Days Of Water Restriction Research Articles

Direct somatic embryogenesis on Coffea arabica L. explants previously subjected to water restriction

Somatic embryogenesis can occur either directly or indirectly. However, Coffea arabica genotypes respond inefficiently to direct somatic embryogenesis. In this way, explants of this species form small embryogenic structures (pre-embryogenic masses) and a few somatic embryos. Studies have shown that the intensity of the osmotic potential can either favor or hinder the somatic embryogenesis response in different species. Plant tissue subjected to water restriction presents a reduction in osmotic potential. Therefore, this study aimed to evaluate the direct somatic embryogenesis response of leaf explants from four genotypes of C. arabica, which were previously subjected to 0, 1, 2, 3, 4 and 8 days of water restriction. At time 0, the explants had an average humidity of 70 %, which decreased to approximately 40 % after 8 days of water restriction. Somatic embryo formation occurred in explants subjected to up to 3 days of water restriction and there was no response in those with 4 and 8 days without hydration. Explants with low intensity osmotic potential of up to -0.8 MPa formed somatic embryos, whereas this response was reduced or inhibited in those with a more negative osmotic potential. However, explants with an osmotic potential equal to or less than -1.6 MPa formed larger embryogenic structures, which is desirable as they also give rise to somatic embryos. Thus, the direct somatic embryogenesis response of C. arabica is influenced by the intensity of the osmotic potential in the explant tissue.

#1408 Dehydration cannot substitute for any of the triple whammy drugs to cause acute kidney injury

Abstract Background and Aims Polymedication in patients with chronic diseases, such as hypertension, can lead to undesired drug interactions. The combination of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) with diuretics and non-steroidal anti-inflammatory drugs (NSAIDs) can cause triple whammy (TW)-induced acute kidney injury (TW-AKI). Up to 9% of hypertensive patients used NSAIDs in combination with ACEIs / ARBs and diuretics. AKI has a mortality rate of 40% and TW increases the risk of AKI by 30% compared to the combination of only two drugs. In addition, TW-AKI is associated with other risk factors such as dehydration, which may exacerbate the injury. Consequently, the aim of our study was to determine whether dehydration combined with two of the TW drugs could induce AKI in an in vivo experimental model. Method Three months old male Spontaneously Hypertensive Rats (SHR) were divided into four experimental groups: control group (CT); TW group (TW), which received four days of double therapy with trandolapril and furosemide, followed by a triple therapy for two days with trandolapril, furosemide and ibuprofen; trandolapril and ibuprofen group (T+I), which received four days of trandolapril followed by two days of trandolapril and ibuprofen; furosemide and ibuprofen group (F+I), which received four days of furosemide followed by two days of furosemide and ibuprofen; and trandolapril and furosemide group (T+F), which received six days of trandolapril and furosemide. All groups were subjected to a 60-70% water restriction of basal intake (i.e. 15 mL/day) to generate mild dehydration. Blood and urine samples were collected at baseline (B), day 4 and day 6. Blood pressure was measured at baseline and day 4. Renal function was assessed by plasma creatinine, plasma urea and creatinine clearance, and hydration status was determined by plasma osmolarity and water balance (i.e. water intake minus urine flow). Results Under basal conditions, all rats were hypertensive. The combination of trandolapril and furosemide significantly reduced the mean blood pressure on day 4 (p = 0.0066), while trandolapril or furosemide alone did not achieve these decreases. After four days of water restriction to 15 mL/day, all groups showed mild dehydration with a decrease in water balance and an increase in plasma osmolarity by. Plasma creatinine and plasma urea values were only increased on day 6 in the TW group (p = 0.0009 and p = 0.02, respectively). Creatinine clearance was also clearly reduced in the TW group (p = 0.0004). F+I and T+F groups showed slight decreases in creatinine clearance at day 6, as well as slight increases in plasma urea. However, these changes were not as pronounced as those observed in the TW group. Conclusion In our in vivo model of TW-AKI, mild dehydration cannot replace any of the TW drugs, although it appears that combination of F+I and T+F in dehydrated rats slightly alter plasma urea and creatinine clearance values at day 6, suggesting that this condition maintained over time might lead to the development of AKI. Funding This research was funded by grants from Instituto de Salud Carlos III (ISCIII), Ministerio de Ciencia e Innovación (PI21/01226 and PI21/00548 co-funded by the European Union; and RICORS2040, RD21/0005/0004, co-funded by the European Union—NextGenerationEU, Mecanismo para la Recuperación y la Resiliencia (MRR)) and from Consejería de Educación, Junta de Castilla y León (IES160P20), co-funded by FEDER funds. Noelia Diaz-Morales is recipient of a Juan de la Cierva-Formación postdoctoral contract (FJC2020-043205-I) funded by MCIN/AEI/10.13039/501100011033 and the European Union “NextGenerationEU/PRTR”. Eva M. Baranda-Alonso is recipient of a predoctoral fellowship from the Junta de Castilla y Leon (Spain) and the European Social Fund from the European Commission.

