Effect of defoliation height and frequency on carbohydrate reserves and tiller development in short and mid grasses grown along highway rights-of-way

Date

2001-05

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

The effect of mowing height and frequency on carbohydrate reserves of total nonstructural carbohydrates (TNC) and tiller development were compared in short and midgrasses grown along highway rights-of-way in west Texas and on the Southern High Plains of Texas. The objectives of this study were: (1) to evaluate seasonal TNC levels at ifferent phenological stages, and (2) to determine the impact of height and frequency of defoliation on basal crown and stem base TNC concentration, plant and tiller number, biomass, fuel moisture, and plant height. Short grasses were represented by blue grama (Bouteloua gracilis), mid-grasses were represented by silver bluestem (Bothriochloa saccharoides), Lehmann lovegrass {Eragrostis Lehmanniana), and little bluestem {Schizachyrium scoparium). These grasses were subjected (with the exception of little bluestem) to two mowing heights (5 and 10 cm) and a non-mowed control, and five mowing frequencies (monthly, bi-monthly, tri-monthly, only one-time at the beginning of growing season, and only one-time at the end of the growing season) during 1999 and 2000. Lehmann lovegrass was studied only through April 2000 due to destruction of plots by highway construction. Results showed that both short and mid-grasses exhibited similar TNC patterns. Plants mowed less frequently at either stubble heights had higher TNC concentrations than plants subjected to more frequent mowing regardless of whether they were short or mid-grasses. Blue grama had higher TNC levels than the midgrasses due to lower growing points (meristematic tissue) and higher photosynthetic capacity for regeneration. Mowing height had little or no effect on number of plants or number of tillers per square meter. Tiller number deceased under the monthly mowing treatment. Mowing did not affect fuel moisture, but decreased biomass, especially under more intensive (short stubble height) and more frequent defoliation treatments. As expected, control plants were taller and attained reproductive stage sooner than plants exposed to defoliation. Closely monitoring TNC level and its relation to growth parameters at different phenological stages in grasses with different growth habits, especialh- mid-grasses at different height and frequency of defoliation, can provide information for management plans along highway rights-of-way and on rangelands.

Description

Keywords

Defoliation

Citation