Periods Of Water Deficit Research Articles

The Effect of Water Stress on Total-Phenolic Content of Barley

Little is known about the relation between water stress and the accumulation of phenolics in plant tissues. The present study aimed to investigate the effect of water stress and maturation on the production of total-phenolics (TP) by four barley (Hordeum vulgare L.) varieties (‘Manel’, ‘Martin’, ‘Rihane’, ‘Espérance’). During three phenological stages (S-8, S-10.5, S-11), following Feekes scale, whole barley plants were pulled out of the field and separated into roots, stems, and leaves. Water extracts were prepared from plant parts and their TP contents were determined by spectrophotometer. To determine periods of water deficit (WD) at field, climatic characterization of the region was carried out. TP accumulated in barley plant and its parts under the influence of water deficit essentially at S8, which coincided with barley spring growth. However, TP content decreased when WD became more pronounced at the following stages. This response may be explained, partially by the biosynthesis of lignin from free phenols when the plant approached maturity. Results suggest that water stress stimulates the synthesis and accumulation of TP in barley tissues during active growth periods (spring growth) at S-8. This response doesn’t persist until the critical periods of WD where barley maturity favors a decrease in TP content for all plant parts. Regardless of growth stage and WD, barley accumulates preferentially phenolics in above-ground plant parts. The evolution of phenolic accumulation under water stress showed the same trends for the tested barley varieties, indicating a genetic control of phenolic production and their partitioning across plant parts.

Water use of selected cover crop species commonly grown in South African fruit orchards and their response to drought stress

Cover crops are widely planted in orchards for a variety of reasons. These include suppressing soil erosion, nutrient cycling, phytosanitary purposes, general orchard aesthetics etc. However, there is need to balance these benefits against use of scarce resources such as water and nutrients. Currently no information exists on how different cover crop species use water in orchards and how they cope with drought stress. The aim of this study was therefore to compare the transpiration dynamics of various cover crop types in order to identify species with conservative water use rates. Studied species included: 1) two exotic legumes i.e. Lupine (Lupinus albus L.), and Common vetch (Vicia sativa), 2) three exotic grasses i.e. Tall fescue (Festuca arundinacea), Rye grass (Loliumperenne), and Kikuyu grass (Pennisetum clandestium) and; 3) grasses that are indigenous to sub-Saharan Africa i.e. African Lovegrass (Eragrostis capensis) and Rhodes grass (Chloris gayana). The crops were planted in pots under controlled greenhouse conditions. Transpiration rates were quantified using miniature stem heat balance sap flow gauges and by manual weighing. Drought stress was imposed by withholding irrigation at selected intervals and the responses were quantified through changes in the water relations of the plants. The study showed that exotic legumes had the highest daily water use which peaked at about 2.4 L per square metre of leaf area per day, followed by exotic grasses at 1.5–2.0 L/m2/d. The indigenous grasses used the least water ranging from 0.8 to 1.2 L/m2/d. The indigenous grasses largely displayed an isohydric response to drought stress by maintaining their leaf water status with increasing soil water deficit. The exotic species, on the other hand, showed risk taking behaviour (anisohydry) wherein both the transpiration and leaf water status decreased sharply as drought stress increased. Consequently, some exotic species failed to recover when stress was relieved. From a water use perspective, this study demonstrates that indigenous grass species are more appropriate as cover crops in South African orchards because of their low transpiration rates and the ability to cope with extended periods of water deficit.

The Dry and the Wet Case: Tree Growth Response in Climatologically Contrasting Years on the Island of Corsica

Stem radial variations of Corsican Black pine (Pinus nigra Arnold subsp. laricio Maire) and Maritime pine (Pinus pinaster Aiton) were monitored to quantify the impact of two meteorologically contrasting consecutive years. On the French island of Corsica, in the western Mediterranean basin, the year 2017 was extremely dry, while 2018 was exceptionally wet. We attached electric band dendrometers to 36 pines along an east–west transect, spanning the central mountain range, and set up automated weather stations at all five sites, ranging from 10 m asl to 1600 m asl. Stem radial variations (SRV) were separated into irreversible growth (GRO) and tree water deficit (TWD) periods. During the drought of 2017, the most severe tree water deficits occurred in the western part of the island, whereas trees at higher elevations were more affected than at lower elevations. A prolonged decrease of SRV, even close to the tree line, suggests bimodal growth and reveals high plasticity of growth patterns in both Corsican pines. Stem radial variations correlated significantly with precipitation and temperature. The positive correlations of GRO with precipitation and the negative correlations of TWD with temperature imply that high evapotranspiration led to the intense period of TWD in 2017. A novel approach was used to further investigate the growth/climate relationship by including synoptic-scale pressure situations. This revealed that an elevation gradient in GRO per weather pattern was only present in the wet year and that even rarely occurring weather patterns can have a substantial impact on tree growth. This novel approach provides a more comprehensive insight into meteorological drivers of tree growth patterns by incorporating different scales of the climatic system.

