Degree Type

Thesis

Date of Award

1-1-1998

Degree Name

Master of Science

Department

Horticulture

Major

Horticulture

Abstract

After drought ended, net assimilation rate and relative growth rate of plants in drought treatments did not decrease compared to undroughted controls. Recommendations for seed propagation of katsura vary. A study was designed to measure the response of C japonicum and Cercidiphyllum magnificum (Nakai) Nakai seed to stratification and irradiance. Germinability of two sources of C. japonicum and one source of C. magnificum was determined after not stratifying or stratifying seeds at 3.5 ± 0.5 ⁰C for 8 days and germinating them at 25 ⁰C in darkness or under a 15-hour photoperiod of 64 ± 8 [Mu]mol·⁻²·.S⁻¹ photosynthetically active radiation (PAR) for 21 days. Stratification was not required for germination, but did increase germination percentage, peak value, and germination value for both species.Stratification increased germination percentages of the two sources of C. japonicum from 41% to 90% and 43 % to 60%, respectively, and germination percentage of C. magnificum from 12% to 24%. PAR enhanced germination of unstratified seeds of one source of C. japonicum and of C. magnificum, increasing germination percentages from 34% to 52% and 8% to 15%, respectively. I conclude that katsura is a drought avoider and that stratification and PAR improve germinability of katsura seeds.The katsura tree (Cercidiphyllum japonicum Sieb. & Zucc.) is highly valued as an ornamental plant, yet has been researched very little. The tree has a reputation as being drought intolerant and also lacks a standardized method of propagation by seed. In a greenhouse study designed to examine the response of trees subjected to drought and non-drought conditions, it was found that trees lowered transpirational water loss and avoided drought stress by the mechanism of drought-induced leaf abscission. Plants in single- and multiple-drought treatments underwent a 34% and 63% reduction in lamina dry mass, respectively. After abscission, trees in the single-drought treatment recovered 112% of the lost leaf dry mass within 24 days.

DOI

https://doi.org/10.31274/rtd-180813-8263

Copyright Owner

Michael Sean Dosmann

Language

en

OCLC Number

39977533

File Format

application/pdf

File Size

57 pages

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