• Inproved Nitrogen Management in Irrigated Wheat Production Using Stem Nitrate Analysis

      Doerge, Thomas; Knowles, Tim; Ottman, Mike; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      The method for predicting the nitrogen (N) requirements of irrigated wheat that is recommended by the University of Arizona requires preplant soil, plus mid-season stem nitrate analysis. Additional information on the relationships between N rates, stem NO₃-N levels and grain yields are needed for the wide range of agronomic conditions typical of Arizona's wheat growing areas. Three N fertility trials were conducted at the Maricopa Agricultural Center to, 1) measure the accuracy of the current University of Arizona procedure on soils of contrasting texture; 2) to evaluate the use of the current stem testing procedure on two durum varieties, "Aldura" and "Westbred-881"; and 3) to evaluate the effect of various N forms on the levels of NO₃-N in stem tissue for wheat grown in a clay loam soil. The University of Arizona procedure was found to over predict slightly the amount of N required for optimum economic return on sandy soils where the maximum yields obtained did not exceed 5100 lbs. grain/a which is considerably below the expected yield possibility for these sites. The procedure accurately predicted the amount of N required for optimum production on a clay loam soil (175 lbs. N/a)at a maximum yield of 6000 lbs. grain /acre. "Aldura" and "Westbred-881" were remarkably similar in their response to a wide range of N applications. There was no significant difference in the yields of these two varieties, but "Westbred-881" did contain somewhat higher protein levels. Little statistical or practical differences were observed in the quantities of N contained in the stem tissue of these two varieties; this should help simplify the interpretation of stem NO₃-N values for various wheat cultivars. The chemical form of N applied to wheat grown in a clay loam soil had no significant effect on the quantity of NO₃-N measured in stem tissue at any time during the growing season. The currently recommended procedure for predicting optimum N fertilization rates in wheat productions shows considerable promise but needs further evaluation, particularly under high - yielding conditions.
    • Late Corn Variety Trial in Greenlee County, 1986

      Clark, Lee; DeRose, Edith; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      Five corn varieties with maturities varying from 95 to 108 days were grown in a double crop situation following barley. The variety that produced the highest net value (after deducting drying costs) yielded only $194.39 per acre, slightly less than the marginal cost of production.
    • Oat Hay Variety Evaluation

      Harper, John; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • One-Irrigation Barley Observations in Graham and Cochise Counties, 1987

      Clark, Lee; Young, Deborah; Schwennesen, Eric; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      A series of experimental plots was planted because ranchers, conservationists, farmers and homeowners in southeastern Arizona were interested in knowing more about one -irrigation barleys. The results of these observations are contained in this paper.
    • Oxyflourfen (Goal) for Selective Control of Little Malva in Seedling Alfalfa

      Thacker, Gary; Heathman, Stan; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      Little Malva (Malva porviflora L.) is an important weed that is resistant to herbicides that will selectively control most other broadleaf weeds in alfalfa. Oxyfluorfen (Goal) has been placed under an Experimental Use Permit for alfalfa. In 1987, this herbicide was evaluated for the selective control of malva in alfalfa in the Avra Valley west of Tucson. Oxyfluorfen stunted both the malva and the alfalfa. However, the alfalfa was stunted to a lesser degree, and had begun to recover three weeks after the application of oxyfluorfen. The malva did not recover, and the alfalfa was relieved from weed competition three weeks after treatment.
    • PEG-Induced Stress on Alfalfa Seedlings

      Ellsworth, Todd; Robinson, David; Dobrenz, Albert; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Performance of Germination Salt Tolerant Alfalfa on a Non-Saline Site

      Smith, Steve; Conta, Debra; Dobrenz, Albert; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Predicting the Nitrogen Requirements of Irrigated Durum Wheat in Graham County Using Soil and Nitrate Analysis

