Low Water Availability Research Articles

Biological Soil Crusts as Ecosystem Engineers in Antarctic Ecosystem.

Biological soil crusts (BSC) are considered as pivotal ecological elements among different ecosystems of the world. The effects of these BSC at the micro-site scale have been related to the development of diverse plant species that, otherwise, might be strongly limited by the harsh abiotic conditions found in environments with low water availability. Here, we describe for the first time the bacterial composition of BSCs found in the proximities of Admiralty Bay (Maritime Antarctica) through 16S metabarcoding. In addition, we evaluated their effect on soils (nutrient levels, enzymatic activity, and water retention), and on the fitness and performance of Colobanthus quitensis, one of the two native Antarctic vascular plants. This was achieved by comparing the photochemical performance, foliar nutrient, biomass, and reproductive investment between C. quitensis plants growing with or without the influence of BSC. Our results revealed a high diversity of prokaryotes present in these soil communities, although we found differences in terms of their abundances. We also found that the presence of BSCs is linked to a significant increase in soils’ water retention, nutrient levels, and enzymatic activity when comparing with control soils (without BSCs). In the case of C. quitensis, we found that measured ecophysiological performance parameters were significantly higher on plants growing in association with BSCs. Taken together, our results suggest that BSCs in Antarctic soils are playing a key role in various biochemical processes involved in soil development, while also having a positive effect on the accompanying vascular flora. Therefore, BSCs would be effectively acting as ecosystem engineers for the terrestrial Antarctic ecosystem.

Evaporation enhancement drives the European water-budget deficit during multi-year droughts

Abstract. In a warming climate, periods with lower than average precipitation will increase in frequency and intensity. During such periods, known as meteorological droughts, the decline in annual runoff may be proportionally larger than the corresponding decline in precipitation. Reasons behind this exacerbation of runoff deficit during dry periods remain largely unknown, and this challenges the predictability of when this exacerbation will occur in the future and how intense it will be. In this work, we tested the hypothesis that runoff deficit exacerbation during droughts is a common feature across climates, driven by evaporation enhancement. We relied on multidecadal records of streamflow and precipitation for more than 200 catchment areas across various European climates, which distinctively show the emergence of similar periods of exacerbated runoff deficit identified in previous studies, i.e. runoff deficit on the order of −20 % to −40 % less than what expected from precipitation deficits. The magnitude of this exacerbation is two to three times larger for basins located in dry regions than for basins in wet regions, and is qualitatively correlated with an increase in annual evaporation during droughts, in the order of +11 % and +33 % over basins characterized by energy-limited and water-limited evaporation regimes, respectively. Thus, enhanced atmospheric and vegetation demand for moisture during dry periods induces a nonlinear precipitation-runoff relationship for low-flow regimes, which results in an unexpectedly large decrease in runoff during periods of already low water availability. Forecasting onset, magnitude, and duration of these drops in runoff have paramount societal and ecological implications, especially in a warming climate, given their supporting role for safeguarding water, food, and energy. The outcome that water basins are prone to this exacerbation of runoff deficit for various climates and evaporation regimes makes further understanding of its patterns of predictability an urgent priority for water-resource planning and management in a warming and drier climate.

Seed and Fruiting Phenology Plasticity and Offspring Seed Germination Rate in Two Asteraceae Herbs Growing in Karst Soils with Varying Thickness and Water Availability

Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions. Annual herbs are pioneers adapted to these areas; however, little is known about the responses of their seeds and infructescence, and the germination of their offspring to these limited water and soil resources. In this study, we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs (Xanthium sibiricum and Bidens pilosa) respond to the harsh karst soil environment, by assessing the seed number, seed biomass and offspring seed germination rate. X. sibiricum and B. pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design. The key results were as follows: (1) The number and biomass of progenies (infructescence and seeds) of X. sibiricum decreased with the decline of soil thickness and/or water availability (P <0.05). The infructescence and seed biomass of B. pilosa increased with the decline of water availability. (2) Seed quantity and seed biomass of X. sibiricum showed no correlation after their parents experienced resource reductions. A significant positive relationship between seed number and seed biomass was observed in B. pilosa (P <0.05). (3) The offspring seed germination rate of X. sibiricum did not change with the decrease of soil thickness under three levels of water treatment. However, the offspring seed germination rate of B. pilosa decreased significantly with the decrease of soil thickness under the control water level (P<0.05). The results show that X. sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats. In contrast, B. pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy. B. pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment, but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.

