Consequence Of Water Stress Research Articles

Drought adaptability of different subspecies of tetraploid wheat (Triticum turgidum) under contrasting moisture conditions: Association with solvent retention capacity and quality-related traits.

Few prior efforts have been made to investigate the genetic potential of different subspecies of Triticum turgidum for drought tolerance and their quality-related traits compared with common wheat (Triticum aestivum) and to identify the association among agronomic, micronutrients, and quality-related traits, especially under climate change conditions. In this research, grain quality, technological properties of flour, and some agronomic traits were studied in 33 wheat genotypes from six different subspecies of Triticum turgidum along with three cultivars of Triticum aestivum in the field, applying a well-watering (WW) and a water stress (WS) environment during two growing seasons. A high degree of variation was observed among genotypes for all evaluated traits, demonstrating that selection for these traits would be successful. Consequences of water stress were manifested as declined DM, GY, and LASRC; and significantly increased GPC, K+/Na+, WAF, WSRC, SuSRC, and SCSRC compared to the well-watering condition. The reductions in the unextractable polymeric protein fraction and glutenin-to-gliadin ratio indicated a poorer grain yield quality, despite higher protein content. This study showed that the early-maturing genotypes had higher water absorption and pentosan, and therefore were more suitable for bread baking. In contrast, late-maturing genotypes are ideal for cookie and cracker production. Two subspecies of T. turgidum ssp. durum and T. turgidum ssp. dicoccum with high micronutrient densities and quality-related traits, and T. turgidum ssp. oriental due to having high values of grain protein content can be used to improve the quality of T. aestivum through cross-breeding programs. Based on the association of different traits with SRC values and other quality-related traits and PCA results, contrasting genotypes can be used to develop mapping populations for genome studies of grain quality and functional properties of flour in future studies.

Evaluation of the LSA-SAF gross primary production product derived from SEVIRI/MSG data (MGPP)

The objective of this study is to describe a completely new 10-day gross primary production (GPP) product (MGPP LSA-411) based on data from the geostationary SEVIRI/MSG satellite within the LSA SAF (Land Surface Analysis SAF) as part of the SAF (Satellite Application Facility) network of EUMETSAT.The methodology relies on the Monteith approach. It considers that GPP is proportional to the absorbed photosynthetically active radiation APAR and the proportionality factor is known as the light use efficiency ε. A parameterization of this factor is proposed as the product of a εmax, corresponding to the canopy functioning under optimal conditions, and a coefficient quantifying the reduction of photosynthesis as a consequence of water stress. A three years data record (2015–2017) was used in an assessment against site-level eddy covariance (EC) tower GPP estimates and against other Earth Observation (EO) based GPP products. The site-level comparison indicated that the MGPP product performed better than the other EO based GPP products with 48% of the observations being below the optimal accuracy (absolute error < 1.0 g m−2 day−1) and 75% of these data being below the user requirement threshold (absolute error < 3.0 g m−2 day−1). The largest discrepancies between the MGPP product and the other GPP products were found for forests whereas small differences were observed for the other land cover types. The integration of this GPP product with the ensemble of LSA-SAF MSG products is conducive to meet user needs for a better understanding of ecosystem processes and for improved understanding of anthropogenic impact on ecosystem services.

Changes in essential oil-content and composition of ajowan ( Carum copticum L.) seeds in response to growth regulators under water stress

