不同带长微喷带灌溉对土壤水分布与冬小麦耗水特性及产量的影响

于2010-2012年度冬小麦生长季,选用高产冬小麦品种济麦22,采用测墒补灌方式,设置40 m(T₄₀)、60 m(T₆₀)和80 m(T₈₀)3种带长的微喷带灌溉处理,研究不同带长微喷带灌溉对土壤水分分布及冬小麦耗水特性和产量的影响.结果表明： 拔节期和开花期采用微喷带补灌,随微喷带带长缩短,灌溉水在土壤中的水平分布均匀系数显著增加.拔节期补灌,T₄₀和T₆₀处理在距畦首0～40 m范围内各小麦行间的0～200 cm土层土壤含水量均无显著差异;T₈₀处理在距畦首38～40 m、58～60 m和78～80 m处各小麦行间的0～200 cm各土层土壤含水量变化规律一致,均表现为随距微喷带的距离增加而减小.T₄₀处理的小麦在拔节至开花期间和开花至成熟期间分别对40～60 cm和20～80 cm土层土壤贮水的消耗量显著高于T₆₀和T₈₀处理,而对深层土壤贮水消耗量和总土壤贮水消耗量、开花期补灌水量、总灌水量和总耗水量显著低于T₆₀和T₈₀处理.随微喷带带长缩短,小麦籽粒产量、产量水分利用效率显著升高,而流量降低,在灌水量一定的情况下,单位时间内的有效灌溉面积减小.综合考虑小麦籽粒产量、水分利用效率和流量,40和60 m是本试验条件下的适宜微喷带带长.     

不同畦长灌溉对小麦耗水特性及产量的影响

在2009-2010和2010-2011年小麦生长季,设置10、20、40、60、80和100 m 6个畦田长度,研究不同畦长对小麦耗水特性及产量的影响.结果表明： ≤80 m畦长处理下,随畦长的增加,灌水量逐渐增加,灌水量占总耗水量的比例增加,土壤贮水消耗量减少,小麦拔节至开花期的耗水量和生长季总耗水量均减少,开花期0～200 cm各土层土壤含水量增加,土壤供水能力提高,籽粒产量和水分利用效率逐渐提高.与80 m畦长处理相比,<80 m畦长处理的灌水量少,上层土壤含水量低,促使小麦吸收更多的深层贮水,总耗水量增加,不利于节水;而100 m畦长处理的灌水量、土壤贮水消耗量和总耗水量均增加,由于一次性灌水量过多且灌溉水分布不均匀,导致小麦千粒重降低,籽粒产量和水分利用效率显著下降,也不利于节水高产.     

不同土层测墒补灌对冬小麦耗水特性与光合速率和产量的影响

于2012—2014年两个冬小麦生长季,在大田条件下设置：全生育期不灌水(W₀)处理,当地定量节水灌溉(拔节期和开花期均灌水60 mm,W₁)处理,依据0～20 cm (W₂)、0～40 cm (W₃)、0～60 cm (W₄)和0～140 cm (W₅)土层土壤含水量测墒补灌处理,于拔节期和开花期补灌至土壤相对含水量为田间持水量的65%和70%,研究依据不同土层土壤含水量测墒补灌对冬小麦耗水特性、光合速率和籽粒产量的影响.结果表明：各处理拔节期灌水量为W₁、W₄＞W₃＞W₂、W₅,开花期灌水量和总灌水量均为W₅＞W₁、W₄＞W₃＞W₂,W₃总耗水量显著高于W₂处理,与W₁、W₄和W₅处理无显著差异.W₃土壤贮水消耗量高于W₁、W₄和W₅处理,其中,W₃在拔节至开花阶段和开花至成熟阶段对40～140 cm和60～140 cm土层土壤贮水消耗量均显著高于其余灌水处理.灌浆中期W₃处理小麦旗叶光合速率、蒸腾速率和水分利用效率最高,W₁和W₄处理次之,W₀处理最低.W₃处理两个生长季的籽粒产量分别为9077和9260 kg·hm^-2,水分利用效率分别为20.7和20.9 kg·hm-2·mm^-1,均显著高于其余处理,灌溉水生产效率最高.综合考虑灌水量、籽粒产量和水分利用效率,小麦拔节期和开花期适宜进行测墒补灌的土层深度为0～40 cm.     

