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1.
Seasonal changes in concentrations of total nitrogen, free amino acids, chlorophyll, starch and sugar were measured in foliage from fertilized and unfertilized conifer forests in New Mexico and Oregon. In the New Mexico Douglas-fir (Pseudotsuga menziesii var glauca (Beissn.) Franco) forest, fertilization resulted in elevated foliar nitrogen concentrations on all dates, from an average of 9 mg g(-1) in unfertilized trees to 14 mg g(-1) in fertilized trees. In the Oregon western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest, fertilization increased total N by only 15%, from 13 mg g(-1) in unfertilized trees to 15 mg g(-1) in fertilized trees. Foliar nitrogen concentrations on a weight basis were lowest in winter and spring, but did not vary seasonally when expressed on a leaf area basis. Chlorophyll concentrations increased with fertilization and had greater seasonal variation than did total nitrogen concentrations. Chlorophyll concentrations were significantly higher during the growing season than in the winter and spring months. Fertilization did not result in major changes in the proportion of total nitrogen in chlorophyll at either the Oregon or the New Mexico site. Concentrations of free amino acids varied with date and fertilization treatment; in New Mexico, amino acids were highest in the winter sample, whereas in Oregon, they were lowest in winter and spring. At both sites, amino acid concentrations were significantly higher in fertilized trees than in control trees on most dates and the ratios of amino acid-N to total N were also significantly higher in fertilized trees. For both sites, starch concentrations were nearly zero for most of the year, but increased sharply just before bud break and initiation of new growth in the spring. Although fertilization resulted in increased nitrogen concentrations in foliage at both sites, the response in New Mexico was much greater than in Oregon. These results are in agreement with forest productivity data that suggest that growth in the New Mexico site is limited by nitrogen, whereas in the Oregon site it is not. 相似文献
2.
《Scandinavian Journal of Forest Research》2012,27(1-4):387-395
Free amino acid and protein levels, and γ‐glutamyltransferase activity in apical buds and shoots of Scots pine during the growing season. The aim of the study was to obtain the basic information about nitrogen mobilization needed in carrying out studies on the optimal nitrate and ammonium ratios in the metabolism of Scots pine (Pinus sylvestris L.). Considerable seasonal changes in the concentrations of free amino acids and other ninhydrin‐positive low molecular‐weight compounds were observed in the buds and shoots of Scots pine. 43 different amino compounds were identified, the concentrations of arginine, glutamine, glutamic acid, γ‐aminobutyric acid, alanine and aspartic acid being highest at the break of dormancy. The amounts of certain amino compounds decreased during the growing season, those of arginine, ethanolamine and various ammonium compounds in particular. The amount of glutamic and aspartic acids, glycine, alanine and γ‐aminobutyric acid, however, remained relatively constant. The protein concentration and the specific activity of γ‐glutamyltransferase increased towards the end of the growing period. Slight differences were found between the fertilized trees and the control trees. 相似文献
3.
Påhlsson AM 《Tree physiology》1992,10(1):93-100
Beginning in 1985, plots in a 120-year-old beech (Fagus sylvatica L.) stand in the province of Scania, southern Sweden were fertilized annually with ammonium nitrate. In August 1989, leaves from both fertilized and unfertilized trees were analyzed for mineral nutrients, soluble carbohydrates, amino acids and phenolic compounds. Leaf concentrations of total nitrogen were increased by N fertilization. Ammonium was not detected in the leaves, but NO(3) (-) was increased by up to 65% as a result of N fertilization. Nitrogen fertilization decreased foliar concentrations of P and Cu, leading to a nutrient imbalance relative to N. Of the free amino acids, glutamic acid and aspartic acid predominated and, together with glutamine and asparagine, were significantly increased by N fertilization. The concentrations of amides were 2-4 times higher in fertilized trees than in unfertilized trees. Soluble carbohydrates did not change in response to N fertilization, but total phenolic compounds decreased markedly. The reduced concentration of phenolics may explain the greater susceptibility to parasite attacks of trees exposed to N deposition and excess N. 相似文献
4.
Seasonal changes in above ground dry-matter, nitrogen (N), and phosphorus (P) accumulation were measured following application of N and P in autumn or spring to 1-year-old Pinus radiata (D. Don). Dry-matter production and nutrient accumulation were measured eight times over two years following fertilization.
