Tree Nutrient Status Research Articles

The long-term effects of logging residue removal on forest floor nutrient capital, foliar chemistry and growth of a Norway spruce stand

This study compared the nutrient capital of the forest floor, the nutrient status of trees, and the growth of a stand of Norway spruce (Picea abies L. (Karst.)) planted on a whole-tree harvesting treatment (needles left on site) with a conventional stem-only harvesting treatment 30 years after clearcutting. No significant treatment effects were detected in the amount of organic matter, the amounts of nutrients in the forest floor, or the concentrations of foliar nutrients. The results indicate that whole-tree harvesting with the needles left on the site did not reduce the long-term nutrient capital of the forest floor or the nutritional status of trees. Whole-tree harvesting significantly reduced the height of dominant spruce compared to stem-only harvesting, however the stem volume of dominant spruce did not differ between the harvesting treatments. The greater height growth of the dominant trees in the stem-only harvesting treatment could be attributed to indirect factors other than changes in site resource availability (e.g. protection against frost damage), and hence the effect of whole-tree harvesting on potential site productivity was inconclusive due to the confounding effect of site factors. In the whole-tree harvesting treatment, the total stem volume of the stand and, consequently, the actual site productivity, was lower when compared to stem-only harvesting due to the lower density of naturally regenerated seedlings.

Effects of irregular cropping on nutrient uptake and status of apple trees

Produce of harmonic nutrient balance and status of trees is basic task of growers for qualified fruit growing. The role of crop loaded is essential to grow the productivity of trees without nutrient disorder or other nutritional problems. To reduce the frequency of biennial bearing there are some ways (site and species selection, crop regulation, irrigation, nutrition etc.) from them one is the best easy way the proper site and species oriented nutrition. Sometimes the responsible for irregular cropping is the insufficient fertilization. Observed irregular cropping at two apple cultivars (Malus domestica Borkh., cv. ‘Summerred’ and cv. ‘Mutsu’) in an integrated apple orchard at Hajdúnánás-Tedej, in 2007 resulted a chance to determine nutritional status of “bearing” and “non bearing” trees and investigate the effects of irregular cropping on nutrient uptake and possibilities of correction. Our results pointed out that irregularity is connection on nutrition status of trees. Irregular cropping results in insufficient nutrient uptake and disharmony of nutrients. For this reason, the establishment of nutrient status of “non bearing” trees is could permit a chance to correct and improve the nutrient supply of trees which help to breakdown the vicious circle of irregularity.

Does exceeding the critical loads for nitrogen alter nitrate leaching, the nutrient status of trees and their crown condition at Swiss Long-term Forest Ecosystem Research (LWF) sites?

Nitrogen (N) deposition exceeds the critical loads for this element in most parts of Switzerland apart from the Alps. At 17 sites (8 broadleaved stands, 8 coniferous stands, and 1 mixed stand) of the Swiss Long-term Forest Ecosystem Research network, we are investigating whether N deposition is associated with the N status of the forest ecosystems. N deposition, assessed from throughfall measurements, was related to the following indicators: (1) nitrate leaching below the rooting zone (measured on a subset of 9 sites); (2) the N nutrition of the forest stand based on foliar analyses (16 sites); and (3) crown defoliation, a non specific indicator of tree vitality (all 17 sites). Nitrate leaching ranging from about 2 to 16 kg N ha−1 a−1 was observed at sites subjected to moderate to high total N deposition (>10 kg ha−1 a−1). The C/N ratio of the soil organic layer, or, when it was not present, of the upper 5 cm of the mineral soil, together with the pool of organic carbon in the soil, played a critical role, as previous studies have also found. In addition, the humus type may need to be considered as well. For instance, little nitrate leaching (<2 kg N ha−1 a−1) was recorded at the Novaggio site, which is subjected to high total N deposition (>30 kg ha−1 a−1) but characterized by a C/N ratio of 24, large organic C stocks, and a moder humus type. Foliar N concentrations correlated with N deposition in both broadleaved and coniferous stands. In half of the coniferous stands, foliar N concentrations were in the deficiency range. Crown defoliation tended to be negatively correlated with N concentrations in the needles. In the majority of the broadleaved stands, foliar N concentrations were in the optimum nutritional range or, on one beech plot with high total N deposition (>25 kg ha−1 a−1), above the optimum values. There was no correlation between the crown defoliation of broadleaved trees and foliar concentrations.

