GERMINATION OF WHEAT AS AFFECTED BY SOIL WATER STRESS

1972 ◽  
Vol 52 (4) ◽  
pp. 619-623 ◽  
Author(s):  
M. C. PAWLOSKI ◽  
C. F. SHAYKEWICH
Keyword(s):  
Water Stress ◽  
Hydraulic Conductivity ◽  
Water Potential ◽  
Soil Water ◽  
Germination Rate ◽  
Membrane System ◽  
Semipermeable Membrane ◽  
Matric Potential ◽  
Soil Water Stress ◽  
Water Potentials

Germination rate of wheat was determined at several water potentials (−0.8, −5.3, −7.8, and −15.3 bars) on two soils and a semipermeable membrane. Germination rate decreased as matric potential decreased. At a given water potential, germination rates were the same for both soils but germination on the membrane system was faster than on soils. Hydraulic conductivity was different on the two media, indicating that the hydraulic conductivity is an important component of soil water stress. Germination rate was not affected by decreasing water potential to −7.8 bars on each medium. At the −15.3-bar potential germination rate was considerably slower.

scholarly journals Potassium Application Positively Modulates Physiological Responses of Cocoa Seedlings to Drought Stress

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 563
Author(s):  
Esther Anokye ◽  
Samuel T. Lowor ◽  
Jerome A. Dogbatse ◽  
Francis K. Padi
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Chlorophyll Content ◽  
Electrolyte Leakage ◽  
Seedling Survival ◽  
Biomass Accumulation ◽  
Biomass Partitioning ◽  
Chlorophyll Content And Fluorescence ◽  
Physiological Functions ◽  
Soil Water Stress

With increasing frequency and intensity of dry spells in the cocoa production zones of West Africa, strategies for mitigating impact of water stress on cocoa seedling survival are urgently required. We investigated the effects of applied potassium on biomass accumulation, physiological processes and survival of cocoa varieties subjected to water stress in pot experiments in a gauzehouse facility. Four levels of potassium (0, 1, 2, or 3 g/plant as muriate of potash) were used. Soil water stress reduced plant biomass accumulation (shoot and roots), relative water content (RWC), chlorophyll content and fluorescence. Leaf phenol and proline contents were increased under water stress. Additionally, compared to the well-watered conditions, soils under water stress treatments had higher contents of exchangeable potassium and available phosphorus at the end of the experimental period. Potassium applied under well-watered conditions reduced leaf chlorophyll content and fluorescence and increased leaf electrolyte leakage, but improved the growth and integrity of physiological functions under soil water stress. Potassium addition increased biomass partitioning to roots, improved RWC and leaf membrane stability, and significantly improved cocoa seedling survival under water stress. Under water stress, the variety with the highest seedling mortality accumulated the highest contents of phenol and proline. A significant effect of variety on plant physiological functions was observed. Generally, varieties with PA 7 parentage had higher biomass partitioning to roots and better seedling survival under soil moisture stress. Proportion of biomass partitioned to roots, RWC, chlorophyll fluorescence and leaf electrolyte leakage appear to be the most reliable indicators of cocoa seedling tolerance to drought.

NITROGEN TRANSFORMATIONS NEAR UREA IN SOIL WITH DIFFERENT WATER POTENTIALS

1988 ◽  
Vol 68 (3) ◽  
pp. 569-576 ◽  
Author(s):  
YADVINDER SINGH ◽  
E. G. BEAUCHAMP
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Incubation Period ◽  
Relative Rate ◽  
Soil Water Potential ◽  
Nitrification Inhibitor ◽  
Silt Loam ◽  
Nitrogen Transformations ◽  
Water Potentials ◽  
Initial Soil

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production

Water stress affects the productivity, growth components, competitiveness and water relations of phalaris and white clover growing in a mixed pasture

1992 ◽  
Vol 43 (3) ◽  
pp. 659 ◽  
Author(s):  
L Guobin ◽  
DR Kemp ◽  
GB Liu
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
White Clover ◽  
Leaf Growth ◽  
Leaf Water ◽  
Water Potentials ◽  
Relative Water ◽  
Dry Conditions ◽  
Leaf Appearance ◽  
Water Contents