All trees produced dry-matter throughout the year, but during the summer, fertilized trees produced more dry-matter than unfertilized trees. In contrast to dry-matter production, nutrient accumulation showed a distinctly seasonal pattern with maximum accumulation of N and P occurring in winter and spring, when rainfall and soil moisture were highest. Accumulation of N and P either slowed markedly or ceased during summer depending on fertilizer treatment. Continued dry-matter production during summer, when nutrient accumulation was low, resulted in the decline of N and P concentrations in needles, branches and stems of all trees. This indicated that nutrients required for new growth during summer were mobilized from existing foliage and wood. Fertilization increased the concentrations of N and P in foliage and wood, and these higher concentrations persisted through summer. Spring fertilization increased N accumulation to a greater extent than autumn fertilization, this effect lasting two years. The greater dry-matter production by fertilized trees during summer indicated that growth during summer was limited by nutrient supply. 相似文献
5.
Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha(-1) year(-1) for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-microm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction. In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds. 相似文献
6.
Yamashita T 《Tree physiology》1990,6(2):191-200
Quantitative changes in carbohydrates, amino acids and adenine nucleotides in the stems of mulberry trees (Morus alba L., cv. Shin-ichinose) were followed from spring to early summer and from autumn to early spring. Both ATP and ADP content of stems increased before bud break, whereas the content of sucrose, the most abundant sugar among the stem carbohydrates, decreased. The sucrose content fell to its lowest value at the beginning of May, and then increased rapidly, whereas the starch content decreased suggesting consumption of reserve carbohydrate and simultaneous accumulation of current photosynthate. This was confirmed by studies in which reserve carbohydrates were labeled with (14)CO(2). Proline content of stems increased from the time of leaf shedding until early spring. Although it was the most abundant amino acid at the time of bud break, proline rapidly decreased as new shoots developed and was hardly detectable by the beginning of May. The asparagine and arginine contents increased transiently following bud break, and then decreased toward summer. Transient increases in glutamine and arginine were noted at the time of leaf shedding. 相似文献
7.
The effects of drought on the free amino acid pools in 21- to 23-week-old seedlings of black spruce (Picea mariana (Mill.) Britt.), white spruce (Picea glauca (Moench.) Voss) and jack pine (Pinus banksiana Lamb.) were followed during soil drying. Although water and pressure potentials were sensitive to water deficits, large changes in osmotic potential were not recorded until after the development of severe drought. Total soluble amino nitrogen in the shoots and roots of the three species rose as turgor declined, with peak concentrations attained late in the drought period when the pressure potentials of the shoots approached zero. All white spruce seedlings were alive at zero turgor and showed large decrements in osmotic potential, but concentrations of free amino nitrogen in the roots and shoots showed only modest increases, reaching 125 to 150% of their control values. In contrast, large numbers of black spruce and jack pine were dead or severely damaged at zero turgor, and only small changes in osmotic potential were detected during soil drying. Nevertheless, concentrations of soluble amino nitrogen in both species reached 150 to 200% of control values a few days before the seedlings died. Alanine, arginine, aspartic acid/asparagine, glutamic acid/glutamine, glycine, hydroxyproline and proline were the major components of the free amino acid pools under both water-stressed and non-stressed conditions, with the largest and most consistent increases observed in the roots of all three conifers. Although proline was an important and dynamic component of the free pools, absolute concentrations were commony equalled or exceeded by other free amino acids in the roots and shoots and nearly always exceeded by the concentration of aspartic acid/asparagine in both tissues. Differences in drought resistance among the three conifers were not reflected by unique patterns of amino acid accumulation or by large differences in absolute concentrations of the free amino acid pools. 相似文献
8.
