Water potentials of Salsola kali L. at differing levels of substrate water availability

1975 ◽  
Vol 42 (2) ◽  
pp. 387-393 ◽  
Author(s):  
Walter T. McDonough
Keyword(s):  
Water Availability ◽  
Salsola Kali ◽  
Water Potentials

Germination characteristics of several grass species as affected by limiting water potentials imposed through a cracking black clay soil

1982 ◽  
Vol 33 (2) ◽  
pp. 223 ◽  
Author(s):  
LA Watt
Keyword(s):  
Water Availability ◽  
Clay Soil ◽  
Grass Species ◽  
Native Grasses ◽  
Exotic Grasses ◽  
Germination Ecology ◽  
Black Clay ◽  
Water Potentials ◽  
Germination Characteristics ◽  
Wilting Point

The effects of limiting water potentials on the germination characteristics of 12 grasses were studied. Germination proper was prevented in all species at water potentials well short of wilting point and different species had their germination prevented at different potentials. Generally the native grasses required wetter conditions to germinate than the exotic grasses, although there were some exceptions. A partial germination condition, caused by limited water availability, occurred to differing degrees amongst the species. Some species retained their viability when desiccated in the partially germinated condition, but other species lost their viability. The partial germination phenomenon appears important to the germination ecology of some species but not to others.

The effect of ecological disturbance on competition between Crinipellis perniciosa and other tropical fungi

1988 ◽  
Vol 94 ◽  
pp. 159-166 ◽  
Author(s):  
Elizabeth Bravo-Velasquez ◽  
John Hedger
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Tropical Forests ◽  
Water Availability ◽  
Tropical Fungi ◽  
Soil Horizons ◽  
Ecological Disturbance ◽  
Crinipellis Perniciosa ◽  
Water Potentials

SynopsisIsolates of the tropical fungus Crinipellis perniciosa obtained from cocoa and lianas in Ecuador were grown on media ranging from −0.45 MPa to −9.0 MPa water potential and their responses compared to those of other agarics and Xylaria species isolated from cocoa. Antagonism between mycelia of C. perniciosa and these isolates was also assessed over the same range of water potentials. It is hypothesised that C. perniciosa and other canopy inhabiting fungi of tropical forests are adapted to water stress, but are not competitive with fungi which colonise later, following litterfall, from lower litter and soil horizons, where water availability is higher. Xylaria spp. proved to be aggressive antagonists of C. perniciosa over a range of water potentials.

Leaf anatomy of species in some dicotyledon families as related to the C3 and C4 pathways of carbon fixation

1970 ◽  
Vol 48 (12) ◽  
pp. 2135-2146 ◽  
Author(s):  
G. W. Welkie ◽  
M. Caldwell
Keyword(s):  
Leaf Anatomy ◽  
Water Availability ◽  
Carbon Fixation ◽  
Bundle Sheath ◽  
Salsola Kali ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon ◽  
Cell Layers ◽  
Highly Correlated ◽  
Halogeton Glomeratus

Species in the families Amaranthaceae, Aizoaceae, Chenopodiaceae, Convolvulaceae, Euphorbiaceae, Nyctaginaceae, Portulacaceae, and Zygophyllaceae were examined for leaf anatomy typical of plants having the C4 type photosynthetic carbon fixation pathway. They are assembled by families into three groups: genera in which all species possess the specialization; genera in which some but not all species possess the specialization; and genera in which no species possess the specialization. The specialization in leaf anatomy was noted in species of 24 genera. Its presence is highly correlated with a habitat of limited water availability and (or) with a tropical origin. The carbon dioxide compensation points of nine species in the Chenopodiaceae family were measured. Low values were obtained only for those species that possess a form of specialized leaf anatomy (Atriplex confertifolia (Torr. & Frem.) Wats., A. falcata (M. E. Jones) Standl., Halogeton glomeratus (Bieb.) Meyer, Salsola kali L. var. tenuiflora Tausch.). The latter two species, having centric leaves, do not possess the more typical differential bundle sheath chlorenchyma but do possess two, individually distinct, single-cell layers of chlorenchyma, adjacent and external to the peripheral veins.

