Leaf area at different positions on new shoots and nutrient- transforming phase in apple trees

摘要

Leaf area growth trends of new shoots in year-on and year-off 'Rails' apple trees were investigated to find out the growth patterns of leaves at different positions as well as the nutrient-transforming phase in relation to plant nutrition level and growth of new shoots, leaves and roots. Year-on trees had high starch level in root system as well as sufficient nutrients stored, and growth peak was consistent for new shoots and roots. At the peak growth of new shoots, leaf area at the 7th - 10th leaf positions reached the highest value. Year-off trees had poor nutrient storage, root growth decreased to the slowest at the peak growth of new shoots and at the same time small leaves appeared at the 8th -9th leaf positions, indicating the nutrient-transforming phase to begin. For year-off trees, nutrient-transforming phase ended at slow-growth stage of new shoots and the largest leaves appeared at the 14th - 16th leaf positions. Year-on trees had no obvious nutrient deficient phase. Their nutrient-transforming phase came when nutrients in plant sufficiently stored after the fast-growth of new shoots and assimilated nutrients began to increase. For year-on trees, single leaf area and total leaf area of the whole spur was significantly higher compared with year-off trees, as a result providing good conditions for high quality flower buds and fruit.