【作者】 何志祥；

【导师】 李建安；

【作者基本信息】 中南林业科技大学 ， 森林培育， 2013， 博士

【摘要】 树体管理粗放、树体结构紊乱、光能利用率低是油茶低产的重要原因,通过整形修剪改善树体结构状况,是提高油茶光合产量和丰产性能的有效途径。针对我国油茶生产中树体调控技术落后、精细化树体管理难度大的突出问题,分析普通油茶树体结构特征,提出油茶丰产树体结构指标体系；研究油茶对不同修剪措施的反应；建立树体结构调控模式,从树体生长发育、冠层光合特性、树体营养生理3个方面探讨不同树体结构调控模式机理,从而建立科学合理、节约高效的树体结构调控模式与技术体系,为油茶树体管理提供理论依据和技术基础。1、油茶生长发育对修剪的反应试验研究了角度调整、回缩、人工造伤和短截4种修剪方法对油茶生长发育的影响。主要研究结果如下：调整侧枝角度对新梢生长和光合特性有不同程度的影响,对油茶花果发育无明显影响,侧枝角度以45°处理的表现最好,花芽分化率、坐果率、新梢长度、光能利用率均高于90°处理和对照。回缩强度对油茶树体生长发育有重要影响,轻度回缩的新梢生长状况最佳,新梢抽梢数量、新梢长度和新梢直径分别较对照提高36.05%、108.60%、35.90%；中度回缩净光合速率最大。环剥与刻芽均在不同程度上抑制油茶新梢生长发育,并提高净光合速率和光能利用率；随着环剥宽度的增加,对新梢抽梢数量和新梢抽梢质量抑制程度增强,环剥宽度在0.6cm时净光合速率最高,为11.59μmolCO2/m2·s.刻芽能促进芽上方的新梢萌发,其中,在芽上方刻芽的新梢短而粗壮。短截不同类型和树冠不同部位枝条对油茶生长发育和光合特性有重要影响。短截强枝会促进萌生长而细的枝条,短截弱枝会抽生短而粗的枝条。短截冠层中层枝条提高新梢抽梢数量和质量；短截冠层上层外围枝条,促发的新梢数量少,但新梢短而粗壮,新梢净光合速率最高。2、油茶树体调控对生长发育的影响试验研究了精细修剪、简化修剪、粗放修剪和对照(不修剪)4种树体调控处理对树体生长发育的影响。主要研究结果如下：简化修剪最有利于春梢的抽梢数量和质量；精细修剪和粗放修剪效果相差不多,均优于对照组。精细修剪最有利于夏梢的抽梢及其生长发育。树体调控后促进了新叶生长,以精细修剪新叶生长状况最好,简化修剪次之。树体调控的花芽数量均高于对照,以简化修剪最有利于花芽形成和分化,平均花芽数量为376个,花芽分化率为55.26%,比对照提高14.56%。简化修剪产量最高,单株鲜果平均产量为6.74kg,是精细修剪的1.6倍,粗放修剪产量的1.2倍。精细修剪的单果性状最好。树体调控能改善树体结构,叶面积系数显著降低,精细修剪、简化修剪、粗放修剪和对照叶面积系数分别为3.83、4.77、6.89、7.56；精细修剪和简化修剪显著减少主枝数量、降低树高、提高主枝分枝高度。3、油茶树体调控冠层光合特性试验研究了精细修剪、简化修剪、粗放修剪和对照(不修剪)4种树体调控处理的冠层光合特性。主要研究结果如下：3种树体调控模式处理后净光合速率、蒸腾速率、气孔限制值、气孔导度、水分利用率、光能利用率的变化规律与对照组基本一致,但对数值大小有差异,其中净光合速率、水分利用效率和光能利用率具有显著性的差异,各调控模式的影响程度为：简化修剪>粗放修剪>精细修剪>对照。相关性分析结果表明,油茶树体调控是通过控制冠层光辐射和空气湿度从而改变净光合速率的。树体调控措施能增强油茶植株对弱光和强光的利用程度,以简化修剪和精细修剪的效果较好,新梢生长期和果实生长期,简化修剪的光补偿点分别为33μmol.m-2.s-1、35μmli.m-2.s-1,光饱和点分别为810μmol.m-2.s-1、715μmol.m-2.s-1。新梢生长期与果实生长期不同调控模式处理下的净光合速率规律一致。其大小顺序均为简化修剪>粗放修剪>对照>精细修剪。新梢生长期与果实生长期不同调控模式处理下的光能利用率大小变化规律与净光合速率相同。树体调控模式在油茶整个年生长周期中均有提高净光合速率的作用,但调控模式与光能利用率无密切关系。树体调控措施能很好的改善冠层相对光照强度。对不同调控模式间变化比较得出,精细修剪处理与简化修剪处理效果相当,整体冠层光照强度分布均呈漏斗形,冠层由上至下,由北向南光照强度逐渐增强；不同调控模式相对光照强度日变化规律均呈单峰变化,在12：00达到峰值,峰值大小随着修剪强度增加而增大。4、油茶树体调控营养生理试验研究了精细修剪、简化修剪、粗放修剪和对照(不修剪)4种树体调控模式的树体营养状况及酶活性。主要研究结果如下：不同调控模式下油茶树体可溶性糖、可溶性淀粉、可溶性蛋白质3种有机营养物质的含量变化呈现规律基本一致,可溶性糖含量和可溶性蛋白含量变化呈单峰曲线,在果实生长期达到峰值；可溶性淀粉含量变化趋势呈V形,在果实生长期含量最低。树体调控措施处理的3种营养物含量均高于对照组,以简化修剪最好,3种营养物含量在不同的生长发育阶段中均最高,精细修剪和粗放修剪基本相同。在新梢生长期和果实生长期3种营养物质含量与新梢长度均呈极显著相关性,但与新梢直径的相关性在不同时期表现不一致。在新梢生长期3种营养物质含量与新梢直径相关性极显著,在果实生长期仅与可溶性蛋白质含量呈显著相关性。对超氧化物歧化酶、硝酸还原酶、蔗糖合成酶、淀粉酶活性测定结果表明,不同调控模式对酶活性影响为简化修剪>粗放修剪>对照>精细修剪。简化修剪模式均最高,而精细修剪模式最低,表明适度修剪能提高酶活性,而过度修剪降低酶活性。更多还原

【Abstract】 Camellia oleifera is a group of camellia species from whose seeds an edible oil with a very high content of unsaturated fatty acids can be extracted. Biologically, oil-tea trees are small and shrubby in tree form, and bloom abundantly twice every year, with the simultaneity of blooming and fruiting in Autumn. Unfortunately, however, the economic production of oil-tea plantations on a large scale is low due to poor management, the disorder of the tree structure, and the insufficient utility of the solar energy. Theory and practice have proved that rationally controlling the tree structure through pruning is an effective way to increase the photosynthetic efficiency and hence the fruit yield, but with thousands of hectares of established orchards tree regulation is complicated and intensive management is no easy job. In this dissertation, the author has piloted four pruning methods in four test plots of Camellia oleifera with different planting densities, hoping to create simple and practicable tree structures aiming at prolificacy. The study concentrated on the three aspects of introducing the system of indicators for high-yield tree structures on the basis of analyzing the characteristics of natural oil-tea tree structures; investigating the response of tree growth and fruiting to pruning; and establishing tree regulation patterns relative to regulation mechanism from the point of view of tree growth and development, photosynthetic features of the tree canopy, and tree nutrition physiology. The research findings are as follows.I. Response of tree growth and development to pruningFour methods of pruning were tried, including branching angle adjustment, shoot