不同带长微喷带灌溉对麦田土壤水分分布和干物质积累及籽粒产量的影响

为了研究麦田用微喷带灌溉的适宜带长,2015—2016和2016—2017两年度以‘济麦22’为材料,设置了带宽80 mm微喷带下带长为60 m (T₁)、80 m (T₂)和100 m (T₃) 3个处理的试验,试验小区长度等于带长,试验小区内沿灌溉方向每20 m为一个取样区段,依次命名为A、B、C、D、E,分析不同带长微喷带灌溉对麦田土壤水分和干物质积累的影响.结果表明:1)两年度不同处理A区段拔节期、开花期灌水后0~40 cm土层土壤相对含水量为T₁23,B区段为T₁、T₂3,C区段为T₁>T₂、T₃,D区段为T₂>T₃;各处理区段间土壤相对含水量的变异系数为T₁23.2)不同处理A、B区段小麦开花后20、30 d的叶面积指数和冠层光截获率、开花后干物质积累量、成熟期干物质积累量均无显著差异,C区段上述指标为T₁>T₂、T₃,D区段为T₂>T₃;不同处理开花后20、30 d叶面积指数、冠层光截获率及开花后干物质积累量为T₁>T₂>T₃,成熟期干物质积累量为T₁、T₂>T₃.3)不同处理A、B区段籽粒产量均无显著差异,C区段为T₁>T₂、T₃,D区段为T₂>T₃,整畦籽粒产量为T₁、T₂>T₃.4)两年度不同处理籽粒产量、水分利用效率为T₁、T₂>T₃,灌溉水利用效率为T₁>T₂>T₃.综合考虑籽粒产量和水分利用效率,本试验条件下带宽80 mm、带长60 m的处理(T₁)是节水高产的最优处理,带长为80 m的处理(T₂)是较优处理.研究结果可为山东省小麦利用微喷带进行节水高产灌溉提供理论依据.     

不同施氮水平下灌水量对小麦水分利用特征和产量的影响

在田间高产条件下,研究了不同施氮水平［180 kg·hm^-2（N₁₈₀）和240 kg·hm^-2（N₂₄₀）］下灌水量对小麦耗水特征和旗叶水分生理特性及产量的影响.结果表明：不灌水的W₀处理100 cm以下土层的土壤贮水消耗量低于各灌水处理,W₁（灌底墒水60 mm）和W₂（灌底墒水和拔节水各60 mm）处理100～200 cm土层和0~200 cm土层土壤贮水消耗量高于W₃（灌底墒水、拔节水和开花水各60 mm）处理;N₂₄₀处理0～80 cm土层土壤贮水消耗量、开花至成熟阶段耗水模系数和农田耗水量高于N_180. W₂和W₃处理灌浆中后期旗叶相对含水量和水势高于W₀和W₁处理;灌浆后期旗叶相对含水量和水势为N₂₄₀W₀和N₂₄₀W₁处理分别高于N₁₈₀W₀和N₁₈₀W₁处理,N₂₄₀W₂和N₂₄₀W₃处理与N₁₈₀W₂和N₁₈₀W₃处理之间无显著差异.施氮180 kg·hm^-2,底墒水和拔节水分别灌60 mm的W₂处理籽粒产量、水分和氮素利用效率高,农田耗水量较低;增加灌水量,籽粒产量无显著变化,农田耗水量增高,土壤贮水消耗量、水分利用效率、灌溉水利用效率和灌溉效益降低.     

拔节期与开花期测墒补灌对小麦旗叶荧光特性和水分利用效率的影响

为研究依据不同土层的土壤质量含水量进行测墒补灌对小麦(Triticum aestivum)拔节期与开花期旗叶荧光特性和水分利用效率的影响, 2011-2012和2012-2013年度两个小麦生长季, 设置0-20 (D1)、0-40 (D2)、0-60 (D3)和0-140 cm (D4) 4个土层进行处理, 测定土壤质量含水量, 以各土层平均土壤相对含水量在拔节期为65%和在开花期为70%为目标相对含水量进行补灌, 全生育期不灌溉为对照(D0)。结果表明: (1) D2处理拔节至开花期40-100 cm土层和开花至成熟期40-140 cm土层的土壤贮水消耗量高于其他处理, 开花至成熟期是小麦贮水消耗的最大时期。(2)开花后旗叶水分利用效率、PSII潜在活性(F_v/F_o)、PSII电子传输活性(F_m/F_o)、相对电子传递速率(ETR)和光化学猝灭系数(q_P) D2处理最高, D3次之, D0最低。(3)两个小麦生长季, 各处理的籽粒产量为D2 > D3 > D1 > D4 > D0, D2的水分利用效率分别为20.19 kg·hm^-2·mm^-1和21.92 kg·hm^-2·mm^-1, 高于D0、D3和D4处理, 与D1处理间无显著差异。综合分析, 小麦拔节期和开花期依据0-40 cm土层的土壤质量含水量进行测墒补灌可兼顾高产和高水分利用效率。     

