EFFECTS OF NITROGEN FERTIGATION ON RESERVE NITROGEN AND CARBOHYDRATE STATUS AND REGROWTH PERFORMANCE OF PEAR NURSERY PLANTS

Bench-grafted ‘Bartlett’ pear (Pyrus communis L.) trees on OHxF97 rootstock were fertigated with six nitrogen concentrations ranging from 0 to 21mM by using a modified Hoagland’s solution during the growing season.
All the plants were harvested after natural leaf fall and stored at 2 °C. One set of the plants was destructively sampled for reserve N and carbohydrate analysis; the remaining plants were transplanted into an N-free medium the following spring.
They were supplied with or without 10 mM N from ¹⁵N-depleted NH₄NO₃ in a Hoagland’s solution for 70 days starting from budbreak.
As N fertigation concentration increased, plant N content increased linearly whereas concentrations of non-structural carbohydrates (including both starch and soluble sugars) of the whole plant decreased.
A negative correlation was found between plant N content and carbohydrate concentration.
Regardless of N supply in the spring, new shoot and leaf growth increased with increasing N reserves, but did not show any consistent relationship with reserve carbohydrates.
The amount of reserve N used for new shoot and leaf growth increased linearly as the total amount of N accumulated in the plant during the previous year increased.
This relationship was not affected by current supply of nitrogen in the spring.
There was no significant difference in either the total amount of current N uptake or the amount of N from current uptake used for new shoot and leaf growth across the range of reserve N status of the plants.

IV International Symposium on Mineral Nutrition of Deciduous Fruit Crops

L. Cheng, S. Dong, S. Guak, L.H. Fuchigami

nitrogen fertigation, reserve nitrogen, reserve carbohydrates, growth potential.

https://doi.org/10.17660/ActaHortic.2001.564.4