Water deficit changes the anatomy of the fruit abscission zone in Raphanus raphanistrum (Brassicaceae)

2009 ◽  
Vol 57 (8) ◽  
pp. 708 ◽  
Author(s):  
Mohammad S. Taghizadeh ◽  
Simon Crawford ◽  
Marc E. Nicolas ◽  
Roger D. Cousens
Keyword(s):  
Water Deficit ◽  
Abscission Zone ◽  
Raphanus Raphanistrum ◽  
Cross Sectional ◽  
Morphometric Analyses ◽  
Severe Water Deficit ◽  
Agricultural Weed ◽  
Xylem Elements ◽  
Time Of Year ◽  
Water Treatments

Raphanus raphanistrum L. is an important agricultural weed that often matures at a time of year when water availability is decreasing rapidly. We examined the development of the abscission zone under contrasting soil water treatments and exogenous application of Ethrel. Morphometric analyses of cell traits were used to quantify the effects. Although the abscission zone was visible in sections after 2 weeks under all water regimes, it was more distinctive for pods that had developed under water deficit and Ethrel application. Pod separation began on the outside and gradually extended through the inner cells until the pod was supported only by the xylem elements. The rate of weakening of the cells accelerated where pods developed under water deficit (both mild and severe) or were treated by Ethrel. Water deficit increased the sizes of cells in and adjacent to the abscission zone, doubling their cross-sectional area from well watered to severe water deficit. Ethrel, but not water deficit, significantly increased the thickness and the number of cells across the separation layer. Abscission scar diameter increased by ~50% with increasing water deficit. Notably, we observed some plants in which no abscission zone formed.

Effects of relative emergence time and water deficit on the timing of fruit dispersal in Raphanus raphanistrum L.

2012 ◽  
Vol 63 (10) ◽  
pp. 1018 ◽  
Author(s):  
M. S. Taghizadeh ◽  
M. E. Nicolas ◽  
R. D. Cousens
Keyword(s):  
Water Deficit ◽  
Emergence Time ◽  
Raphanus Raphanistrum ◽  
Maternal Plant ◽  
Wide Range ◽  
Temporal Phenomenon ◽  
Severe Water Deficit ◽  
Final Length ◽  
Considerable Period ◽  
Fruit Dispersal

Seed dispersal is both a spatial and a temporal phenomenon, although most studies focus on spatial aspects. Seed initiation on the maternal plant may occur over a considerable period, especially in indeterminately flowering species, and thus seeds may be exposed to a wide range of environmental conditions during their development. The result is variation in the timing of seed development, the anatomy of structures related to the dispersal process, and the behaviour and fate of seeds post-dispersal. A key resource during the growth and development of summer-maturing species in most areas, and one that is thus likely to modify these processes, is water. Two experiments were therefore undertaken to describe (i) the development of Raphanus raphanistrum fruits and the timing of fruit dispersal, and (ii) the effects of water availability on the timing of fruit dispersal. Fewer seeds were produced and subsequently dispersed by later emerging plants. The duration of fruit dispersal became shorter when the plants emerged progressively later than the crop, and the time of maximum dispersal was later. For cohorts of fruits initiated at the same time, those that developed under mild and severe water deficit reached their final length sooner, and were dispersed sooner, than those receiving a plentiful supply of water. Thus, the phenology of the maternal plant and the nature of its environment can modify the timing of propagule maturity and consequently dispersal. Such information may provide an opportunity for managers to reduce weed seed return to their field or, conversely, to regulate the amount of contaminated grain or reduce dispersal to other locations.

Defence mechanisms against production of free radicals in cells of ‘resurrection’ plants

1994 ◽  
Vol 102 ◽  
pp. 291-294
Author(s):  
Cristina L. M. Sgherri ◽  
Mike F. Quartacci ◽  
Adriana Bochicchio ◽  
Flavia Navari-Izzo
Keyword(s):  
Free Radicals ◽  
Water Deficit ◽  
Water Loss ◽  
Physiological Activity ◽  
Physiological State ◽  
Resurrection Plant ◽  
Resurrection Plants ◽  
Defence Mechanisms ◽  
Adaptation Mechanism ◽  
Severe Water Deficit

The ability of protoplasm to revive following severe water deficit is at its greatest in desiccation-tolerant or ‘resurrection’ plants. Boea hygroscopica is a resurrection plant that is able to survive air-dryness following slow dehydration (80% RH) in a physiological state called anabiosis (Schwab & Gaff 1990). However, this plant loses the ability to recover complete physiological activity following rapid water loss (0% RH).The ability to recover complete physiological activity following repeated protoplasmic dehydration of fully differentiated tissues is an adaptation mechanism unique to resurrection plants.

scholarly journals Holiday Hunger and Parental Stress: Evidence from North East England

