water deficits

Top PDF water deficits:

COTTON RESPONSE TO WATER DEFICITS AT DIFFERENT GROWTH STAGES

COTTON RESPONSE TO WATER DEFICITS AT DIFFERENT GROWTH STAGES

ABSTRACT – Water deficit at certain cotton growth stages can cause severe damage to crop development, affecting physiological processes and reducing reproductive structures, with consequent yield losses. The objective of this study was to evaluate the response of cotton cultivars under water deficit applied at different stages of the crop cycle. We compared the number of bolls per meter, cotton yield, and water use efficiency for eight different cotton cultivars under a water deficit of 15 days. We selected the following growth stages: Emergence (EM), First Square (FS), First Flower (FL), Peak Bloom (PB), and First Open Boll (FOB). The control treatment was irrigated with 100% ETc. The experiment was conducted in Apodi, RN State of Brazil, semiarid region, using a sprinkler irrigation system. The number of bolls per meter, cotton yield, and water use efficiency were influenced by the interaction of cultivars x deficit periods. Lowest values were observed for water suppression in the FL and PB stages. When the water deficit was imposed in the initial stages of growth (EM to FS) or after the FOB stage, the cotton yield reduction was not significant. At the same stage and water deficit, the behavior of the different cultivars was similar. Producers are urged to take this information into account when developing irrigation schemes for cotton crops, thereby avoiding water deficits during the most critical periods of the crop cycle.
Mostrar mais

11 Ler mais

Oeiras, July, 2011 Biochemistry Of Grape Berries: Post-genomics Approaches To Uncover The Effects Of Water Deficits On Ripening

Oeiras, July, 2011 Biochemistry Of Grape Berries: Post-genomics Approaches To Uncover The Effects Of Water Deficits On Ripening

A large proportion of vineyards are located in regions with seasonal drought (e.g. Mediterranean-type climates) where soil and atmospheric water deficits, together with high temperatures, exert large constraints on yield and quality. The increasing demand for vineyard irrigation requires an improvement in the efficiency of water use. Deficit irrigation emerged as a potential strategy to allow crops to withstand mild water stress with little or no decreases of yield, and potentially a positive impact on fruit quality. Understanding the physiological and molecular bases of grapevine responses to mild to moderate water deficits is fundamental to optimize deficit irrigation management and identify the most suitable varieties to those conditions. How the whole plant acclimates to water scarcity and how short and long distance chemical and hydraulic signals intervene are reviewed. Chemical compounds synthesized in drying roots were shown to act as long-distance signals inducing leaf stomatal closure and/or restricting leaf growth. This explains why some plants endure soil drying without significant changes in the shoot water status. The control of plant water potential by stomatal aperture via feed- forward mechanisms is associated with the ‘isohydric’ behaviour in contrast with ‘anysohydric’ behaviour where lower plant water potentials are attained. We discuss differences in this respect between grapevines varieties and experimental conditions. Mild water deficits also exert direct and/or indirect (via the light environment around grape clusters) effects on berry development and composition; a higher content of skin- based constituents (e.g. tannins and anthocyanins) has generally being reported. Regulation under water deficit of genes and proteins of the various metabolic pathways responsible for berry composition and therefore wine quality are reviewed.
Mostrar mais

202 Ler mais

Responses of reactive oxygen scavenging enzymes, proline and malondialdehyde to water deficits among six secondary successional seral species in Loess Plateau.

Responses of reactive oxygen scavenging enzymes, proline and malondialdehyde to water deficits among six secondary successional seral species in Loess Plateau.

Drought can impact local vegetation dynamics in a long term. In order to predict the possible successional pathway of local community under drought, the responses of some drought resistance indices of six successional seral species in the semi- arid Loss Hilly Region of China were illustrated and compared on three levels of soil water deficits along three growing months (7, 8 and 9). The results showed that: 1) the six species had significant differences in SOD, POD activities and MDA content. The rank correlations between SOD, POD activities and the successional niche positions of the six species were positive, and the correlation between MDA content and the niche positions was negative; 2) activities of SOD, CAT and POD, and content of proline and MDA had significant differences among the three months; 3) there existed significant interactions of SOD, CAT, POD activities and MDA content between months and species. With an exception, no interaction of proline was found. Proline in leaves had a general decline in reproductive month; 4) SOD, CAT, POD activities and proline content had negative correlations with MDA content. Among which, the correlation between SOD activity and MDA content was significant. The results implied that, in arid or semiarid region, the species at later successional stage tend to have strong drought resistance than those at early stage. Anti-drought indices can partially interpret the pathway of community succession in the drought impacted area. SOD activity is more distinct and important on the scope of protecting membrane damage through the scavenging of ROS on exposure to drought.
Mostrar mais

