Biology ETDs

Publication Date

5-19-1969

Abstract

Frost hardiness was investigated in seedlings of Atriplex canescens and Eurobia lanata.Exosmosis, of electrolytes and reduction of triphenyl tetrazolium chloride (T.T.C.) by tissue exposed to sub-freezing temperatures were investigated as objective methods for determining the frost killing temperature of the seedlings as compared to actual seedling survival. The relationship of a seedling age and the influence of a brief preconditioning at a reduced temperature were studied as to their effect on the frost killing temperature. The seedling age best suited to the investigation of the influence of temperature and photoperiod preconditioning on the frost killing temperature was determined. The influence of temperature and photoperiod preconditioning on the frost killing temperature of A. canescens and E. lanata seedlings was studied.

The critical value for determining the frost killing temperature by the exosmosis of electrolytes was determined to be different from that given by Dexter when this method was applied to the study of A. canescens and E. lanata. The reduction of T.T.C. when applied to determining the frost killing temperature of A. canescens proved to be unreliable. Both methods require further refinement before they may be used to determine the frost killing temperature of A. canescens and E. lanata. Seedling survival was used to determine the frost killing temperature in subsequent experiments.

The earliest seedling age tested for both species, 17 days, demonstrated the greatest resistance to sub-freezing temperatures and the greatest ability to harden when preconditioned at reduced temperatures.

It appears. that long-day cold conditions provide the maximum resistance to sub-freezing temperature with of A. canescens and short-day cold conditions provide maximum resistance with E. lanata.

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

Martin William Fleck

Third Committee Member

William Clarence Martin

Fourth Committee Member

Illegible

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