The effect of water stress during summer and recovery after rain on herbage accumulation, leaf growth components, stomatal conductance and leaf water relations of white clover (Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) was studied in an established mixed pasture under dryland (dry) or irrigated (wet) conditions. Soil water deficits under dry conditions reached 150 mm and soil water potentials in the top 20 cm declined to nearly -2 MPa after 50 days of dry weather. Water stress severely restricted growth of both species but then after rain fell, white clover growth rates exceeded those of phalaris. Under irrigation, white clover produced twice the herbage mass of phalaris but under dry conditions herbage production was similar from both species. Leaf appearance rates per tiller or stolon were slightly higher for white clover than phalaris but were reduced by 20% under water stress in both species. Leaf or petiole extension rates were more sensitive to water stress than leaf appearance rates and declined by 75% in phalaris and 90% in white clover. The ratio of leaf or petiole extension rates on dry/wet treatments was similar for both species in relation to leaf relative water contents, but in relation to leaf water potentials phalaris maintained higher leaf growth rates. Phalaris maintained a higher leaf relative water content in relation to leaf water potentials than did white clover and also maintained higher leaf water potentials in relation to the soil water potential in the top 20 cm. Stomata1 conductances for both species declined by 80-90% with increasing water stress, and both species showed similar stomatal responses to bulk leaf water potentials and leaf relative water contents. It is suggested that the poorer performance of white clover under water stress may be due principally to a shallower root system than phalaris and not due to any underlying major physiological differences. The white clover cultivar used in this study came from the mediterranean region and showed some different responses to water stress than previously published evidence on white clover. This suggests genetic variation in responses to water stress may exist within white clover. To maintain white clover in a pasture under dry conditions it is suggested that grazing practices aim to retain a high proportion of growing points.

scholarly journals Unexpected relationships between δ13C and wine grape performance in organic farming

OENO One ◽  
2013 ◽  
Vol 47 (4) ◽  
pp. 269 ◽  
Author(s):  
Edoardo Antonio Costantino Costantini ◽  
Alessandro Agnelli ◽  
Pierluigi Bucelli ◽  
Aldo Ciambotti ◽  
Valentina Dell’Oro ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Soil Water ◽  
Organic Farming ◽  
Water Availability ◽  
Stress Conditions ◽  
Soil Water Availability ◽  
Wine Grape ◽  
Stem Water Potential ◽  
Stem Water

<p style="text-align: justify;"><strong>Aim</strong>: To evaluate the relationship between carbon isotope ratio (δ<sup>13</sup>C) and wine grape viticultural and oenological performance in organic farming.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The study was carried out for four years in the Chianti Classico wine production district (Central Italy), on five non irrigated vineyards conducted in organic farming. The reference variety was Sangiovese. Eleven sites were chosen for vine monitoring and grape sampling. The performance parameters were alcohol and must sugar content, sugar accumulation rate, mean berry weight, and extractable polyphenols. δ<sup>13</sup>C, stem water potential, and soil water availability were also monitored. Finally, soil nitrogen as well as yeast available nitrogen in the must were measured. δ<sup>13</sup>C was directly related to stem water potential and soil water deficit, and indicated a range of water stress conditions from none and moderate to strong. However, its relationship with viticultural and oenological results was contrary to expectation, that is, performance linearly increased along with soil moisture. On the other hand, the worst performance was obtained where both water and nitrogen were more limiting.</p><p style="text-align: justify;"><strong>Conclusions</strong>: The unexpected relationship between δ<sup>13</sup>C and Sangiovese performance was caused by low nitrogen availability. The studied sites all had low-fertility soils with poor or very poor nitrogen content. Therefore, in the plots where soil humidity was relatively higher, nitrogen plant uptake was favoured, and Sangiovese performance improved. Macronutrient being the main limiting factor, the performance was not lower in the plots where soil water availability was relatively larger. Therefore, the best viticultural result was obtained with no water stress conditions, at low rather than at intermediate δ<sup>13</sup>C values.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: Water nutrition is crucial for wine grape performance. δ<sup>13</sup>C is a method used to assess vine water status during the growing season and to estimate vine performance. A good performance is expected at moderate stress and intermediate δ<sup>13</sup>C values. A better knowledge of the interaction between water and nutrient scarcity is needed, as it can affect the use of δ<sup>13</sup>C to predict vine performance.</p>

scholarly journals DINÂMICA DA ÁGUA NO SISTEMA SOLO-PLANTA NO CULTIVO DA PIMENTA TABASCO SOB DÉFICIT HÍDRICO1

Irriga ◽  
2018 ◽  
Vol 1 (01) ◽  
pp. 246
Author(s):  
Lígia Borges Marinho ◽  
José Antonio Frizzone ◽  
João Batista Tolentino Júnior ◽  
Janaina Paulino ◽  
Danilton Luiz Flumigan ◽  
...  
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Deficit ◽  
Water Extraction ◽  
Soil Matric Potential ◽  
Water Restriction ◽  
Matric Potential ◽  
Mato Grosso ◽  
Vegetative Phase ◽  
E Mail

