Changes in photosynthesis and content of ribulose bisphosphate carboxylase and other cellular constituents depending on the level of potassium supplied to mulberry (Morus albaL.)

Abstract

Abstract Among the nutrients supplied for the culture of mulberry, potassium is considered to be as important as nitrogen for improving mulberry growth and a large amount of potassium fertilizer, annually more than 120 kg K2O·ha1, is presently being applied. Reduction of fertilizer application is an important problem in sericultural practice in Japan. With regard to the reduction of the nitrogen supply, it was previously reported that the decrease of the external nitrogen level impaired the internal nitrogen economy in mulberry leaves (YAMASHITA 1986). The effect of potassium supply on mulberry growth has already been examined in more detail (KAWAUCHI and TAKAGISHI 1985). In the present work, the influence of reduced potassium supply on the photosynthetic capacity and cellular constituents of mulberry leaves used for feeding silkworms was analyzed.