A comparison of the growth of seedlings of Mediterranean and temperate tall fescues, phalaris and annual ryegrass

Abstract

Seedlings of tall fescues (Festuca arundinacea), phalaris (Phalaris aquatica) and annual ryegrass (Lolium rigidum) were compared with those of other temperate grasses and cereals at 11 and 47 days after sowing at 18/13¦C (12/12 h) to determine their relative seedling vigour. Also, the growth rates of two Mediterranean and two temperate cultivars of tall fescue were compared with those of phalaris and annual ryegrass at 14/6¦C and 23/20¦C (12/12 h) using growth analysis techniques. Shoot growth rates of seedlings were related to caryopsis weight (r = 0.99 at 11 days after sowing) when the range of weights was large, but there was no correlation among perennials with low caryopsis weights (<0.2 mg). Although they had heavier caryopses, seedlings of tall fescue grew more slowly than seedlings of phalaris. All seedlings grew faster at 23/20¦C than at 14/6¦C. Annual ryegrass had the highest dry matter yield, achieved through a rapid production of tillers, it grew relatively better with respect to ryegrass at 23/20¦C than at 14/6¦C. Phalaris depended on larger tillers for increased yield, and growth of these was favoured by the higher temperatures. Tall fescue seedlings were less vigorous than the other grasses, but temperate types grew much faster than Mediterranean types at 23/20¦C. These trends occurred because of a high leaf area (equivalent to annual ryegrass) and leaf area ratio in phalaris at 23/20¦C, and lower leaf extension rates and smaller leaves in Mediterranean fescues than in temperate fescues. The results indicate that: (1) because of better seedling growth, phalaris may be increasingly preferred to tall fescue for aerial seeding or direct drilling in regions where both are adapted; (2) at optimum temperatures, the Mediterranean fescues have poorer seedling vigour than the temperate types; and (3) at optimum temperatures, annual ryegrass may provide more serious competition to the fescues than to phalaris.