生长发育历程不同的研究主要集中在品种遗传特性上,对影响果实生长发育的其它内部因素研究很少,或者只是简单根据一个或几个指标说明其含量变化,没有将定性和定量结合起来研究影响果实生长发育期的各种内部因子与生长发育期差异产生的相关性。另外,在梨果实生长发育期间关于果实内果糖、葡萄糖、蔗糖、IAA、ABA、GAs、和CTK等物质的变化规律的报道不尽一致,有关不同品种梨果实内多胺、细胞壁酶和LOX等物质的消长规律及其差异尚未见研究报道。而在其它果树如猕猴桃、草莓、柿、葡萄、苹果等上也多利用同一成熟期品种从遗传特性或某一个影响因子来进行果实发育及调控机理研究。因此,对成熟期不同的梨果实生长发育过程中内含物质、细胞壁酶类、内源激素及内源多胺进行研究,不仅可以进一步了解梨果实生长发育中生理生化的变化规律,还可以进一步揭示梨果实生长发育及成熟机理,从而为进一步研究果树生理学和果树生产提供一定的理论依据。本研究以成都平原引种的5年生早蜜梨和黄金梨为试材,在一般生产管理条件下,采用田间试验和室内分析相结合的方法,比较了两个成熟期不同的梨品种的基本性状、叶片光合特性及果实品质,并系统地研究了两品种果实生长发育过程中果实的生长动态、各种内含物质、PE、PG、Cx和LOX的活性以及内源IAA、GA₃、ZT、ABA、内源Put、Spd和Spm含量的变化规律和特点,探讨了两个品种果实生长发育的异同点。其主要结果如下:1、早蜜梨和黄金梨在成都平原的引种表现都较好,基本性状相似。两品种植株生长旺盛,发育良好,物候期较其引种地早,果实品质优良,但早蜜梨口味较黄金梨更甜。在相同季节早蜜梨叶片的光合速率值略高于黄金梨,叶绿素a及总量也高于黄金梨。两品种叶片的光合速率主要取决于叶绿素,特别是叶绿素a含量。早蜜梨较黄金梨更为耐阴。2、两品种梨果实发育的各个阶段长短差异明显。早蜜梨和黄金梨的整个果实生长发育过程都可划分为3个阶段。早蜜梨果实生育期（或果实发育天数）为100d,坐果至花后30d,为果实发育前期;花后30d～70d,为果实发育中期;花后70d～100d,为果实发育后期。黄金梨果实生育期（或果实发育天数）为130d,坐果至花后50d,为果实发育前期;花后50d～100d,为果实发育中期,花后100d～130d,为果实发育后期。就3个时期所持续的时间而言,早蜜梨为30d、40d和30d,黄金梨为50d、50d和30d,后者在果实发育前期和中期分别长20d和10d。另外,两个品种果实纵横径生长都符合logistic曲线变化。3、两品种果实发育期间各种内含物含量变化各有特点。（1）两品种果实中可溶性糖、果糖、葡萄糖和蔗糖含量随着果实发育天数的增加而呈逐渐上升趋势。糖分以果糖为主,含量大小为果糖＞葡萄糖＞蔗糖,且早蜜梨果实的3种糖分含量都明显高于黄金梨,两品种果实成熟时可溶性总糖含量差异极显著（p＜0.01）。两品种在子房膨大初期和果实发育后期都出现两个含量迅速增长期,而果实发育后期是糖积累的关键时期。从增长速度来看,果糖转化和积累最快,葡萄糖次之,蔗糖最慢。另外,早蜜梨果实中果糖、葡萄糖,黄金梨果实中果糖、葡萄糖、蔗糖和可溶性总糖积累都符合logistic曲线变化。（2）两品种果肉中蛋白质含量在果实发育初期较高,随着果实的发育而逐渐降低,但二者在果实发育的大部分时期含量差异不大。整个果实发育期间,早蜜梨出现两次含量高峰,黄金梨变化较为平缓。（3）早蜜梨果实在果实发育初期和后期游离氨基酸含量高于黄金梨,在果实成熟时极显著高于黄金梨（p＜0.01）,而在果实发育中期则低于黄金梨。（4）两品种果肉中核酸含量在果实发育初期都较高,随着果实的发育逐渐降低。早蜜梨果肉中核酸含量分别在花后10d、50d和90d出现高峰,果实成熟时极显著高于黄金梨。黄金梨果肉在花后20d时含量达到最大。4、两品种果实发育期间相关酶类变化趋势相似。（1）两品种果肉中PG活性总体上随果实的发育逐渐升高。早蜜梨在花后50d出现活性高峰,黄金梨果肉呈现升降交替变化的趋势,分别在花后30d、90d和130d出现3次活性高峰。早蜜梨在果实发育中期PG活性高于黄金梨,而果实发育后期二者差异不大。果肉中PG活性与果实发育中期和后期密切相关。（2）两品种果肉中PE活性在果实发育前期较高,随着果实的发育逐渐降低,果实成熟前有所回升。早蜜梨果肉在花后10d、70d和100d出现3次PE活性高峰,黄金梨果肉在花后10d、80d和130d也出现3次活性高峰。整个果实发育过程中,前期黄金梨PE活性高于早蜜梨,而中后期则低于后者。（3）两品种果肉中Cx活性在果实发育前期较低,随着果实发育成熟而逐渐升高,果实成熟前有所降低。早蜜梨在花后30d～70d和花后80d～90d有2次活性迅速升高,而黄金梨在花后20d～30d、花后50d～70d和花后80d～120d共有3次活性迅速升高。（4）两个品种果肉中LOX活性在果实发育初期较低,随着果实的发育成熟而逐渐升高。早蜜梨在花后20d～40d和50d～90d共出现2次活性快速上升,而黄金梨在果实发育的各个时期增加幅度比较均匀。5、果肉和种子中内源激素含量变化差异是导致两品种梨果实发育历程不同的重要因素。（1）同一生境下成熟期相对较晚的黄金梨果实发育初期果肉中IAA和ZT含量高于成熟期较早的早蜜梨,且持续时间更长,而GA₃含量除花后20d时低于早蜜梨外都较早蜜梨高。黄金梨果肉细胞分裂的强度可能大于早蜜梨,分裂时间也可能长于早蜜梨。果实发育的大部分时期黄金梨果实内3种生长促进型激素（IAA、GA₃、ZT）含量高于早蜜梨,但含量高峰出现的时间比早蜜梨滞后10d～20d。（2）两品种果肉中ABA含量在花后30d有一次升高,可能与此期果实的脱落密切相关。两品种果实成熟时果肉中ABA含量差异不显著,但早蜜梨在成熟前出现含量高峰的时间比黄金梨早10d,其果实可能启动成熟较早,成熟期较短。（3）早蜜梨种子中IAA和ZT含量明显高于同期黄金梨的含量,这可能导致早蜜梨比黄金梨种子更早地进入下一个发育阶段,也利于转运至果肉中,促进果肉细胞的发育。黄金梨果实发育的大部分时期种子中GA₃含量高于同期早蜜梨的含量,高含量的GA₃持续时间更长,较早蜜梨花后第1次含量高峰出现的时间提前10d,这可能与黄金梨种子自身合成GA₃能力较强有关,也利于转运至果肉中促进果肉细胞的膨大。另外,早蜜梨种子中ABA含量高峰出现的时间比黄金梨提前约30d,因此,早蜜梨果实更早地启动了成熟。（4）早蜜梨果肉和种子中IAA比值在果实发育的大部分时期都小于1,说明其种子是IAA合成的主要场所,特别在果实发育初期合成能力更强。两品种果肉和种子中ZT含量的比值变化相似,但早蜜梨比值小于黄金梨,可能与其种子中合成ZT的能力较强有关。两品种果肉在果实发育后期合成ZT的能力极低,而种子在成熟前还具有一定的合成能力。早蜜梨果实发育期间果肉和种子中GA₃含量的比值都小于1,说明了胚乳是其合成的主要场所。6、内源多胺与两品种果实幼果发育的差异关系密切。（1）早蜜梨和黄金梨果肉和种子中Put、Spd和Spm及游离多胺总量在果实发育初期都较高,这与两个品种果实发育初期旺盛的细胞分裂有关。两个梨品种果肉中3种游离多胺含量在果实发育初期差异较大,早蜜梨在花后10d时3种游离多胺含量都极显著高于黄金梨（p＜0.01）;种子中,除Put外其它2种游离多胺在花后20d时含量都极显著高于黄金梨（p＜0.01）。综合果肉和种子的情况,可以说明早蜜梨幼果的早期发育更为旺盛。但黄金梨果肉中Spm含量在果实发育的大部分时期高于早蜜梨,特别是在花后20d有一个明显升高的过程,与同期早蜜梨含量差异极显著（p＜0.01）,推测Spm与黄金梨幼果第一次迅速生长关系密切,（2）两品种果肉和种子中Put含量在果实发育后期出现了第2次高峰,峰值接近,但黄金梨出现的时间滞后约30d～40d,成熟期也比早蜜梨晚30d。这可能与梨果实发育后期乙烯的释放和果实成熟启动有关。更多还原