Improving Soil Resource Uptake by Plants Through Capitalizing on Synergies Between Root Architecture and Anatomy and Root-Associated Microorganisms.

Root architectural and anatomical phenotypes are highly diverse. Specific root phenotypes can be associated with better plant growth under low nutrient and water availability. Therefore, root ideotypes have been proposed as breeding targets for more stress-resilient and resource-efficient crops. For example, root phenotypes that correspond to the Topsoil Foraging ideotype are associated with better plant growth under suboptimal phosphorus availability, and root phenotypes that correspond to the Steep, Cheap and Deep ideotype are linked to better performance under suboptimal availability of nitrogen and water. We propose that natural variation in root phenotypes translates into a diversity of different niches for microbial associations in the rhizosphere, rhizoplane and root cortex, and that microbial traits could have synergistic effects with the beneficial effect of specific root phenotypes. Oxygen and water content, carbon rhizodeposition, nutrient availability, and root surface area are all factors that are modified by root anatomy and architecture and determine the structure and function of the associated microbial communities. Recent research results indicate that root characteristics that may modify microbial communities associated with maize include aerenchyma, rooting angle, root hairs, and lateral root branching density. Therefore, the selection of root phenotypes linked to better plant growth under specific edaphic conditions should be accompanied by investigating and selecting microbial partners better adapted to each set of conditions created by the corresponding root phenotype. Microbial traits such as nitrogen transformation, phosphorus solubilization, and water retention could have synergistic effects when correctly matched with promising plant root ideotypes for improved nutrient and water capture. We propose that elucidation of the interactive effects of root phenotypes and microbial functions on plant nutrient and water uptake offers new opportunities to increase crop yields and agroecosystem sustainability.

Rhizobacteria from Brazilian semiarid biome as growth promoters of soybean (Glycine max L.) under low water availability.

Caatinga is the predominant biome in the Brazilian semiarid region. Its vegetation is composed by plants and microorganisms with high tolerance to drought. Microorganisms associated with plants in this biome can develop mechanisms to protect cells from water stress and desiccation. The aim of this study was to identify plant growth-promoting rhizobacteria associated with the drought-tolerant legume Mimosa artemisiana and to examine their effect on the growth of soybean (Glycine max L.) under drought condition (irrigation with 30% of field capacity). Rhizospheric soil was collected along the Caatinga (In the States of Bahia and Pernambuco) at 4 collection points, totaling sixty subsamples. Xerotolerant bacteria with plant growth-promotion characteristics were isolated in a selective culture medium for diazotrophic bacteria. Two strains of the genera Bacillus and one Paenibacillus were promising in in vitro and in vivo tests. Both were able to grow in a medium with low water availability (0.919 Aw) and could produce exopolysaccharides and indole acetic acid (up to 130µgmL-1). In addition, they produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase and formed biofilms under drought conditions. The inoculation with the isolated strains in the seedling root system mitigated the adverse effects of drought, increasing roots and shoots dry weights of soybean seedlings compared with non-inoculated.

Diversity of arbuscular mycorrhizal fungi in the rhizosphere of saffron ( Crocus sativus ) plants along with age of plantation in Taliouine region in Morocco

Saffron cultivation is a viable alternative for marginal areas where low soil fertility and water availability severely limit the cultivation of other crops with higher water and input requirments. Under these conditions, arbuscular mycorrhizal fungi (AMF) are an essential alternative for maintaining fertility and water conservation, stimulating growth, and providing plant protection against soil-borne diseases. The aim of this work is to highlight the diversity of the arbuscular mycorrhizal fungi communities associated with saffron roots in plantations of different ages (two, four and ten years old) in the region of Taliouine (Morocco). The highest number of endomycorrhizal spores was recorded in the rhizosphere of saffron plants harvested at the level of plots that have carried saffron for two years (138.66/100 g soil), while the lowest number was observed in the rhizosphere of plants of plots that are occupied for 10 years by saffron. All collected spores from plots under study represent 17 morphotypes belonging to 5 genera: Glomus (7 species), Acaulospora (7 species), Rhizophagus (one species), Densicitata (one species), and Funneliformis (one species).

