Mingo Darren M, Theobald Julian C, Bacon Mark A, Davies William J, Dodd Ian C
The Lancaster Environment Centre, Lancaster University, LA1 4YQ, UK.
Funct Plant Biol. 2004 Nov;31(10):971-978. doi: 10.1071/FP04020.
Tomato (Lycopersicon esculentum Mill.) plants were grown in either a glasshouse (GH) or a controlled environment cabinet (CEC) to assess the effects of partial rootzone drying (PRD) on biomass allocation. Control and PRD plants received the same amounts of water. In control plants, water was equally distributed between two compartments of a split-root system. In PRD plants, only one compartment was watered while the other was allowed to dry. At the end of each drying cycle, wet and dry compartments were alternated. In the GH, total biomass did not differ between PRD and control plants after four cycles of PRD, but PRD increased root biomass by 55% as resources were partitioned away from shoot organs. In the CEC, leaf water potential did not differ between treatments at the end of either of two cycles of PRD, but stomatal conductance of PRD plants was 20% less at the end of the first cycle than at the beginning. After two cycles of PRD in the CEC, biomass did not differ between PRD and control plants, but PRD increased root biomass by 19% over the control plants. The promotion of root biomass in PRD plants was associated with the alternation of wet and dry compartments, with increased root biomass occurring in the re-watered compartment after previous exposure to soil drying. Promotion of root biomass in field-grown PRD plants may allow the root system to access resources (water and nutrients) that would otherwise be unavailable to control plants. This may contribute to the ability of PRD plants to maintain similar leaf water potentials to conventionally irrigated plants, even when smaller irrigation volumes are supplied.
番茄（Lycopersicon esculentum Mill.）植株种植于温室（GH）或可控环境箱（CEC）中，以评估部分根区干燥（PRD）对生物量分配的影响。对照植株和PRD处理植株接受相同量的水分。在对照植株中，水分在分根系统的两个隔室中平均分配。在PRD处理植株中，仅对一个隔室浇水，而另一个隔室任其干燥。在每个干燥周期结束时，交替干湿隔室。在温室中，经过4个PRD周期后，PRD处理植株与对照植株的总生物量无差异，但由于资源从地上器官分配出去，PRD处理使根生物量增加了55%。在可控环境箱中，经过两个PRD周期中的任何一个周期结束时，各处理间叶片水势无差异，但在第一个周期结束时，PRD处理植株的气孔导度比开始时降低了20%。在可控环境箱中经过两个PRD周期后，PRD处理植株与对照植株的生物量无差异，但PRD处理植株的根生物量比对照植株增加了19%。PRD处理植株根生物量的增加与干湿隔室的交替有关，在先前经历土壤干燥后重新浇水的隔室中根生物量增加。田间种植的PRD处理植株根生物量的增加可能使根系获取到对照植株无法获得的资源（水和养分）。这可能有助于PRD处理植株即使在供水量较少时仍能维持与传统灌溉植株相似的叶片水势。
