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United States Department of Agriculture

Agricultural Research Service

Title: Seeding Practices and Cultivar Maturity Effects on Simulated Dryland Grain Sorghum Yield

Authors
item Baumhardt, Roland
item Tolk, Judy
item Winter, S - TEXAS A&M - RETIRED

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 2005
Publication Date: May 1, 2005
Citation: Baumhardt, R.L., Tolk, J.A., Winter, S.R. 2005. Seeding practices and cultivar maturity effects on simulated dryland grain sorghum yield. Agronomy Journal. 97:935-942.

Interpretive Summary: Usual planting recommendations for dryland grain sorghum in much of the U.S. Southern High Plains are to delay until soil water is adequate for crop establishment. Planting dates, population, and cultivar maturity selections vary by producer. Our objectives were to use a crop simulation model (SORKAM) to identify an optimum planting date, population, row spacing, and cultivar maturity combination for improved grain yield of dryland sorghum grown on a clay loam soil in the southern High Plains. Using SORKAM, long-term (1958-1998) weather records at Bushland, TX, and known Pullman soil properties, we calculated sorghum grain yields for all combinations of planting date (15 May, 5 June, 25 June), population (12,000, 24,000 and 48,000 plants/acre), row spacing (15- and 30-in.), and cultivar maturity (early, medium, late). SORKAM consistently calculated yields within 5% of measured values and reproduced row width and population effects on yield. Our modeled yields increased for narrow row-spacing approximately 9%, independent of planting date or cultivar maturity. Although increasing plant population significantly decreased panicle seed number, seed mass, and plant tillers; the modeled grain yield was unchanged (3570 to 3670 lbs/ac.) by plant populations. Mean grain yields were greatest for 5 June planting dates with early- and medium-maturity cultivars that avoided late summer heat or water deficit stresses and matured before freezing weather. Our data show that early or medium maturity cultivars, planted 5 June, in 15 in. rows, using 12,000 to 24,000 plants/acre achieve the highest dryland grain yield on a southern High Plains clay loam soil.

Technical Abstract: Typical planting recommendations for dryland grain sorghum [Sorghum bicolor (L.) Moench], in much of the U.S. Southern High Plains are to delay until soil water is adequate for crop establishment. Planting dates, population, and cultivar maturity selections vary by producer. Our objectives were to use the SORKAM crop simulation model to identify an optimum planting date, population, row spacing, and cultivar maturity combination for improved grain yield of dryland sorghum grown on a clay loam soil in the southern High Plains. Using SORKAM, long-term (1958-1998) weather records at Bushland, TX, and known Pullman soil (fine, mixed, superactive, thermic Torrertic Paleustoll) properties, we calculated sorghum grain yields for all combinations of planting date (15 May, 5 June, 25 June), population (3, 6, 12 plants m-2), row spacing (0.38 and 0.76 m), and cultivar maturity (early, medium, late). SORKAM consistently (r2 = 0.69, RMSE = 791.7) calculated yields within 5% of measured values and reproduced row width and population effects on yield. Our modeled yields increased for narrow row-spacing approximately 9%, independent of planting date or cultivar maturity. Although increasing plant population significantly decreased panicle seed number, seed mass, and plant tillers; the modeled grain yield was unchanged (3996 to 4106 kg ha-1) by plant populations. Mean grain yields were greatest for 5 June planting dates with early- and medium-maturity cultivars that avoided late summer heat or water deficit stresses and matured before freezing weather. Our data show that early or medium maturity cultivars, planted 5 June, in 0.38 m row widths, using 3 or 6 plants m-2 populations, achieve the greatest dryland grain yield on a southern High Plains clay loam soil.

Last Modified: 7/22/2014
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