Diversity of arbuscular mycorrhizal fungi in the rhizosphere of saffron (Crocus sativus) plants along with age of plantation in Taliouine region in Morocco

Saffron cultivation is a viable alternative for marginal areas where low soil fertility and water availability severely limit the cultivation of other crops with higher water and input requirments. Under these conditions, arbuscular mycorrhizal fungi (AMF) are an essential alternative for maintaining fertility and water conservation, stimulating growth, and providing plant protection against soil-borne diseases. The aim of this work is to highlight the diversity of the arbuscular mycorrhizal fungi communities associated with saffron roots in plantations of different ages (two, four and ten years old) in the region of Taliouine (Morocco). The highest number of endomycorrhizal spores was recorded in the rhizosphere of saffron plants harvested at the level of plots that have carried saffron for two years (138.66/100 g soil), while the lowest number was observed in the rhizosphere of plants of plots that are occupied for 10 years by saffron. All collected spores from plots under study represent 17 morphotypes belonging to 5 genera: Glomus (7 species), Acaulospora (7 species), Rhizophagus (one species), Densicitata (one species), and Funneliformis (one species).

Tap Water Quality Degradation in an Intermittent Water Supply Area

Decentralized tap water systems are an important drinking water source worldwide. A good quality, high-pressure continuous water supply (CWS) is always the target of any urban settlement. However, tap water in some areas are reported with deteriorated water quality even though treated well before supplying. Such deterioration of tap water quality is reported widely from areas with low water availability and in economically poor countries where water are supplied intermittently (IWS). This study focuses in identifying tap water quality in IWS and causes of water quality degradation using nitrate-nitrogen (NO3-N) as an indicator and stable isotopes of hydrogen (δD) as tracer. Nine water reservoirs and ninety municipal tap water (ten per reservoir) samples were collected during the wet (June–September) and dry (November–February) seasons in the Kathmandu Valley (KV), Nepal. Ten percent of the tap water samples exhibited higher NO3-N than those of their respective reservoirs during the wet season, while 16% exhibited higher concentrations during the dry season. Similarly, the isotopic signatures of tap water exhibited 3% and 23% higher concentrations than those of their respective reservoirs during the wet and dry seasons, respectively. Coupling analysis between NO3-N and δD demonstrates close connection of groundwater and tap water. The results indicate groundwater intrusion as the primary component in controlling tap water quality variations within the same distribution networks during IWS. Meanwhile, the obtained results also indicate probable areas of intrusion in the KV as well as usefulness of δD as a tool in the assessment of tap water systems.

Potassium regulates diel leaf growth of Brassica napus by coordinating the rhythmic carbon supply and water balance.

Carbon and water are two main factors limiting leaf expansion. Restriction of leaf growth by low availability of carbon or water is among the earliest visible effects of potassium (K) deficiency. It is not known how K is involved in regulating the rhythmic supply of these two substrates, which differ remarkably across the day-night cycle, affecting leaf expansion. We investigated the effects of different K regimes on the time courses of leaf expansion, carbon assimilation, carbohydrates, and hydraulic properties of Brassica napus. Potassium supply increased leaf area, predominantly by promoting night-time leaf expansion (>60%), which was mainly associated with increased availability of carbohydrates from photosynthetic carbon fixation and import from old leaves rather than improvement of leaf hydraulics. However, sufficient K improved leaf hydraulic conductance to balance diurnal evaporative water loss and increase the osmotic contribution of water-soluble carbohydrates, thereby maintaining leaf turgor and increasing the daytime expansion rate. The results also indicated an ontogenetic role of K in modifying the amplitude of circadian expansion; almost 80% of the increase in leaf area occurred before the area reached 66.9% of the mature size. Our data provide mechanistic insight into K-mediated diel coordination of rhythmic carbon supply and water balance in leaf expansion.

