Carbon and nitrogen assimilation in relation to yield: mechanisms are the key to understanding production systems
Carbon and nitrogen assimilation in relation to yield: mechanisms are the key to understanding production systems
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DOI：
10.1093/jexbot/53.370.773
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发表时间：
2002-04-01
影响因子：
6.9
通讯作者：
Lawlor, DW
中科院分区：
文献类型：
--
作者：
Lawlor, DW
提高对作物生产系统与氮供应关系的理解来自于基本的植物生物化学和生理学知识。基因表达导致蛋白质合成和代谢系统的形成；随后的代谢决定了生长发育和产量生产的能力。这就构成了遗传潜能。这些过程确定了资源供应的要求。二氧化碳（CO2）与硝态氮（NO3-）同化的相互作用及其动态对作物生产具有重要意义。特别是，充足的NO3-供应，其对氨基酸的同化（需要光合碳化合物）和蛋白质合成的可用性，对新陈代谢至关重要。充足的NO3-供应刺激叶片生长和光合作用，前者通过细胞生长和分裂，后者通过较大含量的光反应组分和CO2同化及相关过程组分。如果资源的供给超过遗传潜能所决定的需求，则产量是最大的；如果资源的供给低于遗传潜能，则产量没有达到潜力；使资源与潜力相匹配是农业的目标。然而，代谢和产量之间的关系很少量化。必须更好地利用生化特性和模拟模型，并将其结合起来，以提高氮肥施用、氮肥利用效率和产量。在氮素供应不足的情况下，通过增加生根体积和密度来增加氮素吸收量是可行的，而通过增加亲和性来增加氮素吸收量则不太可行。可提高生物量和氮碳比。在充分遗传潜力的条件下，每单位氮的碳同化增加会增加生物量，但在满冠层时能量有限。增加单位氮的碳同化会增加生物量，但在大氮和小氮供应下均会降低N/C。提高各生化组分的产量可提高生物量和对氮的需求，维持氮碳比。改变C-或n -同化需要对许多过程进行修改，以实现整个系统的改进；基因工程/分子生物学改变中枢代谢的单个步骤不太可能实现这一点，因为目标不明确，也因为过程和环境之间复杂的相互作用。通过农学、育种或基因工程实现以更少的投入和更少的污染提高作物氮素利用和产量的长期目标，需要更好地了解整个系统，从基因到代谢再到产量。
Improved understanding of crop production systems in relation to N-supply has come from a knowledge of basic plant biochemistry and physiology. Gene expression leads to protein synthesis and the formation of metabolic systems; the ensuing metabolism determines the capacity for growth, development and yield production. This constitutes the genetic potential. These processes set the requirements for the supply of resources. The interactions between carbon dioxide (CO2) and nitrate (NO3-) assimilation and their dynamics are of key importance for crop production. In particular, an adequate supply of NO3-, its assimilation to amino acids (for which photosynthesized carbon compounds are required and their availability for protein synthesis, are essential for metabolism. An adequate supply of NO3- stimulates leaf growth and photosynthesis, the former via cell growth and division, the latter by larger contents of components of the light reactions, and those of CO2 assimilation and related processes. If the supply of resources exceeds the demand set by the genetic potential then production is maximal, but if it is less then potential is not reached; matching resources to potential is the aim of agriculture. However, the connection between metabolism and yield is poorly quantified. Biochemical characteristics and simulation models must be better used and combined to improve fertilizer-N application, efficiency of N-use, and yields. Increasing N-uptake at inadequate N-supply by increasing rooting volume and density is feasible, increasing affinity is less so. It would increase biomass and N/C ratio. With adequate N, at full genetic potential, more C-assimilation per unit N would increase biomass, but energy would be limiting at full canopy. Increasing C-assimilation per unit N would increase biomass but decrease N/C at both large and small N-supply. Increasing production of all biochemical components would increase biomass and demand for N, and maintain N/C ratio. Changing C- or N-assimilation requires modifications to many processes to effect improvements in the whole system; genetic engineering/molecular biological alterations to single steps in the central metabolism are unlikely to achieve this, because targets are unclear, and also because of the complex interactions between processes and environment. Achievement of the long-term objectives of improving crop N-use and yield with fewer inputs and less pollution, by agronomy, breeding or genetic engineering, requires a better understanding of the whole system, from genes via metabolism to yield.