Abstract Two separate field experiments were conducted in 2014 and 2015. In 2014 changes in essential oil content and in 2015 changes in essential oil composition of ajowan seeds in response to water tress and growth regulators were investigated. The experiments were arranged as split plot based on RCB design in three replicates, with irrigation treatments in main plots and foliar sprays of water (control), salicylic acid (SA) (0 and 1 mM) and abscisic acid (ABA) (0 and 50 μM) in sub plots. In 2014, seeds were harvested in weekly intervals at six stages. With progressing seed development, seeds per plant, seed weight and seed yield enhanced, leading to an increase in essential oil yield, despite decreasing essential oil percentage and per seed. Essential oil percentage increased, but seed and essence yields decreased as a consequence of water stress in both years. Foliar application of ABA and especially SA enhanced essence yield of ajowan seeds via increasing seed yield and essence content. About 70 compounds were identified in essential oil of ajowan seeds, some of which only induced by the water stress and hormonal treatments. Thymol and γ-terpinene were the major constituents of seed essential oil. The terpineol, trans-carveol and tetrathiapentacene were only induced by water stress. The cyclopropane, trans-decalone-1, isopulegone, hexadecanoic acid, linalool and 1-decanol, 2-hexyl- were specifically synthesized in SA treated plants, and β-phellandrene, 3-fluoro-dl-phenylalanine and 1,5-dimethylbicyclo[3.2.1]octane were only found in ABA treated plants. In general, water stress reduced most of the essential oil components, but foliar spray of SA and ABA enhanced percentages of many constituents and their yield per unit area.

Improving oil and flavonoid contents of milk thistle under water stress by salicylic acid

Adverse environmental conditions such as water deficit can limit production. However, some of these adverse effects may be overcome by application of plant growth regulators including salicylic acid (SA). Thus, a field experiment was conducted in 2015 to evaluate the effects of SA (0 and 1 mM l-1) on yield components, seed yield and oil and flavonoid contents of milk thistle (Silybum marianum L.) under different irrigation treatments (I1, I2, I3 and I4: irrigation after 70, 110, 150 and 190 mm evaporation from class A pan, respectively). The experiment was arranged as split-plot based on randomized complete block (RCB) design in three replicates. Irrigation treatments and SA levels were located in the main and sub plots, respectively. The results indicated that plant biomass, seeds per plant, 1000 seed weight, seed yield per unit area and harvest index of milk thistle decreased as a consequence of water stress. Oil percentage and yield were also reduced, but flavonoid content enhanced with increasing water deficit. All these traits were considerably augmented by foliar application of SA under non-stress and stressful conditions. Therefore, it was conclude that SA can be used to improve field performance of milk thistle under different environmental conditions.

Efeito responsivo de mudas de paricá ao estresse hídrico

The present study objective was identifying mechanisms of response to water deficit of paricá seedlings. The experiment was conducted in a greenhouse, in 8-liter pots, with substrate consisting of soil (dystrophic Red-Yellow Latosol), in randomized block design, with five different irrigations based on the evapotranspiration of the plants (20, 40, 60, 80 and 100%), with six replications. The plants were irrigated daily, with a water volume corresponding to 100% of the evapotranspired water, and, at 90 days after germination, subjected to ten days of water deficit, after that irrigated during ten days with the different percentages of evapotranspiration, then evaluated. The following variables were measured: number of leaves (NL), plant height (PH), stem diameter (SD), total biomass (TB), total daily transpiration (TDT), total chlorophyll (TC), carotenoids (CAR), root mass ratio (RMR), leaf mass ratio (LMR) stem mass ratio (SMR). Concluded that paricá seedlings response to water deficit with slowing down of dehydration, with reduction of content of carotenoids and increase in root volume. As a consequence of water stress, they reduce the number of leaves, stem diameter, plant height, and, of course, total biomass, aiming at maintaining the internal water, indicating low ability to tolerate stress.

VEGETATIVE AND PRODUCTIVE RESPONSE OF YOUNG 'WILLIAMS' PEAR TREES TO REGULATED DEFICIT IRRIGATION (RDI), MULCHING AND THEIR COMBINATIONS

This field experiment was designed to assess the vegetative and productive response of young ‘Williams’ pear trees to regulated deficit irrigation (RDI), mulching and their combinations with the aim of optimising such parameters. Using a water budged methodology, four levels of irrigation, specifically 100% of ET (control) and deficits of 80, 60 and 40%, were applied to 10 trees, 5 of which were mulched by a 10 cm layer. The experiment was conducted in Kosovo (Dukagjini Plain) during 2013 on a pear orchard of 10 ha in third year using a nested experimental design. Using ANOVA two-way with post hoc testing we found significant changes in a series of vegetative and productive parameters. Irrigation levels significantly influenced leaf surface and area, shoot length, total number of fruit and their weight and consequently total yield. In addition, mulching had a positive effect on all parameter values, in particular on shoot length and fruit diameter during all their growth but more remarkably in the third stage. RDI and mulching had a combined effect on shoot length and canopy volume while changes were not significant for number of leaves, number of shoots, number of fruits of extra class and first class. Considering the young age of trees and long-term consequences of water stress the experiment will be continued.

Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency.

Leaf senescence in winter deciduous species signals the transition from the active to the dormant stage. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. Photoperiod and temperature are the main cues controlling leaf senescence in winter deciduous species, with water stress imposing an additional influence. Photoperiod exerts a strict control on leaf senescence at latitudes where winters are severe and temperature gains importance in the regulation as winters become less severe. On average, climatic warming will delay and drought will advance leaf senescence, but at varying degrees depending on the species. Warming and drought thus have opposite effects on the phenology of leaf senescence, and the impact of climate change will therefore depend on the relative importance of each factor in specific regions. Warming is not expected to have a strong impact on nutrient proficiency although a slower speed of leaf senescence induced by warming could facilitate a more efficient nutrient resorption. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. The overall effects of climate change on nutrient resorption will depend on the contrasting effects of warming and drought. Changes in nutrient resorption and proficiency will impact production in the following year, at least in early spring, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling, especially if the changes are consequence of water stress.

The fitness of the environments of air and water for photosynthesis, growth, reproduction and dispersal of photoautotrophs: An evolutionary and biogeochemical perspective

Life has evolved to exploit aquatic and terrestrial environments, but these present very different challenges and opportunities for photoautotrophs. This paper outlines how the physical and chemical ‘fitness’ of air and water have interacted with the evolution of the physical structures and physiological properties of aquatic and terrestrial algae and plants and altered the biogeochemistry of the planet. The two environments are particularly different for photosynthesis and the consequences of water stress in air and potential carbon and light stress under water are discussed, as are the consequences of the lower density of air compared to water for investment in support. The properties of air and water also affect mineral nutrition, reproduction and dispersal of photoautotrophs and the nature of competition between different types of plants. Furthermore, the pivotal role of photoautotrophs in global biogeochemical cycles and major feedbacks are emphasised. They have altered the environment dramatically, changed the availability of essential resources and created niches that can be exploited by new or different species or types of organism. Recent rapid anthropogenic changes, particularly in CO2, are noted and discussed in relation to the security of human requirements.

Rainfall intensifies fruit peel cracking in water stressed pomegranate trees

The purpose of the present study was to study the relationship between the leaf and fruit water relations of pomegranate plants at different water deficit levels during the end of the fruit growth and ripening phases. Moreover, special attention was paid to analysing whether the effect that rainfall has on peel cracking of pomegranate fruits growing in water deficit conditions is associated with changes in turgor within the fruit. For this, field-grown adult pomegranate trees (Punica granatum L.) cv. Mollar de Elche were subjected to five irrigation treatments. During the growing season, control plants (treatment T0) were irrigated above crop water requirements. During the experimental period (DOY 247–283), T1, T2, T3, and T4 treatments were irrigated as T0 except for 6 (DOY 277–283), 15 (DOY268–283), 25 (DOY258–283) and 36 (DOY247–283) days before harvest (DOY 283), respectively, when irrigation was withheld. Rain fell on DOY 270 (3.5mm), DOY 271 (84mm) and DOY 272 (0.9mm), totalling 88.4mm. During the experiment, total ETo was 162mm, and the total amount of water received was 128, 110, 86, 49 and 0mm for T0, T1, T2, T3 and T4, respectively, without considering precipitation. The results indicated that during the end of fruit growth and ripening phases pomegranate fruit was clearly sensitive to water deficit. During these phenological periods water could enter the fruits via the phloem rather than via the xylem. Despite this, T3 and T4 plants reached much more severe water stress levels than those reported in the literature, although leaf turgor was maintained. However, in all treatments fruit turgor was lost as a consequence of water stress, which induced a reduced expansion of fruits. When rainfall affected previously water stressed pomegranate plants an asymmetric increase in fruit turgor pressure took place, because aril turgor increased to a much greater extent than peel turgor, the pressure of the arils on the peel favouring cracking