retraction, artificial injury, and cut-back. It was found that:i) adjusting the angle of the lateral shoots affected the growth of new sprouts and the photosynthesis, but showed no significant influence on floral and fruit development. When the angle was45degrees, the best effect was achieved in terms of floral bud differentiation, fruit set, shoot length, and utility rate of light, as compared to the treatments of90degrees and the check, ⅱ) shoot retraction posed a marked impact on tree growth and development. Slight retraction gave the best performance in shoot growth, and the number of shoots generated, shoot length, and shoot diameter increased by36.05%,108.60%, and 35.90%, respectively, than the check. Medium retraction resulted in the highest photosynthetic rate. iii) both girdling and bud cutting inhibited the shoot growth to some extent, but improved the net photosynthetic rate and the rate of light utility. The wider the girdling was, the worse the shooting percentage and shoot quality became. When the ringing was0.6cm in width, the highest net photosynthetic rate (11.59μ molCO2/m2·s) appeared. Bud cutting promoted shoot sprouting above the bud, and the sprouts were short and thick, iv) cutting back of different typed shoots and on different positions of the crown produced significant effects on the tree growth and development, and the photosynthesis was also remarkably affected. While cutting back of enriching shoots induced long and thin shoots, cutting back of weak shoots generated short and stout sprouts. Cutting back of shoots at the middle part of the crown increased the shooting quantity and quality; however, working with the outside shoots of the crown led to little shooting, although the shoots thus produced were thick with the highest net photosynthetic rate.II. Tree growth and development as affected by tree structure controlFour tree body regulation treatments were conducted, i.e. intensive pruning, simplified pruning, casual pruning, and non-pruning (as for check). It was found that: i) simplified pruning was favorable for Spring shooting and the shoot quality; the effect of both intensive and casual prunings was more or less the same, but both treatments were better than the Check non-pruning in terms of shooting percentage and quality; and intensive pruning was most ideal for Autumn shooting and growth, ii) Tree structure regulation promoted the growth of new leaves, with intensive pruning being the best, followed by simplified pruning, iii) pruned trees were better in increasing the number of floral buds than that of the Check, and simplified pruning resulted in bud formation and differentiation in the most positive degree, with the mean number of376floral buds and55.26%bud differentiation, which is14.56%higher than the Check, ⅳ) simplified pruning produced the highest yield of fruit of6.74kg per individual tree, which is1.6and1.2times more than that of the intensive and casual prunings, respectively. However, with intensive pruning the economic characters of individual fruit ranked the first, ⅴ) tree shape regulation improved the tree structure, and lowered the leaf area coefficient. The leaf area coefficient of intensive, simplified, casual prunings, and non-pruning was3.83,4.77,6.89, and7.56, respectively. Intensive and simplified prunings noticeably lessened the number of leading shoots, minimized the tree height, and raised the branching height of the primary shoots.