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首页> 外文期刊>Plant and Soil >Salinity increases CO2 assimilation but reduces growth in field-grown, irrigated rice.
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Salinity increases CO2 assimilation but reduces growth in field-grown, irrigated rice.

机译：盐分增加了CO2同化作用，但减少了田间灌溉水稻的生长。

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Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium uptake, leaf chlorophyll content, specific leaf area, sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation(PAR)- saturation. Plants were grown in Ndiaye, Senegal, during the hot dry season (HDS) and the wet season (WS) 1994 under irrigation with fresh or saline water (flood water electrical conductivity=3.5 mSthincm-1). Relative leaf chlorophyll content androot, stem, leaf blade and panicle dry weight were measured at weekly intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured at mid-season on the first (topmost) and second leaf.Salinity reduced yields to nearly zero and dry-matter accumulation by 90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase in CER, which was also observed in the other cultivars andseasons, was explained by a combination of two hypotheses: leaf chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation. The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly, energy-consuming processes, such as osmoregulation, interception of sodiumand potassium from the transpiration stream in leaf sheaths and their subsequent storage, drained the assimilate supply.
机译：在光合作用活性辐射（PAR）-饱和状态下，研究了三个不同耐盐水平的水稻品种的生长，钠吸收，叶片叶绿素含量，比叶面积，钠浓度和叶片CO2交换率（CER）。在塞内加尔Ndiaye的炎热干燥季节（HDS）和潮湿的季节（WS）1994期间，用淡水或盐水冲洗（水电导率= 3.5 mSthincm-1），使植物生长。在两个季节中，每周一次测量相对叶绿素含量和根，茎，叶片和穗干重。在八个日期测量了比叶面积，在第一叶（最上层）和第二叶的季节中期测量了CER和叶钠含量。盐度使易感品种的产量降低至接近零，干物质积累降低了90％。 HDS，但在PAR饱和时增加了叶绿素含量和CER。 CER的增加（在其他品种和季节中也观察到）由两个假设的组合解释：叶片中叶绿素含量受对照中可用氮资源的限制，但在盐胁迫植物中不受限制;并且钠浓度不足以引起早期叶片衰老和叶绿素降解。生长减少归因于同化物出口后必然发生的同化物的损失（机制未知）。根据农作物模型的模拟，同化物的表观经常性损失在灌溉水稻ORYZA S中为8％至49％之间，部分原因可能是根系分解和渗出。可能更重要的是，耗能过程（例如渗透压调节，叶鞘蒸腾作用中钠和钾的截留以及随后的储存）耗尽了同化物的供应。

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