Conservative Water Use Research Articles

What Causes Heterogeneous Responses to Social Comparison Messages for Water Conservation?

Social comparisons for water conservation are often implemented in conjunction with a broader set of drought management policies. We investigate the interaction of social comparisons with prior responses to voluntary appeals for water conservation using a large-scale field experiment in Reno, Nevada. We develop a new social comparison framed as performance toward a conservation goal in contrast to the traditional comparison made in gallons. Our new social comparison decouples the performance relative to the peer group from baseline water use, allowing us to investigate the role of the peer comparison independently from baseline water use. Using a traditional and our new social comparison, we investigate prior conservation and baseline water use as drivers of heterogeneous response to social comparisons. Baseline water drives treatment heterogeneity in the traditional social comparison, while prior conservation drives treatment heterogeneity the new social comparison. The results indicate that under-performance relative one’s peers is critical for generating water conservation. Simple targeting of both types of social comparisons can increase aggregate savings by 38% because our new social comparison generates conservation among a different set of households compared to the traditional social comparison.

Variability in physiological responses of Venezuelan cacao to drought

AbstractIn order to assess the response of cocoa trees to drought, changes in water status, gas exchange, leaf carbon isotopic ratio (δ13C), photochemical activity, and leaf N and chlorophyll content during the rainy and dry season were measured in 31 Venezuelan cocoa clones (17 Trinitarios, 6 Criollos, and 8 Modern Criollos) grown in a common garden. Drought caused a 40% decrease in water potential (ψ) in all but the Modern Criollos, and a reduction in net photosynthetic rate (A) and stomatal conductance (gs) without an increase in instantaneous water use efficiency (WUE) in 93% of clones, and an increase inδ13C (long-term WUE) in 74% of clones; these responses suggest differences in tolerance to drought among clones. A positive correlation betweenAand bothgsand leaf N content was found for all genotypes. Leaf N content, chlorophyll content, and photochemical activity were reduced during drought, suggesting that metabolism was also inhibited. The best performance during drought was shown by Modern Criollos with the highest WUE, while five Trinitario clones seemed to be less sensitive to drought, since neither chlorophyll, N, total soluble protein concentration, norgschanged with drought, indicating that those Trinitario clones, with lowerA, have a conservative water use. Modern Criollos showed no reductions in eitherψorgs;Aremained unchanged, as did WUE, which was the highest, suggesting that these clones would be more successful in environments with low water availability. Our results indicate large variation in physiological response to drought over a range of parameters, suggesting possible differences in tolerance among clones.

Grafting cv. Grechetto Gentile Vines to New M4 Rootstock Improves Leaf Gas Exchange and Water Status as Compared to Commercial 1103P Rootstock

M4 is a relatively new rootstock that was selected for increased resilience of vineyards across hot regions where meteorological drought is often coupled to water scarcity. However, M4 has thus far been tested only against water-stress sensitive rootstocks. Against this backdrop, the aim of the present work is to examine the water status and gas exchange performances of vines grafted to M4 in comparison to those of vines grafted to a commercial stock that is drought-tolerant, 1103 Paulsen (1103P), under a progressive water deficit followed by re-watering. This study was undertaken on Grechetto Gentile, a cultivar that is renowned for its rather conservative water use (near-isohydric behavior). While fifty percent of both grafts were fully irrigated (WW), the remaining underwent progressive water stress by means of suspending irrigation (WS). Soil and leaf water status, as well as leaf gas exchanges, along with chlorophyll fluorescence, were followed daily from 1 day pre-stress (DOY 176) until re-watering (DOY 184). Final leaf area per vine, divided in main and lateral contribution, was also assessed. While 1103P grafted vines manifested higher water use under WW conditions, progressive stress evidenced a faster water depletion by 1103P, which also maintained slightly more negative midday leaf water potential (Ψleaf) as compared to M4 grafted plants. Daily gas exchange readings, as well as diurnal assessment performed at the peak of stress (DOY 183), also showed increased leaf assimilation rates (A) and water use efficiency (WUE) in vines grafted on M4, which were also less susceptible to photosynthetic downregulation. Dynamic of stomatal closure targeted at 90% reduction of leaf stomatal conductance showed a similar behavior among rootstocks since the above threshold was reached by both at Ψleaf of about −1.11 MPa. The same fractional reduction in leaf A was reached by vines grafted on M4 at a Ψleaf of −1.28 MPa vs. −1.10 MPa measured in 1103P, meaning that using M4 as a rootstock will postpone full stomatal closure. While mechanisms involved in improved CO2 uptake in M4-grafted vines under moderate-to-severe stress are still unclear, our data support the hypothesis that M4 might outscore the performance of a commercial drought-tolerant genotype (1103P) and can be profitably used as a tool to improve the resilience of vines to summer drought.

