• Evaluation of Plant Growth Regulators on Wheat in Arizona, 1987

      Tickes, B.; Ottman, M. J.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Plant growth regulators are applied to small grains to decrease lodging which can adversely affect crop growth and yield. Wheat is intensively managed in Arizona, and lodging can be a problem. Chlormequat and ethephon were applied at various rates and times in six studies in 1987 to evaluate their use on Arizona's semi -dwarf cultivars with respect to lodging plant height, yield components and grain yield The results indicated that growth regulators applied at the recommended rates and times may decrease plant height and decrease kernel weight. However, the influence of growth regulator treatments on tiller number, head number, kernel number, and grain yield was not demonstrated. The ambiguous results obtained suggest our efforts need to be directed toward documenting the extent of lodging in the state, studying the effects of lodging and predicting when lodging will occur.
    • Oat Varieties Grown for Grain and Forage Production at the Safford Agricultural Center, 1988

      Clark, L. J.; Carpenter, E. W.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Eleven oat varieties were tested for grain and forage yields at the Safford Agricultural Center. Cayuse, the predominant variety grown in the area was the top producer of total dry matter. Four other varieties had higher grain yields than Cayuse.
    • The Effects of Alfalfa Seed Scarification in Saline Environments

      Poteet, D. C.; Robinson, D. L.; Dobrenz, A. K.; Smith, S. E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The handling of alfalfa and other crop seed may result in seed scarification. Scarification may not affect germination of alfalfa seed in a non - saline environment, but may decrease germination where farmer's fields are severely salt-stressed.
    • Barley Variety Trial in Cochise County, 1988

      Clark, L. J.; Schwennesen, E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Eight barley varieties were tested in a replicated variety trial in northern Cochise county. These varieties varied from relatively early maturing varieties, such as Barcot4 to the longer maturing varieties, such as Gustoe. The medium -late variety, Northrup King 1558, was the top - yielding variety, with 7,185 pounds per acre. This exceeded the yield of the standard variety, Gustoe, by 15 percent, making NK 1558 a variety that should be looked at further. It will be marketed by Northrup King under the name Sunbar 458.
    • Development of Grazing-tolerant Alfalfa for the Southwest

      Smith, S. E.; Rodrigues, G. H. S.; Conta, D. M.; McKinley, L.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Bermuda Grass insect Control

      Tickes, B.; Rethwisch, M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Seeding Rate and Row Spacing for WestBred 881 and Aldura Durum at Marana, 1988

      Ottman, M. J.; Day, A. D.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      WestBred 881 durum commands a premium price due to its superior quality, but it produces a lower yield than other commonly grown cultivars. This study was initiated to improve our understanding of how to grow WestBred 881. Two dumm cultivars (WestBred 881 and Aldura) were planted at five seeding rates (30, 60, 120, 180, and 240 lbs seed /A) and five row spacings (3, 6, 12, 18 an 24 inches) at the Marana Agricultural Center. The optimum seeding rate was 180 lbs /A for WestBred 881 and 120 lb /A for Aldura. An increase in seeding rate resulted in decreased kernel weight and number and increased head number. At row spacings of 3, 6 and 12 inches, grain yield of WestBred 881 was 6120, 6300, and 6060 lbs /A and grain yield of Aldura was 6350, 6770, and 7190 lb /A, respectively. WestBred 881 has larger kernels than Aldura but fewer kernels per head and heads per unit area. The yield advantage of WestBred 881 relative to Aldura at higher seeding rates was due to in kernels per head. At the closer row spacings, the advantage was due to kernel weight, kernels per head and heads per unit area.
    • Corn Variety Trial in Greenlee County, 1987

      DeRosa, E.; Clark, L.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Fifteen varieties of about 125+ day corn hybrids were tested in an ongoing variety trial in Greenlee County.
    • Revegetation of Retired Farmland: Evaluation of Six Range Grasses Under Three Irrigation Regimes