【Abstract】 The pear is a plant which belongs to Rosaceae, Pomoideae, Pyrus. Pears are by far one of the most important deciduous tree fruits, and are widely grown in China. Fruit growth and development is one of the foremost life activities for fruit trees and is regulated by complex interactions. The early researches on it focused mainly on fruit quality, or on one endogenous hormone or enzyme only. The systematic studies are not enough. Especially, pear fruits grow and develop more differently on the condition of high temperature and humidity, rich light, caloric and water in south of China than in north. On the other hand, different procedures of growth and development of pear fruits exist among the different cultivars. The characteristics of heredity are looked as one of the important factors to elucidate this physiological phenomenon. But in fact there are so many other factors influencing fruit growth and development. Qualitative and quantitative researches are extremely necessarily combined to clarify the relevance of these factors and ripening-season of pear fruits. The past research indicated that fructose, glucose, sucrose and endogenous IAA, ABA, GAs and CTK contents in pear fruits didn’t change in same regularity during fruit growth and development for different experiments. And there have no reports about the changing regularity of endogenous polyamines contents, activiety of cell wall enzymes and LOX during fruit growth and development among the different pear cultivars. Only one cultivar or factor was selected to study the mechanism of fruit growth and development in kiwifruit, strawberry, persimmon, grape, apple and some other frutis. Therefore, researches on chemical substances, such as carbohydrates, proteins, endogenous hormones and polyamines are very crucial to find the difference of growth regularity and disclose mechanism of fruit growth and development of pear fruits among the pear cultivars in different ripening-seasons. To some extent it could provide advice for fruit physiologist and field production.Both Zaomi and WhangKeumbae pear in 5-year-old trees with uniform growing vigor were selected for this experiment. Trees were grafted on Pyrus pashia Buch-Ham rootstocks and planted in Chengdu plain. Cultural management such as fertilization and pest control were the same as those used in a commercial orchard, without fruit thinning and bagging. Characteristics of trees, photosynthetic characteristics of leaves and fruit quality were analyzed for these two pear cultivars. At the same time carbohydrates, proteins and nucleic acid contents, activities of pectinesterase （PE）, polygalacturonase （PG）, cellulase （Cx） and lipoxygenase （LOX） were determined along with endogenous indol-3-acetic acid （IAA）, gibberellins （GA_s）, zeatin （ZT）, abscisin acid （ABA） and putrescine（Put）, spermidine（Spd）, spermine（Spm） contents during the period of fruit growth and development. The followings were the results:1、Zaomi and Whangkeumbae pear had similar characteristics of trees in Chengdu plain. The trees grew strongly and had earlier phenophase than that in origin region. The fruits of these two cultivars were in similar shape and good in fruit quality. However, Zaomi pear fruits were sweeter than Whangkeumbae. Photosynthesis rate, chlorophyll a and the total chlorophyll contents of leaves of Zaomi pear were little higher than that of Whangkeumbae pear in the same season. Chlorophyll especially chlorophyll a was the key factor influencing photosynthesis rate for this two pear cultivars. And Zaomi pear trees had stronger tolerance of shading.2、There were obvious differences of developmental stages of fruits between these two pear cultivars. The growth curve of fruit showed as single sigmoid and was divided into three phases. The fruit growth and development lasted 100days and 130days for Zaomi and Whangkeumbae pear, respectively. For Zaomi pear fruits, period from fruit setting to 30 days after full bloom （DAFB） was looked as the early stage, period from 30 to 70 DAFB as middle stage, and period from 70 to 100 DAFB as late stage. For Whangkeumbae pear fruits, period from fruit setting to 50DAFB was divided as the early stage, period from 50 to 100DAFB as the middle stage, period from 100 to 130DAFB as the late stage. The early stage of Whangkeumbae pear held longer for 20days than that of Zaomi pear, and the middle stage kept longer for 10days. The growth of longitudinal length and transverse diameter during fruit growth and development accorded with logistic curve for these two cultivars.3、The contents of main chemical substances changed in different regularities during fruit growth and development for the experimental pear cultivars.（1） Content of soluble sugar, fructose, glucose and sucrose rose gradually along with fruit growth and development for both Zaomi and Whangkeumbae pear. The fructose content was the highest at any given stage of fruit development. Glucose content was at second and higher than sucrose. The contents of three sugar components of Zaomi pear fruits were obviously higher than that of Whangkeumbae pear. Significant difference of soluble sugar contents was produced between these two cultivars at the ripening stage of fruit （p<0.01）. Sugar contents increased very fast in the early stage of ovary developing and the late stage of fruit development for the two cultivars. And the latter stage was significant for accumulating sugar. Among the three sugar components fructose transformed and accumulated fastest followed with glucose and sucrose. The accumulation of fructose and glucose of Zaomi pear, and that of fructose, glucose, sucrose and soluble sugar of Whangkeumbae pear accorded with logistic curve during fruit growth and development.