The effect of seed potassium on emergence and root developent of seedlings in potassium-deficient sand

Seeds of silver grass and cape-weed contained so little potassium that the roots of these species could only penetrate a highly potassium-deficient sand to a depth of 3 or 4 cm. By contrast, lupin seeds contained enough potassium to allow root development to a depth of at least 90 cm. The behaviour of other species studied was intermediate between these extremes. With seeds low in total potassium, evidence was obtained of a beneficial effect of applied potassium on seedling emergence. A study of seeds varying in total potassium from 1 µg to more than 20,000 µg showed that most of the variation in total seed potassium was due to variation in seed size, potassium concentration in the seeds being relatively unimportant. The possibility of improving the field establishment of seedlings on potassium deficient soils by increasing the potassium content of the seeds is discussed.