Water availability influences the inhibitory effects of mustard seed meal on Palmer amaranth (Amaranthus palmeri) and Verticillium dahliae

2020 ◽  
Vol 34 (5) ◽  
pp. 756-763
Author(s):  
Joseph B. Wood ◽  
Brian J. Schutte ◽  
Ivette Guzman ◽  
Soum Sanogo
Keyword(s):  
Verticillium Dahliae ◽  
Water Availability ◽  
Implementation Strategies ◽  
Field Capacity ◽  
Palmer Amaranth ◽  
Saturated Soil ◽  
Seed Meal ◽  
Mustard Seed ◽  
Chile Pepper ◽  
Water Potentials

AbstractPalmer amaranth, an annual weed, and Verticillium dahliae, a fungal pathogen, can substantially reduce chile pepper yield. On the basis of the results of this study, we clarified implementation strategies for a potential management tactic for Palmer amaranth and V. dahliae in chile pepper: mustard seed meal (MSM). The objectives were to (1) determine MSM effects on Palmer amaranth seedbanks under different moisture levels, (2) measure glucosinolate degradation in soil hydrated to saturation and field capacity, and (3) determine the effects of decreasing moisture availability on MSM control of Palmer amaranth and V. dahliae. To address objective 1, seedbanks with and without MSM were hydrated to levels expected to both inhibit and promote germination (flooded, saturated, −0.03, −0.6 MPa, respectively). For objective 2, soil columns with MSM were held at different moisture levels and sampled over time. For objective 3, Palmer amaranth seeds were incubated with and without MSM, and with polyethylene glycol (PEG) solutions comprising a range of water potentials (0, −0.03, −0.6, −1.0, and −2.0 MPa). These PEG solutions were also used to hydrate MSM in agar plates with plugs of V. dahliae. All experiments were performed in growth chambers with temperatures and light conditions conducive to Palmer amaranth germination and V. dahliae mycelial growth. MSM-induced mortality in Palmer amaranth seedbanks was greater in soil at field capacity than in saturated soil and flooded soil; however, rates of glucosinolate degradation were greatest in saturated soil. Decreasing water availability progressively decreased the efficacy of MSM on Palmer amaranth because MSM was ineffective on nongerminated seeds. When incubated with PEG solutions with water potentials of 0, −0.03, and −0.6 MPa, MSM stopped growth of V. dahliae; however, MSM-induced control of V. dahliae was reduced by water potentials of −1.0 and −2.0 MPa. The results of this study indicate soils hydrated to field capacity maximize MSM-induced control of Palmer amaranth and V. dahliae.

scholarly journals The risk-takers and -avoiders: germination sensitivity to water stress in an arid zone with unpredictable rainfall

AoB Plants ◽  
2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Corrine Duncan ◽  
Nick L Schultz ◽  
Megan K Good ◽  
Wolfgang Lewandrowski ◽  
Simon Cook
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Water Potential ◽  
Water Availability ◽  
Cold Climate ◽  
Arid Zones ◽  
Water Potentials ◽  
Risk Takers ◽  
Hydrotime Model ◽  
Germination Traits