Drought Hardening Contributes to the Maintenance of Proportions of Non-Embolized Xylem and Cambium Status during Consecutive Dry Treatment in Container-Grown Seedling of Japanese Cedar (Cryptomeria japonica)

Climate models in Japan predict that the annual mean air temperature and number of consecutive dry days will increase in the future, leading to high seedling mortality rates. Maintaining high survival rates of Cryptomeria japonica seedlings, a commercially important tree species, is therefore, important in terms of appropriate forest management under climate change. Although drought hardening, in which seedlings are acclimated to dry conditions in the nursery prior to planting, contributes to increased survival under drought conditions, little is known about the effective irrigation frequency of drought hardening in C. japonica seedlings. In this study, we therefore, examine the effectiveness of different drought-hardening treatments in C. japonica. We first clarify the effects on physiological and morphological traits by comparing three drought-hardening treatments [control (C): Irrigation once daily; mild (M): irrigation once every three days; and severe (S): irrigation once every five days] for one month. Next, to confirm the effects during consecutive dry treatment, we stopped irrigation for 13 days and once again compared the physiological traits between the three drought-hardening treatments. Drought hardening reduced whole-plant transpiration (Ewhole), resulting in conserved water use, and this tendency was particularly evident under the S treatment. Moreover, during consecutive dry treatment, the Ewhole, proportions of non-embolized xylem, and cambium status of basal stem regions were maintained for the longest duration under the S treatment, followed by the M treatment. Our findings suggest that the efficiency of drought hardening increased with drought severity. Furthermore, one month of drought hardening contributed to both water conservation and the maintenance of cell differentiation under consecutive dry treatment, likely increasing the tolerance and survival of C. japonica seedlings under prolonged drought.

The sequence and thresholds of leaf hydraulic traits underlying grapevine varietal differences in drought tolerance.

Adapting agriculture to climate change is driving the need for the selection and breeding of drought-tolerant crops. The aim of this study was to identify key drought tolerance traits and determine the sequence of their water potential thresholds across three grapevine cultivars with contrasting water use behaviors, Grenache, Syrah, and Semillon. We quantified differences in water use between cultivars and combined this with the determination of other leaf-level traits (e.g. leaf turgor loss point, π TLP), leaf vulnerability to embolism (P50), and the hydraulic safety margin (HSM P50). Semillon exhibited the highest maximum transpiration (Emax), and lowest sensitivity of canopy stomatal conductance (Gc) to vapor pressure deficit (VPD), followed by Syrah and Grenache. Increasing Emax was correlated with more negative water potential at which stomata close (Pgs90), π TLP, and P50, suggesting that increasing water use is associated with hydraulic traits allowing gas exchange under more negative water potentials. Nevertheless, all the cultivars closed their stomata prior to leaf embolism formation. Modeling simulations demonstrated that despite a narrower HSM, Grenache takes longer to reach thresholds of hydraulic failure due to its conservative water use. This study demonstrates that the relationships between leaf hydraulic traits are complex and interactive, stressing the importance of integrating multiple traits in characterizing drought tolerance.

Estimation of Water Demand and Alternative Water Resources in Patra Jasa Building Year 2020-2025

The development of the capital city is very rapidly this will cause water demand will continue to increase along with the rate of population growth, all fulfillment of food needs, and activity of the population closely related to the needs of water. This research aims to determine the total number of water needs required by the Patra Jasa building in the years 2020-2025 and to conserve water use and costs with the presence of alternative water sources. This study used the research method of case study approaches with the accumulation of primary data and secondary data, subsequent analysis of the availability and water needs, and replaced with alternative water sources. From the results of this study, the consumption of clean water 63838.5 m3, non-consumptive water per year 46681 M3 with details of flushing needs 36500 m3, watering 6351 m3, and cooling tower 3650 M3. The potential of source research-alternative water sources as in this is a source of rainwater that can be used to meet the daily needs of the building of 879.38 m3/day so that it can cover all the needs of non-consumptive water. FRP tank design used is FRP tank 1200 m3 with a method of rain supply that can be harvested from the roof of Patra Jasa building is 320973.7 m3/year and the average requirement is 174.9 m3/day, 5274 m3/month, 63838.5 m3/year. Annual water uses savings of 57835.71 m3/year or Rp. 725,880,160.00.