Bench-grafted 'Fuji/M.26' apple (Malus domestica Borkh.) trees received a constant nitrogen (N) supply (10.7 mM) from bud break to the end of June, and were then fertigated with 0, 5, 10, 15 or 20 mM N in a modified Hoagland's solution for 2 months during the summer. In mid-October, half of the trees fertigated at each N concentration were sprayed twice with 3% urea, whereas the remaining trees served as controls. All trees were harvested after natural leaf fall and were stored at 2 degrees C. Five trees from each of the N treatment combinations were destructively sampled during dormancy to determine the composition of N and total nonstructural carbohydrates (TNC). As the N supply from fertigation increased, amounts of N in both free amino acids and proteins increased, whereas C/N ratios decreased. Foliar urea applications in the fall significantly increased amounts of N in both free amino acids and proteins, but decreased their C/N ratios. Arginine, the most abundant amino acid in both free amino acids and in proteins, accounted for an increasing proportion of N in free amino acids and proteins with increasing N supply from fertigation or foliar urea application. The ratio of protein N to free amino acid N decreased from about 27.1 to 3.2 as N supply from fertigation increased from 0 to 20 mM, and decreased further to 3.0 in response to foliar urea applications in the fall. Concentrations of glucose, fructose, sucrose and TNC decreased as the N supply from fertigation increased, whereas concentrations of sorbitol and starch remained relatively unchanged. Foliar urea applications decreased the concentration of each TNC component and the TNC concentration in each N fertigation treatment. A negative linear relationship was found between carbon in TNC and N in proteins and free amino acids. The sum of carbon in TNC, proteins and free amino acids remained constant in response to N supply from fertigation. However, foliar urea applications decreased the sum of carbon in proteins, free amino acids and TNC because about 21% of the decrease in TNC carbon was not recovered in free amino acids or proteins. Young apple trees store N and carbon dynamically in response to N supply. As N supply increases, an increasing proportion of N is found in the form of free amino acids, which have a low carbon cost, although proteins remain the main form of N storage. Furthermore, part of the carbon from TNC is incorporated into amino acids and proteins, decreasing the carbon stored as TNC and increasing the carbon stored as amino acids and proteins. 相似文献
9.
四川省不同气候类型核桃氨基酸含量研究 总被引：4，自引：0，他引：4
以四川省26个县的182份核桃优树的风干种仁为材料,采用相关分析、聚类分析和多重比较研究了四川省不同气候类型核桃种仁的氨基酸含量,及其与气候因子的相关性。结果表明：核桃仁氨基酸总量在16％-18％左右,共含有18种氨基酸,其中人体必需氨基酸9种。除胱氨酸外,不同气候类型核桃仁中各种氨基酸含量及氨基酸总量差异显著（P〈0．05）,说明气候条件对核桃氨基酸含量影响较大。气候类型Ⅱ的核桃各种氨基酸含量及氨基酸总量均最高。氨基酸总量、缬氨酸、异亮氨酸、色氨酸、亮氨酸、苯丙氨酸、脯氨酸、丙氨酸、苏氨酸、丝氨酸、酪氨酸、天冬氨酸、组氨酸和精氨酸与7月平均气温、年降水量、大于10℃年积温、年平均气温和年平均相对湿度呈极显著（P〈0．01）或显著（P〈0．05）的正相关关系。说明7月平均气温、年降水量、大于10℃年积温、年平均气温和年平均相对湿度越高,越有利于氨基酸总量、缬氨酸、异亮氨酸、色氨酸、亮氨酸、苯丙氨酸、脯氨酸、丙氨酸、苏氨酸、丝氨酸、酪氨酸、天冬氨酸、组氨酸和精氨酸的形成。蛋氨酸、甘氨酸和胱氨酸与年降水量、7月平均气温和年平均相对湿度呈极显著（P〈O．01）或显著（P〈0．05）的正相关关系。说明年降水量、7月平均气温和年平均相对湿度越高,越有利于蛋氨酸、甘氨酸和胱氨酸的形成,谷氨酸与年降水量呈显著的正相关关系（P〈0．05）。赖氨酸与大于10℃年积温、7月平均气温呈极显著的正相关关系（P〈0．05）。7月平均气温与各种氨基酸含量均呈极显著或显著的正相关关系,表明核桃仁中氨基酸的积累可能取决于核桃成熟期的温度情况,核桃成熟期温度越高,越有利于氨基酸的积累。 相似文献
10.