Functional Diversity and Assembly Rules of Two Deciduous Seasonal Forests in Southeastern Brazil

Abstract Deciduous seasonal forests (DSFs) have a peculiar floristic composition, with species capable of surviving periods of high water deficit in a year. Our goal was to demonstrate that abiotic filters lead to the assembly of two DSF communities that have high floristic dissimilarity. For this, we characterized the environment of the areas and used the community-weighted mean (CWM), functional richness (FRic) and functional dispersion (FDis) indices for regional recognition of functional patterns. The local assessment of assembly rules was carried out using null models. We found differences in the FRic and FDis between the areas, which was attributed to the different floristic influences exercised on the communities. However, in both, the typical attributes of dry formations were dominant (CWM), indicating that, on the regional scale of study, the dry season acts as a filter in the composition of species in the communities. On a local scale, stochastic dispersion was identified as the most influential mechanism in the assembly of communities. We conclude that deterministic and stochastic processes act in the assembly of the studied communities, and the proportion of each of these depends on the scale, with abiotic filtration predominating on a regional scale and stochastic dispersion events on a local scale.

Inter-annual effects of potassium/sodium fertilization and water deficit on wood quality of Eucalyptus grandis trees over a full rotation

In Brazil, most Eucalyptus plantations are located in regions experiencing periods of water shortage, where fertilizers such as potassium (K) are intensively used to achieve high productivity. Recently, sodium (Na) has also been considered a potential nutrient in K-deficient soils. K and Na supply can increase water stress in Eucalyptus grandis trees, which could negatively impact forest productivity over prolonged droughts. Wood properties are determinants of the quality and yield of products. They are important factors to consider when measuring the impacts of silvicultural practices and water deficit on forest productivity. However, alterations in wood properties due to interactions between K/Na fertilization, water availability, and stand age are not well documented.Through annual sampling of E. grandis trees throughout a complete rotation (6 years) in Brazil, we evaluated the interactive effects of K/Na fertilization, water availability, and stand age on stem volume, sapwood/heartwood ratio, wood density, fiber, and vessel features. We also evaluated the relationships between growth rate, wood density, and fiber and vessel features. The split-plot experimental design consisted of two water supply regimes (37% throughfall reduction versus undisturbed throughfall) and three fertilization regimes (K, Na, and control).Until six years of age, K and Na fertilization increased stem volume by 3 and 2-fold, respectively, and only K-fertilized trees affected stem volume by 37% throughfall reduction. Both K and Na detrimentally affected wood density and beneficially affected fiber length. The sapwood/heartwood ratio was highly and negatively related to the growth rate of trees. Wall thickness was not affected by either K or Na. As expected, K and Na affected vessel size due to an increase in basal area growth. However, the effects of Na were more pronounced than those of K. Significant interactions between fertilization and water availability suggest that, under water deficit, wood density will not be affected by K fertilization. In contrast, the effect of Na and control treatments were invariable regardless of water availability.The effects of fertilization on wood properties changed over time, with non-significant effects in the first year and stronger effects from two years of age of trees. The variations in wood density were strongly related to variations in the fiber wall thickness. High increases in basal area growth promoted by K and Na were not related to significant decreases in wood density, but they were related to increases in fiber length. These findings highlight the significant effects of K addition on stem volume without significant losses in wood quality, even under water stress over a complete rotation. The negative impacts observed on wood density and lower productivity in commercial E. grandis plantations with the use of Na as a substitute for K should be considered.

