ABSTRACT
The good health of plants depends upon their ability to maintain normal physical and chemical processes. Many studies have measured effects of defoliation by determining changes in the percentage chemical composition of plant compounds, especially carbohydrates. Growth after defoliation has long been linked to pools or reserves of carbohydrates in roots, rhizomes, stem bases and other ungrazed portions of plants. Fluctuations in these concentrations have been used to explain plant responses to intensity, frequency, and season of defoliation. Increased production at certain levels of defoliation have occurred with short grasses that have rhizomes and stolons and those that maintain growing points near the soil surface. Excessive and frequent defoliations in container and grazing studies have resulted in nearly complete exhaustion of stored total nonstructural carbohydrates (TNC) in roots and stem bases, resulting in loss of plant vigor and plant death. Early physiological principles based on TNC indicating plant vigor and recovery after defoliation were oversimplifications.
