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Pregermination treatments

Suggested pregermination treatments for key nitrogen fixing tree and shrub species that tolerate acid soils.

Species Treatment Seeds/kg
Acacia aneura B 1 min, S 75,000–80,000
Acacia angustissima B, S 90,000–100,000
Acacia auriculiformis B 30 sec, S 30,000–90,000
Acacia holosericea B 1 min, S 70,000–80,000
Acacia koa B 2 min, S 8,500–20,000
Acacia mangium B 30 sec, S 80,000–100,000
Acacia mearnsii B 5 mins 48,000–85,000
Acacia melanoxylon B, S 60,000–100,000
Albizia lebbeck B 3 sec 6,000–16,000
Albizia saman B 2 min, C, S 6,000–8,000
Alnus acuminata R 200,000–2,000,000
Alnus glutinosa R
Calliandra calothrysus B 14,000–19,000
Casuarina cunninghamiana R 1,800,000
Casuarina junghuhniana R 1,000,000–1,600,000
Casuarina sumatrana R
Chamaecytisus palmensis B 1 min
Cedrelinga catenaeformis B
i>Dalbergia nigra C 10,000–30,000
Desmodium gyroides R 500,000
Desmodium nicaraguense R 500,000
Desmodium velutinum R 500,000
Enterolobium cyclocarpum C, S 800–2,000
Enterolobium contortisiliquum C, B
Erythrina abyssinica C
Erythrina berteroana C
Erythrina poeppigiana C 3,000–5,000
Erythrina fusca C
Erythrina variegata B 10 min
Flemingia macrophylla R 50,000–80,000
Gliricidia sepium C, B, or S 7,000–12,000
Inga acrocephala R
Inga codonantha R
Inga edulis R
Inga marginata R
Inga punctata R
Inga spectibilis R
Mimosa scabrella B 3 mins 60,000–90,000
Mimosa caesalpinaefolia B
Paraserianthes falcataria B 10 mins 40,000–50,000
Pithecellobium dulce R
Prosopis juliflora B, S
Pterocarpus indicus R 1,500–2,000
Robinia pseudoacacia B 2 min, S 35,000–50,000
Stryphnodendron adstringens B
Stryphnodendron excelsum B

B: Pour boiling water over seeds (about five times as much water as the volume of the seeds), stir gently for 1 to 2 minutes (or as specified), and then soak in cold water for 12 to 24 hours.
C: Soak seeds in cold water for 12 to 24 hours.
S: Nick the round end of each seed with a file, knife, or nail clipper or rub the round end on a rough surface such as cement until the white interior is barely visible. Soak the treated seeds in cold water for 12 hours.
R: Recalcitrant seed; no treatment needed.

Briscoe, C.B., S.M. de Faria, V. Lambert, G. Minnick, and R. Russo. 1996. Growing Nitrogen Fixing Trees in Acid Soils. In: M.H. Powell (ed) Nitrogen Fixing Trees for Acid Soils – A Field Manual. Winrock International, Morrilton (AR), USA. p. 22.