Quantitative field measurements of biological nitrogen fixation (BNF) and biomass production by four different understorey pastures in a Pinus radiata-pasture agroforestry system were determined over a period of one year. The trees were two years old at the beginning of this study and the understorey pastures were being cut and removed for silage. The BNF was determined using the 15N dilution technique. Pastures of ryegrass+clover, cocksfoot+clover, phalaris+clover and lucerne were used. Substantial amounts of BNF were found (71 to 230 kg N ha–1 year–1) with lucerne showing the highest N fixation. However, lucerne derived only 71 to 72% of its N from the atmosphere (%Ndfa) during the spring/summer period compared to 83–97% with clovers, thus the net N demand from the soil was substantially higher with lucerne. This caused increased N stress to the trees. Clover in ryegrass+clover pasture fixed more N than the other grass+clover pastures. Although pasture position in relation to trees did not affect annual pasture total DMY and %Ndfa, pastures north of tree row grew better than those in other positions. Trees significantly affected the BNF of legumes and the botanical composition of pastures with highest BNF and legume production occurring in pastures midway between two rows of trees. These results suggest that it would be advantageous to evaluate different legumes and grasses for tolerance of shade and moisture stress in future studies. As the trees studied were only 1.5 to 3 m in height, their effects on BNF, seasonal pasture biomass production and botanical composition are expected to increase with tree dominance in the ecosystem with time. Amounts of N fixed were related to the productivity (i.e. dry matter and N yield) and seasonal persistence of the legumes. The productivity was high in spring and summer and low in autumn and winter. 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(1-4):515-525
The role of nitrogenous compounds in the pest‐host interaction of Aradus cinnamomeus and Pinus sylvestris was studied by analysing free amino acids and related compounds in the insects and the cambial layer of Scots pine. About 35 different compounds were identified by means of thin‐layer and automatic ion‐exchange chromatography. The total content of amino acids in the insects was ca. 0.86% of the fresh weight (65 μmoles/g), ca. 0.075% (7.2 μmoles/g) in the young phloem layer of Scots pine, and ca. 0.078% (6.8 μmoles/g) in the young xylem layer. The most abundant free amino acids in the insects were proline and glutamine, followed by alanine, glutamic acid, taurine, histidine, arginine, and lysine. The amino acid composition was similar in males and females, and almost identical in brachypterous and macropterous females. The concentration of glutamic acid was low in the hemolymph but high in the salivary glands and other tissues. In other respects the amino acid composition of the salivary glands resembled that of the whole insect. No distinctly phytotoxic compounds were identified in the insects. The predominant amino compounds in the cambial layer of the pine saplings were γ‐aminobutyric acid, glutamine, ethanolamine, serine and alanine. The amino acid composition was similar in extracts of phloem and xylem. The bulk of the alcohol‐soluble compounds in the pine cambial layer were carbohydrates (ca. 3.5% of fresh weight). 相似文献
12.
Plants can assimilate amino acids from soils. This has been demonstrated in controlled environments and soils of various forest ecosystems. However, the role of root-absorbed amino acids in plant nitrogen nutrition is still poorly understood. We investigated the agroecological performance and nutrient use physiology of two conifers (Abies fraseri and Pinus resinosa) and one hardwood species (hybrid poplar) under amino acid fertilization. Arginine fertilizer (arGrow® Complete) was applied at varying rates (0, 56, 112, 224, and 336 kg N/ha) and compared to an inorganic control treatment (ammonium sulfate 112 kg N/ha). Parameters monitored included tree growth response, foliar nitrogen concentration, and inorganic nitrogen leaching below the rootzone. Results obtained indicate a significant growth and foliar nitrogen response to amino acid treatments, with increasing amino acid application leading to greater growth and foliar nitrogen. However, rates two to three times higher than that of the inorganic control were necessary to provide similar growth and foliar nitrogen responses. These observations were suggested to be due to competition with soil microbes for organic nitrogen, growth inhibition due to the presence of large concentrations of amino acids, or adsorption to cation exchange sites. Amino acid applications did not increase the leaching of inorganic nitrogen due either to the binding of positively charged arginine cations to exchange sites or rapid mineralization followed by plant assimilation. Mineral nitrogen collected in leachate samples increased with the application rate suggesting at least some mineralization in high amino acid application rates. We conclude that growth response and nitrogen use physiology of these species when treated with arginine are largely controlled by soil processes including microbial competition and adsorption. Further studies are being conducted to confirm these hypotheses. 相似文献
13.