Abstract Water availability is a critical driver of population dynamics in arid zones, and plant recruitment is typically episodic in response to rainfall. Understanding species’ germination thresholds is key for conservation and restoration initiatives. Thus, we investigated the role of water availability in the germination traits of keystone species in an arid ecosystem with stochastic rainfall. We measured seed germination responses of five arid species, along gradients of temperature and water potential under controlled laboratory conditions. We then identified the cardinal temperatures and base water potentials for seed germination, and applied the hydrotime model to assess germination responses to water stress. Optimum temperatures for germination ranged from 15 to 31 °C under saturated conditions (0 MPa), and three species had low minimum temperatures for germination (<3 °C). A small proportion of seeds of all species germinated under dry conditions (Ψ ≤ −1 MPa), although base water potential for germination (Ψ b50) ranged from −0.61 to −0.79 MPa. Species adhered to one of two germination traits: (i) the risk-takers which require less moisture availability for germination, and which can germinate over a wider range of temperatures irrespective of water availability (Casuarina pauper and Maireana pyramidata), and (ii) the risk-avoiders which have greater moisture requirements, a preference for cold climate germination, and narrower temperature ranges for germination when water availability is low (Atriplex rhagodioides, Maireana sedifolia and Hakea leucoptera). High seed longevity under physiological stress in H. leucoptera, combined with a risk-avoiding strategy, allows bet-hedging. The hydrotime model predicted lower base water potentials for germination than observed by the data, further supporting our assertion that these species have particular adaptations to avoid germination during drought. This study provides insights into the complex physiological responses of seeds to environmental stress, and relates seed germination traits to community dynamics and restoration in arid zones.

POTENCIAIS HÍDRICOS E TEORES DE ÁGUA NA GERMINAÇÃO DE SEMENTES E CRESCIMENTO INICIAL DE MILHETO

2016 ◽  
Vol 15 (3) ◽  
pp. 619
Author(s):  
TATHIANA ELISA MASETTO ◽  
ELISÂNGELA LEITE VARGAS ◽  
SILVANA DE PAULA QUINTÃO SCALON
Keyword(s):  
Seed Germination ◽  
Moisture Content ◽  
Water Content ◽  
Pearl Millet ◽  
Water Availability ◽  
Pennisetum Glaucum ◽  
Germination Percentage ◽  
Initial Growth ◽  
Water Potentials ◽  
Water Contents

RESUMO – O processo germinativo se inicia com a absorção de água pelas sementes e é influenciado pela disponibilidade hídrica e pelo teor de água das sementes. Objetivou-se avaliar os efeitos de diferentes potenciais hídricos e de teores de água das sementes na germinação e crescimento de plântulas de milheto. Foram utilizadas sementes com teores de água de 14,1%; 16,1%; 20,8% e 21,9% posicionadas em caixas plásticas do tipo “gerbox” sobre duas folhas de papel toalha para germinação previamente umedecidas com 10 mL de soluções de polietilenoglicol (PEG 6000) nos potenciais hídricos de 0,0; -0,1; -0,2; -0,3; -0,4 e -0,6 MPa. As sementes foram mantidas em câmara de germinação a 25 °C sob luz branca constante. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 4 x 5, utilizando-se quatro repetições de 50 sementes cada. As sementes foram avaliadas quanto à primeira contagem, germinação, comprimento da raiz, comprimento da parte aérea, comprimento total, massa fresca e seca de plântulas. A redução dos potenciais hídricos associada aos teores de água das sementes afeta negativamente a germinação e o crescimento das plântulas de milheto, principalmente em sementes com o teor de água de 14,1%. As sementes com os teores de água acima de 16,1% são menos suscetíveis à redução das disponibilidades hídricas do substrato a partir do potencial de -0,1 MPa.Palavras-chave: Pennisetum glaucum, polietilenoglicol, teor de água de sementes.WATER POTENTIAL AND MOISTURE CONTENT ON SEED GERMINATION AND INITIAL GROWTH OF PEARL MILLETABSTRACT – The germination process starts with water absorption by seeds and is influenced by the water availability and seeds moisture content. This work aimed to evaluate the effects of different substrate water potentials and the water contents of the seeds on seed germination of pearl millet. The treatments comprised pearl millet seeds with 14.1%, 16.1%, 20.8% and 21.9% moisture content and submitted to the water availability in the substrate of 0.0 (control); -0.1; -0.2; -0.3; -0.4 and -0.6 MPa. Seeds were sowed in two germination papers and positioned inside plastic boxes of the “gerbox” type and maintained at 25ºC. A completely randomized design in a factorial scheme 4 x 5 was used, with four replications of 50 seeds per treatment. The seeds were evaluated through the first counting, germination percentage, aerial part, root length, total length and fresh and dry mass of seedlings. The reduction of the water potentials associated to the seed water contents affected negatively the seeds germination and seedlings growth of pearl millet, especially in seeds with 14.1% water content. The seeds with water content above 16.1% were less sensitive to the decrease in the water availability of the substrate from -0.1 MPa.Keywords: Pennisetum glaucum, polyethylene glycol, seeds water content.