（2） Protein contents kept at high level at the initial stage and decreased along with fruit development for Zaomi and Whangkeumbae pear. There were no obvious differences during the most stages between them. Zaomi pear fruits showed two peaks of content, but Whangkeumbae pear fruits changed in slow rate.（3） For free amino acid content, it was higher in Zaomi pear fruits than that in Whangkeumbae pear fruits both at initial and late stages, and was significantly higher at fruit maturation （p<0.01）. However, it was lower at the middle stage.（4） Nucleic acid contents kept at high level at initial stage and decreased gradually along with fruit development for the two cultivars. It peaked at 10, 50 and 90 DAFB for Zaomi pear fruits and was significantly higher than that of Whangkuembae pear at fruit maturation （p<0.01）. It peaked at 20DAFB for Whangkeumbae pear fruits.4、The activity of enzymes changed in similar trend during fruit growth and development for these two pear cultivars.（1） For the two cultivars, polygalacturonase （PG） activity increased gradually along with fruit development. It peaked at 50DAFB for Zaomi pear fruits, and peaked at 30, 90and 130DAFB for Whangkeumbae pear fruits. Zaomi pear fruits had higher activity of PG at the middle stage but had no obvious difference with Whangkeumbae pear fruits.（2） The activity of pectinesterase （PE） kept at high level at the early stage and decreased gradually along with fruit development, but rose in slightly range before maturation for the two cultivars. It peaked at 10, 70 and 100DAFB for Zaomi pear fruits, and at 10, 80 and 130DAFB for Whangkeumbae pear fruits which had higher activity at early stage than Zaomi pear fruits, and had lower activity at the middle and late stage.（3） The activity of cellulase （Cx） was a little low at the early stage and increased along with fruit development up to maturation followed with slightly decrease for the two cultivars. It rose sharply from 30 to 70DAFB and from 80 to 90DAFB for Zaomi pear fruits, from 20 to 30DAFB, from 50 to 70DAFB and from 80 to 120DAFB for Whangkeumbae pear fruits.（4） The activity of lipoxygenase （LOX） was a little low at initial stage and increased along with fruit development for the two cultivars. It rose sharply from 20 to 40DAFB and from 50 to 90DAFB, but increased in slow rate for Whangkeumbae pear fruits during fruit development.5、The difference of endogenous hormones contents both in pulp and seeds was the key factor resulting in different fruit growth and development of Zaomi and Whangkeumbae pear.（1） In the same habitat IAA and ZT contents in pulp of Whangkeumbae pear which matured later were higher than that of Zaomi pear which matured earlier at initial stage and held in longer time. GA3 contents were higher than that of Zaomi pear fruits at the most stages except of 20DAFB. Cell division in pulp of Whangkeumbae pear was stronger and held for longer time. The three endogenous hormones IAA, GA₃ and ZT contents in pulp were higher than that of Zaomi pear at the most stages of fruit growth and development. However, peaks of contents for Whangkeumbae pear appeared late for 10 to 20days.