Remote Sensing for Plant Water Content Monitoring: A Review

This paper reviews the different remote sensing techniques found in the literature to monitor plant water status, allowing farmers to control the irrigation management and to avoid unnecessary periods of water shortage and a needless waste of valuable water. The scope of this paper covers a broad range of 77 references published between the years 1981 and 2021 and collected from different search web sites, especially Scopus. Among them, 74 references are research papers and the remaining three are review papers. The different collected approaches have been categorized according to the part of the plant subjected to measurement, that is, soil (12.2%), canopy (33.8%), leaves (35.1%) or trunk (18.9%). In addition to a brief summary of each study, the main monitoring technologies have been analyzed in this review. Concerning the presentation of the data, different results have been obtained. According to the year of publication, the number of published papers has increased exponentially over time, mainly due to the technological development over the last decades. The most common sensor is the radiometer, which is employed in 15 papers (20.3%), followed by continuous-wave (CW) spectroscopy (12.2%), camera (10.8%) and THz time-domain spectroscopy (TDS) (10.8%). Excluding two studies, the minimum coefficient of determination (R2) obtained in the references of this review is 0.64. This indicates the high degree of correlation between the estimated and measured data for the different technologies and monitoring methods. The five most frequent water indicators of this study are: normalized difference vegetation index (NDVI) (12.2%), backscattering coefficients (10.8%), spectral reflectance (8.1%), reflection coefficient (8.1%) and dielectric constant (8.1%).

PENGARUH PERUBAHAN IKLIM TERHADAP EKOFISIOLOGI TANAMAN KELAPA SAWIT (Elaeis guineensis Jacq.)

Distinction in oil palm growth and productivity are caused by the interaction of genotypes and the environment. Therefore, environmental changes, especially climate change, have a negative impact on oil palm growth and production. Climate change that affects oil palm yields in the tropics and sub-tropics consists of two important factors, namely water availability and temperature. The first impact of a period of water deficit is a decrease in gas exchange, during the dry season photosynthesis can be inhibited due to an increase in water pressure deficit which causes stomata to close. The dry season is associated with high temperatures, which causes a decrease in photochemical efficiency temperature, decreased photosynthesis and decreased transpiration. Water deficit affects oil palm male flower production. High temperatures increase photorespiration and dark respiration so that the total biomass production decreases. Oil palm breeding program must be a multidisciplinary effort that involves molecular tools, understanding the response of oil palm cultivation to limiting conditions caused by abiotic.

Scrutinizing the impact of water deficit in plants: Transcriptional regulation, signaling, photosynthetic efficacy, and management

Suboptimal availability of water limits plant growth, development, and performance. Drought is one of the leading factors responsible for worldwide crop yield reduction. In the future, owing to climate changes, more agricultural land will be affected by prolonged periods of water deficit. Thus, understanding the fundamental mechanism of drought response is a major scientific concern for improvement of crop production. To combat drought stress, plants deploy varied mechanistic strategies and alter their morphological, physiochemical, and molecular attributes. This helps plant to enhance water uptake and storage, reduce water loss and avoid wilting. Induction of several transcription factors and drought responsive genes leads to synthesis of stress proteins, regulation of water channels i.e. aquaporins and production of osmolytes that are essential for maintenance of osmotic balance at the cellular level. Self- and hormone-regulated signaling pathways are often stimulated by plants after receiving drought stress signals via secondary messengers, mitogen-activated protein kinases, and stress hormones. These signaling cascades often leads to stomatal closure and reduction in transpiration rates. Reduced carbon dioxide diffusion in chloroplast, lowered efficacy of photosystems, and other metabolic constraints limits the key regulatory photosynthetic process during water deficit. The impact of these stomatal and nonstomatal limitations varies with stress intensity, superimposed stresses and plant species. A clear understanding of the drought resistance process is thus important before adopting strategies for imparting drought tolerance in plants. These management practices at present include exogenous hormone application, breeding, and genetic engineering techniques for combating the water deficit issues.

Drought affects the rate and duration of organ growth but not inter-organ growth coordination.

Drought at flowering and grain filling greatly reduces maize (Zea mays) yield. Climate change is causing earlier and longer-lasting periods of drought, which affect the growth of multiple maize organs throughout development. To study how long periods of water deficit impact the dynamic nature of growth, and to determine how these relate to reproductive drought, we employed a high-throughput phenotyping platform featuring precise irrigation, imaging systems, and image-based biomass estimations. Prolonged drought resulted in a reduction of growth rate of individual organs-though an extension of growth duration partially compensated for this-culminating in lower biomass and delayed flowering. However, long periods of drought did not affect the highly organized succession of maximal growth rates of the distinct organs, i.e. leaves, stems, and ears. Two drought treatments negatively affected distinct seed yield components: Prolonged drought mainly reduced the number of spikelets, and drought during the reproductive period increased the anthesis-silking interval. The identification of these divergent biomass and yield components, which were affected by the shift in duration and intensity of drought, will facilitate trait-specific breeding toward future climate-resilient crops.

