Elementary Morphology of Grass Growth and How It Affects Utilization

Abstract

of thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science int Range Management, Colorado A. and M. College, 1954. Attempts to restore browse cover on depleted big ga.me winter ranges by art.ificial reseeding have gen- erally failed. Successful reseeding of browse plants has been handicapped by a lack of information con- cerning methods of trea.ting browse seeds which will induce satisfactory germination. A study wa.s undertaken to compare the relative effeetiveness of two seed treatments, stratificat,ion and acid scarification, in inducing germina.tion of three shrubs: antelope bitte.rbrush (Purshia tridentata), mountain mahogany (Cercocarpus montanus) and fourwing saltbush (Atriplex canescens). Potential germination of these seeds was also determined for comparative purposes by staining embryos wit.h tetra- zolium chloride by the topogra.phic method. Stratifieation was accomplished by placing seed in moist a.cid peat. at temperatures of 310 F. to 41? F. Samples were removed at weekly intervals to deter- mine t.he optimum period of stratification. Acid searifieation was accomplished by placing seed in a copper-sereen basket and suspending in concen- trated sulfuric acid for ten minute intervals up to 90 minutes. The seed were then washed and planted in flats of vermiculite. in four replications of 50 seeds each for germination a,t temperatures of 620 to 770 F. The best period of stratification for bitterbrush was 49 t.o 70 days. After 49 days in stratifieation a few of the seeds began to sprout. The germination of seed stratified for 70 days was 82.5 percent, while non-t.reated seed germinated 1 percent. Acid treat- ment of bitterbrush for a, period of 50 minutes re- sulted in a germinat.ion of 83.5 percent. The best period of stratification for mounta.in ma.- hogany was four weeks or longer. At the end of nine weeks stra.tification, however, a large portion of the seed began to sprout. The germination of seed stratified for 70 days was 71 percent, while non- treated seed germinated 1 percent. Mountain mahogany seed soaked in acid for 60 minutes ha,d the highest germination, 51.5 percent. This figure is significantly higher than the control, but is also significantly lower than t,he germina.tion resulting from stratification. Nevertheless, a.cid seari- fication removes the hairy styles from the seed which would permit the seed to pass readily through a seed drill for more rapid and effective planting. Fourwing saltbush seed does not require stratifica- t.ion so only a.cid treatment was used on these seeds. The germination of seed soaked for 60 minutes was 15.5 pereent, while the control lot germinated 10.5 percent. Staining of the embryos by use of 2,3,5-triphenyl- tetra.zolium chloride proved inconclusive in indicating germination capacity for hitterbrush and mounta,in mahogany. Fourwing saltbush, however, reacted fa- vorably to the stain. The average potential germi- nation of fourwing saltbush as indicated by staining was 41 percent, while the average germination of acid treated seed was 14.75 percent. These' studies show that acid searification of bitter- brush is as effective as stratifica.tion in inducing bet- ter germina,tion. Acid scarification may be accom- plished in less time than stratification, and the treat- ment is advantageous in instances where seed must be treated and planted in a minimum of time. While stratification induces better germination of mounta,in mahogany than acid sea,rification, the latter treatment removed the hairy styles so that seed ma,y he planted with drills. In view of the known advan- tages of drilling in plant.ing seed more uniformly in the soil, acid searification of mountain mahogany seed is to be prefei-red wherever drilling of seed may be effective. Acid scarification removes the wings of fourving salthush seed so that it may be drilled.-Raymond Johk Boyd, 2090 Leyden Street, Denver, Colorado. This content downloaded from 40.77.167.2 on Sun, 18 Sep 2016 06:31:48 UTC All use subject to http://about.jstor.org/terms