Seasonal variations in leaf nitrogen, phosphorus and potassium concentrations were studied in a mature carob (Ceratonia siliqua L. cv "Mulata") orchard subjected to a 4-year irrigation and fertilization experiment. Three irrigation regimes (0, 50 and 100%), based on the evaporation values obtained from a class A pan, were tested in combination with two nitrogen (N) supply regimes in which 21 kg ha(-1) year(-1) (low-N) and 63 kg ha(-1) year(-1) (high-N) were supplied as ammonium nitrate. Leaf nitrogen concentration increased throughout the experiment, independently of treatments. There were no significant differences in leaf N concentration between trees in the high-N and low-N treatments. Irrigation regimes had no effect on leaf mineral concentration but influenced the amount of leaves shed and slightly modified the pattern of leaf shedding that occurred during the summer drought period. Nutritional balances between N and P and N and K were both closely and significantly correlated. Potassium was translocated from leaves to fruits during spring, independently of treatments. Severe water stress periods occurring during spring or autumn induced shedding of leaves leading to nutrient mobilization. Nutrient retranslocation during these drought periods may represent an adaptive mechanism. Nitrogen retranslocation was higher for trees in the high-N treatments than for trees in the low-N treatments, whereas phosphorus retranslocation was independent of the irrigation and fertilization treatments. 相似文献
14.
The PEACH computer simulation model of reproductive and vegetative growth of peach trees (Grossman and DeJong 1994) was adapted to estimate seasonal nitrogen (N) dynamics in organs of mature peach (Prunus persica (L.) Batsch cv. O'Henry) trees grown with high and low soil N availability. Seasonal N accumulation patterns of fruits, leaves, stems, branches, trunk and roots of mature, cropping peach trees were modeled by combining model predictions of organ dry mass accumulation from the PEACH model with measured seasonal organ N concentrations of trees that had been fertilized with either zero or 200 kg N ha(-1) in April. The results provided a comparison of the N use of perennial and annual organs during the growing season for trees growing under both low and high N availability. Nitrogen fertilization increased tree N content by increasing organ dry masses and N concentrations during the fruit growing season. Dry mass of current-year vegetative growth was most affected by N fertilization. Whole-tree N content of fertilized trees was almost twice that of non-fertilized trees. Although N use was higher in fertilized trees, calculated seasonal N accumulation patterns were similar for trees in both treatments. Annual organs exhibited greater responses to N fertilization than perennial organs. Estimated mean daily N use per tree remained nearly constant from 40 days after anthesis to harvest. The calculations indicated that fertilized trees accumulated about 1 g N tree(-1) day(-1), twice that accumulated by non-fertilized trees. Daily N use by the fertilized orchard was calculated to be approximately 1 kg N ha(-1), whereas it was approximately 0.5 kg N ha(-1) for the non-fertilized trees. During the first 25-30 days of the growing season, all N use by growing tissues was apparently supplied by storage organs. Nitrogen release from storage organs for current growth continued until about 75 days after anthesis in both N treatments. 相似文献
15.
We studied the absorption, assimilation, translocation and distribution of nitrogen (N) from urea applied in autumn to leaves of 1-year-old potted Fuji/M26 apple (Malus domestica Borkh) trees. In early October, all leaves of each tree were painted with either 3% urea (enriched to 10 atom % with 15N) or water (control trees). Four trees were harvested before the treatment and N and amino acid contents were determined. Four trees from each treatment were harvested at 2, 4, 7, 10, 15 and 20 days after urea or water application. Total N, amino acids and 15N in leaves, bark, xylem, shank and roots were analyzed to determine uptake and mobilization of N from urea. Most uptake of 15N by leaves occurred during the first 2 days following application of urea. The mean rate of absorption during these 2 days was 0.29 g m-2 day-1. Amino acids in leaves, bark and roots increased significantly after urea application compared with control values. The highest concentrations of amino acids in leaves and bark occurred 4 days after application, whereas the highest concentrations of amino acids in roots occurred 10 days after application. Total 15N content in leaves peaked 2 days after urea application and then decreased, whereas 15N content in roots and bark increased throughout the experiment. Total 15N content in xylem and shank was low. Leaves absorbed 35% of the 15N applied as urea, and 63.6% of absorbed 15N was translocated out of leaves within 20 days after urea application. We conclude that N from urea was converted to amino acids in leaves after foliar application in autumn, and roots and bark were the main sinks of N from urea applied to leaves. 相似文献
16.
