Thermal Time Requirements for Phenological Development of Peanut
- D. L. Ketring * and
- T. G. Wheless
Temperature is a major environmental factor that determines the rate of plant development. Relation of thermal time to phenological development of peanut would provide a better understanding of this crop's response to temperature. Thermal time measured in day-degrees (°Cd) was used to determine peanut (Arachis hypogaea L.) phenological development of a Spanish botanical-type culitvar, Pronto, and a Virginia botanical-type breeding line, OK-FH15. Peanuts were grown under field conditions, on a Teller sandy loam (fineloamy, mixed, thermic, Udic Argiustoll) in 1985, 1986, and 1987. Irrigation plus rainfall ranged from 840 mm in 1985 to 400 mm in 1987. At 12 d after planting (DAP) when >80% emergence had occurred, 136 ± 18 °Cd had accumulated. Pronto produced more mainstem nodes (vegetative stage) than did OK-FH15. Regression analyses indicated that both vegetative and reproductive development were highly correlated with °Cd for both genotypes. Incipient flowering (R1) began at 313 and 360 °Cd in 1985 and 1986, respectively. At 50% R1 in 1987, 410 and 498 °Cd had accumulated for Pronto and OK-FH15, respectively. Both vegetative and reproductive stage development were slower with less water. Although attainment of a high reproductive stage value (7 to 9) does not indicate a high yield per se, it does indicate the degree of crop maturity. Seasonal accumulation of °Cd in 1985, 1986, and 1987 was 1456,1672, and 1473, respectively. Crop yields (pods) for the fullirrigation treatment were 312, 325, and 288 g m−2 for Pronto and 358, 405, and 308 g m−2 for OK-FH15 in 1985, 1986, and 1987, respectively. Knowledge of °Cd accumulated can provide an estimate of harvest date as well as crop development stage.
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