Environmental and canopy stomatal control on ecosystem water use efficiency in a riparian poplar plantation

Ecosystem water use efficiency (EWUE), defined as the ratio of ecosystem gross primary production (GPP) and evapotranspiration (ET), is regulated by multiple biophysical factors and their interactions. One particular unknown is the relative importance of environmental control and canopy stomatal control on EWUE for their direct and indirect roles in different seasons. We employed the eddy covariance technique and micrometeorological sensors to measure the carbon and water fluxes and environmental variables over a riparian poplar plantation in northern China from 2014 to 2017. We found that canopy conductance (Gc) was the dominant factor regulating EWUE in spring and autumn, while the fraction of diffuse radiation (FDR) was the primary controlling variable in summer. During the growing season, FDR depressed ET and promoted GPP primarily through its direct role rather than indirectly affecting other environmental factors. This plantation could utilize diffuse radiation efficiently by regulating stomatal function when FDR was lower than 0.6. More importantly, the stomatal optimization theory worked merely under certain conditions (i.e., VPD ≤ 3 kPa). Correspondingly, the poplar plantation tended to show less conservative water use strategy with decreasing surface soil water content (SWC) when the non-stomatal function was dominant. Our study highlighted the importance of FDR and Gc on EWUE and the potential of future water resource impact resulting from extensive poplar plantation establishment in northern China.

Shared drought responses among conifer species in the middle Siberian taiga are uncoupled from their contrasting water-use efficiency trajectories

A shift from temperature-limited to water-limited tree performance is occurring at around 60°N latitude across the circumboreal biome, in concord with current warming trends. This shift is likely to induce extensive vegetation changes and forest die-back, and also to exacerbate biotic outbreaks and wildfires, affecting the global carbon budget. We used carbon isotope discrimination (Δ13C) in tree rings to analyze the long-term physiological responses of five representative species that coexist in the middle taiga of Western Siberia, including dark-needled, drought-susceptible (Abies sibirica, Picea obovata, Pinus sibirica) and light-needled, drought-resistant (Larix sibirica, Pinus sylvestris) conifers. We hypothesized that droughts are differentially imprinted in dark and light conifers, with stronger Δ13C-responsiveness in the latter reflecting a more conservative water use. We found similar Δ13C-climate relationships related to the moisture regime of the summer season across species, indicating shared drought responses; however, divergent intrinsic water-use efficiency (WUEi) trajectories from 1950 to 2013 were observed for pines (increasing by ca. 10%) and other conifers (increasing by ca. 25%). These contrasting patterns suggested the passive and active stomatal regulation of gas exchange in these trees, respectively, and led us to discard our initial hypothesis. Discriminant analysis shed light on the climate characteristics responsible for such differential behavior, with years having lower temperatures from May through August (3 °C colder on average) being responsible for reduced pine WUEi. This finding may be related to the higher plasticity of phenology of pines and the greater susceptibility of fir and spruce to cold damage and heat shock during the early growing season (late April–May). Together with recent negative growth trends and increasing ring-width vs. Δ13C coupling, these results indicate the greater susceptibility of spruce and fir, compared with pines and larch, in boreal ecosystems when transitioning from a temperature- to a moisture-sensitive regime.

Switching of dominant positions between two sand‐fixing shrub species during the dune revegetation process is underlain by their contrasting xylem hydraulics and water‐use strategies

AbstractDifferences in key physiological characteristics between plant species can result in their contrasting performances in vegetation restoration projects, but ecophysiological comparative studies in close relation to ecological restoration projects are scarce. Hedysarum fruticosum Pall. and Caragana microphylla Lam. are two leguminous shrub species widely used in combination for fixation of active sand dunes in semiarid regions of northern China, but they clearly differ in fitness at different stages of dune vegetation development; that is, H. fruticosum quickly gains a community dominance at the initial stage but yields to C. microphylla in a few years after the fixation of dunes. To reveal the underlying mechanism of such a pattern, key physiological characteristics related to xylem water transport, leaf water use, and drought tolerance were compared between these two species at a typical site of sand dune fixation project in Inner Mongolia. Compared with C. microphylla, H. fruticosum shows an acquisitive and risky water management strategy with substantially higher hydraulic efficiency and photosynthetic capability but reduced resistance to drought‐induced xylem embolism, which endows it an advantage under conditions of relatively high soil water availability at the early stage of dune fixation. In contrast, C. microphylla exhibits more conservative water use and characteristics of greater drought tolerance, which results in greater dominance under the more drought‐stressed conditions of the later stage of dune fixation. Our study for the first time provides a potential mechanistic explanation for the clear switching of dominant positions between the two important sand‐fixing shrub species during the sand dune revegetation process.

