Wednesday, November 7, 2007
305-7

Skip-row Configuration and Plant Density Effects on sorghum Grain Yield in Nebraska.

Akwasi Abunyewa, Richard Ferguson, Charles Wortmann, Steven Mason, Drew Lyon, and David Tarkalson. University of Nebraska-Lincoln, University of Nebraska Lincoln, 373 Plant Science, Lincoln, NE 68503

Equal spacing of sorghum rows typically results in the highest grain yield when soil water is adequate throughout the season, but skip-row planting may be a means to reduce water deficits during reproductive growth stages. We evaluated the effect of skip-row planting configuration and plant population on grain yield, yield components and water use efficiency at five locations in a transect across southern Nebraska where mean precipitation ranges from 300 mm to 900 mm yr-1. Three row configurations including all rows planted (S0), alternate rows planted (S1), and two rows planted alternated with two skipped rows (S2) were evaluated in a complete factorial with two plant densities. Soil water was measured to 120 cm depth biweekly with a neutron probe. Grain yield was reduced by 20 to 30% with S1 and S2 compared to S0 at the wettest site. At a site with moderate precipitation, grain yield was reduced by18% with S2 and was not affected with S1. At sites with minimal growing season precipitation, grain yield increases with S1 and S2 ranging between 5 and 123 % over S0 were observed. Skip row planting significantly increased the harvest index at all the five sites while yield per panicle were significantly increased at the medium and low rainfall sites. One hundred kernel weight was not affected by row configuration. At anthesis, crop water use efficiency (WUE) and dry matter yield were significantly higher with all rows planted compared to skip-row planting. At physiological maturity WUE was highest with skip-row planting at sites where the mean monthly growing season precipitation ranged between 49 and 63 mm but lowest at sites where the mean monthly precipitation was between 75 and 79 mm.