Logging residue removal after thinning in boreal forests: long-term impact on the nutrient status of Norway spruce and Scots pine needles

The aim of this study was to compare how conventional stem harvesting (CH) and whole-tree harvesting (WTH) in the first, and in some cases also in the second, thinning affect the needle nutrient status of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands in Finland. A series of 12 long-term field experiments was studied. The experiments were established during 1978-86. The effects of logging residue removal after thinnings on the needle nutrient concentrations were generally minor and without any overall trends, but there were differences between experiments. Trees tend to maintain their current needle nutrient concentrations at the same level by re-utilizing the nutrients stored in the older tissues and by changing C allocation in the whole tree. Thus, needle analysis should be combined with stem growth data in order to achieve a more comprehensive understanding of the effects of WTH on the nutrient status of trees.

The Relationship Between Flower and Fruit Abscission and Alternate Bearing of ‘Hass’ Avocado

Despite profuse flowering, ‘Hass’ avocado (Persea americana Mill.) yields are low because of excessive flower and fruit abscission. Whether the dynamics of flower and fruit abscission are influenced by or contribute to alternate bearing, the production of a heavy on-crop followed by a light off-crop that is characteristic of many avocado cultivars, remains unresolved. The objective of this research was to determine whether abscission of reproductive structures from ‘Hass’ avocado trees during specific developmental stages, including flowering, fruit development, and fruit maturity, was influenced by crop status of the current or preceding year. Abscised reproductive structures were collected from commercially bearing trees during two complete crop years. Flower abscission began at about the same time but peaked 1 month later in the off-crop year compared with the on-crop year. Peak abscission rates were lower during the off-crop year than the on-crop year (compare 1836 ± 403 to 5378 ± 856 flowers per day and 50 ± 18 to 280 ± 23 immature fruit per day, respectively). The off- or on-crop status of the tree did not influence the percentage fruit set, average fruit diameter, or biomass of individual fruit that abscised at similar phenological stages. Furthermore, flower and fruit abscission were not influenced by the number of mature fruit from the previous year's crop. In both years of the research, as immature fruit abscission declined, abscission of the preceding year's crop increased, indicating that the processes were controlled independently. During the study, neither weather conditions nor tree nutrient status were associated with key abscission events. Taken together, these results provide evidence that the previous year's yield does not influence flower or fruit abscission and the seasonal abscission of reproductive structures is an independent process that does not contribute to alternate bearing of ‘Hass’ avocado.

Effects of wood ash, vitality fertilizer and logging residues on needle and root chemistry in a young Norway spruce stand

The nutrient status of a 6-year-old Norway spruce stand in south-west Sweden was examined 4 and 5 years after application of soil ameliorative treatments. In addition to control plots, three treatments were tested: granulated wood ash at 4150 kg dry weight (dw) ha−1, a nitrogen-free, dolomite-based vitality fertilizer (SkogVital) at 2×1500 kg ha−1 and the fine fraction of harvest residues (mostly needles) at 15,050 kg dw ha−1. The treatments had no short-term effect on height increment. Nitrogen (N) was probably the growth-limiting element, but phosphorus (P) and potassium (K) were also in suboptimum supply. The vitality fertilizer increased the foliar concentration (or the element/N ratio) of P, calcium (Ca) and zinc, while ash application increased the foliar Ca/N ratio. The vitality fertilizer also increased magnesium and Ca concentrations in roots and decreased aluminium concentrations, whereas logging residues and wood ash only increased manganese concentrations in roots. Thus, the vitality fertilizer had a more marked effect on tree nutrient status than the granulated wood ash.

CanPhytophthora quercinahave a negative impact on mature pedunculate oaks under field conditions?

Ten oak stands in southern Sweden were investigated to evaluate the impact of the root pathogen Phytophthora quercina on mature oaks under field conditions. Phytophthora quercina was present in five of the stands, while the other five stands were used as controls to verify the effect of the pathogen. In each stand, a healthy, a moderately declining and a severely declining tree were sampled. Fine-root length and nutrient status of each tree were analyzed, and the chemistry of the soil surrounding each tree was determined. The results showed that P. quercina can cause substantial reductions in the fine-root length of mature trees under natural conditions. The impact of the pathogen varied depending on tree vitality and season, being most pronounced for declining trees after an unusually dry summer. Despite the significant reduction in live fine-root length of declining trees in Phytophthora-infested stands, no consistent effects were found on the nutrient status of trees. Based on the significant impact of the pathogen on the fine-root systems of declining trees, we suggest that P. quercina contribute to oak decline in southern Sweden at the sites where it is present. No explanation is currently available for the decline of trees in non-infested stands, but the lack of symptoms of root damage indicate, together with the extensive root growth of declining trees, that root pathogens are not involved in the decline at these sites.