8 Ler mais

Deficit irrigation in Mediterranean vineyards - a tool to increase water use efficiency and to control grapevine and berry growth

Deficit irrigation in Mediterranean vineyards - a tool to increase water use efficiency and to control grapevine and berry growth

Transcriptional analysis of grape berries from vines subjected to moderate water deficits at the end-ripening stage showed changes on mRNA expression patterns particularly related to the cell wall and sugar and hormone metabolism (Deluc et al., 2007). The most profound alterations related to hormone metabolism occur in ethylene, auxin and ABA but the expression of several genes of the phenylpropanoid pathway was shown also to increase (Deluc et al., 2007). The impact of water deficit on grape berry proteome (defined as all proteins produced by the genome of an organism or tissue) has also been studied. Grimplet and colleagues (2009) analysed the skin, pulp and seed proteomes of fully ripen berries from non irrigated and well-irrigated vines (irrigation from pre-veraison to the end of berry maturity). They observed that 7% of pericarp (skin and pulp tissues) proteins respond to water-stress. Using an identical approach Francisco (2011) studied the dynamics of berry proteome for the cultivar ‘Aragonez’ (syn. ‘Tempranillo’) along development of berries from non-irrigated (NI), well-irrigated (FI) and RDI plants. Comparison of berries from well irrigated vines with RDI and NI vines, allowed for the identification of several proteins considered water-deficit responsive. One of those proteins was a vacuolar invertase (GIN1), which was down-regulated under non- irrigated and RDI conditions when compared to FI conditions. These results were observed at pre-veraison (green stage) and at veraison and are in accordance with the early hexoses accumulation observed under water deficit conditions, in the same study. Also relevant was the fact that changes occurring at very early stages of berry development (green berry stage) may affect final berry maturity (Francisco, 2011).
Mostrar mais

12 Ler mais

Deficit irrigation in Mediterranean environment. What lessons have we learnt from grapevine studies ?

Deficit irrigation in Mediterranean environment. What lessons have we learnt from grapevine studies ?

Genotype related differences in WUE and water stress resistance may arise from constitutive differences in leaf gas-exchange, plant capacity to osmoregulate and plant hydraulics. Photosynthesis, stomatal conductance and WUEi were shown to vary with grapevine variety (Bota et al., 2001; Schultz 2003; Soar et al., 2006). Still, variation in photosynthetic efficiency seems to be small (Bota et al., 2001), suggesting that genotypic variation in WUE is largely linked to diversity in stomatal conductance, both under well-watered and water deficit conditions (Escalona et al., 1999; Gaudillère et al., 2002; Chaves and Oliveira, 2004). Under drought conditions, stomata seems to keep water flow within safe limits, therefore avoiding xylem embolism (Sperry et al., 2002). Higher stomata sensitivity to water deficits may compensate for higher vulnerability to cavitation under drought (Schultz, 2003). Leaf morpho-anatomy and related biochemistry (epicuticular wax composition, lipid composition, mesophyll thickness etc) may also play a role in explaining plant adaptation to water stress (Boyer et al., 1997). Differences among V. vinifera have been reported in these characteristics (Schultz, 1996). Grapevine is generally considered a “drought avoiding” species, with an efficient stomatal control over transpiration (Chaves et al., 2007; 2010; Shultz, 2003). However, some genotypes have shown a better control of stomata than others in response to water deficits and accordingly have been classified as isohydric (drought avoiders or “pessimistic”); the others, showing lower control over stomatal aperture under water stress, were considered anisohydric, with an “optimistic” response (Schultz, 2003; Soar et al., 2006). Schultz (2003) considered Grenache to be a nearly isohydric genotype showing a marked regulation of stomatal conductance to
Mostrar mais

9 Ler mais

Key words: Carica papaya, environmental factors, photosynthesis, water relations, water-use efficiency

Key words: Carica papaya, environmental factors, photosynthesis, water relations, water-use efficiency