Contrasts in xylem hydraulics and water use underlie the sorting of different sand-fixing shrub species to early and late stages of dune stabilization

Dominating sand-fixing shrubs play crucial roles in the stabilization and rehabilitation of sand dunes. Different sand-fixing shrub species often separate along the temporal-spatial environmental gradient during the sand dune stabilization process; however, the physiological mechanisms underlying such a separation remain poorly understood, which limits our ability to identify the causes of land desertification and the cruxes of rehabilitation. We investigated xylem hydraulics and water use characteristics of four important shrub species used for sand dune fixation projects in northern China that show distinct preferences to different stages of dune stabilization, i.e. two species succeed in active dunes and the other two in fixed dunes. The major aim was to examine the roles of xylem hydraulics, water use and the coordination of these two aspects in determining the habitat preferences of sand-fixing shrubs along the process of dune stabilization in water-limited environments. The two active-dune species consistently exhibited higher stem hydraulic conductivity but lower resistance to drought-induced xylem embolism than the two fixed-dune species, which reflects contrasting requirements to shrub hydraulic functionality in sand dunes of the two successional stages that differ substantially in soil water regimes. In coordination with contrasts in hydraulics, they also diverged clearly in water use strategies with the fixed-dune shrubs showing more conservative water use. Our results highlight the critical roles that hydraulics and water utilization play in determining the adaptation of dominating sand-fixing shrub species to their respective environments shaped by the plant-soil interactions during sand dune vegetation development.

Physiological responses and aquaporin expression upon drought and osmotic stress in a conservative vs prodigal Fragaria x ananassa cultivar

In order to improve the understanding of plant water relations under drought stress, the water use behavior of two Fragaria x ananassa Duch. cultivars, contrasting in their drought stress phenotype, is identified. Under drought, stomatal closure is gradual in Figaro. Based on this, we associate Figaro with conservative water use behavior. Contrarily, drought stress causes a sudden and steep decrease in stomatal conductance in Flair, leading to the identification of Flair as a prodigal water use behavior cultivar. Responses to progressive drought on the one hand and an osmotic shock on the other hand are compared between these two cultivars. Tonoplast intrinsic protein mRNA levels are shown to be upregulated under progressive drought in the roots of Figaro only. Otherwise, aquaporin expression upon drought or osmotic stress is similar between both cultivars, i.e. plasma membrane intrinsic proteins are downregulated under progressive drought in leaves and under short term osmotic shock in roots. In response to osmotic shock, root hydraulic conductivity did not change significantly and stomatal closure is equal in both cultivars. De novo abscisic acid biosynthesis is upregulated in the roots of both cultivars under progressive drought.

An integrated overview of physiological and biochemical responses of Celtis australis to drought stress

Trees in Mediterranean areas frequently face severe drought stress events, due to sudden decreases in soil water availability associated to intense heat waves. The knowledge of strategies adopted by plants to cope with the environmental pressures associated to Mediterranean climate is crucial for reforestation strategies and planning future urban greening. Here we investigated the physiological and biochemical adjustments activated by Celtis australis in response to drought stress during summer. Despite widely used for reforestation in Southern Mediterranean, how C. australis responds to the severe challenges imposed by Mediterranean climate has not investigated yet. In our study, we performed analyses of water relations, gas exchange and PSII performance, the concentration of photosynthetic pigments, the activity and the concentration of primary antioxidants in plants exposed to drought stress of increasing severity. Data of our study reveal that C. australis displays both conservative water use and isohydric behavior in response to drought, and diffusive resistance mostly limits photosynthesis even at severe drought. Our study also reveals an effective down-regulation rather than permanent impairment of PSII photochemistry in response to drought stress of increasing severity, since excess electron transport due to declines in photosynthesis (-61% at severe stress, compared to control) was matched by an increase in nonphotochemical quenching (+71% at severe stress, compared to control). However, our study highlights that under severe drought, zeaxanthin (and neoxanthin) increased by 75% (and 25%), likely served an important function as chloroplast antioxidant, other than sustaining nonphotochemical quenching. Antioxidant enzymes and ascorbate also increased (+132% on average for superoxide dismutase, ascorbate peroxidase, and catalase) and contributed in countering oxidative stress in severely droughted plants. Large adjustments in the suite of physiological and biochemical traits may effectively enable C. australis to gain carbon at appreciable rates while avoiding irreversible damage to the photosynthetic apparatus even when challenged by severe drought stress, thereby making this species an excellent candidate for forest and urban plantings in sites experiencing extended periods of drought stress.

