Master's Theses

Document Type

Thesis - campus only access

Date of Award

Spring 1960

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Committee Chair

Abstract

This investigation was an attempt to determine the vigor of various types of range grasses under different intensities of clipping. Three range grasses selected for study were: (1) a tall grass, big bluestem (Andropogon gerardi Vitman); (2) a mid-grass, side-oats grama (Bouteloua curtipendula (Michx.) Torr.); and (3) a short grass, blue gram (Bouteloua gracilis (H. B. K.) Lag. ex: Steud.). Sods of these grasses were taken from two areas: (1) an area which had been fairly heavily utilized for several years; and (2) an area which had been protected from grazing for over fifty years. Limiting factors in this study were that the areas had been subjected to above average growing conditions, i.e., ideal rainfall and temperature, for two years preceding collection of the sods and that the grazed area had been less heavily grazed than it had in the past. All top growth was removed and sods were transplanted in phytometers, and subjected to the following treatments: (1) those plants which were not clipped form beginning to end of the study; (2) those which were clipped to the crown each week. Three replications for each treatment were established. This phase of the study was carried on for about 12 weeks. Measurements recorded or calculated included: (1) weekly and cumulative height and weight of new shoot growth; (2) bi-weekly variation in number of shoots; (3) cumulative weight per tiller; (4) length and weight of new root growth; and (5) shoot-root ratio. In addition, a method of descending paper chromatography was used to measure the amount of readily available carbohydrates at beginning and end of the study to determine gain or loss under different intensities of clipping. Findings were as follows: (1) When closely clipped, all plants studied were severely restricted in shoot production, new root growth, and production of carbohydrates. (2) Moderate clipping seemed to stimulate shoot growth, but restricted, to some degree, the production of new roots. The production of carbohydrates was no severely affected by moderate clipping. (3) Growth differences in plants form the two areas were not a significant except under non-clipped conditions. (4) Shoot-Root ratio increased with intensity of clipping. (5) Clipping tended to reduce species significance. (6) Development of flowers caused a decrease in carbohydrate content of plants. Tables, graphs, and photographs were used to present and illustrate the results of the various studies.

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© 1960 Jerry J. Crockett

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