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Rate of Leaf Appearance in Crimson Clover
Twain J. Butler1, Gerald W. Evers, Mark A. Hussey
1Texas A&M University Agricultural Research and Extension Center, 1229 N. Hwy 281, Stephenville, TX 76401. Texas A&M University Agricultural Research and Extension Center, P.O. Box 200, Overton, TX 75684-0200. Dep. of Statistics, Texas A&M University, College Station, TX 77843.
Abstract:
Understanding factors that affect growth and development of crimson clover (Trifolium incarnatum L.) are important for the development of management practices to optimize forage utilization. In a 3-yr field experiment at College Station, TX, we evaluated the effects of planting date on rate of leaf appearance of an intermediate- and late-maturing crimson clover. We wanted to determine if growing degree days (GDD) or a photothermal index (PTI) could be used to predict growth. Leaf appearance rates (LAR) did not differ between 'Tibbee' and 'Columbus' crimson clover. Leaf appearance rate was primarily controlled by temperature or GDD, which accounted for 90 to 99% of the variability within each planting date. Photoperiod did not consistently influence the rate of leaf appearance under normal daylengths of 10 h 12 min to 14 h 6 min used in this study. Predictions of LAR were not improved when photoperiod was combined with temperature in a photothermal index than with predictions that used GDD alone. Leaf appearance rate of crimson clover was generally higher when planted in October, November, and December and lower when planted in September, February, and March.