Effects of Defoliation and TIBA (Triiodobenzoic Acid) on Tillering, Dry Matter Production, and Carbohydrate Reserves of Two Cultivars of Kentucky Bluegrass
1978
Ackerson, R. C. | Chilcote, D. O.
The control of lateral bud development in grasses has important implications for turf management and in both forage and seed production. Defoliation, carbohydrate reserves, and growth regulators have been reported to affect this process. Studies were undertaken to evaluate the effects of clipping and Triiodobenzoic acid (TIBA) application on ‘Merion and ‘Pennstar’ cultivars of Kentucky bluegrass (Poa pratensis L.) under controlled environment. Weekly clipping heights of 5.0, 2.5, and 1.25 can were imposed for 6 weeks and tiller number, dry matter production, and carbohydrate reserves as a result of the treatments were determined. A comparison was made between clipping only and clipping plus application of 1,500 ppm TIBA as a foliar spray. Clipping retarded tillering in both cultivars with progressive reductions as clipping height decreased. However, plants of Merion bluegrass clipped and treated with TIBA increased in tillering in comparison to an unclipped, untreated control, or to those only clipped. Application of TIBA to Pennstar resulted in increased tillering when compared to the untreated experiment. However, differences among TIBA treatments were not significant. Dry matter production was reduced with clipping in both TIBA-treated and untreated plants for both cultivars. However, TIBA application increased dry matter productivity when compared to the untreated experiment. When plants were treated with TIBA, a decrease in water soluble carbohydrates (WSC) in the stem bases was observed with decreased clipping height. Untreated plants generally did not show a reduction in WSC. It is suggested that an auxln-carbohydrate balance theory alone cannot account for the release of lateral buds from apical dominance in Kentucky bluegrass.
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