DINÂMICA DA ÁGUA NO SISTEMA SOLO-PLANTA NO CULTIVO DA PIMENTA TABASCO SOB DÉFICIT HÍDRICO1  LÍGIA BORGES MARINHO2; JOSÉ ANTONIO FRIZZONE3; JOÃO BATISTA TOLENTINO JÚNIOR4; JANAÍNA PAULINO5; DANILTON LUIZ FLUMIGNAN6 E DIEGO BORTOLOTI GÓES3    (1) Artigo extraído da tese do primeiro autor (2) Departamento Tecnologia e Ciências Sociais, Universidade do Estado da Bahia, av. Edgard Chastinet, São Geraldo, CEP 48905-680, Juazeiro, BA. Fone (74) 3611-7363. E-mail: [email protected](3) Departamento de Engenharia de Biossistemas/Escola Superior de Agricultura “Luiz de Queiroz” USP, Av. Pádua Dias, 11, CEP 13.418-900, Piracicaba/SP, E-mail(s): [email protected], [email protected]; (4) Campus Curitibanos, Universidade Federal de Santa Catarina, Curitibanos, SC. [email protected] (5) Universidade Federal de Mato Grosso UFMT, campus Sinop, Avenida Alexandre Ferronato Nº 1.200. Bairro: Setor Industrial. CEP: 78.550-000,  Sinop-MT, Email: [email protected] (6) Empresa Brasileira de Pesquisa Agropecuária, Agropecuária Oeste. Rodovia BR 163, km 253, Zona Rural, 79804970 - Dourados, MS,  Email: [email protected]  1 RESUMO  O objetivo da pesquisa foi acompanhar a variação da condição hídrica do solo e da planta de pimenta ‘Tabasco’ em função dos manejos de déficits hídricos impostos e determinar seu coeficiente de estresse hídrico. O experimento foi conduzido em ambiente protegido, no Departamento de Engenharia de Biossistemas da ESALQ - USP, Piracicaba-SP, de setembro de 2009 a julho de 2010. O delineamento experimental foi blocos casualizados, com quatro repetições, utilizando-se lâminas de irrigação a 100, 80, 60 e 40% da evapotranspiração da cultura diferenciadas a partir da fase vegetativa e da fase reprodutiva. O potencial da água na folha e no solo foi aferido com a câmara de pressão e tensiômetros, respectivamente. Houve variação do potencial mátrico, da extração de água no solo e do potencial de água na folha em função das lâminas e das épocas de diferenciação. Menores potenciais mátricos foram verificados quando o déficit de irrigação foi inicializado na fase vegetativa da pimenta. Os valores de coeficiente de estresse hídrico e o potencial de água na folha, ao alvorecer, indicaram que as pimenteiras estavam sob estresse moderado e severo, sendo a época reprodutiva da pimenta Tabasco a mais sensível à restrição hídrica.Palavras-chave: Capsicum frutencens L, tensiômetro, potencial da água no solo.                                                        MARINHO, L. B.; FRIZZONE, J. A.; TOLENTINO JÚNIOR, J. B.; PAULINO, J.; FLUMIGNAN, D. L.; GÓES, D. B.WATER DYNAMICS IN SOIL-PLANT SYSTEM IN THE CULTIVATION OF PEPPER TABASCO UNDER WATER DEFICIT  2 ABSTRACT The objective of the research was to determine the change in soil water condition and in Tabasco pepper plant according to the managements of water deficits. The experiment was conducted in a greenhouse at the Department of Biosystems Engineering of ESALQ - USP, Piracicaba-SP, from September 2009 to July 2010. The experimental design was randomized blocks with four replications, using irrigation depths to 100, 80, 60 and 40% of crop evapotranspiration in the vegetative phase and reproductive phase. The soil matric potential was measured by tensiometers installed at 0-20 and 20-40 cm depth. The most negative values of matric potential occurred in treatments submitted to the greater water deficit treatments that had higher water restriction imposed by the vegetative phase. For these, greater increase in water extraction in the deepest layer (40 cm) were also found.There were differences in matric potential of the soil, in ground water extraction and in leaf water potential in relation to the water depths and differentiation phases. The deficit irrigation that started in the vegetative phase led to greater reduction in soil matric potential due to the accumulated water deficit. The pepper plants have moderate to severe sensitivity to water deficit in the soil, with a higher sensitivity of the plants when water restriction is imposed during reproductive stages than when it is imposed during growing stages. Keywords : Capsicum frutencens, tensiometer; soil water potential

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