This tip was provided by:
Ronnie Schnell, Cropping Systems – Statewide, College Station, firstname.lastname@example.org
Extreme Heat and Sorghum Flowering
High temperatures have affected many portions of Texas in recent weeks and again during the current week. In some regions of Texas, grain sorghum was in critical growth stages that could be affected by high temperatures. Sorghum is known to have good heat and drought tolerance compared to many other crops. However, sorghum is sensitive to extreme temperatures.
Sorghum is sensitive to extreme temperatures during a 10-day period before and 15-day period after pollination. The period 5-10 days before flowering is critical for final floret development. The period 5 days before to 5 days after flowering is also sensitive. It is during this time that pollen shed, fertilization and embryo formation occur. Floret viability, pollination and embryo development can be reduced by temperatures from 97 to 100°F. Some hybrids are more tolerant to heat stress than others. Heat stress during grain set can reduce grain weight. Timing and duration of heat will determine the final impact on yield. Several days of extreme heat (>100°F) or many consecutive days of moderate heat during critical growth periods may result in some yield loss.
Avoidance is the about the only way to manage heat stress in sorghum. Early planting and choosing hybrids with maturity appropriate for your environment are the best to avoid heat stress in Texas. Also, pay attention to hybrid performance trials in your region. Hybrids that consistently perform well in your region are likely better adapted to handle biotic and abiotic stresses encountered in Texas.