Long-term effects of ash and N fertilization on stand growth, tree nutrient status and soil chemistry in a Scots pine stand

The long-term effects of varying quantities and types of ash, given together with nitrogen, on stand growth, tree nutrient status and soil chemical properties were studied in a Scots pine ( Pinus sylvestris) stand on upland soil. The treatments were: unfertilized control (C), nitrogen (N), wood ash and nitrogen (WA + N), bark ash and nitrogen (BA + N) and peat ash and nitrogen (PA + N). The dose of nitrogen was similar (185 kg N ha −1 as urea) in all the fertilizer treatments. The ash doses were 1, 2.5 and 5 t ha −1. Urea was applied in autumn 1978, and ash in March 1979. The C and N treatments had six replicates, and the other treatments two. The amount of elements added in wood ash far exceeded those added in equivalent amounts of bark or peat ash. The resulting differences in soil chemical properties were mainly due to the amount of base cations added in the ash and not to the ash type. Only the treatment with the highest dose of wood ash produced significant changes in most of the soil chemical properties. The increase in humus layer pH given by this treatment was 2.1 pH units after 9 growing seasons, and 0.9 pH units after 23 growing seasons. The concentration of extractable Ca was six- and three-fold compared to the control after 9 and 23 growing seasons, respectively. There was a positive volume growth response to N added either alone or together with various types and doses of ash, during the first two periods (1978–1982 and 1983–1987) after the treatments. No positive response to the N treatment was subsequently detected. In contrast, during the third study period (1988–1998) 2.5 t ha −1 of wood ash given together with N resulted in a significantly higher volume growth than the control or N alone. A corresponding positive, although non-significant, growth response was also obtained with the other doses of wood ash and the highest dose of bark ash.

Tracing the Impact of Adverse Environmental Conditions on the Frost Sensitivity in Trees

The winter hardening of trees is genetically determined; the cellular chemical composition and structure are modified in reaction to cues from the length of daylight and ambient temperature. However, adverse environmental conditions can affect the timing of hardening and dehardening, concentration of cryoprotective compounds and cell membrane stability. The tree nutrient status, air pollutants, infestation of pest and pathogens and extreme weather events can thus increase the probability that the tree will be subjected to freezing temperatures when the hardiness level is not adequate. In this paper, the sensitivity to frost is related to the complex chain of cause and effect among environmental stress factors and to the overall tree vitality. This is discussed in the context of sustainable forestry in a changing climate.

Diagnosis and Recommendation Integrated System for Monitoring Nutrient Status of Mango Trees in Submountainous Area of Punjab, India

The Diagnosis and Recommendation Integrated System (DRIS) was used to identify nutrient status of mango fruit trees in Punjab, India. Standard norms established from the nutrient survey of mango fruit trees were 1.144, 0.126, 0.327, 2.587, 0.263, 0.141% for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S), and 15, 3.5, 145, 155, and 30 mg kg−1, respectively, for zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), and boron (B) in dry matter. On the basis of DRIS indices, 16, 15, 12, 17, and 16% of total samples collected during nutrients survey of mango trees were low in N, P, K, Ca, and Mg, respectively. For micronutrients, 19, 18, 12, 20, and 6% samples were inadequate in Zn, Cu, Fe, Mn, and B, respectively. DRIS‐derived sufficiency ranges from nutrient indexing survey were 0.92–1.37, 0.08–0.16, 0.21–0.44, 1.71–3.47, 0.15–0.37, and 0.09–0.19% for N, P, K, Ca, Mg, and S and 11–19, 1–6, 63–227, 87–223, and 16–44 mg kg−1 for Zn, Cu, Fe, Mn, and B, respectively.