      Thacker, G.; Cox, J.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Buffelgrass, kleingross, "Catalina" lovegrass, "Cochise" lovegrass, bottlebrush, and sideoats grama grass were seeded on retired farmland in the Avra Valley west of Tucson in 1986 and again in 1987. Each grass species was seeded in plots that received no irrigation, or two establishment irrigations or four establishment irrigations. For both year's tests, buffelgrass had a significantly higher percent cover than the other grasses at three months after planting. In the evaluation of the 1986 test in October 1987, buffelgrass, kleingrass, Cochise lovegrass, and Catalina lovegrass had increased their presence in the irrigated plots from one year before and appeared promising for the revegetaion of retired farmland. Plots that did not receive establishment irrigations did not have significantly higher cover ratings than plots with no cover at all. The one exception to this was buffelgrass in the first evaluation of the 1986 test.
    • Barley Variety Trial at the Safford Agricultural Center, 1988

      Clark, L. J.; Carpenter, E. W.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Nine varieties of barley were tested at the Safford Agricultural Center in response to growers' requests for high yielding barley varieties with the potential to mature more quickly than Gustoe. Gustoe was the top- yielding variety with 5,551 pounds per acre. A University of California variety was a close second but it has the same maturity as Gustoe. The varieties that mature more quickly, Barcott and Fiesta, yielded approximately 1,500 pounds fewer than Gustoe.
    • Feed Wheat Variety and Rate of Planting Demonstration in Graham County, 1988

      Clark, L. J.; Cluff, R. E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Three varieties of feed wheat were compared in an on farm demonstration in the Safford valley. AC79 -97, developed by the University of Arizona for the Safford area,produced the largest amount of high protein feed Comparing 200 and 300 pound per acre seeding rates, both AC79 -97 and Super -X yielded slightly more grain at the 200 pound rate than at the 300 pound rate. Yolo, a feed wheat variety that has done well in the Sacramento valley in California, yielded slightly lower than the Super-X.
    • Durum Seeding Methods, 1988

      Ottman, M. J.; Harper, J.; Tickes, B.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      WestBred 881 durum commands a premium price due to its superior quality, but it produces a lower yield than other commercially available cultivars. Studies conducted at Maricopa in 1987 suggested that yields of WestBred 881 may be increased by 3-inch row spacing. Studies were conducted at three commercial farms in an effort to mimic the effect obtained with 3-inch row spacing by using conventional grain drills to obtain more uniform plant spacing. Seeding twice in parallel directions did not result in the desired effect because the seed planted in the first pass was covered by extra soil from the second pass, and the seedlings emerged from cracks made by the disk openers from the second pass. Broadcasting on beds resulted in a poor stand and non- uniform plant distribution compared to drilling the beds. Planting twice in perpendicular directions to each other resulted in a more uniform plant distribution than drilling once, but a slightly poorer stand was achieved due to extra wheel traffic and yields were not significantly increased. The best method to obtain a more uniform plant spacing may be to seed with a 3-inch drill.
    • Stomate Density and Physiological Measurements on Leaves of Alkali Sacaton

      Dobrenz, A. K.; Cox, J.; Munda, B.; Robinson, D.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Comparison of Residual Nitrate and Fertilizer Nitrogen Efficiency in Basin Irrigated Wheat

      Doerge, T.; Knowles, T.; Ottman, M.; Clark, L.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The relative efficiencies of residual soil NO₃⁻N and fertilizer Nin basin - irrigated wheat production are not well defined. A two-year field study was conducted at the Safford Agricultural Center to investigate what these N efficiencies are under optimum yielding conditions. 'Aldura' durum wheat was grown on the same field site two years in succession. In 1987 a wide range of fertilizer N (0 to 419 lbs /A) applications resulted in residual NO₃⁻N accumulations of 36 to 140 lbs /A in the surface four feet of soil. Residual N plots were split in 1988 with one subplot receiving no additional N while the other was treated with 145 lbs of fertilizer N /A. Grain yield response curves for the –N and +N subplots were used to estimate the marginal rate of substitution (MRS) of soil NO₃⁻N for fertilizer N. The marginal efficiency of residual NO₃⁻N was a constant 16.7 lbs. grain produced /lb. of N across the range of profile N values in this study, while the marginal efficiency of fertilizer N varied from over 17 to below 6 lbs. grain /lb. N. When basin- irrigated wheat is supplied with adequate, but not excessive N, the MRS of soil vs. fertilizer N is about 1:1 although absolute N efficiencies under basin irrigation are considerably lower than those achieved in other grain production systems.
    • Effects of Salinity on the Water Potential of Alfalfa Seedlings