Techniques for preparing the Lolium perenne coleorhiza for scanning electron microscope evaluation

1992 ◽  
Vol 50 (1) ◽  
pp. 766-767
Author(s):  
Susan B.G. Debaene ◽  
John S. Gardner ◽  
Phil S. Allen
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Lolium Perenne ◽  
Morphological Study ◽  
Root Hairs ◽  
Inner Pressure ◽  
Water Potentials ◽  
Radicle Emergence ◽  
Standard Fixation ◽  
Scanning Electron

The coleorhiza is a nonvascular sheath that encloses the embryonic radicle in Poaceae, and is generally the first tissue to emerge during germination. Delicate hairlike extensions develop from some coleorhiza cells prior to radicle emergence. Similar to root hairs, coleorhiza hairs are extremely sensitive to desiccation and are damaged by exposure to negative water potentials. The coleorhiza of Lolium perenne is somewhat spherical when first visible, after which a knob forms at a right angle to the caryopsis due to inner pressure from the elongating radicle. This knob increases in length until the radicle finally punctures the coleorhiza. Standard fixation procedures cause severe desiccation of coleorhiza cells and hairs, making morphological study of the coleorhiza difficult. This study was conducted to determine a more successful process for coleorhiza preservation.

Impact of water availability on winter wheat ( Triticum aestivum L.) yield characteristics

2010 ◽  
Vol 59 (1) ◽  
pp. 151-156 ◽  
Author(s):  
H. Klupács ◽  
Á. Tarnawa ◽  
I. Balla ◽  
M. Jolánkai
Keyword(s):  
Winter Wheat ◽  
Water Supply ◽  
Water Availability ◽  
Grain Quality ◽  
Physiological Condition ◽  
Triticum Aestivum L ◽  
Annual Precipitation ◽  
Average Depth ◽  
Experimental Site ◽  
Yield Quality

Water supply of crop plants is the most essential physiological condition influencing quality and quantity performance of grain yield. In a 12-year experimental series of winter wheat agronomic trials run at the Nagygombos experimental site (Hungary) the effect of water availability has been studied. The location represents the typical average lowland conditions of the country, the annual precipitation of the experimental site belonging to the 550–600 mm belt of the Northern edges of the Great Hungarian Plain, while the average depth of groundwater varies between 2 to 3 metres. Crop years with various precipitation patterns have had different impacts on crop yield quality and quantity. Yield figures were in positive correlation with annual precipitation in general. Water availability had diverse influence on quality manifestation. Good water supply has often resulted in poorer grain quality, especially wet gluten and Hagberg values have been affected by that. Drought reduced the amount of yield in general, but contributed to a better quality manifestation in some of the crop years.

Root growth and proline content in drought sensitive and tolerant maize (Zea maysL.) seedlings under different water potentials

2005 ◽  
Vol 33 (4) ◽  
pp. 697-704 ◽  
Author(s):  
Adriana Sánchez-Urdaneta ◽  
Cecilia Peña-Valdivia ◽  
Carlos Trejo ◽  
J. Aguirre R. ◽  
Elizabeth Cárdenas S.
Keyword(s):  
Root Growth ◽  
Proline Content ◽  
Water Potentials
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