不同土层测墒补灌对冬小麦耗水特性及产量的影响

于2010-2011年选用高产小麦品种济麦22进行大田试验,设置0～20 cm（W₁）、0～40 cm（W₂）、0～60 cm（W₃）和0～140 cm（W₄）4个测墒补灌土层,于越冬期（目标相对含水量均为75%）、拔节期（目标相对含水量均为70%）和开花期（目标相对含水量均为70%）进行测墒补灌,以全生育期不灌水处理（W₀）为对照,研究不同土层测墒补灌对冬小麦耗水特性及产量的影响.结果表明： 小麦越冬期、拔节期和开花期补充灌水量为W₃>W₂>W₁,W₄处理小麦越冬期和拔节期补充灌水量较少,但开花期补灌量显著高于其他处理;全生育期补灌量占总耗水量的比例为W₄、W₃>W₂>W₁.土壤水消耗量占总耗水量的比例为W₁>W₂>W₃>W₄;随测墒补灌土层深度的增加,土壤水消耗量占总耗水量的比例减少;W₂处理80～140 cm和160～200 cm土层土壤水消耗量显著高于W₃和W₄处理.各处理的总补灌量为W₃>W₄>W₂>W₁;籽粒产量为W₂、W₃、W₄>W₁>W₀,W₂、W₃、W₄间无显著差异;水分利用效率为W₂、W₄>W₀、W₁>W₃,W₂与W₄之间无显著差异.综合考虑灌水量、籽粒产量和水分利用效率,W₂处理是本试验条件下的最佳处理,即以0～40 cm土层测墒补灌效果最优.     

关中灌区沟垄集雨种植补灌对冬小麦光合特征、产量及水分利用效率的影响

通过大田试验,研究了沟垄集雨种植结合不同补灌量处理对冬小麦光合器官、光合速率、产量和水分利用效率的影响.结果表明:沟垄宽度各为60 cm时,集雨种植不灌溉(T1)、返青期种植沟补灌375 m3·hm-2(T2)和种植沟补灌750 m3·hm-2(T3)3个处理较平作灌水750 m3·hm-2(畦灌,T4)处理的小麦籽粒产量分别提高2.8％、9.6％和18.9％,收获系数提高2.0％～ 8.5％,旗叶叶绿素含量提高41.9％ ～64.4％,整个生育期内0～ 40 cm土壤含水量增加了0.1％～4.6％;开花期和灌浆期的叶片光合速率分别较T4处理提高了22.3％～ 54.2％和-4.3％～67.2％,农田总水分利用效率较T4处理分别提高17.9％、10.4％和15.4％,比平作不灌水处理(CK)提高69.3％、58.6％和65.7％;降水利用效率较CK提高94.3％ ～ 124.5％;T2、T3处理各生育阶段叶面积均显著高于T4处理,灌溉水利用效率分别比T4处理提高119.1％和18.8％.在灌溉量减少50％的条件下,集雨种植比畦灌处理能维持较高的籽粒产量,显著提高灌溉水利用效率,尤其是在降雨量偏少的年份,可以显著提高小麦水分利用效率.     