Non-stomatal effects of soil water deficits are demonstrated when a stressed plant is re-watered but fails to return to the pre-stressed physiological state. Upon withholding watering for ‘Golden’ cv. for 5 d, A rates were reduced by both stomatal and non-stomatal effects (Reis et al., 2004). After re-watering g s , but not A, returned to pre-stress levels; probably A was limited by biochemical and photochemical damage affecting chlorophylls. Campostrini et al. (2004) demonstrated that under severe water deficit, the energy absorbed in the pigment antenna was greater than the electron transport resulting in increased energy dissipation and a smaller quantity of energy used in the photochemistry. Water stress damaged the PSII chemical efficiency and this damage could be measured on the first day after suspending irrigation. Lawlor and Cornic (2002) demonstrated that severe water stress (RWC < 75%) would damage the photochemical and biochemical system and such damage may be associated with ribulose-1,5-bisphosphate regeneration that would decrease ATP synthesis. This damage may chronically reduce the photosynthetic process and delay or even prevent complete re-establishment of photosynthesis after re-irrigation. In contrast, in ‘Baixinho de Santa Amália’, despite A having been progressively decreased over the course of the dehydrating cycle, reaching 73% of the control after 40 d of water deficit, it fully resumed upon re-hydration (Mahouachi et al., 2007), even though the stress caused leaf drop that began to occur 7 d upon suspending irrigation. Non-hydraulic signals such as abscisic acid (ABA) and jasmonic acid (JA), but not indole-3-acetic acid, differed in their accumulation patterns under stress. Whereas ABA continuously increased in leaves and roots during the whole period of stress, JA initially increased and then decreased in both organs. Mahouachi et al. (2007) proposed the involvement of ABA as an accumulative, non-hydraulic hormonal signal that could be involved in the induction of several physiological responses in papaya under progressive water stress such as the reduction in gas exchange parameters and leaf abscission.
Mostrar mais

12 Ler mais

Growth and yield of peanut cultivars and breeding lines under water deficit

Growth and yield of peanut cultivars and breeding lines under water deficit

Col 72, the decreases were not significant. The WH and SP were less affected, and although they presented positive RI values for most genotypes, their means were pooled into a single class to compare the water regimes per genotype. Water deficit period longer than 35 days caused decreased plant growth, although it did not prevent growth (Correia & Nogueira 2004). Water deficits decreased photosynthesis and plant growth and affected grain formation and development, which directly affected production.

9 Ler mais

EFFECTS OF SOIL WATER DEPLETION ON THE WATER RELATIONS IN TROPICAL KUDZU

EFFECTS OF SOIL WATER DEPLETION ON THE WATER RELATIONS IN TROPICAL KUDZU

submitted to similar water deficits and because crop plants usually do not show special features for protection against excessively high temperature, it would be expected that tropical kudzu would have relatively less heat-damaged tissue than other cover crop species when subjected to the same level of soil water depletion. To conclude, a potentially reduced tissue damage, especially in the photosynthetic organs confer additional advantage in selecting tropical kudzu as the cover crop of choice due to its eventually higher CO 2 assimilation rates

7 Ler mais

Previsão de produtividade anual de café arábica por meio do deficit hídrico

Previsão de produtividade anual de café arábica por meio do deficit hídrico

Brazil is the world’s largest coffee producer with 45.563,2 thousand sacks per year (Amarasinghe et al., 2015; Acompanhamento…, 2017), and few studies have forecasted yields as functions of the climatic conditions (Aparecido et al., 2015). Coffee production and bean quality are highly sensitive to changes in microclimatic parameters (Craparo et al., 2015), mainly those related to water availability. Water deficits [DEFs, the lack of evapotranspiration in relation to a maximum (potential) theoretical value] reduce crop yields (Khamssi et al., 2011) by affecting the plant vegetative growth (DaMatta, 2004).
Mostrar mais