      McKimmie, T.; Dobrenz, A. K.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Alfalfa seedlings were grown under saline conditions for six weeks and separated into two populations, based on height. Water potential was measured on roots, stems, leaves, and petioles of tall and short plants. Tall plants had a higher water potential for each plant part.
    • Small Grain Variety Comparisons at the Maricopa Agricultural Center, 1988

      Sheedy, M.; Ottman, M.; Ramage, T.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Effects of P Applications on Wheat Tissue Phosphate Levels and Grain Production in Graham County

      Knowles, T.; Doerge, T.; Ottman, M.; Clark, L.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Collecting additional data to calibrate and refine current guidelines for interpreting soil and plant test values for P is an ongoing need in Arizona. An experiment was conducted at the Safford Agricultural Center during the 1987 -88 crop year to evaluate the response of 'Aldura' durum wheat to P fertilizer applications on a clay loam soil testing low in available P. Maximum grain yields of more than 5,500 lbs. /A were obtained by banding 40 lbs. P₂O₅/A as triple super phosphate with the seed at planting. A December 9 planting date subjected plants to cold soil temperatures early in the season (up to 80 days after planting), rendering soil P less available for plant utilization. Preplant soil P analyses predicted the yield increase observed with P fertilization (11.2 %);however, economic returns were not sufficient to offset the cost of P fertilizer. The recommended preplant soil test for P proved accurate in predicting P status and stem PO₄⁻P tissue analyses seemed reliable in monitoring P nutrition of durum wheat. A critical nutrient range of 1200 - 2000 ppm PO₄⁻P is proposed for basal stem tissue sampled prior to the joint growth stage, and 1500 - 1706 ppm PO₄⁻P is suggested for flag leaf tissue sampled at the boot stage.
    • Alfalfa Varieties from the 1920s to the 1980s: Comparison of Forage Yield During the Seedling Year

      Smith, S. E.; Conta, D. M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • The Role of Cercospora Summer Black Stem and Leaf Spot in the Alfalfa Decline Problem in La Paz County

      Matheron, M.; Winans, S.; Matejka, J.; Rethwisch, M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      An alfalfa decline problem has appeared recently in fields between Poston and Parker in La Paz County. Cercospora summer black stem and leaf spot, a fungal disease of alfalfa, has been associated with the decline problem. The efficacy of three fungicides were tested for control of the disease and the decline problem. Bravo, Kocide, and Spotless significantly reduced the severity of Cercospora summer black stem and leaf spot; however, significant increases in yield were not realized. Alfalfa decline in La Paz County may involve other factors in addition to plant disease.
    • Evaluation of the Accuracy of a Wheat Stem Nitrate Test in Predicting Nitrogen Requirements of Irrigated Durum Wheat

      Doerge, T.; Knowles, T.; Ottman, M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The procedure currently recommended by the University of Arizona for predicting the nitrogen (N) requirements of durum wheat has proven to be quite accurate at sites where grain yields exceeded 5,400 lbs/acre. However, the method slightly overestimated N needs when the yield possibility was below that level. Additional information on the relationships between N rates, stem NO₃⁻N levels and grain yields are needed for the wide range of agronomic conditions found in Arizona. Three N fertility trials were conducted at the Maricopa Agricultural Center to: 1) document the accuracy of the currently recommended soil + stem NO₃⁻N testing procedure in predicting the N needs of durum wheat on soils of varying residual N content and grain yield potentials; and 2) to evaluate the use of the current stem testing procedure on two durum varieties 'Aldura' and 'Westbred -881. The University of Arizona procedure was found to accurately predict the minimum amount of N required for optimum production of durum wheat on two sites where yield potentials were 5,400 and 4300 lbs. grain /A, but it slightly overpredicted N rates on two sites with maximum yield levels of 5,400 lbs /a. 'Aldura' consistently out yielded 'Westbred -881' by about 12 % but 'Aldura' also averaged 0.78 %lower in grain protein content. Little statistical or practical differences were observed in the quantities of NO₃⁻N contained in the stem tissue of these two varieties, which should simplify the interpretation of stem NO₃⁻N values for various wheat cultivars. The currently recommended procedure for predicting optimum N rates in durum wheat production has proven to be accurate when yield levels exceed 5,400 lbs. grain /A. A slight modification of the procedure may be needed to more closely predict N requirements on lower yielding sites.