PHYSIOLOGICAL CHANGES IN BARLEY (HORDEUM VULGARE L.) DURING WATER STRESS.

Persistent Link:
http://hdl.handle.net/10150/187892
Title:
PHYSIOLOGICAL CHANGES IN BARLEY (HORDEUM VULGARE L.) DURING WATER STRESS.
Author:
RIAZI, ARDESHIR.
Issue Date:
1982
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Young barley seedlings (Hordeum vulgare L.) were stressed using nutrient solutions containing NaCl or polyethyleneglycol (PEG) and measurements were made of leaf growth, water status, proline soluble sugar contents of growing (basal) and non-growing (blade) tissues. Leaf growth ceased within seconds following exposure of seedlings to osmotic solutions with water potential values (ψ) = -3 to -11 bars but growth resumed after a lag period. Latent periods were increased and new growth rates were decreased as ψ of nutrient solutions were lowered. Growth ceased before detectable changes occurred in tissue water status but leaf basal tissues began to adjust osmotically, and reductions of 1 to 2 bars in both ψ and osmotic potential (π) usually occurred for the first 1 to 2 hours with lower reduction rates thereafter. After 1 to 3 days exposure of seedlings to solutions with different ψ, cumulative leaf elongation was reduced as the ψ of the root medium was lowered. Reductions in ψ and π of tissues in leaf basal regions paralleled growth reductions, but turgor (P) was largely unaffected by stress. In contrast, ψ, π and P of leaf blades were usually changed little regardless of the degree and duration of stress, and blade ψ were always higher than ψ of basally located cells. It is hypothesized that blades have high ψ and are generally unresponsive to stress because water in most of the mesophyll cells in this area does not exchange readily with water present in the transpiration stream. Measurements of proline contents in different sections of leaf following water stress, showed that in living tissues proline levels are dynamically related to water status of the tissue. In the basal regions where reductions in ψ and π occurred rapidly, proline levels were elevated quickly, whereas, accumulation of proline in mid-blade tissues occurred slowly and in lower concentrations. The combined data of many experiments showed a strong correlation between proline levels and tissue ψ (r = 0.93) and π (r = 0.85). Increase in total soluble sugars (TSS) and ion concentrations, contributed significantly to the stress-induced osmotic adjustment observed in the growing tissue.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Barley -- Physiology.; Plants -- Effect of stress on.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Plant Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Matsuda, Karou

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titlePHYSIOLOGICAL CHANGES IN BARLEY (HORDEUM VULGARE L.) DURING WATER STRESS.en_US
dc.creatorRIAZI, ARDESHIR.en_US
dc.contributor.authorRIAZI, ARDESHIR.en_US
dc.date.issued1982en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractYoung barley seedlings (Hordeum vulgare L.) were stressed using nutrient solutions containing NaCl or polyethyleneglycol (PEG) and measurements were made of leaf growth, water status, proline soluble sugar contents of growing (basal) and non-growing (blade) tissues. Leaf growth ceased within seconds following exposure of seedlings to osmotic solutions with water potential values (ψ) = -3 to -11 bars but growth resumed after a lag period. Latent periods were increased and new growth rates were decreased as ψ of nutrient solutions were lowered. Growth ceased before detectable changes occurred in tissue water status but leaf basal tissues began to adjust osmotically, and reductions of 1 to 2 bars in both ψ and osmotic potential (π) usually occurred for the first 1 to 2 hours with lower reduction rates thereafter. After 1 to 3 days exposure of seedlings to solutions with different ψ, cumulative leaf elongation was reduced as the ψ of the root medium was lowered. Reductions in ψ and π of tissues in leaf basal regions paralleled growth reductions, but turgor (P) was largely unaffected by stress. In contrast, ψ, π and P of leaf blades were usually changed little regardless of the degree and duration of stress, and blade ψ were always higher than ψ of basally located cells. It is hypothesized that blades have high ψ and are generally unresponsive to stress because water in most of the mesophyll cells in this area does not exchange readily with water present in the transpiration stream. Measurements of proline contents in different sections of leaf following water stress, showed that in living tissues proline levels are dynamically related to water status of the tissue. In the basal regions where reductions in ψ and π occurred rapidly, proline levels were elevated quickly, whereas, accumulation of proline in mid-blade tissues occurred slowly and in lower concentrations. The combined data of many experiments showed a strong correlation between proline levels and tissue ψ (r = 0.93) and π (r = 0.85). Increase in total soluble sugars (TSS) and ion concentrations, contributed significantly to the stress-induced osmotic adjustment observed in the growing tissue.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBarley -- Physiology.en_US
dc.subjectPlants -- Effect of stress on.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlant Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMatsuda, Karouen_US
dc.identifier.proquest8217462en_US
dc.identifier.oclc681973233en_US
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