Comparative study on fructan accumulation ability in seventeen tall fescue varieties.

摘要

The main reserve carbohydrates of several turfgrass species are represented by fructans. These sugars have a central role to support re-growth after mowing, since this may induce fructan hydrolysis in the shoots of fructan-accumulating turfgrasses. It is known that a strong reduction of the green part of the tall fescue (Festuca arundinacea) turf (mowing height 30 mm or lower) may reduce its quality especially as long term effect. Here we present results concerning the correlation between fructan accumulation and different tall fescue defoliation. Indeed the shoots of 60 mm tall fescue turf accumulate a really high fructan level (almost 2-fold) when compared with the lowest tall fescue turf (15 mm). The lowest level of fructans in the closest mowed turf (15 mm) may explain the stunted re-growth of these plants over the long period. We also report data concerning winter fructan accumulation in seventeen different tall fescue cultivars weekly mowed at 60 mm. Data clearly showed significant differences in terms of fructan accumulation which depended on the cultivar. A first group of cultivars increased content of hexose and sucrose in the leaf blade and low free sugars and fructan accumulation in the shoot. A second group showed a partial mobilization of hexose and sucrose from the leaf blade to the shoot and a significant accumulation of fructan in this organ. The last group showed a very low level of free sugars in the leaf blade and a very high fructan accumulation level in the shoot. In conclusion, because of the importance of fructan accumulation in low mowed tall fescue turf, our data suggests that those varieties which accumulate high level of fructans could be more resistant to severe defoliation.