PHOSPHORUS SEED COATING INCREASES PHOSPHORUS UPTAKE, EARLY GROWTH ANDYIELD OF PEARL-MILLET (PENNISETUM-GLAUCUM (L) R BR) GROWN ON AN ACID SANDY SOIL IN NIGER, WEST-AFRICA

In pot and field experiments conducted in 1990 and 1991 on an acid san dy, phosphorus (P) deficient soil in Niger, West Africa, the effect of seed coating on seedling emergence, early growth and grain yield of p earl millet (Pennisetum glaucum (L.) R. Br.) was studied. Seeds of pea rl millet were coated with different rates (0; 0.5; 1.0; 2.0; 5.0; 10. 0 mg P seed-1) and types of P fertilizers (single superphosphate, ammo nium dihydrogen phosphate; monocalcium phosphate, sodium dihydrogen ph osphate and sodium triphosphate). Seedling emergence was generally red uced at coating rates higher than 0.5 mg P seed-1 and prevented with s ingle superphosphate and sodium triphosphate at rates higher than 5 mg P seed-1. No correlation was found between the pH and osmomolity of t he coatings and final emergence of millet seedlings. The most favourab le effect on plant growth and P content was achieved with ammonium dih ydrogen phosphate (AHP) as seed coating. This was attributed to the en hancement effect of ammonium on P uptake. Compared to the untreated co ntrol dry matter production at 20 days after planting (DAP) was increa sed by 280%, P content per plant by 330%, total biomass at maturity by 30% and grain yield by 45%. Although seed coating with AHP may be har mful to seedlings emergence, it represents a suitable method to enhanc e early growth and increase yield of pearl millet.