Biology ETDs

Publication Date

7-6-1977

Abstract

Fourwing saltbush [Atriplex canescens (Pursh) Nutt.] seedlings were subjected to water stress treatments and temperature-photoperiod regulation to determine if these treatments might induce greater hardiness to subsequent drought stress. Seedlings ages 2, 4, and 8 weeks after emergence were allowed to wilt before rewatering or kept at minimum soil moisture stress. Seedlings aged 2 weeks after emergence were subjected to four regimes of hot and cold temperatures and long and short photoperiods in growth chambers. Treatments were applied for four weeks. Height, fresh weight and dry weight of shoots, and dry weight of roots were reduced by water stress and cold temperature treatments, and root to shoot ratios were increased by these treatments. No significant changes in leaf osmotic potential, xylem pressure potential, or transpiration rates per unit leaf area were observed for any treatment. Reduction in transpiration rates on a whole plant basis did occur for water stress treated 4- and 8-week-old plants and cold temperature-short photoperiod treatment plants. While drought survival response was not significantly different for any treatment, soil water potential at LD50 was lower for 2-week-old plants than for 4- and 8-week-old plants and was lowest in cold temperature-short photoperiod treatment plants. Overall, fourwing saltbush seedlings change most significantly in morphological features rather than in physiological responses. It is suggested that although survival in this species may be improved by water stress and/or cold temperature-short photoperiod treatments beginning on 2-week-old plants, this species is already genetically adapted to water stress as a drought avoider.

Project Sponsors

U.S. Forest Service

Language

English

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Gordon Verle Johnson

Second Committee Member

Rex Gordon Cates

Third Committee Member

Loren David Potter

Fourth Committee Member

Earl F. Aldon

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