WATER AND AGRONOMIC EVALUATION OF MAIZE HYBRIDS IN RESPONSE TO DIFFERENT ENVIRONMENTS AND NITROGEN DOSES

To achieve water and food safety, it is necessary to identify crops outstanding in regard to efficient water use. In Mexico, the Valles Altos region has frequent water scarcity, so it is necessary to characterize maize genotypes that show outstanding traits under conditions of low water availability. The objective of this study was to identify water productivity, yield and hectolitre weight of white maize hybrids grown in Valles Altos. Ten white maize hybrids were used in the experiment; five from UNAM and five from INIFAP. These hybrids were established under two levels of nitrogen fertilization (low: 80 kg ha-1 and high 160 kg ha-1) in two environments: FESC-UNAM (Cuautitlán Izcalli) and CEVAMEX (Texcoco) in the State of Mexico. The experiment was established as randomized complete blocks, variables were recorded to calculate grain yield at 14 % commercial moisture and related to the volume of water entering each environment, the total water productivity was identified. Statistical analysis was performed with SAS and means were compared with Tukey’s test. With a combined analysis, a significant interaction of environment with hybrids and nitrogen fertilization was found in grain yield. Total water productivity, estimated at an overall mean of 0.78 kg m-3, was significant for environments, hybrids and nitrogen dosage. Grain yield showed an overall average of 4.8 Mg ha-1. In hectolitre weight, a significant difference was found in the environment and hybrid factors, with an overall average of 73.8 kg hL-1. Total water productivity was higher in the FESC-UNAM environment where irrigation was not provided, with no significant difference in grain yield.

Foliar brassinosteroid analogue (DI-31) sprays increase drought tolerance by improving plant growth and photosynthetic efficiency in lulo plants

The use of agronomic alternatives such as plant hormone sprays has been considered a tool to mitigate drought stress. This research aimed to evaluate the use of foliar brassinosteroid analogue DI-31 (BRs) sprays on plant growth, leaf exchange and chlorophyll a fluorescence parameters, and biochemical variables in lulo (Solanum quitoense L. cv. septentrionale) seedlings grown under drought stress conditions. Seedlings were grown in plastic pots (3 L) using a mix between peat and sand (1:1 v/v) as substrate. Lulo plants were subjected to drought stress by suppressing 100% of the water needs at 30–37 and 73–80 days after transplanting (DAT). Foliar BRs analogue (DI-31) sprays were carried out at four different rates (0, 1, 2, 4, or 8 mL of analogue per liter) at different times (30, 33, 44, 60, 73, and 76 DAT). Drought stress caused a reduction in the Fv/Fm ratio, leaf gas exchange properties, total biomass, and relative water content. Foliar DI-31 sprays enhanced leaf photosynthesis in well-watered (WW) (∼10.7 μmol m−2 s−1) or water-stressed plants (WS) (∼6.1 μmol m−2 s−1) when lulo plants were treated at a dose of 4 and 8 mL·L−1 compared to their respective controls (0 mL·L−1 for WW: 8.83 μmol m−2 s−1 and WS: 2.01 μmol m−2 s−1). Also, DI-31 sprays enhanced the photochemical efficiency of PSII, and plant growth. They also increased the concentration of photosynthetic pigments (TChl and Cx + c) and reduced lipid peroxidation of membranes (MDA) under drought conditions. The results allow us to suggest that the use of DI-31 at a dose of 4 or 8 mL·L−1 can be a tool for managing water stress conditions caused by low water availability in the soil in lulo-producing areas to face situations of moderate water deficit at different times of the year.

Sustainability of the Water Footprint of Various Soil Types on Oil Palm Plantations

There are significant studies that have quantified oil palm water footprint as an indicator of environmental sustainability but an estimation of water footprint under varying soil types furthermore is still limited. The objectives of the study were to estimate whether annual variations of soil type and yields significantly effects for the oil palm water footprint. The data from three types of soil (spodosol, inceptisol, ultisol) were collected from an oil palm plantation in Pundu village, Central Kalimantan, Indonesia. To perform the water footprint analysis we utilize water balance accounting equations via application Cropwat 8.0. From that, we determine the crop irrigation scheduling to compute the blue, green, and grey water footprint of oil palm fresh fruit bunch in the area. Our analysis found that the actual evapotranspiration of spodosol and inceptisol have the same value: 1242 mm/year whilst ultisol is 1239 mm/year. The total water footprint of oil palm varied considerably with the largest value being 1310.04 m3/ton for ultisol. The actual evapotranspiration of spodosol and inceptisol have the same value of 1242 mm/year whilst ultisol is 1239 mm/year. The higher production resulted in a lower water footprint and vice versa. Moreover, the total water footprint from ultisol soil type has the highest value due to the lowest yields. The difference in evapotranspiration value resulted in the insignificant value of total water footprint. The lower water availability, the lower water use, and the higher actual irrigation requirement in oil palm plantation yet showed the unnotable impact on water footprint in different soil types for the oil palm plantation.

Strong Environmental Filtering Based on Hydraulic Traits Occurring in the Lower Water Availability of Temperate Forest Communities.