Influences of calcium silicate fertilization to physiological and bio-active responses of maize under drought and well-watered conditions

A pot experiment was conducted to investigate the effects of silicon (Si) on morpho-physiological and bio-chemical traits of maize under different irrigation regimes. Experimental treatments comprised of irrigations [60% and 100% of field capacity (FC)], treatments (0, 50, 100, 150, 200 mg kg−1 CaO4Si) and growing stages (GS) [7th (first) and 14th (second) days of water restriction]. 150 mg kg−1 Si increased the growth of maize by inducing transpiration rate (67.56%), water use efficiency (138.36%) and seedling length (19.83%) at first GS whilst enhanced carotenoids (10.95%), total phenolic compounds (45.04%) and decreased proline (7.87%) at the second GS of 60% treatment. In addition, 200 mg kg−1 Si elevated photosynthesis rate (40.54%), total antioxidant activity (12.69%) and decreased proline (52.77%) at the first GS while increased total anthocyanin content (14.99%) during the second GS of 60% application. Silicon had positive impacts on maize under full irrigation conditions too such that 150 mg kg−1 Si reduced transpiration rate (48.43%) and induced total antioxidant activity (39.95%) at first GS while 200 mg kg−1 Si increased water use efficiency by 144.30% at the second GS. In conclusion Si increased drought resistance due to increasing application doses, and on contrary of the literature, Si positively affected many characters at well-watered environment.

O ácido salicílico alivia o estresse hídrico no aparato fotoquímico e qualidade das mudas de Schinus terebinthifolia

ABSTRACT Water deficit adversely affects photosynthetic pigment synthesis, photochemical processes, and seedling quality. Exogenous foliar application of salicylic acid (SA) is hypothesized to contribute to photochemical regulation and increase stress tolerance. This study aimed to evaluate the effect of SA in alleviating the effects of water deficit stress on the photosynthetic photochemical activities and quality of Schinus terebinthifolia Raddi. seedlings. The seedlings were subjected to four regimes of water deficit: 0, 4, 8, and 12 days of water restriction (DWR), associated with the application of four concentrations of SA: 0, 50, 100, and 200 mg L-1 (via foliar spray; 10 mL per plant) during 48 days. Growth of S. terebinthifolia seedlings was adversely affected by longer duration of water restriction in absence of SA treatment. However, application of 200 mg L-1 of SA increased photosynthetic pigment levels, photochemical quantum efficiency in photosystem II, and absorbed energy conversion efficiency in seedlings under 12 DWR. The seedling quality was better at 7 and 12 DWR when associated with application of 100 and 200 mg L-1 SA, respectively. The exogenous application of SA contributed positively to pigment concentration and photochemical stability of photosynthesis, and it improved the quality of S. terebinthifolia seedlings subjected to long water restriction periods.

Stomatal conductance tracks soil-to-leaf hydraulic conductance in faba bean and maize during soil drying.

