Nitrogen Uptake by Three- to Four-year-old Potted Trees of Japanese Persimmon 'Nishimurawase'

Abstract

Nursery trees of Japanese persimmon 'Nishimurawase' were propagated through shoot tip culture and transplanted after rooting in plastic cloth pot filled with artificial media. Trees were cultured for four years with different nitrogenous fertilizers (Table 1). Dry weight of total shoots and trunk increased in June to October, especially in August to October. Dry weight of leaves was highest in August ; root weight remained stable from June to August, but it subsequently increased dramatically. Nitrogen content was stable in current shoots at 5-6mg/g (dw), whereas in lateral shoots and trunk, it stayed at 4mg/g. Leaves have 15 to 16mg/g N in June, decreasing steadily thereafter until August ; N decreased rapidly between August and October. Nitrogen content of fine roots and tap and lateral roots was at 7-9 and 3-4mg/g respectively. In fruits, it reached 15.9mg/g in June and subsequently dropped suddenly. The total nitrogen content of current shoots is stable but low ; that of lateral shoots and trunk remained low before August but subsequently increased. Slight increase in leaves was reversed after August 1 ; autumnal leaf fall occrred in early November. Total nitrogen content of roots decreased from winter to June 1 because nitrogen is translocated to new growing organs during this period. Roots accumulated an abundance of total nitrogen until October 1. A 10% reduction in nitrogen fertilizer inhibited the uptake of nitrogen, especially in roots ; it had little effect on the nitrogen levels of the trunk, shoots and leaves.