黄土高原不同降水区休闲期土壤贮水效率及其对冬小麦水分利用的影响

土壤贮水是影响黄土高原冬小麦生产力的最重要因素,分析休闲期贮水效率对有效利用水资源具有重要意义。利用黄土高原旱作区4个农业气象观测站土壤水分长期观测资料和冬小麦产量资料,探讨了不同气候区休闲期土壤贮水和耗水特征及对冬小麦水分利用的影响。结果表明:(1)黄土高原旱作区休闲期1 m土层多年平均贮水量半湿润区为9 1mm,贮水效率为30.7%,半干旱区为32 mm,贮水效率为16.5%,且不同降水年型、不同气候区休闲期贮水量和贮水效率差别较大;(2)黄土高原旱作区1 m土层贮水量从土壤解冻至封冻期间基本呈波谷型分布,休闲期为主要贮水阶段,冬小麦返青—开花期为休闲期贮水的主要消耗阶段。半湿润区休闲期土壤贮水量主要消耗在起身至开花期,半干旱区主要消耗在越冬至拔节期;(3)黄土高原旱作区播种—越冬前消耗0—40 cm土层贮水,越冬-起身期各土层贮水量都有消耗,起身—开花期半湿润区主要消耗0—40 cm土层贮水量、半干旱区主要消耗0—60 cm土层贮水量,开花—成熟期半湿润区主要消耗40 mm以下土层贮水量、半干旱区主要消耗60 cm以下土层贮水量;(4)黄土高原休闲期贮水效率与冬小麦产量显著相关,半湿润区水分利用效率远高于半干旱区。黄土高原不同区域降水时空分布不均和土壤贮水能力的差异是造成不同气候区休闲期水分贮存差异的主要原因,通过调整耕作方式、水肥管理、种植结构进一步实现冬小麦增产和水分高效利用。     

旱地土壤铵态氮和硝态氮累积特征及其与小麦产量的关系

在陕西永寿和河南洛阳分别进行了11处和7处小麦大田试验,设对照(不施氮)和施氮(150 kg N·hm^-2)2个处理,测定了小麦生物量、籽粒产量及不同土层(0～20、20～40、40～60、60～80、80～100 cm)土壤铵态氮、硝态氮浓度.结果表明: 两地土壤铵态氮浓度均很低,而硝态氮浓度较高,其中硝态氮数量占铵态氮、硝态氮总量的91%,在反映土壤供氮特性方面与两者之和有完全一致趋势.不施氮情况下,永寿0～40、0～60、0～80和0～100 cm土层累积的硝态氮与小麦生物量和产量显著相关;而洛阳无显著相关关系.施氮后,永寿不同深度土层累积的硝态氮与小麦生物量和产量的相关关系显著下降,而洛阳出现负相关;两地小麦产量增量与0～80 和0～100 cm土层累积的硝态氮显著或极显著相关.小麦苗期主要依赖0～20 cm土层硝态氮;返青期、拔节期分别利用0～40 cm和0～60 cm土层硝态氮,成熟期则能利用0～100 cm土层累积硝态氮.小麦收获后对照土壤的铵态氮浓度与播前起始值无明显差异,而硝态氮大幅下降.     

Evaluation of methodology for detection of human adenoviruses in wastewater,drinking water,stream water and recreational waters

Aims: This study evaluates dialysis filtration and a range of PCR detection methods for identification and quantification of human adenoviruses in a range of environmental waters. Methods and Results: Adenovirus was concentrated from large volumes (50–200 l) of environmental and potable water by hollow fibre microfiltration using commercial dialysis filters. By this method, an acceptable recovery of a seeded control bacteriophage MS2 from seawater (median 95·5%, range 36–98%, n = 5), stream water (median 84·7%, range 23–94%, n = 5) and storm water (median 59·5%, range 6·3–112%, n = 5) was achieved. Adenovirus detection using integrated cell culture PCR (ICC‐PCR), direct PCR, nested PCR, real‐time quantitative PCR (qPCR) and adenovirus group F‐specific direct PCR was tested with PCR products sequenced for confirmation. Adenovirus was routinely detected from all water types by most methods, with ICC‐PCR more sensitive than direct‐nested PCR or qPCR. Group F adenovirus dominated in wastewater samples but was detected very infrequently in environmental waters. Conclusions and Implications: Human adenoviruses (HAdv) proved relatively common in environmental and potable waters when assessed using an efficient concentration method and sensitive detection method. ICC‐PCR proved most sensitive, could be used semiquantitatively and demonstrated virus infectivity but was time consuming and expensive. qPCR provided quantitative results but was c. ten‐fold less sensitive than the best methods.     