Although regulation of stomatal conductance is widely assumed to be the most important plant response to soil drying, the picture is incomplete when hydraulic conductance from soil to the leaf, upstream of the stomata, is not considered. Here, we investigated to what extent soil drying reduces the conductance between soil and leaf, whether this reduction differs between species, how it affects stomatal regulation, and where in the hydraulic pathway it occurs. To this end, we noninvasively and continuously measured the total root water uptake rate, soil water potential, leaf water potential, and stomatal conductance of 4-week-old, pot-grown maize (Zea mays) and faba bean (Vicia faba) plants during 4 days of water restriction. In both species, the soil-plant conductance, excluding stomatal conductance, declined exponentially with soil drying and was reduced to 50% above a soil water potential of -0.1 MPa, which is far from the permanent wilting point. This loss of conductance has immediate consequences for leaf water potential and the associated stomatal regulation. Both stomatal conductance and soil-plant conductance declined at a higher rate in faba bean than in maize. Estimations of the water potential at the root surface and an incomplete recovery 22 h after rewatering indicate that the loss of conductance, at least partly, occurred inside the plants, for example, through root suberization or altered aquaporin gene expression. Our findings suggest that differences in the stomatal sensitivity among plant species are partly explained by the sensitivity of root hydraulic conductance to soil drying.

Arbuscular mycorrhizae alleviate water deficit in Dipteryx alata Vogel: seedling quality and resilience

Dipteryx alata Vogel (Fabaceae) is a fruit tree species native to the Cerrado with ecological and economic potential. However, a water deficit can be a limiting factor to the initial growth of this species, requiring knowledge on technologies that can alleviate this stressful effect. We hypothesized that inoculation with arbuscular mycorrhizae fungi contributes to stress mitigation during and after water deficit. Dipteryx alata seedlings were subjected to two water regimes (control: seedlings irrigated daily; and water deficit: irrigation suspension), associated with inoculation with arbuscular mycorrhizal fungi (AMF) (AM–, without inoculation; AM+, inoculation with Rhizophagus clarum), and three evaluation periods (T0, time zero; F0, zero photosynthesis (7 days of water restriction); REC, recovery (100 days)). Water deficit impaired water relations, decreasing the quality of D. alata seedlings. AM+ seedlings showed higher relative water content (RWC), leaf area ratio, chlorophyll index, and Rubisco carboxylation capacity (A/Ci), which helped in photosynthetic metabolism. Inoculation with R. clarum alleviated the impact of stress on water use efficiency, water potential, RWC, and A/Ci in REC. Inoculation with AMF is a promising management technique in the production of D. alata seedlings for increasing seedling quality and resilience to water deficit.

Performance of Hevea brasiliensis under drought conditions on osmoregulation and antioxidant activity through evaluation of vacuolar invertase and reducing sugars

Rubber tree cultivation is limited in many regions by abiotic factors such as drought. We investigated the biochemical mechanisms responsible for responses to, and recovery from, drought conditions during the establishment phase of four high latex producing rubber tree clones (RRIM600, IAC40, PR255 and GT1). Five-month-old plants were exposed to 32 days of water restriction, followed by 15 days of soil rehydration. Leaf area, as well as their osmolyte accumulations, saccharolytic enzyme activity, and oxidative stress markers, were accompanied. Although clones IAC40 and PR255 responded more precociously to drought conditions, halting leaf expansion before clones GT1 and RRIM600, they demonstrated slow recuperation after reestablishing irrigation. The greater tolerances of clones RRIM600 and GT1 to drought conditions were related to greater vacuolar invertase (VINV) activity in their leaves, which guaranteed more significant accumulations of vacuolar reducing sugars (RS). Similar to RS, glycine betaine accumulations were related to osmoprotection and to reducing oxidative damage (lipidic peroxidation) caused by water deficit conditions. The observed decreases in cytosol neutral invertase (AINV) and cell wall insoluble invertase (CWINV) activities, which resulted in cytosol hexose decreases, may be related to increases in antioxidant enzyme (superoxide dismutase and ascorbate peroxidase) activities in the leaves in response to water deficit conditions. As such, the introduction of specific sugars (RS) and the modulation of key carbon metabolism enzymes, such as VINV, are promising strategies for promoting drought tolerance in rubber tree clones.

