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 Rapid and Efficient Determination of Relative Water Contents of Crop Leaves Using Electrical Impedance Spectroscopy in Vegetative Growth Stage

2020 ◽  
Vol 12 (11) ◽  
pp. 1753
Author(s):  
Rinku Basak ◽  
Khan A. Wahid ◽  
Anh Dinh ◽  
Raju Soolanayakanahally ◽  
Reza Fotouhi ◽  
...  
Keyword(s):  
Water Stress ◽  
Impedance Spectroscopy ◽  
Electrical Impedance ◽  
Growth Stage ◽  
Leaf Water ◽  
Electrical Impedance Spectroscopy ◽  
Crop Water ◽  
Relative Water ◽  
Water Contents ◽  
Crop Water Stress

Crop water stress is a deficiency in plants in water supply when the transpiration rate becomes higher than the water absorption capacity. The stress may be detected by a reduction in soil water content, or by the change in physiological properties of the crop. The leaf water content (LWC) is commonly used to assess the water status of plants, which is one of the indicators of crop water stress. In this work, the leaf relative water contents of four different crops: canola, wheat, soybeans, and corn—all in vegetative growth stage—were determined by a noninvasive tool called, electrical impedance spectroscopy (EIS). Using a frequency range of 5–15 kHz, a strong correlation between leaf water contents and leaf impedances was obtained using multiple linear regression. The trained dataset was validated by analysis of variance tests. Regression results were obtained using the least square method. The optimized regression model coefficients for different crops were proposed by selecting features using the wrapper backward elimination method. Multi-collinearity among the features was considered and individual T-tests were made in the feature selection. A maximum correlation coefficient (R) of 0.99 was obtained for canola compared to the other crops; the corresponding coefficient of determination (R2) of 0.98, an adjusted R2 of 0.93, and root mean square error (rmse) of 0.30% were obtained for 36 features. Therefore, the results show that the proposed technique using EIS can be used to develop a low-cost and effective tool for determining the leaf water contents rapidly and efficiently in multiple crops.

The Influence of Water Stress on the Physiology and Competition of Soybean (Glycine max) and Florida Beggarweed (Desmodium tortuosum)

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 544-551 ◽  
Author(s):  
Blair S. Griffin ◽  
Donn G. Shilling ◽  
Jerry M. Bennett ◽  
Wayne L. Currey
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Leaf Water ◽  
Water Potentials ◽  
Influence Of Water ◽  
Soybean Leaf ◽  
Different Levels ◽  
Optimum Water

Replacement studies were conducted under greenhouse conditions to determine if available soil water influences the competitive interaction between soybean and Florida beggarweed. Stomatal conductance and leaf water potential were determined for both species under different levels of available soil water to identify possible mechanisms involved in changes in the relative competitiveness induced by the water deficits. Soybean leaf area and aboveground biomass were greater than for Florida beggarweed under optimum water, but equal to or less than Florida beggarweed with water stress. Soybean was more competitive than Florida beggarweed when there was adequate soil water but less competitive than Florida beggarweed under water stress. Stomatal conductance was higher for soybean with optimum soil water (at high leaf water potentials) but equal to Florida beggarweed as soil water became limiting (low leaf water potentials). These data indicated that water stress differentially affected soybean and Florida beggarweed.

MITIGATION YIELD SCALED METHANE EMISSION FROM RICE GROWN IN WATER STRESS CONDITIONS WITH BIOCHAR AND SILICATE AMENDMENTS

2021 ◽  
Author(s):  
MUHAMMAD ASLAM ALI ◽  
SANJIT CHANDRA BARMAN ◽  
MD. ASHRAFUL ISLAM KHAN ◽  
MD. BADIUZZAMAN KHAN ◽  
HAFSA JAHAN HIYA
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Capacity ◽  
Saturated Soil ◽  
Rice Grain ◽  
Standing Water ◽  
Water Contents ◽  
Soil Water Contents

Climate change and water scarcity may badly affect existing rice production system in Bangladesh. With a view to sustain rice productivity and mitigate yield scaled CH4 emission in the changing climatic conditions, a pot experiment was conducted under different soil water contents, biochar and silicate amendments with inorganic fertilization (NPKS). In this regard, 12 treatments combinations of biochar, silicate and NPKS fertilizer along with continuous standing water (CSW), soil saturation water content and field capacity (100% and 50%) moisture levels were arranged into rice planted potted soils. Gas samples were collected from rice planted pots through Closed Chamber technique and analyzed by Gas Chromatograph. This study revealed that seasonal CH4 emissions were suppressed through integrated biochar and silicate amendments with NPKS fertilizer (50–75% of the recommended doze), while increased rice yield significantly at different soil water contents. Biochar and silicate amendments with NPKS fertilizer (50% of the recommended doze) increased rice grain yield by 10.9%, 18.1%, 13.0% and 14.2%, while decreased seasonal CH4 emissions by 22.8%, 20.9%, 23.3% and 24.3% at continuous standing water level (CSW) (T9), at saturated soil water content (T10), at 100% field capacity soil water content (T11) and at 50% field capacity soil water content (T12), respectively. Soil porosity, soil redox status, SOC and free iron oxide contents were improved with biochar and silicate amendments. Furthermore, rice root oxidation activity (ROA) was found more dominant in water stress condition compared to flooded and saturated soil water contents, which ultimately reduced seasonal CH4 emissions as well as yield scaled CH4 emission. Conclusively, soil amendments with biochar and silicate fertilizer may be a rational practice to reduce the demand for inorganic fertilization and mitigate CH4 emissions during rice cultivation under water stress drought conditions.

