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Agronomy Journal Abstract -

Effect of Slope Position on the Microclimate, Growth, and Yield of Barley1


This article in AJ

  1. Vol. 77 No. 5, p. 663-669
    Received: Mar 9, 1984

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  1. C. E. Whitman,
  2. J. L. Hatfield and
  3. R. J. Reginato2



Analyses of the relationship between microclimatic data, yield and growth response usually have been conducted utilizing data collected on level terrain and in small experimental plots. A field study was conducted on 290 ha of undulating topography of a Sehorn-Balcolm complex soil (Entic Chromoxeret and Typic Xerochert) near Dunnigan, CA (38°48′ 121°58′W) during 1977–78 to evaluate the effect of slope position and microclimate differences on the growth and yield of barley (Hordeum vulgare L. cv. Briggs). The crop was planted on 3 to 9 Dec. 1977 at 112 kg ha−1 density in a 0.15-m row spacing. Sixteen sites were selected in the field prior to planting ranging from level to 36% slope with aspects from north- to south-facing slopes. At each site twice-weekly measurements were made of plant growth, i.e., height, number of green leaves, leaf area, number of tillers, dry weight, and phenological stage, on 10 randomly selected plants. Yield and all yield components were measured on 20 1-m2 samples at each site at the end of the experiment. Microclimatic data were measured at each site. The largest variations in crop development occurred prior to jointing and after anthesis. Both drainage and irradiance had large effects on plant growth, exhibited through differences in plant height, maximum leaf area, tiller survival, green leaves per plant, tillers per plant, relative growth rate, and dry matter production. A linear relationship was found between dry weight at the end of the season and intercepted radiation with a slope of 1.28 g MJ−1. Dry matter production and yield were affected by irradiance and drainage. The date of 50% heading was inversely related to the final yield and suggested that delayed flowering was detrimental to grain production in the dryland conditions of the Central Valley.

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