Water status response of pineapple using destructive and non-destructive indicators and their relations in two contrasting seasons

Abstract The use of indicators to assess the water status of pineapple grown inside greenhouses is essential to obtain higher yields. Although destructive and non-destructive indices are widely applied to monitor several crops, there are no previous reports that evaluate their response to different seasons or the relationship between the indicators and the water status of pineapple plants. The experiment was conducted during the warm and cold seasons, comparing two treatments: plants irrigated to field capacity (FC) and non-irrigated (NI). The water status was measured using a destructive index, Relative Water Content (RWC), and non-destructive indices, Normalized Difference Vegetation Index (NDVI), and Stress Degree Day (SDD). The environmental conditions monitored were temperature, humidity, and photosynthetically active radiation (PAR). At the end of each season, plant biomass and assimilate partitioning (AP) were also determined. The recovery of the NI treatment by irrigation was measured using NDVI and RWC. In the cold season, differences between treatments were detected after 45 days of water restriction by NDVI, while in the warm season, the RWC index found differences a week after the experience began (p

Juvenile plants of an epiphytic bromeliad exhibit rapid changes in carbohydrate content and antioxidant capacity to cope with water withholding

Global warming reduces water availability, exposing plants to more pronounced wet/dry cycles during their lifetime. Under these circumstances, epiphytic bromeliads can be more responsive due to their lack of contact with soil and high dependence on atmospheric water, especially in the case of juvenile individuals, which lose water more intensely than conspecific adults. In this study, we hypothesized that juvenile plants of Acanthostachys strobilacea (Schult. & Schult.f.) Klotzsch would exhibit rapid metabolic defense mechanisms to tolerate the leaf water loss caused by short-term water withholding (i.e. mild to moderate stress). We exposed plants to an 8-day water restriction and assessed their enzymatic antioxidant capacity and carbohydrate content. At 4 days of water restriction, A. strobilacea plants showed starch mobilization and increased the soluble carbohydrate content. After 8 days, carbohydrate reserves were depleted and the antioxidant enzyme activity was stimulated. Our results demonstrated that juvenile epiphytic bromeliads exhibit rapid metabolic adjustments to short-term water deficiency, which might be crucial for their survival in the face of the expected intensification of drought.

Evaluation of wheat events transformed with the p5cs gene under conditions of water stress

The enzyme ∆1-pyrroline-5-carboxylate synthetase (P5CS), encoded by the p5cs gene, is the rate-limiting step for proline biosynthesis, which acts as an osmoprotectant. The launch of transgenic commercial varieties depends on physiological and phenotypic characterization of events. The objective of this study was to evaluate five p5cs gene events (591, 14, 326, 164, 312), through physiological analyses and production rates during droughts. Plants of events and irrigated (IC) and stressed controls (SC) in flowering stage were submitted to 16 days of complete water restriction. The following elements were evaluated: relative water content (RWC); malondialdehyde concentration (MDA%); membrane stability index (MSI%); proline content; and production rates. As a result, the effect of water stress was only perceived after 12 days of water restriction with a decrease in the RWC values. Transgenic plants showed higher proline levels on the 16th day, compared to the SC (33 to 62%). The levels of MDA were lower on the 12th and 16th days for all the plants evaluated, but the MSI were similar to the IC for the events 591, 326, and 164, demonstrating the osmoprotectant effect. However, higher levels of proline did not result in higher production rates in the transgenic plants.