In spring, nitrogen (N) uptake by apple roots begins about 3 weeks after bud break. We used 1-year-old 'Fuji' Malus domestica Borkh on M26 bare-root apple trees to determine whether the onset of N uptake in spring is dependent solely on the growth stage of the plant or is a function of soil temperature. Five times during early season growth, N uptake and total amino acid concentration were measured in trees growing at aboveground day/night temperatures of 23/15 degrees C and belowground temperatures of 8, 12, 16 or 20 degrees C. We used (15NH4)(15NO3) to measure total N uptake and rate of uptake and found that both were significantly influenced by both soil temperature and plant growth stage. Rate of uptake of 15N increased with increasing soil temperature and changed with plant growth stage. Before bud break, 15N was not detected in trees growing in the 8 degrees C soil treatment, whereas 15N uptake increased with increasing soil temperatures between 12 and 20 degrees C. Ten days after bud break, 15N was still not detected in trees growing in the 8 degrees C soil treatment, although total 15N uptake and uptake rate continued to increase with increasing soil temperatures between 12 and 20 degrees C. Twenty-one days after bud break, trees in all temperature treatments were able to acquire 15N from the soil, although the amount of uptake increased with increasing soil temperature. Distribution of 15N in trees changed as plants grew. Most of the 15N absorbed by trees before bud break (approximately 5% of 15N supplied per tree) remained in the roots. Forty-six days after bud break, approximately one-third of the 15N absorbed by the trees in the 12-20 degrees C soil temperature treatments remained in the roots, whereas the shank, stem and new growth contained about two-thirds of the 15N taken up by the roots. Total amino acid concentration and distribution of amino acids in trees changed with plant growth stage, but only the amino acid concentration in new growth and roots was affected by soil temperature. We conclude that a combination of low soil temperature and plant developmental stage influences the ability of apple trees to take up and use N from the soil in the spring. Thus, early fertilizer application in the spring when soil temperatures are low or when the aboveground portion of the tree is not actively growing may be ineffective in promoting N uptake. 相似文献
17.
Nitrogen fertilization and aspects of fruit yield in a Missouri black walnut alley cropping practice
Increasing nut production through cultural practices is important to landowners for maximizing economic gain from agroforestry
plantings. This project studied the effects of applying low rates of nitrogen (N) fertilizer during either the spring or late
summer, on pistillate flowers formed, fruits retained, and fruit quality (percentage kernel) in black walnut (Juglans nigra
L.) grown under alley cropping management. Treatments consisted of two forms of nitrogen fertilizers (NH4NO3 and NaNO3) applied in mid-April, or mid-August of 1995 and 1996, and a nonfertilized control group. Pistillate flowers counted in May,
1996, showed that fertilized trees, regardless of timing or form of N applied, produced from 2.3 to 3.4 times the number of
pistillate flowers as unfertilized control trees. Through the season, the fertilized trees had greater fruit retention, and
ended with 2.9 to 4.8 times more walnuts (on a whole tree basis) than nonfertilized control trees. In addition, all fertilizer
treatments resulted in increased nut yields from 1995 to 1996, while unfertilized control tree yields decreased approximately
70%. Summer application of fertilizer showed the greatest benefit to kernel weight. Average kernel weights of nuts from the
summer-fertilized trees increased from 1995 to 1996, while kernel weight averages from spring-fertilized and nonfertilized
trees remained unchanged or decreased.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
Studies of small trees growing in pots have established that individual amino acids or amides are translocated in the xylem sap of a range of tree species following bud burst, as a consequence of nitrogen (N) remobilization from storage. This paper reports the first study of N translocation in the xylem of large, deciduous, field-grown trees during N remobilization in the spring. We applied 15N fertilizer to the soil around 10-year-old Prunus avium L. and Populus trichocharpa Torr. & Gray ex Hook var. Hastata (Dode) A. Henry x Populus balsamifera L. var. Michauxii (Dode) Farwell trees before bud burst to label N taken up by the roots. Recovery of unlabeled N in xylem sap and leaves was used to demonstrate that P. avium remobilizes N in both glutamine (Gln) and asparagine (Asn). Sap concentrations of both amides rose sharply after bud burst, peaking 14 days after bud burst for Gln, and remaining high some 45 days for Asn. There was no 15N enrichment of either amide until 21 days after bud burst. In the Populus trees, nearly all the N was translocated in the sap as Gln, the concentration of which peaked and then declined before the amide was enriched with 15N, 40 days after bud burst. Xylem sap of clonal P. avium trees was sampled at different positions in the crown to assess if the amino acid and amide composition of the sap varied within the crown. Sap was sampled during remobilization (when the concentration of Gln was maximal), at the end of remobilization and at the end of the experiment (68 days after bud burst). Although the date of sampling had a highly significant effect on sap composition, the effect of position of sampling was marginal. The results are discussed in relation to N translocation in adult trees and the possibility of measuring N remobilization by calculating the flux of N translocation in the xylem. 相似文献
19.