12 Ler mais

Water Stress Induced by Mannitol and Sodium Chloride in Soybean Cultivars

Water Stress Induced by Mannitol and Sodium Chloride in Soybean Cultivars

Hypocotyl and root length of seedlings exposed to different NaCl induced water deficits can be seen in Table 7. Treatments interfered differently in hypocotyl and root length. For hypocotyl length, cultivars showed the best result at no water deficit, decaying till zero at -1.2MPa, what was according the obtained data of Torres et al. (2000), where the increase in water deficit represented a reduction in seedling. Root growth presents its best result at water deficits between 0 and -0.3MPa, reducing the growth above this mark. There was no difference between cultivars for hypocotyl length, but for root length ‘Xingu’ was superior not differing from ‘Pioneira’ but differing from ‘Conquista’ and ‘Pintado’. Shalhevet et al. (1995)
Mostrar mais

9 Ler mais

J. Soc. Bras. Fonoaudiol.  vol.23 número4 en v23n4a07

J. Soc. Bras. Fonoaudiol. vol.23 número4 en v23n4a07

Purpose: To describe the performance of individuals with myelomeningocele regarding psycholinguistic and scholastic abilities. Methods: Participants were five individuals with myelomeningocele and lumbar sacral abnormalities, and chronological age between 9 years and 10 months and 11 years and 7 months (Group 1 – G1); five subjects with typical development (Group 2 – G2), matched to G1 for age, gender, and educational level. The evaluation consisted of interview with parents/caregivers, and application of the following tests: Illinois Test of Psycholinguistic Abilities (ITPA); School Performance Test; Speed Reading Test; and Rapid Automatized Naming Test. Results: The between-groups comparison in the ITPA subtests showed that the maximum values obtained by G1 corresponded approximately to the minimum values obtained by G2, confir- ming the difference between the groups, except for the auditory closure subtest. In the Scholastic Performance Test, significant alterations were observed on the performance of G1 in all tasks. In the Speed Reading and Rapid Automatized Naming tests, individuals in G1 also presented considerable deficits, making more mistakes and spending more time than G2 to perform the same tasks. Conclusion: Individuals with myelomeningocele present deficits in psycholinguistic abilities, school performance, reading speed, and rapid automatized naming.
Mostrar mais

7 Ler mais

Evidence for deficits in the temporal attention span of poor readers.

Evidence for deficits in the temporal attention span of poor readers.

The notion that resource competition might underlie item identification in both spatial and temporal arrays and the existence of abnormal VA span in poor readers begs the question of whether poor readers might also allocate attention differently to sequential items presented in a rapid temporal sequence (henceforth, temporal attention span) compared to their normal reading peers. Put differently, one may ask whether poor readers have a more general problem in allocating attention to sequential stimuli in both the spatial and temporal domains. To investigate this issue, a number of studies have examined the AB in impaired readers. In general, results have shown a larger AB in readers with dyslexia [32–36] and less-skilled readers [38] (but see [37]). However, as noted by McLean and colleagues, T2 impairments in these studies have often been equivalent across inter-target intervals [39] (but see [33,34,38]). This implies that T2 deficits amongst poor readers were not the result of resource competition between T1 and T2, but rather due to a general difficulty processing T2 that occurred independently from T1 processing. On the face of it, then, it would seem that the evidence is inconclusive about whether poor readers show parallel spatial and temporal attention span difficulties.
Mostrar mais

7 Ler mais

Mielite transversa como manifestação clínica inicial de linfoma não Hodgkin disseminado e mielopatia vacuolar associada ao HIV: relato de caso.

Mielite transversa como manifestação clínica inicial de linfoma não Hodgkin disseminado e mielopatia vacuolar associada ao HIV: relato de caso.

, os deficits neurológicos associados ao linfoma não Hodgkin do SNC, resultam provavelmente de vários fatores como: (1) natureza multifocal da doença; (2) infecções associadas, como he[r]

6 Ler mais

UNIVERSIDADE FEDERAL DE SANTA CATARINA CENTRO SÓCIO-ECONÔMICO DEPARTAMENTO DE CIÊNCIAS ECONÔMICAS MARCELO MANOEL GONÇALVES

UNIVERSIDADE FEDERAL DE SANTA CATARINA CENTRO SÓCIO-ECONÔMICO DEPARTAMENTO DE CIÊNCIAS ECONÔMICAS MARCELO MANOEL GONÇALVES

0 governo via-se então, envolvido em um circulo vicioso: para manter a taxa de câmbio (mantendo o controle sobre a inflação) e financiar seus deficits crescentes, teria que realiz[r]

105 Ler mais

Physical and biogeochemical forcing of oxygen changes in the tropical eastern South Pacific along 86° W: 1993 versus 2009

Physical and biogeochemical forcing of oxygen changes in the tropical eastern South Pacific along 86° W: 1993 versus 2009

along the whole P19 section are already visible from individual parameter distributions (e.g. presented in Tsuchiya and Talley, 1998). In brief, the shallow layers are composed by subtropical (STW) and subantarctic (SAAW) water masses, while at intermediate depth, the equatorial waters (ESSW) overlay the antarctic waters (AAIW); for levels deeper than about 1100 m the predominant water mass is PDW.

