|Baumhardt, Roland - Louis|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/30/2004
Publication Date: 12/1/2004
Citation: Stewart, B.A., Varaprasad, B., Baumhardt, R.L., Reddy, S.A. 2004. Response of dryland grain sorghum to planting geometry [abstract]. In: Rainwater, K.A. editor. 2004 High Plains Groundwater Resources: Challenges and Opportunities, December 7-9, 2004, Lubbock, Texas. p. 6.
Technical Abstract: Grain sorghum [Sorghum bicolor (L.) Moench] is a major dryland crop in the southern Great Plains that will become increasingly important as irrigated land reverts to dryland. Dryland sorghum is generally seeded during the period when the probability of favorable precipitation is high. Therefore, early growth of dryland sorghum plants occurs under very favorable conditions so individual plants normally tiller extensively. Significant amounts of water and nutrients are utilized to produce the plant tillers and many, and in some cases all, of the tillers do not produce grain. Studies in 2002 and 2003 showed that planting grain sorghum in clumps of four to six plants and spacing the clumps every meter in 0.75 m rows essentially eliminated sorghum tillers. When this planting geometry was compared to the same number of uniformly spaced plants, grain yields were significantly higher with a higher harvest index. Uniformly spaced plants generally produced more tillers and aboveground biomass, but less yield because most of the tillers did not produce grain, particularly when water was severely limited. There were also treatments comparing clumps and equally spaced plants grown on bare and mulched soil. Surface mulch appears to be an important factor when clumps are used because there is less soil surface shaded by the canopy. The plants grown in clumps showed significantly less water stress than the uniformly spaced plants, possibly because the plants in clumps shade one another and maintain a more favorable microclimate. Although preliminary results are encouraging, more studies are needed to determine the interactions of plant density as well as geometry.