1Department of Plant Pathology, University of California, Davis, CA 95616.
2Department of Plant Sciences and Landscape Architecture, University of Maryland, College Park, MD 20742.
Phytopathology. 2019 Aug;109(8):1441-1452. doi: 10.1094/PHYTO-03-18-0096-R. Epub 2019 Jul 5.
In containerized (potted) annual nursery and greenhouse crops, set point-controlled irrigation allows adaptation to increasing water insecurity by precisely reducing water inputs. A key factor influencing adoption is lack of information on disease risk. To facilitate adaptive water use, effects of set-point substrate moisture (SM) control on disease risk and water savings in containerized annual production were evaluated using the -tomato pathosystem (a model system for water stress predisposition to pathogen infection), comparing outcomes of imposing midrange SM (15% volumetric water content [VWC]) and low-range SM (10% VWC) with well-watered (20% VWC) plants. Reducing soil moisture to 10% VWC differentially reduced stem water potential ( < 0.05) and enhanced rate of wilt progress ( = 0.006) and root rot severity ( = 0.03) in inoculated plants compared with noninoculated plants. Furthermore, incidence of fine root infections in inoculated asymptomatic plants was greater under reduced SM (10% VWC) compared with in well-watered plants ( < 0.05). Mild reductions to 15% VWC did not influence plant performance (root and shoot weights and plant height) or pathogen infection in either inoculated or noninoculated plants compared with well-watered plants and reduced water inputs by 17%, indicating potential for reducing water usage without increasing disease risk. Furthermore, inoculated plants had lower shoot biomass and greater root infection incidence when 15% VWC was applied to older compared with younger plants; the inverse was true for root rot severity, although root rot development was minor overall ( < 0.05). These results indicate that water use reductions pose disease risks, but there is potential to reduce water use and effectively manage plant pathogens in containerized production. Overall, this study indicates that physiological indices should not be solely relied on to develop water reduction methods.
在容器化（盆栽）一年生苗圃和温室作物中，设定点控制灌溉可以通过精确减少水的输入来适应不断增加的水不安全。影响采用的一个关键因素是缺乏有关疾病风险的信息。为了促进适应性用水，使用番茄病理系统（一种用于研究水分胁迫对病原体感染易感性的模型系统）评估了设定点基质水分（SM）控制对容器化一年生生产中疾病风险和节水的影响，比较了中范围 SM（15%体积含水量[VWC]）和低范围 SM（10%VWC）与充分浇水（20%VWC）的植物的结果。与非接种植物相比，将土壤水分降低到 10%VWC 会显著降低接种植物的茎水势（<0.05），并加速萎蔫进展（=0.006）和根腐病严重程度（=0.03）（<0.05）。此外，与充分浇水的植物相比，在低 SM（10%VWC）下，接种无症状植物的细根感染发生率更高（<0.05）。与充分浇水的植物相比，轻度降低到 15%VWC 不会影响植物的性能（根和茎的重量以及植物高度）或接种或非接种植物的病原体感染，同时将水的输入减少 17%，表明在不增加疾病风险的情况下减少用水量的潜力。此外，与年轻植物相比，当 15%VWC 应用于较老植物时，接种植物的地上生物量较低，根感染发生率较高；虽然根腐病的发展总体上较小（<0.05），但根腐病的严重程度则相反。这些结果表明，用水减少会带来疾病风险，但有可能在容器化生产中减少用水并有效管理植物病原体。总的来说，本研究表明，不应仅依靠生理指标来开发节水方法。
