A Study On Compensatory Growth Of Tall Fescue And Perennial Ryegrass Following Drought Stress

Tall fescue (Festuca arundinacea Schreb.) and perennial ryegrass (Loliumperenne L.) are important grasses in forage production and turf establishment. With agriculture structure adjustment and turf development, pfanting area of tall fescue and perennial ryegrass enlarged rapidly. Drought stress occurs frequently in forage production and turf management, and affects adversely the grass growth. The study focused on water shortage and its effect on forage production. Mechanism and characteristics of compensatory growth and variance of nutrition component of tall fescue (cv. Fawn) and perennial ryegrass(cv. Barlet) were studied with a pot trial after treatment with the water stress (i.e. soil holding water were 60%, 45% and 30% compared with control) in different growth period.Tall fescue and perennial ryegrass in elongating stage were inhibited to some degree by the water deficit. The result showed that they grew slowly during drought period. Plant height, tiller number and dry weight of aerial part decreased. However, the plants grew rapidly after rewatering. Plant height, tiller number and dry weight of aerial part increased rapidly, which showed significant compensatory growth. Plant height and tiller number of tall fescue in tillering stage with water stress were restrained more strongly than those in elongating stage. And compensatory growth after rewatering were also enhanced.Leaf area, chlorophyll content and net assimilation rate (NAR) of tall fescue and perennial ryegrass decreased with the water stress. Leaf area increased promptly and chlorophyll content and NAR almost recovered after rewatering. NAR of treated plants was higher than those of control and photosynthesis increased significantly during compensatory growth.Concentration of water-soluble carbohydrates (WSC) in leaf tissue of tall fescue and perennial ryegrass decreased by the water stress, and stem bases increased rapidly. WSC in leaf of treated plants increased after rewatering, but showed a reversed result in stem bases.Relative water content (RWC), weight of per unit leaf area, leaf/stem ratio, in vitro dry matter digestibility (IVDMD), and crude protein (CP) content of tall fescue in tillering stage decreased by the water stress, but neutral detergent fiber (NDF) content increased. After 8 days of rewatering, RWC of leaf, leaf/stem ratio, CP content and IVDMD increased rapidly and weight of per unit leaf area did not differ from the control plants. NDF content decreased after rewatering.The result showed that, growth of tall fescue and perennial ryegrass in vegetative stage inhibited by short-term drought and then compensatory growth appeared obviously after irrigation. Dry matter production was compensated partly even entirely, and foragequality had not been affected. The compensatory growth has great application potential in forage production in arid and semi-arid regions.