|Evett, Steven - Steve|
|HOWELL, TERRY - Retired ARS Employee|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2014
Publication Date: 12/31/2014
Citation: Oshaughnessy, S.A., Evett, S.R., Colaizzi, P.D., Tolk, J.A., Howell, T.A. 2014. Early and late maturing grain sorghum under variable climatic conditions in the Texas High Plains. Transactions of the ASABE. 57(6):1583-1594.
Interpretive Summary: In the Texas High Plains, water resources for crop production are limited and rainfall amounts and timing are unpredictable. This makes it difficult for producers to select a crop and decide on the best planting date. In this semi-arid region, corn commands a high commodity price, but its consumptive water use is also high. Sorghum, on the other hand, is typically irrigated at deficit levels since it is more drought tolerant. In this study, ARS scientists at Bushland, Texas compared yields and water use efficiency (WUE) or yield per unit of evapotranspiration (ET) between a later maturing sorghum hybrid planted early in the growing season with an early maturing hybrid planted in June. Both hybrids were harvested at the same time. The study was conducted for growing seasons 2009 through 2011. During these years, climatic conditions were highly variable between seasons. Four deficit irrigation treatments were applied to each hybrid. Grain yields averaged across irrigation treatments were not significantly different between hybrids in 2009 and 2011. The advantage to using the early maturing hybrid in these years was that WUE was 27 and 29 percent greater, respectively, than for the LM hybrid. For irrigation treatments at the highest level (80% of ET), the late maturing hybrid yields were always greater compared with the early maturing hybrid. During the exceptional drought year of 2011, both late and early maturing hybrids were only able to produce expected yields if irrigation was applied at 80 percent of ET.
Technical Abstract: In the Texas High Plains, variable climatic conditions prevail between and within growing seasons. As this area continues to experience drought conditions, and water resources for irrigation become more limited, sorghum [Sorghum bicolor (L.) Moench] production may become a more popular choice to sustain profitable crop water productivity with limited water. Regional sorghum production functions are helpful in strategizing adaption methods for coping with climatic variability, but new varieties often exhibit new production functions This paper compares sorghum responses of grain yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE), between a late (LM) and early (EM) maturing hybrid during recent growing years exhibiting climatic variability, 2009 – 2011. Total annual precipitation in 2009 (537 mm) was 7 percent greater than the mean annual precipitation for the past 60 years (499 mm), while in 2010 (438 mm) and 2011 (144 mm) it was 13 percent and 71 percent less, respectively, than the historical mean. The hybrids were irrigated at levels of 80 percent, 55 percent, 30 percent and 0 percent replenishment of soil water depletion to field capacity. Mean maximum daily air temperatures and mean daily reference evapotranspiration for the 2009 (28.2 deg Celsius, 6.5 mm per day) and 2010 (28.6 deg Celsius, 6.4 mm per day) growing seasons were similar; while in 2011 these parameters were considerable greater, 32.6 deg Celsius and 8.8 mm per day, respectively. Grain yields averaged across irrigation treatments in 2009 (0.62 kg per square meter for the LM vs. 0.58 kg per square meter for the EM hybrid) and 2011 (0.33 kg per square meter vs. 0.34 kg per square meter) were not significantly different between hybrids, however, WUE were 22 percent and 29 percent greater in 2009 and 2011, respectively, for the EM hybrid. In 2010, with an initially full soil water profile, grain yield, WUE, and IWUE were significantly greater in the LM hybrid compared with the EM hybrid. In the exceptional drought year of 2011, irrigation applied at less than 80 percent of ET greatly reduced grain yields; and irrigation applied at less than 55 percent of ET produced minimal to no grain yields. For irrigation treatment amounts of 80% ET, grain yields in the LM hybrid were always greater compared with the EM hybrid. However, the advantage to using the EM hybrid in 2009 and 2011 was that WUE was 27 peercent and 29 percent greater, respectively, than for the LM hybrid.