Sustained deficit irrigation affects the colour and phytochemical characteristics of pomegranate juice

No information exists on the consequences of water stress on the pomegranate (Punica granatum L.) tree in terms of the quality and health/nutritional properties of its juice. In this study the influence of two different sustained deficit irrigation treatments on the colour, antioxidant activity and total phenolic compound, total anthocyanin, punicalagin and ellagic acid contents of pomegranate juice was assessed. Control plants were irrigated at 75% ETo (crop reference evapotranspiration) in order to ensure non-limiting soil water conditions, while others were subjected to sustained deficit irrigation at 43 and 12% ETo throughout the experimental period. Both moderate (43%) and severe (12%) water stress treatments led to pomegranate juices with a more yellowish colour, lower antioxidant activity and lower total phenolic compound, punicalagin and total anthocyanin contents than those from control plants. Pomegranate juice from trees under sustained deficit irrigation was of lower quality and less healthful than that from trees without water stress. From a nutritional point of view, this means that a reduction in irrigation provides a dramatic decrease in bioactive phenolic compounds, especially anthocyanins and punicalagin, and consequently a lower visual attraction of the juice owing to the weak red colour of the fruit.

Antioxidant content in two CAM bromeliad species as a response to seasonal light changes in a tropical dry deciduous forest

Plants have evolved photoprotective mechanisms to limit photodamage; one of these mechanisms involves the biosynthesis of antioxidant metabolites to neutralize reactive oxygen species generated when plants are exposed to excess light. However, it is known that exposure of plants to conditions of extreme water stress and high light intensity results in their enhanced susceptibility to over-excitation of photosystem II and to photooxidative stress. In this investigation we used the 2,2-diphenyl-1-picrylhydrazyl reduction assay to conduct a broad survey of the effect of water availability and light exposure conditions on the antioxidant activity of the leaf extracts of two bromeliad species showing crassulacean acid metabolism. One of these was an epiphyte, Tillandsia brachycaulos, and the other a terrestrial species, Bromelia karatas. Both species were found growing wild in the tropical dry deciduous forest of Dzibilchaltún National Park, México. The microenvironment of T. brachycaulos and B. karatas experiences significant diurnal and seasonal light variations as well as changes in temperature and water availability. The results obtained showed that, for both bromeliads, increases in antioxidant activity occurred during the dry season, as a consequence of water stress and higher light conditions. Additionally, in T. brachycaulos there was a clear correlation between high light intensity conditions and the content of anthocyanins which accumulated below the leaf epidermis. This result suggests that the role of these pigments is as photoprotective screens in the leaves. The red coloration below the leaf epidermis of B. karatas was not due to anthocyanins but to other unidentified pigments.

Growth, biochemical modifications and proline metabolism in Helianthus annuus L. as induced by drought stress

In the present investigation, two watering treatments, viz., 100% and 60% field capacity (FC) were used to understand the effects of water deficit on early growth, biomass allocation, pigment and biochemical constituents and proline metabolism of five varieties of Sunflower ( Helianthus annuus L.) plants. We found that there was a significant difference in early growth, dry matter accumulation, pigment, biochemical constituents and proline metabolism among the five varieties. The root length, shoot length, total leaf area, fresh and dry weight, chlorophyll a, b, total chlorophyll and carotenoid were significantly reduced under water stress treatments. Water stress increased the proline, free amino acid and glycinebetaine contents along with increased activity of γ-glutamyl kinase but the activity of proline oxidase reduced as a consequence of water stress.

