Predicting the interaction between the effects of salinity and climate change on crop plants
Predicting the interaction between the effects of salinity and climate change on crop plants
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DOI：
10.1016/s0304-4238(98)00193-9
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发表时间：
1998-11
影响因子：
4.3
通讯作者：
Anthony Yeo
中科院分区：
文献类型：
--
作者：
Anthony Yeo
人口预计将翻一番，因此对粮食生产的需求将至少翻一番。这将增加对灌溉的需求，因为灌溉比非灌溉农业单位面积的潜在产量更高，而且产量更稳定。灌溉需求将特别集中在人口众多的半干旱地区，如地中海盆地和印度北方和巴基斯坦的印度-恒河平原。由于大气中二氧化碳浓度的增加所引起的气候变化，“热/暖半干旱”农业气候带预计将相对扩大。半干旱气候下的灌溉是次生盐渍化（由于人类活动）的主要原因，已经影响到五个灌溉土地的1公顷。由于人口增长和气候变化，半干旱气候对灌溉的需求增加，往往会增加次生盐渍化的程度。次生盐渍化程度的任何增加都可以被大气CO2浓度升高对单位面积和单位水输入作物产量的积极影响所抵消。在受保护的环境中，或者在CO2是唯一的实验变量的情况下，CO2的升高通常会在短期内提高植物的生长和水的利用效率，并且也可以在长期内这样做。然而，对于世界范围内的作物生产，二氧化碳浓度升高本身并不是一个可以与它所带来的气候变化分开看待的因素。无论是预期的“CO2施肥”还是CO2浓度升高对植物的“水利用效率”的好处，都不一定超过CO2浓度升高对温度、水供应和蒸发需求的气候影响。预计气候变化将导致被列为半干旱土地的比例净增加。温度升高可能有利于某些地方的某些作物，但通过增加蒸发蒸腾和热损害而不利于其他作物。提高水分利用效率可能不会降低叶盐浓度在含盐环境。缓冲和反馈效应在农业和生态系统的阴谋缓和，甚至混淆预期的净同化和水的利用效率在实验系统中发现的收益。因此，CO2浓度升高可能不会提供预期的用水量减少、叶盐浓度降低和可用于重新分配的固定碳增加：这些因素可能会提高作物在盐胁迫下的表现。如果这些好处没有实现，那么大气中二氧化碳浓度的升高将加剧而不是缓解农业中的次生盐渍化问题。
The human population is expected to double so there will be at least a doubled demand for food production. This will increase the demand for irrigation because irrigation gives a higher potential yield per unit area than non-irrigated agriculture, together with more yield stability. The demand for irrigation will be especially focused in semi-arid regions supporting a large population, such as the Mediterranean basin and the Indo–Gangetic plain of northern India and Pakistan. The `hot/warm semi-arid' agro-climatic zone is the one projected most to expand in relative proportion as a consequence of climate change brought about by the increase in atmospheric carbon dioxide concentration. Irrigation in semi-arid climates is a major cause of secondary salinisation (that due to human activity) which already affects 1ha in five of the irrigated lands. Increased demand for irrigation in semi-arid climates, as a result of both population increase and climate change, will tend to increase the extent of secondary salinisation. Any increase in the extent of secondary salinisation could be offset by positive effects of elevated atmospheric CO2on crop yield per unit area and per unit input of water. In protected environments, or where CO2is the only experimental variable, elevated CO2usually enhances plant growth and water-use-efficiency in the short-term and can also do so in the longer term. However, for crop production in the field world-wide, elevated CO2per se is not a factor that can be viewed separately from the climate change that it will bring about. Neither the anticipated `CO2-fertilisation' nor the `water-use-efficiency' benefits to the plant of elevated CO2is certain to outweigh the climatic effects of elevated CO2on temperature, water availability and evaporative demand. Climate change is expected to cause a net increase in the proportion of land classed as semi-arid. Raised temperatures may benefit some crops in some places but disadvantage others through increased evapotranspiration and thermal damage. Increased water-use-efficiency may not reduce leaf salt concentration in a saline environment. Buffering and feedback effects in both agricultural and ecological systems conspire to moderate or even to confound the anticipated gains in net assimilation and water-use-efficiency found in experimental systems. Elevated CO2may not, therefore, provide the anticipated decrease in water-use, decrease in leaf salt concentration, and increase in fixed carbon available for re-allocation: factors that might enhance crop performance under salinity stress. If these benefits are not realised then elevated atmospheric CO2will exacerbate rather than moderate the problems of secondary salinity in agriculture.