Effects of nitrogen and radiation on dry matter and nitrogen accumulation in the spike of winter wheat
Effects of nitrogen and radiation on dry matter and nitrogen accumulation in the spike of winter wheat
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DOI：
10.1016/j.fcr.2003.11.014
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发表时间：
2004-05-10
影响因子：
5.8
通讯作者：
Jeuffroy, MH
中科院分区：
文献类型：
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作者：
Demotes-Mainard, S;Jeuffroy, MH
小麦开花期前的穗生长是影响籽粒结实率的关键时期。在花期观察到，入射辐射和作物氮状况影响穗中干物质和氮的积累。然而，这两个因素对花前期穗生长动态的影响尚不完全清楚。我们的目的是研究入射辐射和作物氮营养对花前期穗干物质、氮浓度和氮含量动态的影响，并提出描述穗生长过程中单位面积穗干物质和氮含量的模型。我们还研究了籽粒数是否与开花时穗N含量相关，而与穗DM无关，这是一个有争议的问题。田间试验用“Tremie”冬小麦进行了两个季节，用“Arche”和“Soissons”进行了另外一个季节。处理包括在不同阶段和速率施用氮肥以实现不同程度的氮亏缺，并在穗生长的不同时期使用遮阳网以减少入射辐射。遮荫降低了穗DM，但增加了穗N浓度；当入射光合有效辐射（PAR）大幅降低时，它会降低穗氮含量。所有这些影响只发生在穗生长的后半期，即使从穗生长开始施用遮光。作物缺氮降低了穗DM、氮浓度和氮积累。如果在穗生长开始前就开始亏缺，则整个穗生长期都会影响穗干物质和氮含量，且亏缺程度严重。持续和暂时缺氮引起了类似的反应。遮荫与施氮的交互作用对穗DM和氮含量影响不显著，但对穗氮浓度影响显著。建立了两个预测穗DM和穗N含量的模型。它们通过独立的数据集和初始数据库的交叉验证进行验证。两个模型都很好地拟合了观测数据。输入变量播后累积PAR、作物氮素营养指数（NNI）和播后累积热时间易于测量和模拟。籽粒数与穗DM和穗N含量均相关，表明N含量对籽粒数的影响不依赖于穗DM。(C) 2004 Elsevier B.V All rights reserved。
In wheat, spike growth prior to anthesis is a key period influencing kernel set. Incident radiation and crop N status affect the accumulation of dry matter (DM) and nitrogen (N) in the spike, as observed at anthesis. However, the influence of these two factors on the dynamics of spike growth throughout the pre-anthesis period is not fully understood. Our objective was to investigate the effects of incident radiation and crop N nutrition on the dynamics of spike dry matter, N concentration and N content throughout the pre-anthesis period and to propose models describing spike DM and N content during spike growth, per unit area. We also investigated whether kernel number was related to spike N content at anthesis independently of spike DM, a controversial issue. Field experiments were conducted over two seasons with 'Tremie' winter wheat and over an additional season with 'Arche' and 'Soissons'. Treatments involved the application of N fertiliser at different stages and rates to achieve various levels of N deficit and the use of shading nets at various periods during spike growth to reduce incident radiation. Shading reduced spike DM but increased spike N concentration; it reduced spike N content whenever there was a large decrease in incident photosynthetically active radiation (PAR). All these effects occurred only during the second half of the spike growth period, even if shading was applied from the onset of spike growth. Crop N deficit reduced spike DM, N concentration and N accumulation. Spike DM and N content were affected throughout the spike growth period if the deficit started before the beginning of spike growth, and was severe. Continuous and temporary N deficits induced similar responses. The interaction between shading and N fertilisation was not significant for spike DM and N content, but was significant for spike N concentration. Two models, one predicting spike DM and the other predicting spike N content at any time during spike growth were developed. They were validated with an independent data set and by cross-validation with the initial database. Both models fitted the observed data well. The input variables, cumulative PAR after sowing, nitrogen nutrition index (NNI) of the crop and cumulative thermal time after sowing are easy to measure or to simulate. Kernel number was correlated with both spike DM and spike N content at anthesis, demonstrating that N content played no role in determining kernel number independently of DM. (C) 2004 Elsevier B.V All rights reserved.