Toward a New Use for Carbon Isotope Discrimination in Wheat Breeding

A major obstacle in the effort to develop drought tolerant varieties of wheat (Triticum aestivum L.) is phenotyping. Traits known to contribute to improved drought tolerance, such as water-use behavior, reliance on stem reserve carbohydrates, and the ability to develop deep roots, require time and resource-intensive screening techniques. Plant breeding programs often have many thousands of experimental genotypes, which makes testing for each of these traits impractical. This work proposes that carbon isotope discrimination (∆) analysis of mature grains may serve as a relatively high-throughput approach to identify genotypes exhibiting traits associated with drought tolerance. Using ∆ as a proxy for stomatal conductance and photosynthetic capacity, assumptions can be made regarding fundamental plant physiological responses. When combined with knowledge of the terminal drought severity experienced in a particular environment, genotypes exhibiting conservative and rapid water use, deep roots, and reliance on stem reserve carbohydrates may be identified. Preliminary data in support of this idea are presented. Further verification of this use for grain ∆ will better equip wheat breeding programs to develop more drought tolerant varieties.

Land and Water Usage in Beef Production Systems.

Simple SummaryConsumers increasingly demand sustainable food production, including using world resources efficiently, avoiding environmental damage and ensuring good welfare of animals. Reports have suggested that beef production is costly in relation to world resource use and greenhouse gas production, so some consumers avoid beef. However, many reports refer mainly to feedlot systems. Ruminants can eat leaves that humans cannot eat, so if they are not fed grain, systems can be sustainable and valuable. This paper presents an analysis of the production of beef comparing all aspects of the use of land and conserved water for four production systems. It is suggested that conserved water use is a useful measure. Land use was the highest in extensive unmodified pasture systems, especially if the land became degraded. Less land was used in both feedlot and fertilised pasture systems and much less in semi-intensive silvopastoral systems. Conserved water use was the highest in feedlot systems, partly because of the grain fed to the cattle, lower in pasture systems and lowest in semi-intensive silvopastoral systems. This research indicates that, when beef production systems are being selected or consumers are deciding which beef to buy, extensive systems that degrade the land should be avoided, and well-managed extensive systems, especially semi-intensive silvopastoral systems, should be preferred to feedlot systems.This analysis, using published data, compared all land and conserved water use in four beef production systems. A widespread feedlot system and fertilised irrigated pasture systems used similar amounts of land. However, extensive unmodified pasture systems used three times more land, and semi-intensive silvopastoral systems used four times less land, so the highest use was 13 times the lowest. The amount of conserved water used was 64% higher in feedlots with relatively intensive rearing systems than in fertilised irrigated pasture; in extensive unmodified pasture systems, it was 38% and in semi-intensive silvopastoral systems, it was 21% of the fertilised irrigated pasture value, so the highest use was eight times the lowest. If there was no irrigation of pasture or of plants used for cattle feed, the feedlot water use was 12% higher than the fertilised pasture use and 57% higher than that in semi-intensive silvopastoral systems. These large effects of systems on resource use indicate the need to consider all systems when referring to the impact of beef or other products on the global environment. Whilst the use of animals as human food should be reduced, herbivorous animals that consume food that humans cannot eat and are kept using sustainable systems are important for the future use of world resources.

Can the turgor loss point be used to assess drought response to select plants for green roofs in hot and dry climates?

