Effect Of Sea-salt Stress On Growth And Quality Of Tall Fescue And Italian Ryegrass

With decreasing of the arable land and the exhaustion of the fresh water resource, the exploitation of saline land is paid more and more attention. Grasses have wild adaptation and can be used as the pioneer plant in saline land.Tall fescue (Festuca arundinacea Schreb.) and Italian ryegrass (Lolium multiflorum L.) are important grasses in forage production and turf establishment. In this experiment, tall fescue (cv. Fawn) and Italian ryegrass (cv. Barspectra) in different growth period were treated with sea-salt solution containing different concentrations. The response of seed germination, seedling and tillering growth to sea-salt and variance of nutrition component of tall fescue and Italian ryegrass were studied in pot experiments.The results indicated that seed germination was not affected adversely when the sea-salt concentration was lower than 9.6g·L-1. With the increasing of sea-salt concentration the germination time was delayed, cumulative germination rate and vitality rate decreased gradually and the seedling growth was restrained. The seed sea-salt tolerance of Italian ryegrass was higher than that of tall fescue.Growth of young plant of tall fescue and Italian ryegrass were inhibited under sea-salt stress of different concentrations. The result showed that they grew normally at low salt concentrations. With increased salinity, relative extension rate of new leaf and leaf area reduced, rate of yellow leaf increased, content of water soluble carbohydrate (WSC) decreased. To compare with the control, with increasing salinity plant height, till number and dry weight of aerial part both grasses decreased. Proline content and chlorophyll content in leaf blade increased to adapt the saline environment.The growth retardation of tall fescue by salinity was more significant than that of Italian ryegrass. Na+/K+ ratio in leaf blade of Italian ryegrass was lower than that in tall fescue, while the relative increase rate of chlorophyll content in Italian ryegrass was higher than that in tall fescue at the same sea-salt concentration. The capacity of maintaining metabolism of Italian ryegrass was higher than that of tall fescue.The change of cations in the two grasses was similar under sea-salt stress. Na+, Mg2+, content increased and Ca2+ content decreased with increasing salinity. At low saltconcentration K+ content was higher than that in the control and decreased with increasing salinity.There was no consistency in the effect of salinity on P content of the two grasses. Increasing in salinity tended to decrease P content in tall fescue but to increase in Italian ryegrass.To compare with the control, forage quality was not affected at low and middle sea-salt concentrations. Crude protein (CP) and crude ash (CA) content of tall fescue and Italian ryegrass increased with increasing salinity. Neutral detergent fiber (NDF) content gradually increased with increasing salinity in two grasses.The results suggested that the germination, growth and forage quality of the two grasses were not affected adversely at low sea-salt concentrations. With increasing salinity they were affected significantly. To compare with tall fescue, sea-salt tolerance of Italian ryegrass during seed germination and seedling period was higher. Italian ryegrass could be sowed in the seashore where salinity concentration was low than 22.4 g · L-1(80% sea water). And growth and quality of the two grasses were not affected significantly when salinity concentration was low than 12.8 g·L-1(40% sea water).