2020 ◽  
Vol 12 (10) ◽  
pp. 4141
Author(s):  
Paul B. Stretesky ◽  
Margaret Anne Defeyter ◽  
Michael A. Long ◽  
Liesel A. Ritchie ◽  
Duane A. Gill
Keyword(s):  
Parental Stress ◽  
Economic Hardship ◽  
Mental Wellbeing ◽  
School Age Children ◽  
Stressful Event ◽  
Cross Sectional ◽  
Impact Of Event Scale ◽  
Event Scale ◽  
North East ◽  
Time Of Year

Summer is a stressful time of year for many parents as they struggle to meet household expenses and feed children. The aim of the present study is to determine if there is an association between summertime food insecurity (i.e., holiday hunger) and parental stress among a sample of UK parents with school age children living in North East England. A cross-sectional sample of (n = 252) parents are analyzed using holiday hunger as the independent variable and a subjective measure of stress that treats summer as a ‘stressful event’ as the dependent variable. Of the parents in the sample, 64.8% reported at least some level of holiday hunger. We find parents facing any holiday hunger scored substantively higher on the overall 75-point Impact of Event Scale (mean difference = 30.4, 95% confidence interval ((CI) 24.2–36.6), the 35-point intrusion subscale (13.7, 95% CI 10.8–16.5), and the 40-point avoidance subscale (16.7, 95% CI 13.3–20.2). These findings are replicated in a regression analysis. In addition, we find that holiday hunger partially mediates the association between economic hardship (i.e., unemployment and poverty) and parental stress. We conclude by suggesting that government policies addressing economic hardship are not only likely to reduce holiday hunger, but also improve mental wellbeing.

Anatomical adaptations of the desert species Stipa lagascae against drought stress

Biologia ◽  
2015 ◽  
Vol 70 (8) ◽  
Author(s):  
Façal Boughalleb ◽  
Raoudha Abdellaoui ◽  
Zied Hadded ◽  
Mohammed Neffati
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Deficit ◽  
Cortical Cell ◽  
Severe Drought ◽  
Leaf Rolling ◽  
Drought Period ◽  
Severe Water Deficit ◽  
Anatomical Adaptations ◽  
Stipa Lagascae

AbstractStipa lagascae R. & Sch. (perennial bunchgrass) is one of the most promising steppic species for arid and desert lands of Tunisia. The present study was designed to study the effect of drought on root and leaf anatomy, water relationship, and the growth of three- month-old S. lagascae plants, submitted to water deficit (5, 10, 15, 20, 30 days of withheld irrigation) and grown in pots in greenhouse conditions. The results show that water deficit treatments reduced the biomass accumulation (MS) and leaf water potential (Ψw) of plants. However, leaf relative water content (RWC) decreased significantly only at severe drought. The root’s anatomical features showed reduced root cross-sectional diameter under water deficit. Conversely, epidermis was unaffected by water stress. Moderate and/or severe water deficit (20-30 days) reduced significantly the cortex thickness, cortical cell size, stele diameter, xylem vessel diameter and the stele/root crosssectional ratio, while the number of cortical cells increased for severe water deficit. The cuticles and mesophyll of S. lagascae was thickened by moderate to severe drought and the entire lamina thickness was increased significantly by 5.8% only after 30 days of water deficit while epidermis was unaffected by water deficit. However, severe water deficit (30 days) decreased the width and the length of the bundle sheath. At the same time, the mesophyll cells size and both the xylem and phloem vessels diameter diminished by 12, 16.8 and 17.5%, respectively. Leaf rolling occurs as a response to water deficit and its level increases as the drought period is progressing in plants while reduced bulliform cells size occurred only at severe water deficit. Our findings suggest a complex network of root and leaf anatomical adaptations such as a reduced vessel size with lesser cortical and mesophyll parenchyma formation and increased leaf rolling. These proprieties are required for the maintenance of water potential and energy storage under water stress which can improve the resistance of S. lagascae to survive in extremely arid areas

Tonsillectomy return-to-theatre rates demonstrate a monthly and seasonal variation: an analysis of 256 799 patients

2007 ◽  
Vol 121 (11) ◽  
pp. 1088-1093 ◽  
Author(s):  
N K Chadha
Keyword(s):  
Seasonal Variation ◽  
High Risk ◽  
Seasonal Variations ◽  
Lower Incidence ◽  
Cross Sectional Study ◽  
Seasonal Distribution ◽  
Sectional Study ◽  
Cross Sectional ◽  
Risk Of Bleeding ◽  
Time Of Year

AbstractObjective:To explore whether the incidence of post-tonsillectomy haemorrhage requiring a return to theatre demonstrates a monthly or seasonal variation.Design:Retrospective, cross-sectional study including all 256 799 tonsillectomies performed between April 2000 and March 2005 in NHS trusts in England.Outcome measures:Return-to-theatre rates for each calendar month and each three-month ‘season’, over the five-year study period.Results:A statistically significant association was found between the calendar month and the proportion of patients requiring a return to theatre for post-tonsillectomy haemorrhage (p=0.005). There was a bimodal seasonal distribution peaking in the winter and summer months, with winter rates significantly higher than spring rates (p=0.0104).Conclusions:The incidence of severe post-tonsillectomy haemorrhage showed monthly and seasonal variations. This is clearly a multi-factorial problem. However, in patients at high risk of bleeding or of the complications of bleeding, consideration should be given to performing tonsillectomy at a time of year of lower incidence.

