Abstract
1. This investigation was made for clarifying some differences which controlled the manganase content in new mature leaves (3-month-old) of Satsuma orange trees grown on soils having fairly low available manganese.
2. One-year-old shoots with new and old leaves were collected at flowering period and green mature stage from 10 trees growing in 5 groves at Yugawara region of Kanagawa Prefecture. Hitherto they had not been suffered from the manganase deficiency. In Ito region of Shizuoka Prefecture, old leaves were collected before bud break and at flowering period from 16 alternative fruit bearing trees, which showed the manganese deficiency symptoms on the new leaves of“off”year trees at their green mature stage. New flushes were collected at flowering period and their green mature stage from above trees, and fine roots were dug out from 3 places at the drip region of each tree.
3. From flowering period to green mature stage of new leaves, both manganese contents of new and old leaves on healthy trees increased significantly, and a significant positive correlation existed between the manganese contents of new leaves at 3-month-old stage and those of old leaves at 15-month-old stage.
4. Before bud break of first flush of growth cycle, the difference of manganese contents of old leaves on“off”year tree and“on”year tree was not found, but the significant difference was found in manganese contents of new 3-month-old leaves from above trees.
5. At flowering period, differences in distributed percentages of absolute manganese contents in each part on 1-year-old shoots of“on”and“off”year trees were found only in the composition of new organs, but was not found in the rate of “old”and“new”part.
6. Growth in fine roots in unit soil volume at the drip region of trees which had heavy crop load in previous year was less than that of the trees which had light crop load.
7. These results confirmed that manganese contents of new mature leaves are controlled by soil available manganese contents, rates of growth of new flush to old flush, and volumes of fine roots which were affected by different crop loads in the previous year.
