Regrowth performance of pear nursery plants effects of nitrogen fertigation on reserve nitrogen and carbohydrate status

摘要

Both nitrogen and carbohydrate reserves are essential for the initial growth of deciduous fruit crops in spring as they provide energy and building blocks for the new growth before any photosynthesis and significant root uptake of nitrogen can take place. However, the limitation imposed by reserve nitrogen or carbohydrates on the initial growth is not clear. Compared with bearing trees in the orchard, nursery trees only have vegetative growth, and the assimilated carbon is only partitioned between growth and storage. Therefore, the requirement for reserve carbohydrates may be readily achievable unless the trees keep growing very late into the season. Nursery trees, on the other hand, may be more dependent on reserve nitrogen for their regrowth during establishment because root uptake of nitrogen is delayed by damaged root system, lack of new roots, or low soil temperatures in spring.