Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
INFLUENCE OF ENVIRONMENTAL FACTORS ON ROOT BUD GROWTH AND DEVELOPMENT, AND ON ASSIMILATE AND GLYPHOSATE TRANSLOCATION IN CANADA THISTLE (CIRSIUM ARVENSE)
Abstract
Seasonal variations in the presence and growth of adventitious root buds on Canada thistle {Cirsium arvense (L.) Scop.} roots observed over a 2-year period were consistent with normal patterns of shoot emergence and growth. Vigorous, much enlarged root buds appeared in late fall following the death of aerial shoots. Under constant temperature conditions roots initiated new shoot growth at any time of the year, following removal of existing shoots. Carbohydrate energy reserves were stored preferentially in roots rather than in root buds or stem bases. Soil temperature is probably a major influence in governing root bud activity following death of shoot growth in the fall. Translocation of ('14)CO(,2)-labelled photoassimilates was compared to movement of ('14)C-glyphosate {N-(phosphonomethyl)glycine} in Canada thistle plants under field and controlled environment conditions. Field-grown plants treated at mid-flower stage translocated similar amounts of assimilates and glyphosate to the roots from mature upper leaves, while most of the translocated compounds were recovered from mature stems and leaves. Glyphosate was able to move a considerable distance from the treated shoot in the root system. Translocation patterns of labelled assimilates and glyphosate in 7-week old Canada thistle plants grown in controlled environment chambers were little affected by photoperiod. Relatively more glyphosate than assimilates accumulated in roots of plants treated in the controlled environment chambers. Root bud growth and development and assimilate translocation were studied in Canada thistle plants grown under two photoperiods, three shoot temperatures, and three root temperatures. Root bud elongation was greatest under long photoperiod, moderate shoot temperature and high root temperature, while the number of root buds produced was favored by short photoperiod and moderate shoot and root temperatures. Assimilate translocation from a mature leaf following 24-h acclimation to temperature regimes was little affected by shoot and root temperatures, but was greater under the shorter photoperiod. After 7-day temperature preconditioning, assimilate translocation increased with both root and shoot temperature, but no photoperiod effects were evident. Assimilate accumulation by roots was favored most by short photoperiod and low shoot temperature following 24-h temperature acclimation, and by low root temperature following 7-day temperature preconditioning.
Subject Area
Agronomy
Recommended Citation
MCALLISTER, RAY SCOTT, "INFLUENCE OF ENVIRONMENTAL FACTORS ON ROOT BUD GROWTH AND DEVELOPMENT, AND ON ASSIMILATE AND GLYPHOSATE TRANSLOCATION IN CANADA THISTLE (CIRSIUM ARVENSE)" (1982). ETD collection for University of Nebraska-Lincoln. AAI8217544.
https://digitalcommons.unl.edu/dissertations/AAI8217544