Germination and Emergence of Crownvetch as Affected by Seed Maturity and Depth of Planting1

Abstract

AbstractBecause of the indeterminate flowering habit of crownvetch (Coronilla varia L.) some seedlots contain appreciable amounts of immature seed. Our objectives were (i) to study the relationship of seed maturity in ‘Penngift’ crownvetch as indicated by seedcoat and seedpod color to germination and emergence and (ii) to compare the emergence of ‘Chemung,’ ‘Emerald,’ and ‘Penngitt’ crownvetch; ‘Saranac’ alfalfa (Medicago sativa L.); ‘Pennscott’ red clover (Trifolium pratense L.); and ‘Empire’ birdsfoot trefoil (Lotus corniculatus L.). The development of Penngift crownvetch seed required 7 to 9 weeks with seedpods progressing through a sequence of color changes: green (3 to 4 weeks), greenish‐purple (1 to 2 weeks), greenish‐brown (1 to 2 weeks), tan and dull brown (1 to 2 weeks), and reddish‐brown (full maturity). Seedcoat color paralleled seedpod color. The total germination percentages (normal seedlings plus hard seeds) of seeds with greenish‐brown (immature), tan or dull brown, and reddish‐brown (mature) seedcoats were respectively, 30, 64, and 92. Immature seeds produced significantly fewer emergent seedlings from depths of 6, 13, and 25 mm than did more mature seeds. Emergence of seedlings of three cultivars of crownvetch from 19, 25, and 38 mm was 97, 98, and 76% of emergence from 13 mm. Crownvetch required 5 weeks for maximum seedling emergence, compared to 3 weeks for birdsfoot trefoil, red clover, and alfalfa. While under most field conditions the optimum planting depth for crownvetch is 6 to 13 mm, vigorous seedlings can emerge from depths of 25 to 38 mm.