Mango fruit quality improvements in response to water stress: implications for adaptation under environmental constraints

Mediterranean farming is facing increasing periods of water shortage and, in the coming decades, the water reduction is expected to exert the most adverse impact upon growth and productivity. This study was performed to assess the response of the physico-biochemical quality parameters of mango fruits to different doses of irrigation in a Mediterranean subtropical area in Spain. During two-monitoring seasons, trees were subjected to deficit-irrigation strategies receiving 33, 50, and 75% of a crop evapotranspiration (ETC), and a control at 100% ETC. According to the findings and respect to control, the yield was reduced in 8, 11, and 20% for the water-stressed trees at 75, 50, and 33% ETC, respectively, producing smaller fruits in line with the amount of applied irrigation. However, the water-stressed fruits significantly enhanced their quality, in particular at 33% ETC, with regards to the content of the health-promoting phytochemicals (total soluble solids, vitamin C, and β-carotenoids). Thus, sustainable water management without a detrimental effect on the yield could be possible, and farmers should be encouraged to adapt to the environmental constraints, producing improved quality fruits.

Ecophysiology of peanuts grown under water deficit regimes

This study evaluates physiological aspects of two peanut cultivars ( Arachis hypogaea L. IAPAR 25 Tição and IAC Tatu ST) grown under water regimes in order to verify drought tolerance. The randomized block experi­mental design was used in a 2 x 3 factorial design (two cultivars and three water regimes). The water regimes were, namely: control, in which plants were maintained at field capacity conditions (FC - without water deficit); moderate water deficit (MD - 50% of water deficit); and severe water deficit (SD - 75% of water deficit) in relation to control. Relative water content, gas exchange, dry matter, and leaf proline content were analyzed. Both cultivars developed physiological mechanisms of acclimatization to water deficit, such as reducing leaf relative water content, CO 2 assimilation rate, stomatal conductance, and transpiration in the initial period of water deficit, besides increasing proline production. Such physiological changes negatively affected dry matter accumulation in the grains and the number of grains, as well as dry matter accumulation in shoots and roots.

Climate change impact on tree mortality differs with tree social status

Changes in temperature and rainfall linked to recent climate change increase the mortality rates of European temperate tree species. The economic importance of trees and the ecosystem services they provide differ according to their social status (dominant or suppressed trees) and their size. The extent to which climate change impacts these different categories in different ways remains little explored.Ecophysiological differences between tree size and status suggest different sensitivities to climate change. Dominant trees are exposed to more evapotranspiration than suppressed trees that benefit from buffered climatic conditions. Large trees are able to develop a network of fine roots that allow deeper water and nutrient uptake during water shortage periods, but that have higher water requirements and more physical constraints than small trees due to the fact that they must lift water to greater heights.We used 207,100 trees from the French forest inventory data (including 3,514 dead trees), representing eight common European tree species. For each species, we separated the tree population into three subsets of suppressed, small dominant and large dominant trees. For each subset, we modelled the mortality observed in a stand in the absence of disturbances (background mortality), with a focus on the differences in sensitivity to recent changes in temperature and rainfall.After having taken the main mortality drivers related to competition into account, as well as stand characteristics including logging intensity effect, we assessed the over-mortality linked to the recent changes in temperature and rainfall for each of the three subsets.When considering both changes in temperature and rainfall, the climate change related to over-mortality was greater for suppressed than for small or large dominant trees, for all the species. Over-mortality of suppressed trees was related to temperature increase, whereas a maximum vulnerability related to rainfall decrease was observed for large dominant trees.Over-mortality driven by climate change not only concerns large and dominant trees, but small and especially suppressed ones as well. These results suggest that in addition to wood production, forest renewal and ecosystem services associated with understorey vegetation are threatened by the recent changes in temperature and rainfall in European temperate forests.

Transpiration and leaf growth of gladiolus in response to soil water deficit

The objective of this study was to evaluate the response of transpiration and leaf growth of gladiolus cultivars to a drying soil represented by the FTSW. Three experiments (E1, E2 and E3) were individually carried out in 20 pots, with four gladiolus cultivars. Plants did not experienced water deficit until they had less than seven leaves in E1, four leaves in E2 and, four and seven leaves in E3. At these stages, water deficit was imposed in 10 pots of each experiment, while the other 10 pots remained without water deficit. The FTSW, transpiration and leaf growth were measured daily, during the period of water deficit. Results indicated that the threshold FTSW for transpiration is higher when water deficit occur during the reproductive phase. We concluded that the FTSW threshold for NTR in gladiolus varies depending on the developmental stage at which the water deficit is applied, being higher when it occurs during the reproductive phase and lower when it occurs during the vegetative phase. Water deficit reduces leaf appearance rate in gladiolus, delaying the harvesting point of the flower stems.

