Indole acetic acid (IAA) induced changes in growth, relative water contents and gas exchange attributes of barley (Hordeum vulgare L.) grown under water stress conditions

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.

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

Australian Journal of Experimental Agriculture ◽

10.1071/ea9740076 ◽

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.

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Water stress and the catabolism of (�)-abscisic acid by excised leaves of Hordeum vulgare L. cv. Dyan

Plant Growth Regulation ◽

10.1007/bf00024739 ◽

1987 ◽

Vol 5 (2) ◽

pp. 115-124 ◽

Cited By ~ 4

Author(s):

Ian D. Railton ◽

A. Keith Cowan

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Hordeum Vulgare ◽

Hordeum Vulgare L

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Biosynthesis of indole-3-acetic acid in protoplasts, chloroplasts and a cytoplasmic fraction from barley (Hordeum vulgare L.)

Planta ◽

10.1007/bf00392778 ◽

1982 ◽

Vol 156 (6) ◽

pp. 541-545 ◽

Cited By ~ 12

Author(s):

Goran Sandberg ◽

Einar Jensen ◽

Alan Crozier

Keyword(s):

Acetic Acid ◽

Hordeum Vulgare ◽

Cytoplasmic Fraction ◽

Hordeum Vulgare L ◽

Indole 3 Acetic Acid

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Comparison of Strawberry F. chilocnsis and F. ×ananassa in Response to Water Stress: I. Leaf Water Potential, Relative Water Content, and Gas Exchange Characteristics

HortScience ◽

10.21273/hortsci.31.4.601c ◽

1996 ◽

Vol 31 (4) ◽

pp. 601c-601

Author(s):

Chuhe Chen ◽

J. Scott Cameron ◽

Stephen F. Klauer

Keyword(s):

Water Stress ◽

Gas Exchange ◽

Water Potential ◽

Water Content ◽

Leaf Water Potential ◽

Relative Water Content ◽

Leaf Water ◽

Severe Water Stress ◽

Relative Water ◽

Gas Exchange Characteristics

Leaf water potential (LWP), relative water content (RWC), gas exchange characteristics, and specific leaf weight (SLW) were measured six hours before, during, and after water stress treatment in F. chiloensis and F. ×ananassa grown in growth chambers. The leaves of both species showed significantly lower LWP and RWC as water stress developed. F. ×ananassa had consistency lower LWP under stressed and nonstressed conditions than F. chiloensis. F. ×ananassa had higher RWC under nonstressed conditions, and its RWC decreased more rapidly under water stress than F. chiloensis. In comparison to F. ×ananassa, F. chiloensis had significantly higher CO2 assimilation rate (A), leaf conductance (LC), and SLW, but not transpiration rate (Tr), under stressed and nonstressed conditions. LC was the most sensitive gas exchange characteristic to water stress and decreased first. Later, A and stomatal conductance were reduced under more severe water stress. A very high level of Tr was detected in F. ×ananassa under the most severe water stress and did not regain after stress recovery, suggesting a permanent damage to leaf. The Tr of F. chiloensis was affected less by water stress. Severe water stress resulted in higher SLW of both species.

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