Growth and water status responses of mung bean (Vigna mungo L.) and other dicot species to osmotic stress.

Persistent Link:
http://hdl.handle.net/10150/184668
Title:
Growth and water status responses of mung bean (Vigna mungo L.) and other dicot species to osmotic stress.
Author:
Passos, Leonidas Paixao.
Issue Date:
1989
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:
Intact dark- and light-grown mung bean (Vigna mungo L.), black bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) cowpea (Vigna unguicul a ta (L.) Wa lp.) and squash (Cucurbita pepo L.) seedlings on hydroponic medium were osmotically stressed by exposing their roots to PEG 8000 of various concentrations (-0.2 to -0.6 MPa) to determine stress effects on growth and tissue water status. Growth of dark-grown mung bean hypocotyls ceases within 40 sec upon exposure to any level of stress, and resumes within 10 to 45 min. Growth of all other seedlings were measured usually after 3 to 24 h stress, and in 3 h, elongation is inhibited in dark-grown and is stopped in light-grown tissues. In dark-grown mung bean, black bean and squash hypocotyls and pea epicotyls, growth rates after 24 h stress were found to be proportional to the Ψ of the medium. In mung bean hypocotyls, growth stopped before any change in Ψ or Ψ(π) occurred in the growing region. In this tissue and also in dark-grown squash hypocotyls, pea epicotyls, and in lightgrown cowpea hypocotyls, equivalent reductions in Ψ and Ψ(π) were evident in the growing region after 3 h, so turgor remained constant. In other species, osmotic adjustment with turgor maintenance was evident after 24 h in both the growing and expanded regions. The results with mung bean hypocotyls provided the first demonstration that stress causes an almost instantaneous stress-caused cessation of elongation in dicots. Since data from all plants showed that stress causes growth rate inhibition or cessation without a concomittant decrease in Ψ(p), it is concluded that turgor is not the factor regulating growth. More likely, stress-caused growth and water status changes are responses to an earlier signal, such as a stress-caused reduction in the apoplastic Ψ.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Mung bean -- Seedlings.; Mung bean -- Growth.; Seedlings -- Water requirements.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Plant Sciences; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleGrowth and water status responses of mung bean (Vigna mungo L.) and other dicot species to osmotic stress.en_US
dc.creatorPassos, Leonidas Paixao.en_US
dc.contributor.authorPassos, Leonidas Paixao.en_US
dc.date.issued1989en_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.abstractIntact dark- and light-grown mung bean (Vigna mungo L.), black bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) cowpea (Vigna unguicul a ta (L.) Wa lp.) and squash (Cucurbita pepo L.) seedlings on hydroponic medium were osmotically stressed by exposing their roots to PEG 8000 of various concentrations (-0.2 to -0.6 MPa) to determine stress effects on growth and tissue water status. Growth of dark-grown mung bean hypocotyls ceases within 40 sec upon exposure to any level of stress, and resumes within 10 to 45 min. Growth of all other seedlings were measured usually after 3 to 24 h stress, and in 3 h, elongation is inhibited in dark-grown and is stopped in light-grown tissues. In dark-grown mung bean, black bean and squash hypocotyls and pea epicotyls, growth rates after 24 h stress were found to be proportional to the Ψ of the medium. In mung bean hypocotyls, growth stopped before any change in Ψ or Ψ(π) occurred in the growing region. In this tissue and also in dark-grown squash hypocotyls, pea epicotyls, and in lightgrown cowpea hypocotyls, equivalent reductions in Ψ and Ψ(π) were evident in the growing region after 3 h, so turgor remained constant. In other species, osmotic adjustment with turgor maintenance was evident after 24 h in both the growing and expanded regions. The results with mung bean hypocotyls provided the first demonstration that stress causes an almost instantaneous stress-caused cessation of elongation in dicots. Since data from all plants showed that stress causes growth rate inhibition or cessation without a concomittant decrease in Ψ(p), it is concluded that turgor is not the factor regulating growth. More likely, stress-caused growth and water status changes are responses to an earlier signal, such as a stress-caused reduction in the apoplastic Ψ.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectMung bean -- Seedlings.en_US
dc.subjectMung bean -- Growth.en_US
dc.subjectSeedlings -- Water requirements.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.committeememberBartels, Paul G.en_US
dc.contributor.committeememberKatterman, Frank R.en_US
dc.contributor.committeememberO'Leary, James W.en_US
dc.identifier.proquest8915977en_US
dc.identifier.oclc702370123en_US
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