Effects of available soil volume on growth, bud fertility and water relations of young Shiraz grapevines

Effects of available soil volume (ASV) on growth, water relations and bud fertility of drip-irrigated Shiraz grapevines (Vitis vinifera) were examined during their establishment in the 2000/01 growing season under field conditions in the Goulburn Valley, Australia. Vines were planted into different size subterranean containers to create a range of confined ASV treatments (viz. 0.15, 0.4, 0.8 and 1.2 m3/vine referred to as ASV15, ASV40, ASV80 and ASV120, respectively) and compared with a deep ripped treatment where the ASV was unconfined (ASVUC). Pruning weight, trunk cross-sectional area, and daily average fractional photosynthetically active radiation interception (fdaily) increased with increasing ASV but were lowest in the ASVUC treatment. fdaily attained a maximum by mid-February 2001 in ASV15 but continued to increase in all other treatments. Water relations data showed high leaf water potential (?leaf) in ASV15 compared to the other treatments. Our results suggest that reduced growth in smaller soil volumes was not a consequence of water stress. Leaf conductance (gL) tended to be low in the ASV15 treatment in comparison with the ASVUC treatment. Increasing ASV from 0.15 to 1.2 m3/vine increased the number of bunches per vine in the following season by 32%. This increase was not due to improvement in the number of bunches per shoot, but resulted from an increased number of shoots bursting per node. By contrast, ASVUC significantly reduced bud fertility. The implications of these results for vine establishment in shallow soils are discussed.

Atividade fotossintética e peroxidação de lipídios de membrana em plantas de aroeira-do-sertão sob estresse hídrico e após reidratação

Avaliaram-se os efeitos do estresse hídrico e da reidratação sobre parâmetros de fluorescência, condutância estomática e peroxidação de lipídios em plantas de Myracrodruon urundeuva Fr. All. (Anacardiaceae). As plantas foram cultivadas em casa de vegetação e a seca foi induzida por suspensão da irrigação durante 14 dias. Sob estresse hídrico, observou-se queda acentuada no conteúdo relativo de água foliar, o qual alcançou valores próximos a 60 %. Essa queda foi acompanhada por grande diminuição na condutância estomática e na taxa aparente de transporte de elétrons (ETR) e extensivos danos às membranas evidenciados por aumentos na peroxidação de lipídios. Apesar do decréscimo nos valores de ETR, não se observaram alterações nos valores do rendimento quântico potencial do fotossistema II (Fv/Fm) em conseqüência do estresse hídrico. Durante a fase de recuperação, as plantas apresentaram valores de condutância estomática, parâmetros de fluorescência e peroxidação lipídica similares àqueles verificados antes do período de seca. Todos os parâmetros fotossintéticos investigados mostraram valores normais 6h após o início de reidratação. O ajuste linear entre os valores de condutância e ETR mostrou alta correlação entre essas duas variáveis, sugerindo que os estômatos representam o principal fator limitante da fotossíntese em plantas de Myracrodruon urundeuva sob estresse hídrico.

The influence of water deficits on mRNA levels in tomato

Abstract. The levels of particular mRNAs in tomato leaves are altered in response to water stress. Certain transcripts appear as a consequence of the stress whereas others diminish in abundance. These changes were analysed by cell‐free translation of leaf RNA followed by two‐dimensional polyacrylamide gel electrophoresis of the translation products. Within 20 min of the onset of reduced leaf water potential in detached leaflets, stress‐induced mRNAs appear in the transcript population. Other mRNAs accumulate more slowly and include among their in vitro translation products a prominently labelled group of polypeptides of about 18–19 kD. These transcripts are recovered from detached leaflets incubated for 2 and 8h at low water potential and from leaflets of intact plants that were stressed in situ for 10d. An additional water stress‐induced mRNA that encodes a 64‐kD polypeptide is detected in the transcript population from detached leaflets when [3H]glycine is used in place of [35S]methionine in the cell‐free translations. Among the transcripts that decline in abundance as a consequence of water stress is an mRNA that encodes the small subunit of ribulose‐1,5‐bisphosphate carboxylase. Within 2h of rewatering stressed plants, certain mRNAs that were lost from the population return and those in the 18–19 kD range that are associated with the stress are not detectable.

Ethylene and water stress

ABSTRACTLike some other growth regulators, internal ethylene levels in plants fluctuate as a consequence of water stress and this phenomenon may be responsible for some of the developmental responses which result. Current work seeks to determine how internal ethylene levels are controlled, i.e. by biosynthesis, translocation, diffusion out of the plant or metabolism. The levels of other growth regulators in the same tissue are also being investigated in relation to the changes in internal ethylene.