Green roofs are important novel urban ecosystems, but their shallow substrates can create plant water deficits in dry climates. Physiological approaches can improve green roof plant selection, and shrubs with high drought tolerance and conservative water use under water-deficit should perform well. The water potential at turgor loss point (Ψtlp) has been used to predict drought resistance. Therefore we aimed to determine whether Ψtlp could be used as a screening tool to assess drought resistance for green roof plant selection. We evaluated 20 shrub species, originating from ecosystems varying in water availability, quantified by heat moisture index (HMI) and mean annual precipitation. We conducted a water-deficit experiment to measure Ψtlp, the degree of iso-anisohydry (△ΨMD) and water use (ET) in response to drought. Shrubs with lower Ψtlp were more anisohydric (greater △ΨMD) and had a more conservative water use (lower ET). However, Ψtlp, ΔΨMD and ET were not related to HMI. These results suggest that Ψtlp could be used to select shrubs for green roofs, as species with lower Ψtlp tended to be more drought tolerant, more anisohydric and used less water under water-deficit. However, species with higher Ψtlp could also potentially survive through drought avoidance.

Water source identification for plants growing on karst rock outcrops based on rainfall-exclusion experiment.

Although lack of soil coverage, rock outcrops with developed fractures in karst region can maintain water consumption of plants with different life forms. Water sources for plants on these habi-tats are unclear. Isolated rocky outcrop with relatively simple sources of water was selected for this study. We focused on typical plant species that still thrived after excluding rainfall (removing the water supply to the shallow water) over one year, compared with the same plant species living without rain shelter (always receiving rainfall supplies). Water sources of three representative tree species (Radermachera sinica, Celtis biondii, and Pittosporum tonkinense) were analyzed by using stable isotope techniques and combining with the measurement of plant water potential. The results showed that all the three species depended on deep water sources with similar isotopic values to spring water under rain-sheltered condition, during the rainy season, which explained why plants could still grow normally after rainfall-exclusion over one year. The predawn water potential of R. sinica and P. tonkinense under rain-sheltered condition was not significantly different from those living in natural conditions, which indicated both species were not under water stress. The predawn water potential of C. biondii under rain-sheltered condition was significantly lower than individuals living in natural conditions, which indicated it was under water stress. Under natural condition, water isotope values of stems of all the three species were significantly lower than that under rain-sheltered condition and were within the range of fluctuation of recent rainwater isotope values, indicating that these plants relied on shallow water sources that dominated by recent rainfall. Under both rain-sheltered and natural conditions, there was no obvious difference between the predawn water potential and the midday water potential of P. tonkinense, showing a conservative water use strategy. The midday water potential of other two species was significantly lower than the predawn water potential, showing a profligate/opportunistic water use strategy. Our results indicated that the ability to utilize shallow and deep water sources is key for the plants growing on the habitat of Karst rock outcrops where they could adapt different water environments and maintain diversified water use strategies under the condition with no soil coverage.

Limited-transpiration rate under high atmospheric vapour pressure deficit: a trait for developing genotypes for water-deficit conditions.

Abstract Water deficits are the major limitation in increasing crop yields in many regions of the world. Various plant traits that might result in yield increases in water-limited environments have been discussed for decades. Conservative use of soil water is an important breeding strategy in drought-prone environments that can be achieved by traits based on partial stomatal closure under specific environmental conditions to limit transpiration rate (TR). The focus of this review is on a specific trait for conservative soil water that results in partial stomatal closure that can be supported by a plant. This limit on TR is expressed in terms of the atmospheric vapour pressure deficit (VPD) at which partial stomatal closure occurs. The review provides the physiological background of partial stomatal closure under elevated VPD. Simulation studies that analyse the potential benefits of this trait are also discussed. Finally, we provide a review of the various research that has been made in the identification of genetic variability of this trait in major crops.

Promoting consumer adoption of water-efficient washing machines in China: Barriers and countermeasures

The increasing popularity of water-efficient appliances is vital for water conservation. However, only few studies have investigated the purchasing behaviour of consumers and its influencing factors, particularly the use of water-saving washing machines (h-axis cloth washers). In this study, we analysed the effects of individual characteristics (e.g. knowledge, attitude and information source), selection criteria and selling points on the purchase of h-axis cloth washers and distinguished the buyers of h-axis cloth washers from those of conventional washing machines (v-axis cloth washers) by conducting a detailed survey of 321 consumers in four cities of northern China. We then evaluated data via one-way ANOVA and binary logistic regression. The choice of a consumer to purchase h-axis cloth washers was positively associated with his/her education, income and water conservation awareness, the energy and water use efficiency of the product and the popularisation of e-commerce and manufacturer websites. High price, information opacity, perceived negative benefits and ineffective communication were identified as the main barriers for selecting h-axis cloth washers. Public programs for promoting the purchase of h-axis cloth washers need to enhance information transparency and effectively communicate the benefits and costs of buying these appliances. Community-based education, salesman supervision, information transparency of water and electricity bills and cloth washer labels are also recommended.

