Effects of Planting Date and Hybrid on Sugarcane Aphid Population and Drought Tolerance in Dryland Grain Sorghum.
Abstract: Grain sorghum (Sorghum bicolor) is a major cash crop grown in the US Southern Great Plains including Texas High Plains. Currently, drought and infestation by sugarcane aphid (Melanaphis sacchari) are the two major challenges to grain sorghum production in the Texas High Plains. A field study was conducted in Bushland, TX to investigate how different planting dates and hybrids (86P20, SP-31A15, AG1201, AG1203, and DKS37-07) affect drought tolerance and sugarcane aphid pressure in a dryland production system. Data collected included aphid population, biomass, grain yield, harvest index, seasonal evapotranspiration (ET), and water use efficiency (WUE). The planting dates were May 5th in 2017 and May 15th, 2018 for the early planting date (PD1). The late planting dates (PD2) were June 27th in 2017 and June 18th in 2018. Precipitation amounts and timing during the growing season varied causing variations in most measurements. In 2017 the PD1 precipitation total 223mm while in the PD2 it reached to 347mm. In 2018 the PD1 received only 83mm precipitation. At this time the PD2 of 2018 is still actively growing but will be harvested by the end of October. Sugarcane aphid populations also varied as no sugarcane aphids were present in PD1 in 2017, but were present at different levels in the PD2 in 2017 and both planting dates in 2018. In 2017, grain yield in the PD2 (4405 kg/ha) was significantly higher than PD1 (1576 kg/ha) this is also compared to the PD1 of 2018 with average yield of 3160 kg/ha. Significant differences were also found among hybrids within planting dates for grain yield, biomass, harvest index. Based on these results, we conclude that water availability and timing was more influential on grain yield determination than sugarcane aphid pressure in dryland production. Further, hybrid selection was also important for dryland production.
Zane Jenkins*, Qingwu Xue, Brock Blaser, Sushil Thapa, Kirk Jessup, and Jourdan Bell
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