A Survey of Fertility Practices, Soil Fertility Status, and Tree Nutrient Status on Eastern North Carolina Christmas Tree Farms

“Choose and cut” Christmas tree production is gaining popularity in North Carolina, as well as the Southeastern United States. There are few recommendations concerning the fertility of Christmas trees except for the large Fraser fir (Abies fraseri) industry in the Appalachian mountain region. Outside of the mountains, Virginia pine (Pinus virginiana), eastern white pine (Pinus strobus), red cedar (Juniperus virginiana), and Leyland cypress (X Cupressocyparis leylandii) are commonly grown as “choose and cut” trees. This study was conducted in the piedmont and coastal plain of North Carolina with the objectives to determine (1) the fertility practices currently being used and (2) the current soil and tissue nutrient status of “choose and cut” Christmas tree fields. A mail survey was used to accomplish the first objective. Twenty farms, selected from survey respondents, were sampled to determine current soil and tissue nutrient status. Soil samples were taken at three depths to 45 cm. Survey data indicated that a wide variety of fertilization materials and practices were being used. Spring applications were somewhat common, but actual time of application varied. Tissue and soil levels of nutrients also varied. There was a poor relationship between soil test nutrient levels and tissue nutrient levels, indicating the need for routine tissue analysis. This study indicated the need for future research and extension programs focusing on eastern Christmas tree fertility. In particular, the survey indicated that Leyland cypress, for which no specific soil fertility recommendations exist, is grown widely enough to merit recommendation development.

Leaf nutrient spatial variability and site-specific fertilization maps within olive ( Olea europaea L.) orchards

Spatial variability of leaf nutrients (N, P, K, B and Fe) in a 30 ha olive orchard located in southern Spain was examined in two consecutive years for determining their spatial distribution for the implementation of a site-specific fertilization programme. A regular 75 m×75 m sampling grid was established and intersection points (nodes) were georeferenced. Every sampling node was composed of an experimental unit of four nearest olive trees. Leaf samples were collected within every experimental unit. The leaf nutrients were analysed statistically and geostatistically. Based on the semivariograms, kriged estimates were used to draw contour maps for each leaf nutrient and to study the possibility of saving fertilizer recommendations. Positive correlations existed during both years between N and P ( r=0.8, P≤0.01), N and B ( r=0.48, P≤0.01), and P and B ( r=0.37 and 0.51 for 1999 and 2000, respectively, P≤0.01). Correlation between K with B was strong in 1999 ( r=0.54, P≤0.01), and not so strong in 2000 ( r=0.22, P≤0.05). Fe did not show any significant correlation during both years, except with K (−0.29, P≤0.05). Geostatisitcal analysis of leaf nutrients revealed that N had both strong and moderate patchy distribution depending on the year, whereas P, K and B had strong patchy distributions both years. Fe showed a lack of spatial dependence both years. Contour maps of each leaf nutrient achieved by kriging were used to estimate the percentage of farm surface needing fertilization where concentration of the respective nutrients did not exceed the fertilization threshold. The study revealed the necessity of determining spatial variability in nutrient status of olive trees before planning a differential fertilizer programme. A consistent saving in N, K and B fertilizers could be achieved in the studied olive orchard both years, for example only 3 and 17% of the surface should be fertilized with N in 1999 and 2000, respectively.

The nutrient status of Norway spruce in pure and in mixed-species stands

Atmospheric deposition of N and S appears to have caused nutrient imbalance in Norway spruce stands in southern Sweden. This calls for a change of forest management to procedures that promote nutrient balance. Studies have shown lower soil acidity in Norway spruce/deciduous mixed stands than in spruce monocultures, but the tree nutrient status in such mixtures has not been much investigated so far. The nutrient status of Norway spruce foliage and top mineral soil chemistry in monocultures and in stands mixed with beech, birch, or oak was investigated through paired comparisons on 30 sites in southern Sweden (27 sites) and eastern Denmark (three sites). In total, 45 mixed stands and 34 pure stands were included in the study. Spruce needles from mixed stands had higher concentrations and ratios to N of K, P, and Zn than needles from pure spruce stands. Among the mixed stands, the K status appeared to be positively correlated with the percentage of deciduous tree basal area. Soil samples from mixed stands had a higher Mg concentration, base saturation, and BC/Al ratio than soil samples from pure stands. The spruce needle nutrient status was comparable in pure stands on fertile sites and in mixed stands on poor sites. We did not detect any differences in spruce tree growth between pure and mixed stands. This paper discusses possible reasons for a positive effect on the tree nutrient status in mixed-species stands and the possibility of using mixed-species stands as a forest management procedure to avoid nutrient imbalance.