Indole-3-acetic acid (IAA), carbohydrates, total nitrogen and amino acids in the cambial region and bark were measured at the top (10-year-old internode) and bottom (1.3 m) of the main stem of 50-year-old Pinus sylvestris L. trees, having different rates and longitudinal gradients of annual ring width formation. The trees were sampled during the most active period of wood production (June 23, July 15) and at the end of this period (August 23). Trees with a small crown and relatively slow growth rate (S-trees) were compared with trees in the same stand that had a large crown and fast growth rate (F-trees) as a result of thinning and fertilization. The effect of bottom pruning fast-growing trees (pruned F-trees) was also investigated. The F-trees had greater wood production than the S-trees at both the stem top and bottom. The difference was larger at the stem bottom, thus the relative decrease in ring width down the stem was steeper in the S-trees. The amount of sucrose and IAA per cm(2) in cambial region tissues was higher in F-trees than in S-trees. However, the differences in annual ring width between treatments and within trees were not reflected in the concentrations (expressed per gram fresh weight) of these substances, measured either in differentiating xylem, the cambium plus phloem, or in the cambial region as a whole. The concentrations of total nitrogen and amino acids were slightly higher in the F-trees than in the S-trees. Pruning the F-trees reduced wood production, particularly at the stem bottom, inhibited the springtime increase in starch, and decreased the amounts of sucrose and IAA per cm(2) in the cambial region. However, it was evident that the concentrations of sucrose, IAA, amino acid and nitrogen in the cambial region were not related to ring width. During June and July, the concentrations of these substances were generally higher at the stem bottom in the pruned F-trees than in the F-trees. The results provide evidence that it is the activity of the cambium rather than the availability of carbohydrates that determines the allocation of wood production along the tree stem. The results also indicate that tracheid production is not directly related to the IAA concentration in the cambial region. 相似文献
20.
Maier CA 《Tree physiology》2001,21(16):1183-1193
Stem respiration and growth in 10-year-old loblolly pine (Pinus taeda L.) plantations were measured monthly during the third year of fertilization and irrigation treatments to determine whether soil resource availability differentially altered growth and respiration in stem tissue. Fertilized trees had significantly greater stem biomass, stem nitrogen concentration ([N]) and growth rate than unfertilized trees. Stem respiration (Rt) was significantly greater in fertilized trees when expressed on a per unit surface area (Rt,a, micromol CO2 m-2 s-1), sapwood volume (Rt,v, micromol CO2 m-3 s-1), or mass (Rt,w, nmol CO2 g-1 s-1) basis; however, there was no difference between treatments when expressed as a function of stem N content (Rt,n, micromol CO2 (mol N)-1 s-1). Irrigation had no significant effect on Rt or annual stem growth. Daily total respiration (Rd, mol CO2 m-2 day-1) and stem diameter growth both had a seasonal bimodal pattern with peaks in early spring and midsummer. Stem [N] declined significantly during the growing season. Stem growth rate and [N] explained 75% of the seasonal variation in temperature-normalized Rt,a. The mature tissue method was used to partition total stem respiration (Rt) into maintenance (Rm) and growth (Rg) components. There was a linear correlation between winter Rt,v, a measure of basal Rm, and sapwood N content; however, Rt,v per unit N was greater in January before diameter growth started than in the following December after growth ceased, indicating that Rt,v declined as stem diameter increased. Consequently, estimates of annual maintenance respiration (RM) based on January data were 44% higher than estimates based on December data. Growth respiration was correlated with stem growth rate (r2 = 0.55). The growth respiration coefficient (rg)-the slope of the relationship between Rg and stem growth rate-was 0.24. Respiration accounted for 37% of annual stem carbon budget. Stem carbon-use efficiency (CUE)-the ratio of stem growth to stem growth plus respiration-averaged 0.63 and was unaffected by fertilization. 相似文献