Effects of varying soil and atmospheric water deficit on water use characteristics of tropical street tree species

Urban trees provide several ecosystem services, yet they are less studied compared to trees in natural ecosystems. Investigating ecophysiological responses of different tree species to seasonal conditions and drought will help determine which would succeed in urban conditions. Here, we examined water use characteristics of common species in Bangkok, Thailand: Pterocarpus indicus (Pi), Swietenia macrophylla (Sm) and Lagerstroemia speciosa (Ls), with different phenology, under seasonal variations and soil drying. Thirty small trees were potted and irrigated to ≥80% of the field capacity (θFC) of the soil. Granier-type sensors were used to measure sap flux density from 23 August to 18 December 2017. Drought treatments were imposed on five trees of each species by withholding irrigation until θ reached ∼50% θFC. Results suggested that water use patterns of semi-evergreen and evergreen species (Pi and Sm) were not sensitive to either seasonal or soil moisture variations while deciduous species (Ls) exhibited decreased water use and earlier stomatal closure upon soil drying in the dry season. These findings suggested that water use characteristics of the evergreen species may conserve water use regardless of atmospheric and soil moisture conditions while those of the deciduous species may result in high cost for irrigation in the wet season. Nevertheless, we believe that both evergreen and deciduous species may be selected for planting to maximize greening areas in cities throughout the year. However, knowledge of different water use characteristics of street tree species should be applied to devise strategic planning for optimized irrigation in urban greening.

Light spectral and thermal properties govern biomass allocation in tomato through morphological and physiological changes

We investigated the effects of light spectral and thermal properties on biomass allocation among vegetative and reproductive structures in tomato (Solanum lycopersicum L. ‘Merlice’) plants during growth and development and to determine its underlying mechanisms. Plants were grown in a greenhouse under a DLI of 3.4 mol m2 day−1 with/without supplemental lighting and a 16-h photoperiod, provided at equal photosynthetic photon flux density (PPFD of 230 μmol m‒2 s‒1 either from overhead high-pressure sodium (HPS) lamps or intracanopy light-emitting diode (LED) arrays: red light alone (R100; 100% of photosynthetically active radiation (%PAR)), red plus low far-red (R100+FR21), red plus high far-red (R100+FR41), and red plus blue (R61+B39). Supplemental lighting substantially increased total biomass and fruit yield, but to a greater extent by LED lighting regardless of spectrum. However, spectral contribution to leaf morphological traits and biomass allocation pattern varied greatly among the light treatments. HPS-supplemented plants had higher leaf temperature, photosynthetic rate (Pn), and transpiration rate (E) in the upper foliar canopy (161 to 240 cm from the base of the shoot) and contained higher water content in all tissues, particularly in roots by 2-fold, compared to LED-supplemented plants. They also had thinner, smaller leaves and allocated a higher fraction of total biomass to vegetative tissues, demonstrating their allocation strategies for effective transpiration and heat dissipation. Meanwhile, LED-supplemented plants allocated biomass preferentially to reproductive structures at the expense of vegetative tissues. Inclusion of higher FR or B with R light decreased leaf biomass fraction relative to total biomass but increased leaf dry mass and leaf thickness. Particularly, supplemental FR light significantly lowered the water content of leaves and fruits compared to B light. Long-term exposure of tomato plants to low R:FR was associated with reductions in leaf area, chlorophyll content, and vegetative shoot biomass fraction, increases in leaf thickness and fruit biomass, and acceleration of flowering and fruiting. Light-induced biomass allocation changed between vegetative and reproductive structures during plant growth and development. FR light had the most pronounced effect in this regard by significantly shifting dry-mass accumulation to fruits, via more efficient photosynthetic mechanisms and conserved water use. We conclude that light spectral and thermal properties affect biomass allocation among plant parts during tomato growth and development, and such responses involve morphological and physiological changes in tomato plants, ultimately affecting crop performance and yield.