scholarly journals Effects of soil water depletion on the water relations in tropical kudzu

1999 ◽  
Vol 34 (7) ◽  
pp. 1151-1157
Author(s):  
Adaucto Bellarmino de Pereira-Netto ◽  
Antonio Celso Novaes de Magalhães ◽  
Hilton Silveira Pinto
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Content ◽  
Soil Water ◽  
Cover Crop ◽  
Soil Water Depletion ◽  
Pueraria Phaseoloides ◽  
Water Depletion ◽  
Relative Water ◽  
Dry Soil

Tropical kudzu (Pueraria phaseoloides (Roxb.) Benth., Leguminosae: Faboideae) is native to the humid Southeastern Asia. Tropical kudzu has potential as a cover crop in regions subjected to dryness. The objective of this paper was to evaluate the effect of soil water depletion on leaflet relative water content (RWC), stomatal conductance (g) and temperature (T L) in tropical kudzu. RWC of waterstressed plants dropped from 96 to 78%, following a reduction in SWC from 0.25 to 0.17 g (H2O).g (dry soil)-1.Stomatal conductance of stressed plants decreased from 221 to 98 mmol.m-2.s-1, following the reduction in soil water content (SWC). The day after re-irrigation, g of water stressed plants was 15% lower than g of unstressed plants. Differences in T L between waterstressed and unstressed plants (deltaT L) rose linearly from 0.1 to 2.2ºC following progressive water deficit. RWC and T L of waterstressed plants paralled RWC and T L of unstressed plants the day after reirrigation. The strong decrease in SWC found in this study only induced moderate water stress in tropical kudzu. In addition, tropical kudzu recover rapidly from the induced water stress after the re-irrigation.

Effects of water stress and soil type on photosynthesis, leaf water potential and yield of olive trees (Olea europaea L. cv. Chemlali Sfax)

2007 ◽  
Vol 47 (12) ◽  
pp. 1484 ◽  
Author(s):  
B. Ben Rouina ◽  
A. Trigui ◽  
R. d'Andria ◽  
M. Boukhris ◽  
M. Chaïeb
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Sandy Soil ◽  
Clay Soil ◽  
Sandy Loam ◽  
Leaf Water ◽  
Severe Drought ◽  
Relative Water ◽  
Olive Trees

In Tunisia, olives are grown under severe rain-fed, arid conditions. To determine the behaviour of olive trees (cv. Chemlali Sfax) during the severe drought affecting Tunisian arid areas in 2002, a range of physiological parameters were investigated in three adjacent orchards. Two olive orchards were rain-fed, one located on a sandy soil, and the other on a sandy-loam clay soil. A third orchard was also located on sandy soil, but received remedial irrigation (415 mm of water per year; ~40% of olive evapotranspiration). Predawn leaf water potential (Ψpd) did not fall below –1.52 MPa for irrigated olive trees. However, a large decrease in Ψpd was observed for rain-fed olive trees in the same period with Ψpd measured at about –3.2 MPa on sandy soil and –3.6 MPa on sandy-loam clay soil. At the same time, the minimal leaf water potential recorded at midday (Ψmin) decreased to –4.15 MPa and –4.71 MPa in the rain-fed trees for sandy and sandy-loam clay soil, respectively. For irrigated trees, the Ψmin was –1.95 MPa. These results were associated with relative water content, which varied from 80% for irrigated trees to 54 and 43.6%, respectively, for rain-fed trees and trees subjected to severe drought. In August, when the relative water content values were less than 50%, a progressive desiccation in the outer layer of canopy and death of terminal shoots were observed in trees, which grew on the sandy-loam clay soil. Furthermore, low soil water availability also affected (negatively) the net photosynthetic rate in rain-fed orchards (10.3 µmol/m2.s for irrigated trees v. 5.3 µmol/m2.s in rain-fed trees on sandy soil) and stomatal conductance (98.5 mmol/m2.s v. 69.3 mmol/m2.s). However, it improved water use efficiency (7.6 v. 4.7 µmol CO2/mmol H2O), which increased by more than 50% in both groups of rain-fed trees compared with the irrigated ones. We can conclude that olive trees respond to drought by showing significant changes in their physiological and biological mechanisms. These results also help our understanding of how olive trees cope with water stress in the field and how marginal soils can restrict growth and lower yields.