The trait-based approaches have made progress in understanding the community assembly process. Here, we explore the key traits that may shape community assembly patterns of the same community type but within different water availabilities. Natural Quercus wutaishanica forests were chosen as a suitable study system to test the difference between economic and hydraulic traits across water availability on the Loess Plateau (LP, drought region) and Qinling Mountains (QL, humid region) of China. A total of 75 plots were established separately in two sites, and 12 functional traits (seven hydraulic traits and five economic traits) of 167 species were studied. Community-weighted mean trait values and functional diversity indices were compared between the two sites. Canonical component analysis was performed to infer whether the changes of community traits and their relationships are driven by intraspecific variation or species turnover. Evidence for likely community assembly processes was tested using the null model to determine whether functional structure among seven hydraulic traits and five economic traits was dominated by different ecological processes between two sites. We found that forests in the Loess Plateau and Qinling Mountains showed different hydraulic and economic traits. Hydraulic and economic traits coupled at the community level were driven by species turnover. Hydraulic traits showed more significant convergent patterns on LP than that in QL. Our results suggest a strong environmental filtering process occurred in hydraulic-based community assembly in the temperate forest with low water availability. Reveal the relationship of hydraulic and economic traits at the community level. Emphasize the critical role of multi-dimensional traits selecting like hydraulic traits in community ecology.

Early insights on the fracking impacts to the water-energy nexus in Brazil: is there a risk of water scarcity in the shale gas prospective areas?

Brazil has the 10th largest shale gas reservoir, and the Paraná sedimentary basin has a potential area for shale gas production in the western portion of the São Paulo state. Despite that, the knowledge about the impacts of fracking on the local water resources is still limited. This study presents a novel reproducible method to compute the risk of water scarcity in areas with restricted or no shale gas development. Using geospatial numerical simulations under five scenarios from 500 to 2500 wells, we find that the fracking-related risk of water scarcity in the São Paulo state is low. For the 2013–2019 period, the long-term average seasonal water availability is between 0.05 and 1 Gm³ per water resources management unit, whereas fracking water demand would hardly overcome 6 Mm³ y−1. For instance, with 2500 wells, the fracking demand in Pontal do Paranapanema, the most prospective region for shale gas, would not overcome 3% of the yearly local water demand. The riskier areas are in Aguapeí and Baixo do Tietê water resources management units, during winter and autumn, and the most water-stressed area is São José dos Dourados. In regions and periods of low water availability, fracking operators can use adaptative strategies for shale gas production. In the context of imminent droughts, this research debates national energy security and casts doubt on the water efficiency and sustainability of the state's energy generation. At last, this research provides early insights to support shale gas and water policy, and future studies to further investigate relevant aspects to the Brazilian Water-Energy nexus.

Soybean sowing under low water availability conditions: impacts of seed treatment and soil management

Abstract: The aim of this work was to evaluate the impact of soybean sowing in soil with low water availability, under two management systems, using seeds with and without chemical treatment, on the physiological quality of seeds and seedling emergence. For this, two experiments were set up, one under no-tillage system (NTS) and the other under conventional tillage system (CTS), in a randomized block design, both in a 2x6 factorial scheme, with two seed treatment conditions (with and without) and six periods of seed permanence in the soil (0, 24, 48, 72, 96 and 120 h), with four replications. Germination, vigor, percentage of abnormal seedlings and percentage of dead seeds were evaluated. Seed treatment made it possible to maintain germination at acceptable levels for up to five days of permanence of the seeds in the soil, even in CTS. Sowing in soils with low water availability can lead to reductions of 0.2 and 0.5 percentage points per hour of exposure to dry soil in germination and vigor of soybean seeds, respectively.

ISOLATION OF MICROALGAE FROM ANTARCTIC SOIL

Microalgae are unicellular photosynthetic microorganisms which are able to survive in extreme environmental conditions, specifically low temperature, high evaporation rates as well as low water availability. Polar microalgae from the Antarctic region have received attention from researchers due to their special adaptations for surviving in extremely cold environments and being isolated from various types of samples. Four Antarctic soil samples were used on this study namely-Sample A, Sample B, S18 and S30. All soil samples were subjected to serial dilution and spread on BBM followed by 3 weeks incubation at 25oC with periodic light. Only soil sample S30 showed positive microalgae growth after additional 3 weeks incubation period. Consequently, soil sample S30 was proceeded to isolation of microalgae using BBM, 3N- BBM+V, JM and MWC media. Observable growth of green microalgae could only be obtained using 3N-BBM+V and JM media. Moreover, 3N-BBM+V medium successfully produced the highest number of microalgae colonies recovered from Antarctic soil sample. Isolation of microalgae from Antarctic provides resources for various industrial and commercial applications.

