Soil Temperature Reduction During Pollination and Grain Formation of Corn and Grain Sorghum
1973
Adams, John E. | Thompson, D. O.
Factors other than total seasonal rainfall may be affecting corn (Zea mays L.) and possibly grain sorghum [Sorghum bicolor (L.) Moench] yield in central Texas. It has been suggested that high temperatures in central Texas during pollination and grain filling decrease the carbohydrate reserves of corn. Soil temperature was lowered in corn and grain sorghum plots during pollination and grain formation to observe the effect of soil temperature during this critical period on grain yield. Chilled water (12 to 14 C) was circulated through copper tubing 11 cm below the soil surface in plots 6.1 m long and 4.0 m wide located on Houston Black clay soil. Soil temperature in the upper part of the root zone (7.5- to 46-cm depth) during soil cooling averaged 23 C in mulched, cooled grain sorghum plots; 22 C in mulched, cooled corn plots; and 26 C in bare, noncooled corn and grain sorghum check plots. Decreasing average soil temperature (7.5- to 46-cm depth) during pollination and grain formation from 26 to 23 C reduced grain sorghum yield, but reducing average soil temperature to 22 C had no effect on corn yield. Soil cooling caused a significant (5% level) decrease stem temperature to a height of 61 cm in corn and some stem cooling at 61 cm in grain sorghum. Stem cooling of both corn and grain sorghum decreased with distance above the soil surface. Yield data obtained indicate that soil temperature during pollination and grain filling is not a factor limiting grain yield of corn and grain sorghum in central Texas.
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