36 Ler mais

Rapamycin reverses status epilepticus-induced memory deficits and dendritic damage.

Rapamycin reverses status epilepticus-induced memory deficits and dendritic damage.

Our finding that SE-induced altered mTOR signaling occurs in both neurons and microglia suggests that mTOR effectors are activated in diverse cells types following SE and may thereby change neuronal and glial properties. In parallel with a reduction in P-S6 staining (Figs. 4–5), there was a decrease in microgliosis in the CA1 region of the SE+Rap group when compared to the SE+Veh group (Fig. 6). In a separate cohort of rats, we found that these alterations were already evident 2 weeks after SE, suggesting that rapamycin reversed the changes (Fig. S4). These data also suggest that SE-induced dendritic damage is mTOR-dependent and that microgliosis may play a role in this process. Indeed, it has been shown that lipopolysaccharide- and cytokine-induced pro- inflammatory activation of microglia is mTOR-dependent [17,18] and microgliosis is suppressed with rapamycin [17,18,60,61]. Under physiological conditions microglia play critical roles in synaptic pruning during development [62] and in mature synaptic connections [63]. Furthermore, prolonged microglia-synapse contacts induced by ischemia are followed by a large loss of synapses [63], and lipopolysaccharide-induced microgliosis results in loss of spine density and dendritic branching [64]. Based on these studies we speculate that the presence of reactive microglia within CA1 following SE may contribute to the significant loss of dendrites and spines in this region (Fig. 8). Hippocampal microgliosis has been widely reported in humans and animal models of epilepsy [43] and existing evidence suggests that microgliosis in the hippocampus contributes to cognitive deficits [65].
Mostrar mais

17 Ler mais

Calcium Hardness Analysis of Water Samples Using EDXRF Technique

Calcium Hardness Analysis of Water Samples Using EDXRF Technique

For calcium determination in water samples, the first reference was 1M CaCO 3 solution and second reference was mixture of water and first reference in known ratios. The two references were irradiated, in turn, in the same set- up and under same tube conditions. The counts under the x photo peaks were recorded for sufficient time to obtain the counting statistics <1%. The spectrum for first reference i.e. 1M CaCO 3 solution is shown in figure 4.

9 Ler mais

Dependência do crescimento das plantas ao regime de umidade do solo.

Dependência do crescimento das plantas ao regime de umidade do solo.

A ocorrência de deficits hídricos mais severos durante o período caracterizado pelo desenvolvimen to de um grande numero de tubérculos (tratamento C e G no segundo estádio e, C e I, n[r]

16 Ler mais

Nitrous oxide in the North Atlantic Ocean

Nitrous oxide in the North Atlantic Ocean

37.3 nmol L −1 in South Atlantic Central Water (SACW) of the eastern basin, whereas Oudot et al. (2002) reported values of up to 60 nmol kg −1 . Oudot et al. (2002) assumed enhanced biological activity and remineralization of organic matter in upwelling ecosystems to be responsible for these higher val- ues in the east. However, upwelling in this area is a tempo- rary event (Voituriez et al., 1982; Siedler et al., 1992), and during our cruise no upwelling was observed.

13 Ler mais

Bootstrap Panel Granger-Causality Between Government Budget and External Deficits for the EU

Bootstrap Panel Granger-Causality Between Government Budget and External Deficits for the EU

Our results support the hypothesis of a causal relation from budget deficits to current account deficits for several countries in the EU: Bulgaria, Czech Republic, Estonia, Finland, France, Italy, Hungary, Lithuania, Poland, and Slovakia, along the lines of the so-called twin-deficit relationship. On the other hand, the possibility of a reverse causality is found to be statistically significant for a somewhat different sub-set of OECD countries. Considering the effective real exchange rate in the SUR system does not substantially alter the causality results.

18 Ler mais

Show all 7049 documents...