The growth and the respiration in roots of sweet potato plants under a moderate potassium deficiency

A seven days' culture of sweet potato plants under a deficient potassium application induced various metabolic disturbances in the roots (1,2) and the leaves (3). Prolonged cultures of taro (4), broad bean plants (5), and barley (5) suggested that a half level of the normal potassium content in roots might be a critical point of K -deficiency resulting in a higher respiration rate than its normal status. Such a temporary enhancement of respiration accompanied by accumulation of amino-N and reducing sugars may not necessarily contribute to the accumulation and the assimilation of salts, but accelerate the disturbance of plant metabolism to cause early death of the tissues. This work deals with supplemental data on the effects of K -deficiency on the plant growth and the respiration in roots, comparing these effects in a 15 days' culture of sweet potato plants with those in a longer term culture of other plant species (4,5).