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Removing the inefficiencies of 3-dimensional canopy photosynthesis by the alteration of leaf light-response dynamics and plant architecture

通过改变叶片光响应动力学和植物结构来消除 3 维冠层光合作用的低效率

基本信息

批准号：
BB/J003999/1
负责人：
Erik Murchie
金额：
$ 56.79万
依托单位：
University of Nottingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FJ003999%2F1
关键词：
Removing inefficiencies dimensional canopy photosynthesis

项目摘要

Photosynthesis in plants is the uptake of CO2 by leaves and its assimilation into carbohydrates within specialized organs (chloroplasts), a process that requires the absorption of light by chlorophyll. However the rate of photosynthesis over a given period of time varies according to environmental changes such as light intensity, leaf age, temperature and other factors.This has consequences for productivity of crops which depend on high rates of photosynthesis for high yields. Productivity is the sum total of a large number of leaves in a canopy, many of which shade (or partly shading each other) and are usually different ages. We can calculate the potential productivity of whole canopies based on leaf photosynthetic attributes and other physical and physiological factors. When we do this the theoretical productivity tends to be much higher than the measured productivity. The reasons are unclear but a large part is thought to be due to the way leaves respond when re-constructed into a large 3D canopy. In this state, plants exist as a community which has emergent properties that we cannot necessarily predict from plants grown individually. If we can eliminate the gap between the theoretical and measured productivity we can achieve a step change in productivity. Photosynthetic rate is very sensitive to light intensity. The difference in light intensities that exist within the canopy (an exponential decline from top to bottom) is significant and is affected by the precise architecture of the canopy i.e. the amount of leaf area per unit ground area, the angle, shape and size of leaves and their position within 3 dimensional space. This means that the light intensity has great variability in space and time within canopies e.g with frequent and transient appearance of 'light-flecks'. The movement of the canopy plays a major part in how fast or slow light flecks are generated, and where in the canopy they appear. Photosynthesis should be optimized to these rapidly changing conditions, but there are indications that it is not. The environment can cause a 'down-regulation' of photosynthesis in the field and this can be measured by comparing actual leaf photosynthesis against the maximum. It is not clear how this down-regulation interacts with canopy architecture and the responses of leaves.One problem is that we do not have detailed images of crop canopies in 3 dimensions and we do not have sophisticated models that allow us to map the complex changes in light intensity to photosynthesis. Crop canopies perform a number of important agronomic roles, some photosynthetic , others not. Therefore we need to understand the problem 'in reverse' - i.e. to take good 3D images of crop canopies, both still and moving, calculate the typical changes in light intensity that occur in that canopy and then change photosynthetic dynamics so that it matches those changes. We will grow canopies of productive crop plants, rice and wheat in a special glasshouse that will enable us to image crop canopies, when still, and produce 3D high resolution images using laser scanning and camera techniques. Novel techniques will be tested for detecting plant movement in wind and we will then distort these images to examine the effect of wind induced leaf 'flutter' and stem bending on light distribution. We will use these images in a mathematical ray-tracing program to finely map the changes in light that occur within the canopy. These changes will be used to predict which processes dominate the canopy-productivity process. This is essentially a modelling and imaging project of plant canopies: we will begin the following phase by ordering rice mutants altered in key reactions identified from these models and grow these to test whole canopy productivity. If successful we can achieve a step change in productivity by eliminating any wasteful processes that occur within the canopy.

植物的光合作用是叶片吸收二氧化碳并在特定器官（叶绿体）中将其同化为碳水化合物，这一过程需要叶绿素吸收光。然而，在一段时间内，光合作用的速率根据环境的变化而变化，如光强、叶龄、温度和其他因素。这对依靠高光合作用速率来获得高产量的作物的生产力产生了影响。生产力是冠层中大量叶片的总和，其中许多叶片遮阳（或部分遮阳），通常年龄不同。我们可以根据叶片光合特性和其他生理因素来计算全冠层的生产力潜力。当我们这样做时，理论生产率往往比实际生产率高得多。原因尚不清楚，但很大程度上被认为是由于树叶在重建成一个大型3D树冠时的反应方式。在这种状态下，植物作为一个群落存在，具有我们无法从单独生长的植物中预测到的涌现特性。如果我们能消除理论生产率和实际生产率之间的差距，我们就能实现生产率的阶梯式变化。光合速率对光强非常敏感。冠层内存在的光强差异（从上到下呈指数下降）是显著的，并且受冠层精确结构的影响，即每单位地面面积的叶面积，叶子的角度，形状和大小以及它们在三维空间中的位置。这意味着在冠层内，光强度在空间和时间上有很大的可变性，例如，“光斑”的频繁和短暂的出现。树冠的运动在产生光斑的快慢以及它们在树冠的何处出现方面起着重要作用。光合作用应该优化以适应这些快速变化的条件，但有迹象表明，情况并非如此。环境可以导致田间光合作用的“下调”，这可以通过将实际叶片光合作用与最大叶片光合作用进行比较来衡量。目前尚不清楚这种下调如何与冠层结构和叶片的反应相互作用。一个问题是，我们没有三维的作物冠层的详细图像，也没有复杂的模型，使我们能够绘制出光强对光合作用的复杂变化。作物冠层起着许多重要的农艺作用，有些起光合作用，有些不起作用。因此，我们需要“反过来”理解这个问题——也就是说，拍摄农作物冠层的3D图像，包括静止的和移动的，计算冠层中光强度的典型变化，然后改变光合作用动力学，使其与这些变化相匹配。我们将在一个特殊的温室中种植农作物、水稻和小麦的冠层，这将使我们能够在静止时对作物冠层进行成像，并使用激光扫描和摄像技术产生3D高分辨率图像。我们将测试用于检测植物在风中运动的新技术，然后我们将扭曲这些图像，以检查风诱导的叶子“颤振”和茎弯曲对光分布的影响。我们将在数学光线追踪程序中使用这些图像来精细地绘制树冠内发生的光线变化。这些变化将用于预测哪些过程主导了冠层生产力过程。这本质上是一个植物冠层的建模和成像项目：我们将通过订购在这些模型中识别的关键反应中改变的水稻突变体开始下一阶段，并种植这些突变体来测试整个冠层的生产力。如果成功，我们可以通过消除树冠内发生的任何浪费过程来实现生产力的逐步变化。