（2） An increase for ABA contents appeared in pulp of the two cultivars at 30DAFB. It might result in dropping of young fruits at this stage. ABA contents in pulp of Zaomi pear peaked earlier for 20days before fruit maturation. Thus Zaomi pear fruits might shift to maturate much earlier, and had shorter period of fruit growth and development.（3） IAA and ZT contents in seeds of Whangkeumbae pear were obviously lower than that of Zaomi pear at the same stage. It might result in shifting into next developing stage for seeds, and was advantageous of being transferred into pulp for cell development. At the most stages GA₃ contents in seeds of Whankeumbae pear were higher than that of Zaomi pear at the same time. And it lasted for longer time with high contents and got to the first peak earlier for 10 days. This could indicate that Whangkeumbae pear fruits had vigorous production of GA₃ in seeds, which could be transferred into pulp to promote cell expansion. On the other hand, ABA contents in seeds of Zaomi pear peaked earlier for 30days. Therefore it could go into maturing earlier than Whangkeumbae pear.（4） The ratio of IAA contents between pulp and seeds was less than 1 at the most stages for Zaomi pear. Therefore IAA might be mainly synthesized in seeds, especially at initial stage of fruit growth and development. For the ratio of ZT contents this two pear cultivars had similar changing trend. But Zaomi pear, which had vigorous synthesis of ZT in seeds, showed lower ratio value than Whangkeumbae pear. Few of ZT could be synthesized in pulp at the late stage for the two cultivars, but in seeds some ZT could be synthesized before maturation. The ratio of GA₃ contents was less than 1 for Zaomi pear during fruit development, so endosperm was the important place to produce endogenous GA₃.6、Endogenous polyamines were very important for development of young fruits.（1） This two pear cultivars contained high level of Put, Spd, Spm and free polyamines contents both in pulp and seeds at initial stage. It could stimulate vigorous cell division. Put, Spd and Spm contents in pulp of Zaomi pear were significantly higher than that of Whangkeumbae pear at 10DAFB （p<0.01）. In seeds, Spd and Spm contents were significantly higher than that of Whangkeumbae pear at 20DAFB （p<0.01）. It could speculate that young fruits of Zaomi pear developed more vigorous. However, the Spm contents in pulp of Whangkeumbae pear were higher at the most stages, especially it rose sharply from 10 to 20DAFB and was significantly higher than that of Zaomi pear at the same stage. So Spm contents might be very crucial for the first fast growth of young fruits of Whangkeumbae pear.（2） Put contents both in pulp and seeds got the peak value for two times at the late stage for the two cultivars. And these two peaking values were approximate, but it appeared late for 30 to 40 days for Whangkeumbae pear. The fruit maturated late for 30days, too. This could be correlated with releasing of ethylene and starting to maturate at the late stage.更多还原