Nitrogen Metabolism, Translocation, and Recycling in Apple Trees

Carbon and nitrogen allocation in trees

“…The two amides, asparagine and glutamine, are major transport compounds in trees and many other plants and move readily in both xylem and phloem (Bollard, 1958;Pate, 1980;Dickson et al, 1985;Schubert 1986). In addition to glutamine and asparagine, many other amino acids and ureides are transported in xylem (Barnes, 1963;Titus and Kang, 1982;Kato, 1986). Although 5-15 amino acids are commonly found in xylem sap (Dickson, 1979), as many as 25 amino acids and ninhydrinpositive compounds have been found (Sauter, 1981;Kato, 1986).…”

“…No such detailed quantitative information on carbon and nitrogen allocation is available for any tree species. However, there is considerable descriptive information for carbon allocation in Populus (Isebrands and Nelson, 1983; Dickson, 1986;Bonicel et al, 1987), and for carbon and nitrogen allocation in fruit trees (Titus and Kang, 1982;Tromp, 1983;Kato, 1986 (Schulze, 1982 (Dickson and Nelson, 1982;Smith and P;aul, 1988 (Schulze, 1982 (Pearcy et al, 1987). However, only a small portion of total leaf mass is renewed each year.…”

“…However, passive diffusional uptake may also occur (Lee and Stewart, 1978 (Lee and Stewart, 1978;Pate, 1983;Runge, 1983;Kato, 1986 (Smirnoff and Stewart, 1985;Andrews, 1986;Keltjens et al, 1986;Rufty and Volk, 1986;MacKown, 1987), in fruit trees (Titus and Kang, 1982;Kato, 1986), and in forest trees (Blacquiere and Troelstra, 1986;Wingsle et al, 1987;Margolis et al, 1988 (Schulze, 1982;Chapin and Tryon, 1983 (Runge, 1983;Kato, 1986;Salsac et al, 1987). However, there is much contradictory literature concerning growth and nitrogen source, even on the same species (Titus and Kang, 1982;Kato, 1986 (Runge, 1983). In contrast, high levels of NH 4 can decrease soil pH and cation uptake, increase loss of cations from root tissue and lead to cation (e.g., K, Mg, Ca) deficiencies (Boxman and Roelofs, 1988).…”

Isolation and Spring Mobilization of Proteins in Citrus Trees (Citrus unshiu Marc.)

“…It is well known that protein nitrogen is accumulated during fall and winter and decreases during the growth period in fruit trees (5,9). However, there is no clear definition of what the storage proteins in plant tissues other than seeds are.…”

“…One of characteristics of nitrogen nutrition of fruit trees is the accumulation of high amounts of nitrogen during the fall, and its use for new shoot development in the following spring (5,9). Storage proteins in fruit trees have received little attention until quite recently, although in apple trees there is a fund of information emerging.…”