Leaf absorption, withdrawal and remobilization of autumn-applied urea-N in apple

Abstract

. 2004. Leaf absorption, withdrawal and remobilization of autumn-applied urea-N in apple. Can. J. Plant Sci. 84: 259-264. Six-year-old well-nourished Jonagold/M9 apple (Malus domestica) trees were sprayed 7 d after harvest with a 2% urea solution enriched with 9.9% atom 15 N. Through 3 d of the absorption period, leaves absorbed 19.2% of the intercepted urea 15 N. This low absorption could be in part due to unfavourable conditions, i.e., low temperatures (daily mean ≈5°C) and windy conditions following treatment. During leaf senescence, 48% of the urea 15 N absorbed was withdrawn from leaves and most of that (95%) remained in the treated branch section. Of this portion, 65% of the urea 15 N was found in dormant bark, 29% in wood, and 6% in flower buds. In the following spring, 46% of the stored urea 15 N was remobilized for growth of the flower buds when sampled at the "pink" stage of bud development. This accounted for 3.8% of total N in these tissues. This contribution did not influence flower quality, estimated by the length of the period between flower opening and petal fall and the level of fruit set. urée-15 N interceptée au cours des trois jours de la période d'absorption. La faible quantité d'azote absorbée pourrait résulter en partie de conditions défavorables, notamment la basse température (moyenne quotidienne ≈ 5°C) et le temps venteux après le traitement. L'arbre retire 48 % de l'urée-15 N absorbée par les feuilles à la sénescence de ces dernières, la majeure partie (95 %) de l'azote récupéré demeurant dans la partie de la branche traitée. De cette proportion, 65 % de l'urée-15 N s'est retrouvée dans l'écorce dormante, 29 % dans le bois et 6 % dans les bourgeons floraux. Le printemps suivant, un échantillonnage au stade du bouton rose a révélé que le pommier mobilise 46 % de l'urée-15 N stockée pour la croissance des bourgeons floraux, soit 3,8 % du N total présent dans ces tissus. Pareil apport n'affecte pas la qualité des fleurs, estimée d'après le laps de temps séparant le débourrage des fleurs de la chute des pétales et d'après l'importance de la nouaison.

Dynamics of nitrogen translocation from mature leaves to new shoots and related gene expression during spring shoots development in tea plants (Camellia sinensis L.)

“…The close correlation between 15 N of these two fractions with 15 N amount in mature leaves provided supporting evidence. Our finding supports the suggestion that urea is hydrolyzed in situ and assimilated into proteins and amino acids before translocation to other organs ( Tan et al., ; Guak et al., ). However, because the soluble fraction, including amino acids and urea, was not further separated, the possibility that the urea was transported out of the mature leaves to other organs could not be completely excluded ( Tan et al., ).…”

“…In previous studies with apples, peaches, and nectarines (Rosecrance et al, 1998;Tagliavini et al, 1998;Guak et al, 2004), foliar N (as urea) applied in autumn was mostly exported to roots and branches for storage, whereas in spring, the N was primarily exported to newly growing tissues. In this study, 15 N accumulation was observed in the new shoots, which is consistent with previous results in tea plants (Ruan and Gerendá s, 2015).…”

Inorganic Nitrogen-Containing Aerosol Deposition Caused “Excessive Photosynthesis” of Herbs, Resulting in Increased Nitrogen Demand

“…However, these results usually came from experiments spraying or smearing the nitrogenous solution on the leaves of fruit trees or other crops, while the spraying of nitrogen fertilizer on leaves, known as foliar fertilization, is an important management method in agriculture [33], in which the effect of nitrogen application is more through infiltration than through penetration into the sub-pores [34]. The nitrogen concentration in PM 2.5 is usually represented by the unit µg/m 3 [35,36] (such as 13.9-14.7 µg m −3 in 2004-2005 from Hangzhou City, China) [37], which is much less than the application concentration in foliar fertilization that usually uses the unit g N [38,39] (such as leaves spraying 0.5-1 g N plant −1 week −1 in a foliar fertilization experiment) [40].…”

The Impact of Foliar Fertilization on the Potassium and Phosphorus Content in Apple Shoots

“…В научной литературе имеются сведения о влиянии некорневых подкормок на накопление, распределение и реутилизацию запасных питательных веществ плодовыми растениями, но они относятся преимущественно к азотному питанию [7,8].…”