Modeling the Effect of Planting Dates and Nitrogen Application Rates on Potatoes Water Productivity in Jordan Valley

Agricultural sector in Jordan is facing serious challenges in meeting the growing needs of food security because of its low water availability. Maintaining and enhancing agricultural water productivity under such prevailing environmental constraints are hard to achieve. Potatoes water productively in Jordan Valley was modeled using Decision Support System for Agrotechnology Transfer (DSSAT) under six nitrogen applications (0, 60, 80, 100, 120 and 140 kg/ha) and twelve planting dates every two weeks from October 1 to March 15 scenarios. The potatoes yield increased from 0% to 100% nitrogen treatment and then no considerable increase occurred. The potatoes’ crop yield increased from October 1st to January 15 and then decreased after which until the last day of planting date. The seasonal cumulative crop evapotranspiration for potatoes about doubled from 0% to 60% nitrogen treatment and then kept increasing gradually until the last treatment. The growing season cumulative crop evapotranspiration for potatoes increased gradually from October 1 to March 1. The water productivity increased from 0% nitrogen treatment to 100% and then decreased. The potatoes’ water productivity increased from October 1 until November 15 and then decreased to the end. From these results, we recommend that 100% of nitrogen requirements should be applied. The best window for potatoes’ planting date is the last two weeks in November.

Osmoprotection in Salvia hispanica L. seeds under water stress attenuators.

Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-1), gibberellic acid (0.4 mM.L-1), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

Funkcionalna ekologija rastlin: preverjanje izbranih konceptov na primeru rastlinskih vrst gozdnih rastiščnih tipov v Sloveniji

Using Slovenian forest flora as an example, we investigated four plant functional traits: specific leaf area (SLP), leaf dry matter content (VSS), plant height (VIŠ) and seed/spore mass (MAS). The first two traits define the leaf economics spectrum (way and efficiency of resource utilization), whereas the other two are linked to the size of plant organs. This study tested the correlations between plant traits and their phytoindication values for the ecological factors of light (L), temperature (T), continentality (K), soil moisture (F), soil reaction (R) and nutrients (N). We found statistically significant correlations between SLP and R, N, L, F and K; between VSS and R and N; between VIŠ and N, T, R and F; and between MAS and K, R, N and T. Along the first axis of the ordination space, we identified a leaf economics spectrum ranging from species with higher SLP values growing on more productive but also more shaded sites to plants with higher VSS values adapted to more stressful conditions (e.g. low soil reaction or low availability of nutrients and water, respectively). The VSS trait contributed the most to explaining the variability in the functional profile of forest plants, while the MAS trait contributed the least. These findings are comparable with previous studies, as the selected concepts allow for the identification of diversity of plant form and function on a global scale.

Evapotranspiration and crop coefficients for coffee production systems in Colombia using the eddy covariance method

AbstractTo optimize coffee (Coffea arabica L.) production in Colombia, adaptation strategies that improve water use must be developed. Therefore, the objective of this study was to determine evapotranspiration under standard conditions (ETc), reference evapotranspiration (ETo), and the crop coefficient (Kc) of coffee plants interplanted between maize (Zea mays L.) (coffee–maize) for the first 12 mo of growth and coffee grown without maize from 13 to 46 m after transplanting (MAT). In this study, ETc was measured using the eddy covariance method. The ETc of coffee–maize ranged from 4.17 to 4.71 mm d–1, while ETc of coffee–sun averaged 4.32 ± 0.07 mm d–1 between 13 and 24 MAT and 4.09 ± 0.03 mm d–1 between 25 and 43 MAT for coffee trees in the reproductive stage. The Kc was 0.87 for coffee plants between 0 and 12 MAT, 0.98 ± 0.01 between 13 and 24 MAT, and 0.97 ± 0.02 between 25 and 43 MAT. Maize intercropped between coffee trees produced an adapted microclimate for the first 2 mo, allowing energy used for evapotranspiration processes (latent heat flux) to be greater than energy used for air warming (sensible heat flux), although there was low soil water availability. Kc values are a foundation for optimizing coffee crop water use under climate and soil conditions for the intertropical Andean hillside region.