Small Differences in Rehydration Volume Affect 24h Urinary Concentration

OBJECTIVESub‐optimal water intake may be unavoidable in certain occupations, or when access to water is limited. Additionally, some individuals chronically consume low fluid volumes ad libitum despite free access to water. In all of these situations, low urine volume and high concentration indicate insufficient water intake. Therefore, the purpose of the current study was to evaluate the impact of various volumes of increased water intake on 24h urinary hydration biomarkers (volume, Uvol; specific gravity USG; and osmolality, Uosmo) following three days of water restriction.METHODS115 participants [56 women (31±9 y, 166±7 cm, 65±12 kg, 34±8 %BF); 59 men (32±8 y, 180±7 cm, 83±18 kg, 22±8 %BF)] volunteered to record all food and beverages consumed over 11 days (d). On d 1 through 7, participants consumed food and beverages ad‐libitum. On d 8 through 10, participants were restricted to 1 L of plain water in addition to their habitual food intake. On d 11, participants were randomly assigned to maintain plain water intake at 1 L (Wbev+0) or into one of four intervention groups in which plain water intake increased to 1.5 L (Wbev+0.5), 2.0 L (Wbev+1.0), 2.5 L (Wbev+1.5), or 3.25 L (Wbev+2.25). 24 h urine collections were completed at baseline (d 3), during fluid restriction (d 9 and 10), and during the increased water intake (d 11). Repeated measures ANOVA was utilized to determine the effect of the water restriction and the increased intakes on urinary hydration biomarkers. Within group, paired sample t‐tests were used post‐hoc to determine if urinary biomarkers returned to baseline values.RESULTSNo differences existed between any groups for demographic or habitual intake variables at baseline (all F[4,114] < 1.5, all P >.206). Fluid restriction (d 8–10) resulted in decreased total fluid and total water intake (food & fluids) similarly in all groups (from 2652±1168 to 1006±59 mL·d−1 and from 3326±1224 to 1763±349 mL·d−1, respectively; F[3,330] = 229.7, P < .001 and F[3,330] = 194.3, P < .001). Correspondingly, urinary hydration biomarkers changed equally within all groups (all F[4,110] < 0.7, all P >.653), 24h Uvol (−1068±858 mL), USG (+0.009±0.006), and Uosmo (+340±233 mOsm·kg−1). Significant group X time interactions revealed that different increased water intake volumes resulted in different changes in Uvol, USG and Uosmo (all F[4,110] > 10.7, all P <.001). Follow up t‐tests demonstrated that all urinary biomarkers returned to baseline in Wbev+1.5 and Wbev+2.25 (all |t|< 1.6, all P >.126), while in Wbev+0, Wbev+0.5, and Wbev+1.0 urinary variables remained significantly elevated (all |t|> 2.8, all P <.011).CONCLUSIONThe current analysis quantifies the changes in 24h urinary biomarkers that can be expected in response to different increases in daily water intake when starting from a similar degree of under‐hydration. These results can be used to help educate individuals who notice their urine concentration increasing in order to assist with properly adjusting water intake following days of low water intake or after situations where access to water is limited.Support or Funding InformationFunding for data collection provided by Danone Research, Palaiseau, FranceThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Chemical control of morning glory as a function of water restriction levels

Among the herbicides recommended for the dry season and registered to sugarcane crop, amicarbazone, isoxaflutole and the association diuron + hexazinone + sulfomethuron-methyl can be highlighted. These are pre-emergence herbicides efficient against broad-leaved weeds. Morning glory causes large losses in infested sugarcane fields by bending the stalks and interfering in harvesting. In this study the effectiveness of pre-emergence herbicides for two species of morning glory (Ipomoea hederifolia and Ipomoea grandifolia) was evaluated. Treatments were arranged in completely randomized factorial design (4 x 7). There were four periods of water restriction (0, 30, 60 and 90 days), seven chemical treatments [diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1507.5 + 425 + 36.25 g a.i. ha-1), diuron + hexazinone + sulfometuron-methyl (1658.25 + 467.5 + 39.87 g a.i. ha-1), diuron + hexazinone + sulfometuronmethyl (1809 + 510 + 43.5 g a.i. ha-1), amicarbazone (1190 g a.i. ha-1), amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha-1)] and a control with no application. At 7, 14, 21 and 28 days after the restoration of moisture, control was visually evaluated. After the final evaluation, the dry mass of morning glories was measured. At 90 days of water restriction, diuron + hexazinone + sulfometuron-methyl was more effective to control I. hederifolia than the amicarbazone + isoxaflutole tank mixture. The four diuron + hexazinone + sulfometuronmethyl doses have reduced morning glory dry mass to zero; whereas treatments with amicarbazone have not. The most effective treatment for morning glory control was diuron + hexazinone + sulfometuron-methyl. This result may be due to a possible synergistic interaction.

