Nitrate uptake ability by maize roots during and after drought stress
Nitrate uptake ability by maize roots during and after drought stress
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DOI：
10.1023/a:1004879201623
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发表时间：
2001-02-01
期刊：
影响因子：
4.9
通讯作者：
Engels, C
中科院分区：
文献类型：
--
作者：
Buljovcic, Z;Engels, C
研究了不同强度和持续时间的土壤干旱和复水对玉米根系硝酸盐吸收能力的影响。使植物生长在分根容器中，使根系的一部分经受不同强度和持续时间的土壤干旱和再灌溉，而根系的另一部分连续灌溉至23%（w/w）土壤含水量（70%水容量）。在分根容器中进行实验，以保持较高的生长速度，从而确保高营养需求的拍摄，无论土壤水分状况。为了避免在干燥土壤中运输过程对硝酸盐吸收的限制，并确保根表面均匀的N-14/N-15比例，将N-15置于含0.5 mM Ca（（NO3）-N-15）的通气营养液中，施用于根（2）。当一个根室土壤保持湿润时，另一个根室的地上部伸长和生物量仅受干旱的轻微影响。因此，与生长相关的营养需求的新梢保持在一个较高的水平。在中等水平的土壤干旱（10%w/w的水含量）的N-吸收的能力，根不受影响，即使在10天的干旱。只有当土壤含水量降低到5%时，氮吸收能力才降低到正常灌溉对照的20%左右。根系可溶性总糖含量随土壤干旱程度的增加而增加，表明严重土壤干旱条件下根系氮素吸收能力的降低并不是由于地上部同化物供应的降低造成的。在非常干燥的土壤（5%土壤含水量W/W），即使是8天的延长期，根系的硝酸盐吸收能力，恢复后3天内复水。复水后一天，根系生长增加。短期试验表明，在土壤干旱条件下，老根和幼根段的硝酸盐吸收能力在复水2d后恢复。显然，复水后氮吸收能力的增加不仅是由于新根的生长，而且是由于先前受胁迫根吸收能力的恢复。
The effects of different intensities and durations of soil drought and re-watering on the nitrate uptake ability of maize roots were studied. Plants were grown in split-root containers with one part of the root system subjected to different intensities and durations of soil drought and re-watering while the other part of the root system was continuously watered to 23% (w/w) soil water content (70% water capacity). Experiments were performed in split-root containers to maintain a high growth rate, thus ensuring high nutrient demand of the shoot irrespective of the soil water regime. To avoid limitation of nitrate uptake by transport processes in the dry soil, and to ensure a uniform N-14/N-15 ratio at the root surface, N-15 was applied to the roots by placing them into an aerated nutrient solution with 0.5 mM Ca((NO3)-N-15)(2). Shoot elongation and biomass were only slightly affected by drought in one root compartment when the soil in the other root compartment was kept wet. Therefore, the growth-related nutrient demand of the shoot remained at a high level. At moderate levels of soil drought (10% w/w water content) the ability of the roots for N-uptake was not affected even after 10 d of drought. N-uptake ability was reduced to about 20% of the well-watered control only when the soil water content was decreased to 5%. Total soluble sugar content of the roots increased with increasing soil drought, indicating that low N-uptake ability of roots subjected to severe soil drought was not caused by low assimilate supply from the shoot. Nitrate uptake ability of roots maintained in very dry soil (5% soil water content w/w) even for a prolonged period of 8 d, recovered within 3 d following re-watering. Root growth increased one day after re-watering. A short-term experiment with excised roots formerly subjected to severe soil drought showed that nitrate uptake ability recovered in old and young root segments after 2 d of re-watering. Obviously, the increase in N-uptake ability after re-watering was caused not only by new root growth but also by recovery of the uptake ability of formerly stressed roots.