Genotypic differences in leaf area maintenance contribute to differences in recovery from water stress in soybean

2008 ◽  
Vol 59 (12) ◽  
pp. 1075 ◽  
Author(s):  
R. J. Lawn ◽  
A. A. Likoswe
Keyword(s):  
Leaf Area ◽  
Water Deficit ◽  
Leaf Tissue ◽  
Water Deficit Stress ◽  
Dead Leaf ◽  
Genotypic Differences ◽  
Leaf Stage ◽  
Severe Water Deficit ◽  
Soybean Plants ◽  
Root Effects

Genotypic effects on leaf survival during water deficit stress and subsequent recovery were evaluated using soybean plants grown in tall cylinders in the glasshouse. An initial experiment sought to verify reported genotypic differences in leaf area maintenance under severe water deficit stress. A second experiment sought to test the hypothesis that these putative differences might affect recovery after stress was relieved. Two shoot genotypes, G2120 and cv. Valder, reported to have high and low leaf area retention, respectively, were used in both experiments. In order to preclude the possibility that the reported differences between G2120 and Valder were related to root rather than shoot traits, each shoot was grafted at the cotyledonary stage onto 2 non-self root genotypes, cv. Leichhardt and PI416937. Leichhardt has an apparently normal root, while PI416937 has been reported to be ‘extensively fibrous-rooted’. In the first experiment, water was withheld at the first trifoliolate leaf stage and the plants subjected to terminal water deficit stress. Consistent with the previous report, leaf area was maintained for longer into the stress by the G2120 shoots, with rapid loss of lower leaves not starting until c. 90% of plant-available water (PAW) had been depleted, compared with c. 80% for Valder. The Valder leaves also showed more ‘firing’ damage, with large patches of dead leaf tissue on the retained leaves. Also consistent with the previous report, leaf epidermal conductance to water vapour was lower in G2120 than in Valder. There were no apparent root effects. In the second experiment, water was again withheld at the first trifoliolate leaf stage, and treatments were re-watered when 80%, 85%, 90%, and 95% of the estimated PAW was extracted. Again, G2120 shoots showed better leaf area maintenance during the drying cycle, and less firing damage. When the plants were re-watered, the re-growth of G2120 generally exceeded that of Valder at all levels of PAW depletion. The differences in recovery between G2120 and Valder shoots were sufficient to have agronomic relevance, and confirmed the hypothesis that leaf area retention can affect recovery after severe water deficit stress. Root effects were relatively small. During the drying cycle, leaflet growth was marginally enhanced by Leichhardt relative to PI416937 roots. After re-watering, there was stronger recovery of plants with PI416937 roots, especially those with G2120 shoots. The basis of the differences between the root genotypes is not known but the stronger recovery of PI416937 may reflect its putative ‘extensively fibrous’ nature.

scholarly journals Adaptation of Cowpea (Vigna unguiculata (L.) Walp.) to Water Deficit during Vegetative and Reproductive Phases Using Physiological and Agronomic Characters

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Vincent Ezin ◽  
Artoche Gloria Christelle Tosse ◽  
Ifagbémi Bienvenue Chabi ◽  
Adam Ahanchede
Keyword(s):  
Water Stress ◽  
Drought Stress ◽  
Water Deficit ◽  
Vigna Unguiculata ◽  
Agronomic Traits ◽  
International Institute ◽  
Relative Water ◽  
Cowpea Varieties ◽  
Reproductive Phases ◽  
Water Treatments

Cowpea (Vigna unguiculata (L.) Walp.) is an important commodity in West Africa. Its seeds are a valuable source of protein, vitamins, and income for humans. However, cowpea cultivation in Benin faces climatic constraints such as water stress caused by a prolonged absence of rain during the rainy season. Thus, this work aims at selecting cowpea varieties that can be cultivated in times of drought without compromising their yields and yield components. Twenty cowpea varieties were used, including 17 improved cultivars and 3 landraces. The experiment was conducted at the International Institute of Tropical Agriculture in Benin and laid at a split-plot design with four replicates. Each genotype was exposed to three water treatments: fully irrigated control, vegetative stress (when plants were 23 days old, drought stress was imposed for 30 days), and reproductive stress (once the first flowers were observed, water stress was imposed for 30 days). The results showed that photochemical yield, chlorophyll content, and relative water content were reduced under water deficit at the vegetative and reproductive stages. But there were no significant differences in proline content among cowpea varieties. Agronomic traits such as number of days to flowering, number of pods, yield per plant, the weight of 100 seeds, and harvest time showed significant differences under water stress. Overall, the landraces and cultivars including Kpodjiguegue, KVX 61-1, and IT 06-K-242-3 were the most tolerant to drought stress at the vegetative and reproductive stages and could potentially be used in breeding programs to improve drought tolerance of cowpeas.

Sign in / Sign up

Export Citation Format

Share Document