Dynamics of Bioelectric Potential in the Root Zone of Plants during Irrigation

The paper concerns influence of water distribution on the bioelectric potential in the soil–plant system. Two methods for measuring bioelectric potentials (BEPs) of plants have been compared, namely an invasive installation of needle electrodes (a) and a noninvasive method of providing contact due to root intergrowth through a metal grid (b). It has been shown that needle electrode installation into plant tissue leads to a decrease in the biopotential difference from 70 mV to a noise level within ~ 30 minutes; in fact, this means measuring the potentials generated by the plant organism due to the stress caused by the damage. On the contrary, noninvasive electrode installation provides long-term measurements for months and even longer. A specific system is suggested for automated electrophytogram based on the noninvasive method. It allows one long-term measurement of the plant electrophysiological signal directly under normal living conditions for the rhizosphere; it indicates the current functional state of a plant. An equivalent BEP measurement scheme has been proposed accounting for both electrical properties of the plant and root–inhabited medium. BEPs have been measured under conditions of varying water content in the root zone and water movement along and against the root growth direction. The biopotential is constant on average and fluctuates stochastically in the range from 245 to 275 mV at 60–70% of the total water capacity of the soil substrate. The bioelectric potential decreases almost twice when the soil dries. It is restored after irrigation and the restoration delay time increases with increasing water-deficit period. A model is proposed describing the effects in the system during a water-deficiency regime and irrigation.

Introducing an economic agricultural water distribution in a hyper-arid region: a case study in Iran

AbstractOperational management of agricultural water based on an economic perspective was investigated as a sustainable approach in water shortage periods. Accordingly, an automatic water distribution system was coupled with the Positive Mathematical Programming economic model for a sustainable agricultural water operation in the Roodasht irrigation network, Iran. Operational management was carried out based on the economic value of water in each irrigated unit. According to the results, the existing operating system was able to supply 71 and 22% of farmers’ water requirements under normal and water shortage conditions, respectively. However, employing the proposed automated operational-economic approach reduced water consumption by 14.3%, while maintaining the cultivation area by 11% and increasing farmers’ net profit to 840,000 USD under water scarcity. The economic operation can reduce water losses, implement economic strategies in those districts without water marketing mechanisms, and provide sustainable management of limited water resources in hyper-arid regions.

Assessing Available Water Content of Sandy Soils to Support Drought Monitoring and Agricultural Water Management

In the future, according to regional climate-model simulations, the Carpathian Basin (in Central Europe) is predicted to be exposed to intensifying weather extremes that will exert a growing pressure on water resources. In recent past decades, water already has become a significant limiting factor for the natural environment and many agro-economic sectors in the southern Carpathian Basin. Therefore, there are increasing attempts to develop monitoring systems to detect water stress. In this study, changes in soil moisture conditions were monitored within two Arenosol profiles of extreme water balance during years characterised by different hydrologic conditions and under the impact of irrigation in the Great Hungarian Plain. Hourly data series of hydrometeorological parameters and soil moisture from six different soil depths during 2014–2018 were provided by on-site monitoring stations; humus, carbonate content, porosity, field capacity and wilting point were measured in the laboratory. On the basis of the newly definied so-called ‘available water percent’ (AW%) and a developed classification method, the rate, time and duration of water-shortage periods were evaluated for the years 2014–2018. The results show that drought monitoring cannot be effective without investigation of soil moisture content. Detailed analysis of available water percentage (AW%) can be used for real-time drought monitoring and as a precise indicator of the evolution of drought. This can help us prevent and manage damage from drought, and it is extremely important for agriculture.