Soil properties and tree growth on rehabilitated forest landings in the interior cedar hemlock biogeoclimatic zone: British Columbia

We studied operational landing rehabilitation programs in three forest districts of interior British Columbia (BC). Winged subsoiling and grass/legume seeding, followed by planting of lodgepole pine ( Pinus contorta var. Latifolia) generally resulted in successful re-establishment of forest cover on landings. In the Boundary district, fifth year tree heights on landings were not significantly different from those in adjacent plantations, and fifth year growth increments were also similar despite evidence of delayed seedling establishment caused by cattle grazing damage. Trees on landings in the Kalum district were shorter than those in plantations, but fifth year increments were similar. Landings in the Kalum with >20% clay had lower stocking densities, tree heights, and probe depths compared to landings with <20% clay content. In the Kispiox district, average fifth year tree heights and fifth year increments were lower on landings than those on plantations. In the Kispiox district, landings with >20% clay content had shorter trees growing on them when compared to tree heights on landings with <20% clay. Landings in the Kispiox had the least probe depth of the three districts, and the greatest difference in height and increments between landings and plantations, supporting field reports of poor decompaction effectiveness there. In all districts, there was no forest floor present on landings 7 years after subsoiling, and cover of non-coniferous vegetation was lower than for plantations. Higher soil temperatures and lower soil moisture contents were recorded on landings relative to plantations in all districts during the growing season of 1998. Landing soils also had lower total C, N and mineralizable-N (min-N) than plantation soils in the Boundary and Kispiox, but such differences were not statistically significant in the Kalum. Reduced levels of total C, N and min-N on landings did not appear to have affected current foliar nutrient status of trees growing on these sites, as most nutrients appeared in concentrations considered adequate or only slightly deficient, except for foliar S on all sites. Average concentrations of N, P, K and S in foliage were either similar to or significantly higher for trees on landings relative to plantations, but these differences were attributed to dilution in plantation foliage rather than deficiency. Our results support the conclusion that operationally feasible techniques for soil rehabilitation can create conditions suitable for establishment of a new forest on sites that otherwise would be considered non-productive. Stocking levels and tree growth rates observed in our study are consistent with the conclusion that a commercial forest may be produced on some of the rehabilitated areas.

Comparative Growth Behaviour and Leaf Nutrient Status of Native Trees Planted on Mine Spoil With and Without Nutrient Amendment

The effect of nutrient amendment on growth of nine indigenous tree species planted on coal mine spoil was studied. Greater growth in fertilized plots was accompanied by greater foliar N and P concentrations in all species. The response to fertilization varied among species and was greater in non-leguminous than in leguminous species. Furthermore, leguminous species exhibited higher growth rates compared to non-leguminous species. The log-transformed height-diameter relationships were significant for all tree species and treatments. Acacia catechu, Dalbergia sissoo, Gmelina arborea and Azadirachta indica fitted the elastic similarity model of tree growth; whereas Pongamia pinnata and Phyllanthus emblica followed the constant stress model. Tectona grandis was the only species which fitted the geometric similarity model. In Albizia lebbeck and Terminalia bellirica, the b -values (the gradients of the log-transformed height to diameter relationships) were considerably lower (<0.5), and these two species did not fit any model of tree growth. In several cases, the b -values were considerably influenced by nutrient amendment. The log-transformed crown mass and trunk mass relationships were significant for all treatments and species. The slope of the crown mass:trunk mass relationship was near unity in A. indica, D. sissoo, G. arborea, P. emblica, P. pinnata, T. grandis, and T. bellirica. However, in A. catechu and A. lebbeck, this slope was well below unity suggesting a greater allocation to non-photosynthetic tissue. Fertilizer amendment resulted in a heavier crown relative to trunk in A. indica, T. grandis and T. bellirica.

Predicting Response of Southeast Texas Loblolly Pine to Fertilization

Abstract The Diagnosis and Recommendation Integrated System (DRIS), vector analysis, and critical level approaches are diagnostic tools commonly used for assessing nutrient status of trees by foliar analysis. This study evaluated the relative merits of the three approaches for identifying N and P deficiencies in stands of loblolly pine (Pinus taeda L.) in southeast Texas. Only 25% of the time did all three approaches select the same stands as N deficient, and only once did they agree that a stand was N sufficient. The three approaches agreed 25% of the time that stands were P deficient and 13% of the time that stands were P sufficient. No method was universally accurate in predicting response across soil groups. The critical level approach proved best for identifying all responsive sites, and it would be useful if the cost of fertilization was deemed low in comparison with the cost of lost growth when responsive sites are not fertilized. The DRIS approach failed to identify some responsive sites, but a high proportion of the sites it predicted would respond, did respond. It would be useful if the cost of fertilization were deemed high in comparison with the cost of lost growth when responsive sites are not fertilized. The vector analysis approach proved most useful because of its ability to predict response to N and P when added together. Soil group alone was a reasonable predictor of response to fertilization. South. J. Appl. For. 25(2):84–87.