      Doerge, Thomas; Knowles, Tim; Ottman, Mike; Clark, Lee; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      The high yielding spring wheats grown in Arizona usually require applications of fertilizer nitrogen (N) to achieve optimum grain yields and acceptable quality. The University of Arizona's currently recommended procedure (preplant soil plus periodic stem tissue analysis for NO₃-N to predict the N needs of wheat) is not widely used by Graham County growers for various reasons. A nitrogen fertility trial was conducted at the Safford Agricultural Center during the 1986-87 crop year to: 1) examine the relationships between basal stem nitrate-N levels, grain yields of durum wheat, and N fertilizer rates; and 2) to test the accuracy of the recommended procedure for predicting the N needs of durum wheat. Five rates of N from O to 419 lbs N /acre were applied in three split applications. One additional N treatment was made as indicated by the current University of Arizona procedure. Maximum grain yields of 5500 to 6200 lbs /a and protein levels in excess of 14.5% were attained with the application of at least 186 lbs NIA. An untimely early season irrigation induced a temporary N deficiency condition for all plots, which may have kept grain yields below the maximum yield possibility for this site. In spite of this, the amount of N predicted by the University of Arizona procedure (197 lbsN/acre) did attain an adjusted economic return which was not significantly different from the maximum numerical yield that was achieved for any of the other N treatments.
    • Response of Alfalfa to Phosphorus Fertilizer Sources

      Stroehlein, Jack; Clark, Lee; DeRosa, Edith; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      A field study was carried out to determine the effects of different fertilizers on yield and quality of alfalfa. Two harvests over a period of four cuttings did not reveal any differences due to treatment. While alfalfa often responds to phosphorus (P) fertilizer application, conditions in this study provided adequate P as well as nitrogen (N) and potassium (K).
    • Response of Barley and Wheat to Sewage Sludge Loading Rates

      Day, Arden; Solomon, Mengste; Taylor, Brooks; Pepper, Ian; Minnich, Martha; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      A greenhouse experiment was conducted to evaluate the responses of barley and wheat to sewage sludge loading rates of 150 to 750 lb /acre plant-available N and to recommended inorganic N (150 lb/ acre). All sewage sludge rates delayed maturity in both barley and wheat. Sludge loading rates up to 450 lb /acre of plant-available N increased vegetative growth and grain yield in both crops. Sludge rates higher than 450 lb/acre of plant-available N resulted in a reduction in the number of plants per pot; however, the stand reduction was greater for wheat than for barley.
    • Russian Wheat Aphid, Diuraphis noxia (Mordvillko): A New Insect Pest of Small Grains in Arizona

      Dick, Gary; Moore, Leon; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Salt Tolerance During Seedling Establishment in Alfalfa

      McKimmie, Tim; Dobrenz, Albert; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      Deposition of salts from irrigation water is an increasing concern for Arizona farmers and agronomists. Selection for salt tolerance during the seedling stage has been undertaken over the past three years. Yield tests were conducted in greenhouses and a significant increase in dry matter production was shown in the selected material.
    • Seeding Rate and Row Spacing for Westbred 881 and Aldura Durum Wheat at Maricopa, 1987

      Ottman, Mike; Day, Arden; Harper, John; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      Westbred 881 durum wheat commands a premium price due to its superior quality, but produces a lower yield than other commonly grown commercial cultivars. This study was initiated to improve our understanding of how best to manage Westbred 881. Two durum wheat cultivars (Westbred 881 and Aldura) were planted at 5 seeding rates (30, 60, 120, 180, and 240 lbs. seed/A), 5 row spacings (3, 6, 12, 18, and 24 inches), and two planting dates (Dec. 1 and Jan. 16) at the Maricopa Agricultural Center. Both cultivars produced optimum yields at seeding rates of 120 to 180 lbs/A for the Dec. 1 planting date. At the Jan. 16 planting date, however, yields of Westbred 881 increased linearly with seeding rate up to 240 lbs/A, while Aldura produced optimum yields between 120 and 180 lbs. seed/A. At the Dec. 1 planting date, Aldura produced similar yields at row spacings from 3 to 12 inches, while the yield of Westbred 881 decreased linearly with an increase in row spacing. The highest yield achieved in this study was with Westbred 881 at the 3 -inch row spacing. Row spacings of 6 to 12 inches were optimum for both Westbred 881 and Aldura at the Jan. 16 planting date. The seeding rate and row spacing responses attained with Westbred 881 may be related to its tittering characteristics.
    • Seeding Rate, Nitrogen Rate, and Planting Date of One-Irrigation Barley at Marana, 1987

