TOTAL NONSTRUCTURAL CARBOHYDRATES AND REGROWTH IN HONEY MESQUITE (PROSOPIS-GLANDULOSA) FOLLOWING HAND DEFOLIATION OR CLOPYRALID TREATMENT

Greenhouse experiments were conducted to assess the storage of nonstru ctural carbohydrates in the stems and roots of honey mesquite and thei r mobilization and utilization following defoliation by hand or clopyr alid. All leaves were removed by hand from one group of plants while l eaving stems intact. Another group received a foliar spray of clopyral id at a sublethal acid equivalent rate of 0.07 kg ha(-1). Samplings at treatment on day 0 and at 14, 28, 42, and 58 d after treatment measur ed leaf area; dry weight of leaves, stems, and roots; and grams and pe rcent total nonstructural carbohydrates in stems and roots. Controls a ccumulated dry weight and grams total nonstructural carbohydrates in s tems and roots, while maintaining a constant percent total nonstructur al carbohydrates throughout the experiment. Percent and grams total no nstructural carbohydrates in stems and roots of hand defoliated plants decreased by about one-half from day 0 to 14 as new leaf growth occur red, but increased and returned to pretreatment levels on day 28. A si miliar, though slower, pattern of decline and recovery of total nonstr uctural carbohydrates in stems and roots occurred in response to defol iation by clopyralid. These results showed that the nonstructural carb ohydrates in stems and roots of honey mesquite were important sources of carbohydrates to support new leaf regrowth following defoliation by hand or herbicide.