Oxygen consumption rates of tilapia in fresh water, sea water, and hypersaline sea water

Whole animal oxygen consumption rates and plasma constituents were determined in the tilapia O. mossambicus , acclimated for 1 month in fresh water, sea water, and 1·6 × sea water. Oxygen consumption rates for the three water salinities were: 177·2 ± 16·86, 78·6 ± 2·32, and 195·4 ± 15·39 mg O₂ kg⁻¹ h⁻¹ (means ± 1 s.e.), respectively. Plasma prolactin (tPRL₁₈₈) concentration was significantly lower in 1·6 × sea water compared to fresh and sea water. There were no significant differences among mean plasma cortisol concentration and lysozyme activity. Ventilation was significantly higher in fish in sea water compared to the fish in fresh and 1·6 × sea water. The lowest oxygen consumption rates were found in fish acclimated to sea water. That salinity is probably closest to the brackish waters from which they were captured in the wild, and this agreement likely reflects the selection for optimal morphological and physiological characteristics to live in that environment.     

Relationships between mercury in lake water,water colour and mercury in fish

The relationship between mercury content in fish (pike and perch), the different fractions of mercury in lake water and water color was investigated in 76, mainly oligotrophic lakes distributed over a large part of Sweden. The lakes were classified in terms of drainage area characteristics, lake morphometry and water chemistry. The dominant fraction of mercury in lake water was RIHg (fraction reducible to elemental mercury by NaBH₄). RIHg and water color were strongly positively correlated. Water color (determined by the comparative method using colored disks) was used as a surrogate for the amount of humic matter in the water. Thus, humic matter appears to be acting as an important carrier of mercury. A positive relationship between mercury content in fish and water color was found only in deep lakes (average depth > 5 m). It is suggested that the bioavailability of mercury attached to humic matter increases due to anoxic conditions, common in the hypolimnion of deep lakes.     

Foliar water uptake: Processes,pathways, and integration into plant water budgets

Nearly all plant families, represented across most major biomes, absorb water directly through their leaves. This phenomenon is commonly referred to as foliar water uptake. Recent studies have suggested that foliar water uptake provides a significant water subsidy that can influence both plant water and carbon balance across multiple spatial and temporal scales. Despite this, our mechanistic understanding of when, where, how, and to what end water is absorbed through leaf surfaces remains limited. We first review the evidence for the biophysical conditions necessary for foliar water uptake to occur, focusing on the plant and atmospheric water potentials necessary to create a gradient for water flow. We then consider the different pathways for uptake, as well as the potential fates of the water once inside the leaf. Given that one fate of water from foliar uptake is to increase leaf water potentials and contribute to the demands of transpiration, we also provide a quantitative synthesis of observed rates of change in leaf water potential and total fluxes of water into the leaf. Finally, we identify critical research themes that should be addressed to effectively incorporate foliar water uptake into traditional frameworks of plant water movement.     

北京市水足迹及农业用水结构变化特征

运用水足迹的理论和方法计算评价了1990—2005年北京市水足迹及水资源利用的可持续性,在此基础上进一步分析了北京市农业用水结构的变化特征。结果表明:(1)北京市水足迹从1990年的81.5亿m3上升至2005年的168.6亿m3,人均水足迹由750.1m3上升为1096.0m3;(2)北京市水资源匮乏度不断升高,1995年以来水资源自给率呈下降趋势,与之相对应的水资源依赖度越来越高;(3)农业部门用水量在本地用水量中的比例平均每年为55.1%,虚拟水净输入量在虚拟水净输入总量中的比例平均每年达到89.1%;(4)高耗水型作物产品生产用水比例升高加大了农业用水压力,动物产品生产用水量呈增加趋势,2001—2005年动物产品生产引入的虚拟水占到其虚拟水总量的81.3%。北京市水资源利用呈不可持续状态,通过农业系统内部结构的优化调整,实现农业部门水资源的高效利用是缓解北京市水资源紧缺问题的关键。     

高效净水细菌的分离鉴定及其净水能力分析

[目的]分离筛选获得能高效净化污水的净化细菌。[方法]利用氨氮降解筛选培养基对某污水处理厂的活性污泥进行净水细菌的分离筛选,并研究分离菌株对污水有机质、氨态氮、总磷与总氮含量的去除效果以及药敏性分析。[结果]比较去除效果,获得了1株最高效的净水细菌,该菌株对污水有机质、氨态氮、总氮与总磷均具有较强的净化效果,其去除率分别达58. 90%、65. 45%、51. 91%和35. 00%。结合菌落形态特征观察、生理生化分析及分子鉴定,鉴定该菌株为暹罗芽胞杆菌(Bacillus siamensis)。该菌株对7种常见抗生素均具有一定敏感性,其中对氨苄青霉素最敏感,卡那霉素次之,对庆大霉素最不敏感。[结论]分离筛选获得1株能高效净化污水的暹罗芽胞杆菌,对常见抗生素具有一定敏感性。     

