Crop density and seed production of tall fescue (Festuca arundinacea Schreber).: 2.: Reproductive components and seed characteristics

The population density and spatial arrangement of plants may influence the productive life and performance characteristics of a perennial grass-seed crop. A study was conducted to determine the effects of the initial density (1.6, 3.1, 6.3, 12.5, 25, 50 and 100 plants m(-2)) and row spacing (20, 40, and 80 cm) of plants on reproductive yield components and seed characteristics of tall fescue (Festuca arundinacea Schreber), over 3 consecutive production years ( 1991-1993) in the Peace region of Canada. The weight proportion of cleaned-to-uncleaned seed was 85-86% for the three lowest plant densities and then decreased, as density increased, to 82% at 12.5 plants m(-2) and 66% at 100 plants m(-2) The 1000-seed weight decreased as density increased and ranged from 1.68 to 2.22 g (i.e., 595 000 to 450 000 seeds kg(-1)). The specific seed weight ranged from 18 to 31 kg hL(-1); it differed among years, but the effect of plant density was inconsistent. The germination capacity of the seed was unaffected by plant density, but differed among years; it averaged 87%, 88% and 59% in 1991, 1992 and 1993, respectively. The seed yield/plant, the number of panicles/plant, and the number of seeds/plant decreased exponentially as plant density increased. The number of clean seeds/panicle decreased, as plant density increased, in the first year but was less affected subsequently, particularly with the 20-cm row spacing. The seed yield was correlated closely with the number of panicles m(-2) (r = 0.659***). An initial density no greater than 25 plants m(-2) in rows spaced 20-40 cm apart enhanced seed quality by producing a greater proportion of clean seed which had a higher 1000-seed weight. Such a plant density, however, is at the low end of the optimum range for maximizing seed yield per unit land area.