The effect of selection and inbreeding on growth of Andropogon Furcatus Muhl. (Big bluestem)

Andropogon furcatus exhibits a wide range of adaptati and is found over much of the temperate region of North America.Hitchcock (28) lists It as occuring in "dry soil, prairies and open woods, Quebec and Maine to Saskatchewan and Montana, south to Florida, Wyoming, Utah, and Arizona; Mexico."It was the dominant species of the virgin prairie or tall grass region of central United States where, accord- ing to Weaver and Pitzpatrick (79), it made up 90 percent of the cover on the well watered areas and as much as 25 percent on all but the driest uplands.Sarvis (54) found that it occurred only rarely at Mandan, North Dakota, but that it was highly relished by livestock.Harvey (25) noted the prominence of A. furcatus a nd A, scoparlu3 In the prairies of southeastern South Dakota where they assume facial rank, A. furcatus being the taller and far more conspicuous.To- gether with A. scopariuB it consitiuted 80 percent of the cover of the prairie grassland of Nebraska, according to Weaver and Fitzpa trick (80) , and Stieger (65) reported the A. furcatus association as dominant In that area.A similar condition was found by Aldous (2) in Kansas with A. furcatus the dominant species in the eastern one-third of the state.Schaffner (57) listed A. furcatus as the most important species in a study of the typical prairie of Clay County, Kansas with A. scoparius , S orgha strum nutans, and Pan! cum virgatum following In that order.Bruner (9) stated that *The Andropogon assocles constitutes the sub-climax prairie of eastern Oklahoma and is also represented extensively in the post climax prairie of the sandy soils which occur along river courses throughout the true and mixed prairie and even into the short grass plains.*Following the droughts of 1934, Weaver and Albertson (77) reported losses of 80 percent and more of the original cover of grass on native prairie, with A. furcatus suffering least because of its deep root system.Savage (56) and Aldous (5) agreed essentially with this report; Aldous, how- ever, cited overgrazing as an important factor in the loss of vegetation.Later studies by Weaver and Albertson (78) substantiated these earlier observations.They found that a reduction of 50 to 66 percent in basal cover had occurred during the drought period, 1934-37.This was largely due to the almost complete destruction of A. scoparius although the deeper rooted A. furcatus also suffered great losses to- ward the end of the period.According to Cornelius (15) approvimately 190,000 head of cattle are shipped from the short grass ranges of Texas, New Mexico, Oklahoma, Arizona, and Colorado each year to fatten for market on the nutritious grass of the bluestem section of Kansas.Aldous (3) considered the bluestem grasses valuable from a pasture standpoint because they make a major portion of their growth during June and July, and if moisture is available, a substantial amount of forage will be produced during August.The Forest Service, United State Department of Agriculture, gives A. furcatus a palatability rating of 70 percent for the eastern one-half of Kansas.Newell (48) found the bluestems very desirable forage species in Nebraska and stressed the importance of develop- ing seeding methods.Stapledon (59), in discussing the important character- istics of forage species, stated, "The economic value of a grass depends, in the last resort, not only upon its pal atability and nutritive value but equally upon its ability to maintain itself and withstand the conditions of manage- ment superimposed upon it?Aj, furcatus is possessed of this ability to a marked degree, being described by Aldous (4) as very vigorous, standing close grazing, and recovering rapidly from abuse i: protected.In discussing the problems of the herbage plant breeder, Sauleecu (55) says, *In no other cultivated plant in the breeder attended by so many difficulties.The pri- mary reason is to be Bound in the many sided demands made upon the herbage plants, the most important of which are re si stance to cold and disease, early ripeninsr, then longevit quality, adaptability, and finally productivity."In addi tion to these, Cornelius (15) listed resistance to drought

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