• Water Stress Indices for Research and Irrigation Scheduling in Pearl Millet

      Teowolde, Haile; Voigt, Robert L.; Osman, Mahamoud; Dobrenz, Albert K.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      The capability to measure the magnitude of water stress in plants is useful for precision irrigation scheduling and other purposes. This paper reports an evaluation of leaf (TL) and canopy (Tc) temperatures, leaf minus air (TL -Ta) and canopy minus air (Tc -Ta) temperatures, and leaf water stress index (LWSI) and crop water stress index (CWSI) in detecting stress in pearl millet (Pennisetum americanum (L.) Leeke) over two growing seasons. Baselines which were used to compute LWSI and CWSI were obtained. The upper and lower baselines for the Tc data, respectively, were Tc -Ta = 4.10 C and Tc -Ta = 3.87- .2001VPD where VPD is vapor pressure deficit in mbars. For the TL data, the upper and lower baselines, respectively, were TL -Ta = 1.97oC and TL -Ta = 1.308- .03006VPD. Tests against photosynthesis, transpiration, and grain yield showed that LWSI and CWSI are better indices of stress than TL -Ta, Tc -Ta, TL, Tc, or Ta. Average seasonal LWSI and CWSI ranged from approximately 0.03 for non- stressed to 0.80 for stressed plants. The reliability of LWSI and CWSI to detect stress and their relation with grain yield suggested the possibility of using these indices for irrigation scheduling decisions.
    • Wheat and Barley Variety Test at the Bruce Church Range, Poston, 1987

      Winans, Sherwood; Ottman, Mike; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      A wheat and barley test on the Bruce Church Ranch, Poston, Arizona, La Paz County, harvested June 8 & 9, 1987, gave crop and variety performance differences under grower management conditions. The top yielding barley variety was Fiesta, 6990 lbs /ac. The leading durum varieties were Turbo, Gem and Aldura. Durum wheat Westbred 881 was highest in protein (13.7 %). In red wheat varieties, yields ranged from 4660 to 5750 lbs/ac. The top three varieties were Baker, Probred and Yecora Rojo. Baker was highest in protein (14.6 %), followed by Yecora Rojo (14.2%). Continued testing over several years is necessary to assess variety performance under grower management conditions.
    • Wheat Germplasm Releases by the Agricultural Experiment Station in 1987

      Thompson, Rex; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Wheat Variety Demonstration in Roll, 1987

      Tickes, Barry; Ottman, Mike; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
    • Wheat, Barley and Oats for Forage and Grain Production at the Yuma Valley Agricultural Center, 1986-87

      Tickes, Barry; Ottman, Mike; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      The potential of various types of small grains for winter forage production was investigated in this study. Two varieties of red wheat, durum wheat, barley, and oats were harvested at various stages. Harlan if barley produced the most forage at the early cutting while Mesa oats yielded the most forage at the later cutting. Gustoe barley produced the highest grain yields.
    • Winter Wheat Variety Trial in Cochise County, 1987

      Clark, Lee; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      Sixteen winter wheat varieties (including three hybrids) were evaluated in a randomized, complete block experiment, with four replications. Stephens, the standard variety grown in the area, was outyielded by four of the winter wheat cultivars, including two of the hybrids. The highest yielding cultivar was a hybrid, Bounty 100, which yielded 5853 pounds per acre (23% higher than Stephens).
    • Yield and Water Use of Barley Cultivars Compared Under an Irrigation Water Gradient at Marana, 1987

      Ottman, Mike; Ramage, Tom; Brown, Paul; Thacker, Gary; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      This study was initiated to determine how barley cultivars perform outside the environment for which they were selected. Also, a comparison was made of water use by a one-irrigation barley with water use of a commercial cultivar selected for high yield conditions. Six barley cultivars bred for differing growing conditions (Westbred Gustoe and Westbred Barcott - high input; Arivat and Prato - medium input; and, Seco and 2-22-9 - low input) were compared under 12 water regimes delivered by a line -source sprinkler system. Water use of Seco, a one-irrigation barley, and Westbred Gustoe, a commercial barley, was monitored with a neutron probe. The barley cultivars bred for high, medium, and low input conditions performed best in their respective optimum water levels with the exceptions of Westbred Barcott and Prato. Westbred Barcott (high input) yielded relatively well over all water levels, and Prato (medium input), performed similar to a high input barley. Seco (low input) used slightly less water than Westbred Gustoe (high input), primarily due to its earlier maturity. The water extraction pattern with depth was similar for both cultivars due to the frequent shallow irrigations applied in this study. The water extraction pattern of Seco needs to be investigated under one- irrigation conditions.
    • Yield and Water Use of Wheat as Influenced by Early Irrigation at Maricopa, 1987

      Ottman, Mike; Brown, Paul; Harper, John; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      When the first irrigation in wheat is applied early, it is usually done to bank or save water for later in the season. On the other hand, when the first irrigation is applied late, it is done to force deep rooting. The objective of this study was to determine the influence of an early irrigation and an early stress period on yield and water use of two durum wheat cultivars when subjected to water stress during the grain fill period. Grain yield of Westbred 881 was not influenced by irrigation treatment, but the grain yield of Aldura was higher with early irrigation rather than early stress. Part of this response may be explained by the poorer stand and the lower stem number of Aldura compared to Westbred 881 under early stress conditions. Water use later in the season was unaffected by irrigation treatment. Early irrigation did not save water for later in the season, and early stress did not improve the plant's ability to extract deep moisture under the conditions of this study.
    • Yield Comparisons of Alfalfa Cultivars and Experimentals at Maricopa and Yuma, 1986 to July 1987

      Ottman, Mike; Smith, Steve; Tickes, Barry; Harper, John; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1987-09)
      This study is part of an ongoing effort on evaluate alfalfa cultivar performance at various locations in Arizona. Forage yields of 25 alfalfa cultivars and experimentals were measured at the Maricopa and Yuma -Mesa Agricultural Centers. During the time period reported, many of the newer cultivars were more productive than the popular cultivar CUF 101 . Selection of alfalfa cultivars should be based upon fall dormancy, pest resistance, seed cost, and yield potential.