Nitrogen‐15 in apple nutrition investigations

Abstract

Young apple treesgrowinginpots of soil were treated withN-15 labelled potassium nitrate or urea at different times of year. Over periods of several months whole trees were harvested and divided into their component tissues for total N and N-15 analyses; the latter were carried out using an emission spectrometer. Following treatments in mid-October 1972 and harvest in the following February, about 16 % of N-15 from soil-applied nitrate and almost 47 % of that from leafapplied urea was recovered in the trees. A later harvest in May 1973 showed that by then one-third to one-half of this fertiliser N had been translocated to the new leaves. Soil applications of nitrate were also made in March or August 1973 and the maximum recoveries of fertiliser N were about 40% and 60% respectively, much of which was in the leaves. In the fruit from the March-N trees, seeds and flesh were almost equally labelled but in that from the August-treated trees the seeds contained no excess N-15, although there was a considerable concentration in the flesh. Urea foliar sprays were also made in June or August 1973. The distributions of isotope were very similar following these treatments, in that the greater part remained in the leaves. The results are discussed in relation to previously published work on N in apple trees, with particular emphasis on the advantages in using N-15 to follow unambiguously the movement of N between the tissues of the tree.

Method of Nitrogen Application in Summer Affects Plant Growth and Nitrogen Uptake in Autumn in Young Fuji/M.26 Apple Trees

“…It has been reported that N taken up from the soil application during the growing season can be quickly translocated to aboveground and directly used for the production of new growth (Gu, Shu, and Zhou 1987), while the N absorbed by leaves from foliar N applications in the summer remains mostly in the leaves (Hill-Cottingham and Lloyd-Jones 1975). This may also partially explain the growth-promoting effects found by soil N applications during the summer.…”

“…The higher the N concentration in the roots, the more 15 N was translocated to the stem. Other researchers also reported that most of 15 N absorbed by roots late in the season was kept in the roots (Hill-Cottingham et al 1975;Tagliavini et al 1999), but they did not relate this distribution with root N status. Our results indicated that the distribution 15 N from root uptake in the autumn depended on root N status.…”

Carbohydrate and nitrogen reserves in two cultivars of Japanese plum grown under organic and conventional management

“…However, based on our results we believe that it would be premature to conclude that the type of management (i.e., organic or conventional) does not affect the concentrations of reserves in the plant, and we suggest that in future studies levels of reserves should be determined in different parts of the tree, including in higher trunk biomass, main branches and thicker roots. Moreover, the study of reserves in trees is a complex issue due to the fluctuations observed throughout the annual cycle (Yamashita 1986;Keller, Loescher 1989), in addition to differences in carbohydrate and nitrogen concentrations in the different tissues of the tree (Hillcottingham, Lloydjones 1975;Loescher et al 1990). Another aspect that increases the difficulty of the study of carbohydrate and nitrogen reserves is the relationship between these two fractions, since some authors have reported a negative correlation between the content of nitrogen and carbohydrates (Cheng, Fuchigami 2002).…”

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

“…This value is lower than that reported by previous studies on foliar urea application. Hill-Cottingham and Lloyd Jones (1975) found that about 62% of the leaf N absorbed from autumn application of foliar urea to apple trees was recovered in dormant 49.2 ± 3.9 -25.4 ± 4.5 z Values are means (± SE) of 10 replicates. y Total N concentrations in the untreated branch were 1.24 ± 0.05%, 0.43 ± 0.02% and 1.26 ± 0.02% for bark, wood and flower buds, respectively.…”

“…Values can depend on application rate and timing (Rosecrance et al 1998;Khemira et al 1999), leaf age, air temperature and humidity (Orbović et al 2001). The proportion of the urea-derived N absorbed to perennial tissues in apple trees ranges from 60 to 90% (Hill-Cottingham and Lloyd-Jones 1975;Cheng et al 2002;Dong et al 2002). The period of leaf senescence likely affects withdrawal efficiency (Del-Arco et al 1991), with a longer period resulting in more N translocation.…”