Fiebig Antje, Dodd Ian C
Lancaster Environment Centre, Lancaster University, Lancaster, UK.
Physiol Plant. 2016 Jan;156(1):70-83. doi: 10.1111/ppl.12343. Epub 2015 May 26.
Although physiological effects of acute flooding have been well studied, chronic effects of suboptimal soil aeration caused by over-irrigation of containerized plants have not, despite its likely commercial significance. By automatically scheduling irrigation according to soil moisture thresholds, effects of over-irrigation on soil properties (oxygen concentration, temperature and moisture), leaf growth, gas exchange, phytohormone [abscisic acid (ABA) and ethylene] relations and nutrient status of tomato (Solanum lycopersicum Mill. cv. Ailsa Craig) were studied. Over-irrigation slowly increased soil moisture and decreased soil oxygen concentration by 4%. Soil temperature was approximately 1°C lower in the over-irrigated substrate. Over-irrigating tomato plants for 2 weeks significantly reduced shoot height (by 25%) and fresh weight and total leaf area (by 60-70%) compared with well-drained plants. Over-irrigation did not alter stomatal conductance, leaf water potential or foliar ABA concentrations, suggesting that growth inhibition was not hydraulically regulated or dependent on stomatal closure or changes in ABA. However, over-irrigation significantly increased foliar ethylene emission. Ethylene seemed to inhibit growth, as the partially ethylene-insensitive genotype Never ripe (Nr) was much less sensitive to over-irrigation than the wild type. Over-irrigation induced significant foliar nitrogen deficiency and daily supplementation of small volumes of 10 mM Ca(NO3 )2 to over-irrigated soil restored foliar nitrogen concentrations, ethylene emission and shoot fresh weight of over-irrigated plants to control levels. Thus reduced nitrogen uptake plays an important role in inhibiting growth of over-irrigated plants, in part by stimulating foliar ethylene emission.
尽管急性淹水的生理效应已得到充分研究，但容器栽培植物过度灌溉导致土壤通气性欠佳的慢性效应却未被研究，尽管其可能具有商业意义。通过根据土壤湿度阈值自动安排灌溉，研究了过度灌溉对番茄（Solanum lycopersicum Mill. cv. Ailsa Craig）土壤性质（氧气浓度、温度和湿度）、叶片生长、气体交换、植物激素[脱落酸（ABA）和乙烯]关系及养分状况的影响。过度灌溉使土壤湿度缓慢增加，土壤氧气浓度降低了4%。过度灌溉的基质中土壤温度约低1℃。与排水良好的植株相比，对番茄植株进行2周的过度灌溉显著降低了株高（降低25%）、鲜重和总叶面积（降低60 - 70%）。过度灌溉未改变气孔导度、叶片水势或叶片ABA浓度，这表明生长抑制并非由水力调节，也不依赖于气孔关闭或ABA变化。然而，过度灌溉显著增加了叶片乙烯释放量。乙烯似乎抑制生长，因为部分乙烯不敏感基因型Never ripe（Nr）对过度灌溉的敏感性远低于野生型。过度灌溉导致显著的叶片氮素缺乏，每天向过度灌溉的土壤中补充少量10 mM Ca(NO3 )2可使过度灌溉植株的叶片氮素浓度、乙烯释放量和地上部鲜重恢复到对照水平。因此，氮素吸收减少在抑制过度灌溉植株生长中起重要作用，部分原因是刺激了叶片乙烯释放。