Leaf area development of ABA-deficient and wild-type peas at two levels of nitrogen supply

2003 ◽  
Vol 30 (7) ◽  
pp. 777 ◽  
Author(s):  
Ian C. Dodd
Keyword(s):  
Growth Response ◽  
Leaf Growth ◽  
Nitrogen Supply ◽  
Genotypic Differences ◽  
Wild Type ◽  
Ethylene Evolution ◽  
Relative Water ◽  
Ca 50 ◽  
Area Development ◽  
Water Contents

The ABA-deficient wilty pea (Pisum sativum L.) and its wild-type (WT) were grown at two levels of nitrogen supply (0.5 and 5.0 mM) for 5–6 weeks from sowing, to determine whether leaf ABA status altered the leaf growth response to N deprivation. Plants were grown at high relative humidity to prevent wilting of the wilty peas. Irrespective of N supply, expanding wilty leaflets had ca 50% less ABA than WT leaflets but similar ethylene evolution rates. Fully expanded wilty leaflets had lower relative water contents (RWC) and were 10–60% smaller in area (according to the node of measurement) than WT leaflets. However, there were no genotypic differences in plant relative leaf expansion rate (RLER). Growth of both genotypes at 0.5 mM N increased the RWC of fully expanded leaflets, but did not alter ethylene evolution or ABA concentration of expanding leaflets. Plants grown at 0.5 mM N showed a 20–30% reduction in RLER, which was similar in magnitude in both wilty and WT peas. Thus,�leaf ABA status did not alter the leaf growth response to N deprivation.

Visual assessment of total plant relative water content, with the aid of photographic standards, as a guide to scheduling irrigation

1974 ◽  
Vol 14 (66) ◽  
pp. 76
Author(s):  
GJ Luke
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Visual Assessment ◽  
Whole Plant ◽  
Accurate Indication ◽  
Relative Water ◽  
Total Plant ◽  
Scheduling Irrigation ◽  
Maize Plants ◽  
Water Contents

The relative water contents (RWC) of the top and bottom leaves of maize plants were measured. The RWC of the top leaf was higher than that of the bottom leaf when the plant was under water stress. Photographic standards based on the RWC of the whole plant were developed and tested against plants in the field. The results showed that the standards give an accurate indication of the plant's water status. Standards based on the upper leaf only would result in irrigations too infrequent to prevent severe restrictions to photosynthesis.

Effects of soil water supply and temperature on the photosynthesis of white clover and paspalum in irrigated pastures

1988 ◽  
Vol 28 (3) ◽  
pp. 321 ◽  
Author(s):  
SJ Blaikie ◽  
FM Martin ◽  
WK Mason ◽  
DJ Connor
Keyword(s):  
Soil Water ◽  
Water Deficit ◽  
Photosynthetic Rate ◽  
White Clover ◽  
Root Zone ◽  
High Irradiance ◽  
Water Deficit Stress ◽  
Summer Temperatures ◽  
Dry Soil ◽  
Water Contents

Field canopy chambers were used to measure the effect of a range of soil water contents from surface ponding to very dry soil and the effect of high summer temperatures on the photosynthesis of irrigated white clover and paspalum pastures. Water was ponded for 5-12 days on swards of white clover and paspalum at full cover and on others that had been defoliated to a height of 50 mm. Photosynthetic rate was monitored each day and compared with a non-ponded control. In all cases there was little response in photosynthetic rate to ponding either with or without supplemental nitrogen fertiliser. Photosynthesis of full swards of white clover and paspalum was monitored during a drying cycle following irrigation and compared with the photosynthesis of a well-watered control. Soil water deficit was expressed in terms of cumulative evaporation minus rainfall (mm E - R) after irrigation. Water deficit stress reduced the maximum photosynthetic rate of white clover by 50% (from 0.8 mg CO2/m2.s at 25 mm E - R to 0.4 mg CO2/m2.s at 75 mm E - R), but the photosynthetic rate of paspalum did not decline until 70 mm E - R. At high irradiance, temperatures between 24 and 33�C had little effect on the photosynthetic rate of well-watered white clover, whereas the rate in paspalum was higher at temperatures between 29 and 38�C than at temperatures of 24-29�C. The slow surface drainage and subsequent rapid drying of the root-zone of flood irrigated soils, combined with the high temperatures experienced in northern Victoria during summer, favour paspalum and severely limit the productivity of white clover.

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