• Alfalfa Variety Demonstration at the Safford Agricultural Center, 1990

      Clark, L. J.; Carpenter, E. W.; Cluff, R. E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Yields are given for 22 varieties of alfalfa grown at the Safford Agricultural Center. Yields were 2 to 3 tons lighter than those in 1989. Mecca retained its number one position with a yield of 8.86 tons per acre and a total of five varieties had yields above 8 tons per acre. It is of interest to note that three of the top five varieties were developed by the Plant Genetics group in California.
    • Alfalfa Variety Trials in Greenlee County, 1986-90

      Clark, L. J.; Schneider, M. A.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Ten alfalfa varieties, ranging from very non - dormant to moderately dormant cultivars, have been grown and yields compared over a five year period. The yields decreased dramatically this last year, to 5.3 tons per acre down from 10 tons per acre during the second season. Differences in production between the top and bottom varieties was 4.75 tons per acre. Figuring hay values at $100 per ton, this difference would mean a loss of $19,000 over the 5 year period on a 40 acre field.
    • Describing the Tradeoffs Between Persistence and Productivity in Alfalfa

      Hotchkiss, Jay R.; Smith, Steven E.; Conta, Debra M.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Substantial plant loss is a commonly accepted phenomenon in commercial alfalfa production. Frequently less than 2% of the seeds originally sown are present in productive mature stands. Optimum yields may not be achieved if the small proportion of plants that survive do not represent the most productive individuals in the original population. We began a study in 1989 to describe the relationships between survival (persistence) and productivity in alfalfa. Sixty 5 yr-old plants were dug from a field of CUF -101 in Pinal Co. (= "Persistent population "). Field performance of progenies of these plants were compared with those of 60 greenhouse -grown CUF-101 plants (= "Random population ") in a 2-yr study in Tucson. In the second year of production spring and fall forage yield and average rate of stem elongation were significantly lower in the Persistent population than in the Random population. These data suggest that plants that are able to persist for the average life of a stand may represent a subset of the original sown population which exhibit more conservative growth patterns. This indicates that simultaneous selection for traits associated with productivity and persistence may be necessary in alfalfa breeding.