A comprehensive analysis of blue water scarcity from the production,consumption, and water transfer perspectives

The issue of growing water scarcity has been increasingly perceived as a global systemic risk. To solve it, an integrated approach considering different perspectives of water scarcity is at a premise. In this study, we developed an approach to calculate the blue water scarcity (BWS) and integrated the production, consumption, and water transfer perspectives into a single framework. The results are as follows: The average BWS in the Hetao irrigation district was 0.491 during the 2001–2010 year period, which was much larger than the threshold of 0.30, indicating a high water stress level. From the production perspective, the agricultural sector was the largest contributor to regional water scarcity and the average BWS was as high as 0.479. From the consumption perspective, BWS related to virtual water export was much larger than that related to water consumption for making products to be consumed locally and the values were 0.422 and 0.069, respectively. Under the influence of physical and virtual water transfer, BWS changed from 0.242 (medium to high water stress level) to 0.491 (high water stress level). Strategies for reducing agricultural water consumption, such as increasing crop water productivity, improving irrigation efficiency, and promoting more reasonable irrigation water price, could be adopted in the Hetao irrigation district to alleviate regional BWS. Compared with physical and virtual water import, the virtual water export played a more important role in influencing the regional water scarcity, and the increase in crop water productivity, decrease in crop export volume, or adjustment of trade pattern from water-intensive crops to water-extensive ones could be feasible measures to decrease virtual water export for lower water stress, while the trade-offs in the product-consuming regions should be considered.     

中国水生态足迹广度、深度评价及空间格局

运用生态足迹方法对水资源进行流量资本和存量资本区分,测算分析了中国31个省市1997—2014年的水生态足迹广度与深度。结果显示:(1)中国的水生态足迹广度受年际水资源量丰枯影响,总体呈波动趋势;各省市的水生态足迹广度存在着明显差异,南方地区水生态足迹广度普遍大于北方地区;(2)研究期内,中国的水生态足迹深度只有1998年为1,其余年份的水资源流量资本已不能满足人类生产生活的需求,需要消耗水资源存量资本;各省市之间水生态足迹深度相差较大,整体上北方高南方低,其中14个省份18年的平均水生态足迹深度为1,平均水生态足迹深度最高的地区是宁夏的308.12;(3)运用空间自相关方法对31个省市的水生态足迹广度和深度进行分析得出,中国省际水生态足迹广度与深度均存在明显的空间集聚现象。水生态足迹广度H-H集聚地区主要集中在中国南方地区,水生态足迹深度H-H集聚地区主要集中在中国北方地区。通过对全国水生态足迹广度与深度的测度分析为水生态足迹分析提供新的研究方法,同时也为区域水资源可持续利用提供理论依据。     

Relations between water content, potential and permeability in stems of conifers

Abstract. The influence of sapwood water content on the conductivity of sapwood to water was measured on stem sections of Pinus contorta. A reduction in relative water content from 100 to 90% caused permeability to fall to about 10% of the saturated value.
Pressure–volume curves of branchwood and stem sapwood of Pinus contorta and Picea sitchensis have been analysed to definè the tissue capacitance and the time constant and resistance for water movement between stored water and the functional xylem as functions of tissue water potential. Three phases in water loss were discernible. In the initial phase at high water potentials (> –0.5 MPa), the capacitance was large, the time constant long and the resistance to flow large in comparison with intermediate water potentials (−0.5 to −1.5 MPa). At still lower water potentials (−1.5 to −3.0 MPa), the time constant and resistance declined still further but the capacitance had a tendency to increase again, especially in the stemwood of Sitka spruce. Typical values in the second phase were for the time constant 5 s, for the resistance 4 × 10⁻¹³ N s m⁻⁵ and for the capacitance (change in relative water content per unit change in potential) 1×10⁻¹¹ m³ Pa⁻¹. These parameters define the availability of stored water and are being used in a dynamic model of water transport in trees.