Procedures for Behavioral Experiments in Head-Fixed Mice

The mouse is an increasingly prominent model for the analysis of mammalian neuronal circuits. Neural circuits ultimately have to be probed during behaviors that engage the circuits. Linking circuit dynamics to behavior requires precise control of sensory stimuli and measurement of body movements. Head-fixation has been used for behavioral research, particularly in non-human primates, to facilitate precise stimulus control, behavioral monitoring and neural recording. However, choice-based, perceptual decision tasks by head-fixed mice have only recently been introduced. Training mice relies on motivating mice using water restriction. Here we describe procedures for head-fixation, water restriction and behavioral training for head-fixed mice, with a focus on active, whisker-based tactile behaviors. In these experiments mice had restricted access to water (typically 1 ml/day). After ten days of water restriction, body weight stabilized at approximately 80% of initial weight. At that point mice were trained to discriminate sensory stimuli using operant conditioning. Head-fixed mice reported stimuli by licking in go/no-go tasks and also using a forced choice paradigm using a dual lickport. In some cases mice learned to discriminate sensory stimuli in a few trials within the first behavioral session. Delay epochs lasting a second or more were used to separate sensation (e.g. tactile exploration) and action (i.e. licking). Mice performed a variety of perceptual decision tasks with high performance for hundreds of trials per behavioral session. Up to four months of continuous water restriction showed no adverse health effects. Behavioral performance correlated with the degree of water restriction, supporting the importance of controlling access to water. These behavioral paradigms can be combined with cellular resolution imaging, random access photostimulation, and whole cell recordings.

Eficácia de herbicidas em condições controladas para o controle de gramíneas infestantes de canaviais em estiagem

Chemical control of weeds in sugarcane crop may be performed in dry season, mainly due to agricultural operations planning, and logistics in relation to the use of equipment and labor. This study aimed to evaluate the agronomic efficacy of herbicides for controlling sugarcane grass weeds by using different periods of water restriction. Evaluated weeds were Digitaria nuda , Panicum maximum and Brachiaria decumbens . Herbicides treatments applied in total pre-emergency condition were: diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35; 1507.5 + 425 + 36.25 1658.25 + 467.5 + 39.87 and 1809 + 510 + 43.5 g a.i. ha -1 ; amicarbazone (1190 g a.i. ha -1 ); amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha -1 ) and an check without application. After application, plots were submitted to 0, 30, 60 and 90 days of water restriction. Control visual evaluations were performed 28 days after humidity restoration, with the weeds biomass determination. All studied doses of diuron + hexazinone + sulfometuron-methyl were effective in controlling the plants studied in all water restriction periods. Amicarbazone sprayed alone was not efficient on weeds control under the condition of 60 days with water restriction. Amicarbazone + isoxaflutole presented satisfactory weeds control, except for Digitaria nuda , in 60 days of water restriction.