Ⅲ. Canopy photosynthetic properties as regulated by tree structure controlThe crown photosynthesis was studied with four treatments of intensive pruning, simplified pruning, casual pruning, and non-pruning (as for Check). It was found that: i) The pattern of change in net photosynthetic rate, transpiration rate, stomatal limitation value, stomatal conductance, water use efficiency, and efficiency for solar energy utilization by intensive, simplified, and casual prunings was basically the same as that of the Check, but they varied in logarithm value, among which net photosynthetic rate, water use efficiency, and efficiency for solar energy utilization showed significant variation. With the four regulation patterns, the impact of regulation followed the pattern in the descending order of simplified pruning, casual pruning, intensive pruning, and non-pruning. Correlation analysis revealed that the tree structure regulation in oil-tea camellia was completed through the chang of net photosynthetic rate via regulation of the light output and air humidity, ii) more weak light as well as strong light were utilized through tree structure control, and better effects were achieved with simplified and intensive prunings. At the stages of fresh shoot growth and fruit development, the light compensation point was33with simplified pruning and35with intensive pruning, whereas the light saturation point was810and715, respectively, iii) the pattern of net photosynthetic rate with the four regulation treatments was regular at both the shoot growing stage and the fruit development stage. The value of net photosynthetic rate followed the descending order of simplified, casual, non-, and intensive prunings. At both stages the efficiency for solar energy utilization coincided with net photosynthetic rate. Tree structure regulation increased the net photosynthetic rate in the annual life cycle of oil-tea camellia, but each treatment as not closely correlated with the utility efficiency of solar energy, iv) tree shape regulation could well improve the relative lighting intensity of the crown canopy. Comparative analysis indicated that the effect of improvement of intensive pruning was largely the same as simplified pruning, the overall distribution of light intensity on the crown fell in the shape of a funnel, with lighting intensified from top and north to bottom and south of the canopy layer. The diurnal change of relative lighting intensity by different treatments demonstrated a single curve, the peak value came at12:00, and the value increased with the enhancement of the pruning intensity.Ⅳ. The physiological foundation of tree structure regulation in Camellia oleiferaThe nutritional condition and enzyme activity of the trees in the test plot whose tree structure was regulated by either intensive pruning, simplified pruning, casual pruning, or non-pruning were analyzed. Results showed that:i) the soluble sugar, soluble starch, and soluble protein in the tree under different pruning treatments followed basically the same pattern of change. While the content of soluble sugar and soluble protein presented a single curve with the peak appearing at the fruit growth stage, the content of soluble starch was in the Ⅴ shape with the lowest content recorded at the fruit development stage. The three nutritional elements were all higher in content with the pruning treated trees than the non-pruned trees. Simplified pruning induced the highest nutritional content in different growth and development stages, followed by intensive and casual prunings whose nutritional content was almost identical, ⅱ) three nutritional elements by content were significantly in positive correlation with the length of the fresh shoots both at the shoot growing and fruit enlargement stages, but this was not true of the shoot size at varied growth periods. With shoot growth the content of nutrients posed an enormously positive correlation to the shoot size; however, fruit growth was only significantly correlated to the content of soluble protein, ⅲ) measurement of activity of superoxide dismutase, nitrate reductase, sucrose synthetase, and amylase showed that different regulation treatments presented activity in the descending order of simplified, casual, non-, and intensive prunings. The activity of all enzymes was the highest with simplified pruning, and the lowest with intensive pruning, indicative of the fact that moderate pruning could increase the enzyme activity, whereas excessive pruning could lower the enzyme activity.更多还原