      Ottman, Mike; Ramage, Tom; Thacker, Gary; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      One-irrigation barleys were bred to be grown with only a single irrigation near planting time. To further our understanding of how to manage these new cultivars, one-irrigation barleys were grown at 4 seeding rates (20, 40, 60, and 80 lbs seed /A), 4 nitrogen rates (0, 50, 100, and 150 lbs/A), and 3 planting dates (Nov. 17, Dec. 15, and Jan. 22). Seeding rates 01 40 to 60 lbs seed/A resulted in the highest yields at the Dec. 15 planting date, comparing all planting dates combined. However, in individual analyses of the Nov. 17 and Jan. 22 planting dates, no significant differences in yield due to seeding rate were detected. Grain yield increased linearly with nitrogen rate at the Nov. 17 planting date, but was not influenced by nitrogen rate at the other planting dates. Yields were similar for the Nov. 17 and Dec. 15 planting dates, but decreased considerably in the Jan. 22 planting date due partially to lower head number. Grain yields of 2-22-9 were consistently higher than Seco this year.
    • Seedling Alfalfa Root Research

      Reffruschinni, Katie; Robinson, David; Dobrenz, Albert; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      There has been limited research on the rooting patterns of alfalfa. This information would be important in developing new germplasm sources that are more water efficient, salt tolerant and drought tolerant. Ten alfalfa varieties were evaluated for possible genetic control of rooting traits. Seedlings were grown hydroponically in a growth chamber. The cultivars evaluated showed a significant statistical difference for width of lateral root system and number of lateral roots. The variation in seedling rooting patterns is sufficient to warrant a selection program for improved lateral rooting patterns.
    • Small Grain Comparisons at the Maricopa Agricultural Center in 1987

      Thompson, Rex; Sheedy, Michael; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Small Grain Variety Comparisons at the Yuma Agricultural Center in 1987

      Thompson, Rex; Sheedy, Michael; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Standardization of the Wheat Stem Tissue NO₃-N Procedure

      Knowles, Tim; Doerge, Thomas; Ottman, Mike; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      Current University of Arizona recommendations require periodic stein NO₃-N tests to determine nitrogen (N) fertility status of wheat crops. Lack of data on the importance of sample handling techniques, plant part selection, grinding criteria and extraction conditions have resulted in a reluctance by some growers and laboratory operators to utilize this test procedure. A laboratory study was carried out to examine factors important in wheat stem tissue analysis for NO₃-N. Sample handling, fineness of tissue grinding, and different extraction ratios were examined to determine their effects on NO₃-N recovery. Detailed partitioning of wheat plants at the 3-4 leaf, joint and boot growth stages was conducted to document which plant part is the best indicator of the N status of wheat. Optimal recovery of tissue NO₃-N existed for stem tissue separated immediately in the field and dried within 8 hours; stem tissue ground to 30 mesh or less and extracted for at least 30 minutes; and when using a sample size of 0.1000 g, in conjunction with 25 ml of extractant (i.e. 1:250 plant tissue to extractant ratio). Partitioning data confirmed current University of Arizona wheat tissue sampling guidelines which suggest sampling of the basal portion of the stem tissue.
    • Stomatal Response to Water Stress in Two Pearl Millet Genotypes

      Osman, Mohamoud; Dobrenz, Albert; Tewolde, Haile; Voigt, Robert; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      A study was conducted in the field to test whether stomatal sensitivity to water stress can be used as a selection criterion for drought tolerance in two pearl millet genotypes. In both cultivars, stomatal aperture was significantly reduced by the water stress. However, the proportion of reduction per 20 mm decrease in applied water was much higher for the hybrid than for the female parent. This is clearly an indication of a higher stomatal sensitivity in the hybrid, which probably explains the superior performance under water stress that was previously observed in this genotype.
    • Strain Crossing for Large-Leaflet Alfalfa: A First Look

      Dobrenz, Albert; Robinson, David; Smith, Steve; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)