Haematological and serum biochemical responses of chickens to hydric stress

Dehydration can be extremely damaging to the performance and welfare of indigenous chickens. The effect of water restriction on haematological and biochemical parameters was compared in Naked Neck (NNK) and Ovambo (OVB) chickens. A total of 54 8-week-old pullets each of NNK and OVB chickens with an initial average weight of 641 ± 10 g/bird were randomly assigned to three water intake treatments with three replications, each having six birds. The water restriction treatments were ad libitum, 70% and 40% of ad libitum intake. Nine experimental pens with a floor space of 3.3 m2 per strain were used. Feed was provided ad libitum. Packed cell volume (PCV), erythrocyte count (RBC), mean corpuscular volume (MCV) and total leucocyte count (WBC), and biochemical parameters (uric acid (UA)), creatinine (CREAT), total protein (TP), albumin (ALB), globulin (GLOB), triglyceride (TGA), total cholesterol (TC), high- (HDLC) and low- (LDLC) density lipoprotein cholesterol and activity of alanine transaminase (ALT), alkaline phosphatase (ALP) and aspartate transaminase (AST) were determined from blood collected after 60 days of water restriction. PCV was higher (P < 0.05) in NNK than OVB chickens offered water ad libitum, but similar in birds offered 70% and 40% of ad libitum. There were no differences in RBC and MCV values between strains, but MCV was higher in birds on 40% than 70% of ad libitum water intake, irrespective of strain. Naked neck chickens had higher (P < 0.05) WBC values than OVB at 40% restriction level, but lower WBC than OVB at 70% water restriction level. UA, CREAT, TGA, TC, LDLC, TP and GLOB increased (P < 0.05) with each increment in water restriction, but the increase in CREAT and TC was more pronounced in OVB than NNK chickens. The opposite was observed for UA. ALT activity indicated that liver function was not affected by water restriction. It was concluded that the two strains can withstand up to 40% of ad libitum water restriction, but NNK tolerated water stress better than OVB chickens.

Eficácia de herbicidas em condições controladas para o controle de gramíneas infestantes de canaviais em estiagem

Chemical control of weeds in sugarcane crop may be performed in dry season, mainly due to agricultural operations planning, and logistics in relation to the use of equipment and labor. This study aimed to evaluate the agronomic efficacy of herbicides for controlling sugarcane grass weeds by using different periods of water restriction. Evaluated weeds were Digitaria nuda , Panicum maximum and Brachiaria decumbens . Herbicides treatments applied in total pre-emergency condition were: diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35; 1507.5 + 425 + 36.25 1658.25 + 467.5 + 39.87 and 1809 + 510 + 43.5 g a.i. ha -1 ; amicarbazone (1190 g a.i. ha -1 ); amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha -1 ) and an check without application. After application, plots were submitted to 0, 30, 60 and 90 days of water restriction. Control visual evaluations were performed 28 days after humidity restoration, with the weeds biomass determination. All studied doses of diuron + hexazinone + sulfometuron-methyl were effective in controlling the plants studied in all water restriction periods. Amicarbazone sprayed alone was not efficient on weeds control under the condition of 60 days with water restriction. Amicarbazone + isoxaflutole presented satisfactory weeds control, except for Digitaria nuda , in 60 days of water restriction.

Morphological Changes in Soybean under Progressive Water Stress

The aim of the experiment was to investigate and evaluate morphological changes provoked by the progressive water stress on Leaf Relative Water Content (LRWC), height of plant, number of leaves, shoot dry matter, root dry matter in plants of soybean cultivar sambaiba. The experimental design was at randomized entirely factorial, with 2 hydric conditions (stress and control) and 4 stress points (0, 2, 4 and 6 days). It were showed in the plants under water stress drop in LRWC of 81.5 until 60.9% due water deficiency in substrate, the number of leaves increase at both the treatments, it being showed after of 6 days the increase of 24.2 and 44.8% in the plants under stress and control, respectively. It was showed different behavior of the root dry matter in plants under water stress, with higher root matter until the 2 days and lower matter after of this point, when compared with control plants. The study with soybean cultivar sambaiba under progressive water stress reveal that occurred reduction in the parameters from the experiment beginning, however significant morphological changes in the number of leaves and root dry matter were showed only after 6 days of water restriction.

Effect of Water Restriction and Rehydration on Haemato-Biochemical, Enzymatic and Hormonal Activity of Hoggets during Summer Season