Genesis and classification of carbonate soils in the State of Rio de Janeiro, Brazil

Carbonate rocks occur in Brazil under diverse climatic and environmental conditions, and therefore are of great importance for pedological studies. The northwest region of the State of Rio de Janeiro, Brazil, is composed of calc-silicate rocks and marbles that occur under tropical climate with a long period of water deficit, which provides conditions for peculiar pedogenesis. The objective of this study was to characterize the attributes of soils formed from carbonate materials and to understand the role of the main factors and processes in pedogenesis, as well as to provide information to the WRB (World Reference Base for Soil Resources) to improve carbonate soils classification. A toposequence was selected in the municipality of Italva, RJ, Brazil, with six profiles being described and sampled. All profiles presented median CaCO3 equivalent contents, high base saturation with the predominance of Ca+2 and Mg+2, and high activity clay. The absence of effervescence and low CaO/MgO ratio obtained by acid digestion suggest the dolomitic nature of the carbonates. Pedogenic carbonates were amorphous, since no XRD peaks were found. The high Mg+2 concentration provided by the parent material increases the dispersion of clays and favors clay illuviation, which is manifested in the micromorphology through a large amount of clay infillings and coatings. Four profiles on the highest part of the landscape were classified as Kastanozems (Mollisols), the footslope profile as Fluvisol (Inceptisol), and the toeslope profile as Vertisol. The mineralogy of the Vertisol's clay fraction was predominantly composed of kaolinite interstratified with 2:1 phyllosilicates, mainly illite. Acid digestion can complete the analysis of the CaCO3 equivalent content by quantifying CaO and MgO concentration in fine earth samples, presenting the potential to distinguish the Dolomitic/Calcaric qualifiers. The recognition of Dolomitic/Calcaric qualifiers for the Kastanozem reference soil groups is suggested, considering that the carbonate present in the calcic horizon may be diverse.

Timing of short period water stress determines potato plant growth, yield and tuber quality

Potato growth in humid climate regions is facing increasing challenges due to short period stresses in water deficit and excess. However, there is a lack of quantitative information on the effects of short period of water stress on potato plant growth and its implications on potato yield and tuber quality. In this study, we conducted a pot experiment to test the effects of short period (2weeks) of water deficit and water excess, respectively, applied at four different potato growth stages (sprouting, vegetative, tuberization and bulking stage) on potato vegetative development and tuber yield and quality. The results show that short period of water deficit overall had negative impacts while short period of water excess had slightly positive impacts on potato vegetative development and tuber yield and quality. For water deficit, the most sensitive periods were the vegetative and tuberization stage whereas for water excess, there were mostly no-significant differences between different potato growth stages. Although the impact of water deficit at the sprouting stage was minor, it was broad and long-lasting. These results confirm the benefits of supplemental irrigation and suggest the low risk of over-irrigation in well drained fields. They further suggest that when the availability of water for irrigation is limited, using water strategically during the period when potato needs water the most can maximize the benefits of supplemental irrigation.

Mild reductions in guard cell sucrose synthase 2 expression leads to slower stomatal opening and decreased whole plant transpiration in Nicotiana tabacum L

The understanding of the dynamics of stomatal movements has increased substantially through genetic manipulation of plant metabolism either at the whole plant level or specifically in guard cells. However, the regulation of stomatal speediness remains not completely elucidated. Here we shown that reduced expression of guard cell sucrose synthase 2 (NtSUS2) of Nicotiana tabacum L. altered the topology and the connectivity of the guard cell metabolic network and the accumulation of metabolites positively correlated with stomatal speediness during dark-to-light transition. This leads to a slower light-induced stomatal opening, lower steady-state stomatal conductance and a strong reduction (up to 44 %) in daily whole plant transpiration in the transgenics, when compared to wild type plants. Furthermore, the transgenic lines transpired more or have lower reduction in whole plant transpiration under short water deficit periods, indicating a higher effective use of water under this condition. Our results collectively suggest that the regulation of stomatal movement and speediness involve a complex modulation of the guard cell metabolic network, in which NtSUS2 has an important role. The results are discussed on the role of guard cell metabolism for the regulation of both stomatal speediness and whole plant transpiration.

Regeneration of roots and seedlings from Eugenia involucrata seeds under water deficit conditions

Abstract: The aim of this study was to analyze the regenerative capacity of Eugenia involucrata seeds as a possible strategy to ensure the production of new seedlings when they are going through a period of water deficit. Progressive water deficit conditions over time (up to 60 days for seeds and 270 days for seedlings) and in intensity (up to -5 MPa for seeds and -10 MPa for seedlings) were simulated, and seedling regeneration was analyzed. The results showed that these seeds can survive even under the most extreme conditions (-5 MPa for 60 days) and some seedling tissues as well (-5 MPa for 270 days). Furthermore, roots and seedlings continued to develop from apparently necrotic tissue on the seed surface, showing that, when necessary, these seeds use their mechanism of formation of new roots and seedlings to ensure species survival under water stress conditions.