Carbohydrate Reserves of Grasses: A Review

Abstract

Carbohydrate reserves are nonstructural carbohydrates. Sucrose and fructosan are the predominant reserve constituents of temperate-origin grasses; sucrose and starch, of tropical-origin grasses. Nitrogenous compounds are used in respiration, but probably are not alternately stored and utilized as are carbohydrate reserves. Most carbohydrate reserves are stored in the lower regions of the stems-stem bases, stolons, corms, and rhizomes. Nonstructural carbohydrates in the roots of grasses are probably not used directly in herbage regrowth following herbage removal. Plant development stage, temperature, water stress, and nitrogen fertilization can drastically change the reserve level. The seasonal variation of carbohydrate reserves is often different for the same species when grown in different environments. The level of carbohydrate reserves in the lower regions of the stems apparently affects the regrowth rate for the first 2 to 7 days following herbage removal. Following the initial period, plant regrowth rate depends on other factors, such as leaf area and nutrient uptake. This initial effect from the level of carbohydrate reserves can be maintained during subsequent exponential growth. Grazing may be more detrimental than clipping if it removes herbage from some plants and not others. The ungrazed plants may take the available nutrients and water away from the grazed plants. However, grazing may be less detrimental than clipping if grazing leaves ungrazed tillers on a plant while removing others, thus allowing for the transfer of carbohydrates.