Present experiment was conducted with the objective to study the effect of water restriction and rehydration on haemato-biochemical, hormonal and enzymatic activity of indigenous sheep under intensive production system. Eighteen farm born unshorn hoggets (25-30 kg) of Patanwadi and Marwari breeds were randomly distributed in to three treatment groups on the basis of body weight comprising of six in each group viz., T1 Control (ad libitum water), T2 (20% water restriction) and T3 (40% water restriction). The experiment was conducted in summer season for 30 days i.e. 28 days of water restriction and 2 days of rehydration phase. The feed, in accordance with physiological and production needs of the animals, was offered twice a day (09:00 and 18:00 hrs). Water intake was recorded thrice a day (09:00, 14:00 and 19:00 hrs) and blood samplings was done on day 0, day 28 and after 48 hrs of rehydration. The values of haemoglobin, were significantly decreased, while, serum urea, uric acid, alkaline phosphatase, creatinine phosphokinase, cortisol, triiodothyronine and aldosterone were significantly (p less than 0.05) increased in water restricted groups of animals on 28th day, with significant improvement in values on 48 hrs of rehydration in most of the traits. However, the decrease in glucose was non-significant between 0 and 28 days and no change was noted in thyroxin levels due to water restriction or rehydration. It indicated that water restriction resulted significant changes in blood variables of hoggets. Blood variables recovered significantly after 48 hr of rehydration, but the serum cortisol, urea, AKP, CPK and T3 values till did not attain normalcy, thereby demonstrating that the animals did not recover completely from dehydration stress.

Distrofia muscular nutricional em ovinos na Paraíba

Descreve-se um surto de distrofia muscular nutricional em ovinos no semi-árido Nordestino. Foram afetados animais de 3-4 meses de idade, da raça Dorper, pesando 30-40 kg. Os animais eram alimentados, à vontade, com leite, ração balanceada, capim Tifton e sal mineral. Dos 70 animais Dorper, 6 adoeceram e morreram em um período de 48 horas. Apresentaram temperatura, entre 40 e 41ºC, incoordenação com posterior paralisia e decúbito, depressão, prostração e diminuição dos reflexos pupilar e de ameaça, flacidez da língua e mandíbula, salivação, edema submandibular, dispnéia e aumento da freqüência cardíaca. A morte ocorreu após curso clínico de 6- 12 horas. Na necropsia de 3 animais, os músculos esqueléticos estavam de coloração pálida, o fígado estava aumentado de volume e de coloração amarelada, os gânglios parotídeos, submandibulares, retrofaríngeos, prescapulares e mediastínicos estavam aumentados de volume e avermelhados e os pulmões apresentavam áreas vermelhas. Na histologia havia necrose segmentar de todos os músculos examinados e congestão dos gânglios linfáticos e pulmão. Posteriormente mais três animais adoeceram, sendo tratado com oxitetraciclina e complexo vitamínico A,D e E. Desses 3 animais, 2 morreram e um sobreviveu. Na mesma fazenda havia e não adoeceram 20 ovinos da raça Santa Inês, da mesma idade que os animais afetados, que recebiam a mesma alimentação exceto o leite, e 900 ovinos de outras idades. A superalimentação em animais com rápido crescimento e o estresse causado pela restrição de água durantes 2 dias, para aumentar o consumo de leite, parecem ter sido fatores predisponentes para a ocorrência da doença. É possível, também, que algum dos minerais suplementados tenha antagonizado o Se presente na alimentação.

Regulation of Corticosterone Production by Vasopressin during Water Restriction and after Drinking in Rats

Plasma vasopressin (VP) and corticosterone have each been shown to be rapidly suppressed after drinking in different models of osmotic stimulation in rats; however, no causal relationship between these responses has been investigated. Studies were performed to determine if plasma VP and corticosterone are reduced in parallel after drinking and if manipulation of plasma VP affects plasma, ACTH corticotropins and corticosterone in a model of water restriction. A strong correlation between changes in plasma VP and corticosterone, but not between plasma ACTH and corticosterone, was observed after drinking induced by 6 days of water restriction. Similarly, ingestion of isotonic saline resulted in a biphasic VP response that was paralleled by adrenal and plasma corticosterone, but not by plasma ACTH. Administration of an immunoneutralizing antibody directed against VP resulted in a rapid decrease in plasma corticosterone, but not ACTH, in water-restricted rats, but not in rats receiving water ad libitum. These data suggest that during dehydration, elevated plasma VP can stimulate the production of corticosterone by the adrenal, independently of ACTH. Moreover, they support the hypothesis that the decline in corticosterone after restriction-induced drinking is due, in part, to a decline in plasma VP.