Tree‐Ring Cation Response to Experimental Watershed Acidification in West Virginia and Maine

AbstractThe impact of experimental watershed acidfication on xylem cation chemistry was evaluated in eight tree species at two sites in West Virginia (Clover Run and Fernow) and one site in Maine (Bear Brook). All sites had received regular additions of (NH4)2SO4 equivalent to twice the ambient annual wet plus dry atmospheric deposition of N and S. Multiple wood cores were extracted from tree boles in five trees of each species on treatment and control areas at each site with increment borers. Cores were divided into several age segments and composited for each tree. Ground wood samples were destructively analyzed for Ca, Mg, Mn, and Al concentrations using inductively coupled plasma emission (ICP) methods. All tree species sampled at the two West Virginia sites exhibited significant Ca and/or Mg concentration decreases and Mn concentration increases in sapwood on the treated relative to control areas after 8 yr of treatment. At Bear Brook, tree‐ring concentrations in three species showed similar trends after 5 yr of treatment, but differences were generally not significant. Sapwood molar ratios of Ca/Mn and Mg/Mn were better indices to soil acidification than Ca/Al, due to low Al concentrations and insensitivity of sapwood Al concentrations to treatments. Overall, sapwood chemistry appeared to be a reliable indicator of the current nutrient status of trees; but, except for Japanese larch (Larix leptolepis Sieb. and Zucc.), sapwood chemistry did not preserve a record of the chronology of past changes due to treatments.

Rapid living crown reduction caused by Gremmeniella abietina affects foliar nutrient concentrations of Scots pine

SummaryThe foliar chemistry of diseased and healthy trees was studied one growing season after severe reduction in living crown caused by Gremmeniella abietina in four young Scots pine (Pinus sylvestris) stands. Sample trees were chosen pairwise on the basis of the living crown length: a diseased tree with about 50% live crown reduction and a healthy tree in each pair. Fifteen elements were determined in the youngest healthy needles on the lateral top shoots of each sample tree. Diseased trees had higher foliar boron, manganese and sodium concentrations and lower magnesium, iron, zinc, copper, potassium, nitrogen and sulphur concentrations compared to the healthy trees. Foliar calcium, aluminium, phosphorus, carbon and hydrogen concentrations did not differ between the diseased and healthy trees, except for P and A1 in two of the stands when the stands were analysed separately. Significant correlations between the needle element concentrations and crown ratio (length of the living crown/tree height) were found especially for B (increasing B with decreasing crown ratio) and for Mg, Fe and Zn (decreasing concentrations with decreasing crown ratio). The effect of G. abietina‐induced living crown reduction on tree nutrient status and the role of these mineral nutrients in the susceptibility are discussed.

カキ‘次郎’における着花数と樹体栄養との関係

The relationship between the nutrient status of Japanese persimmon trees cv Maekawa Jiro and the number of normal flowers and yield was studied. 1. The relationship between leaf soluble sugar in the June of the previous year and the number of normal flowers in the following spring was barely significant (r=0.48). No significant relationship existed between leaf N, starch, and soluble sugars on all other sampling dates and the number of flowers the following season. 2. A positive correlation existed between nitrogen content in 1-year-old wood and the number of normal flowers; a coefficient of correlation, r=0.57, was found between the number of normal flowers versus trunk cross-sectional area. Date for three years reveal that a small quantity of nitrogen is stored in the winter of the off-year. 3. A multiple regression equation reveal that the number of normal flowers is highly correlated with the nitrogen content in 1-year-old dormant wood and the leaf soluble sugar of the previous June. 4. Thus, we conclude that leaf carbohydrate content at the beginning of flower-bud initiation and the nitrogen level in 1-year-old wood about the time flowers are differentiating are important factors which determine the number and quality of flowers. 5. To obtain an optimum yield of good quality fruit annually in 'Maekawa Jiro', a leaf-fruit ratio of 40 is required, provided the nitrogen and carbohydrate levels are likewise optimum.

Fertilizer method and container size effects on shade trees grown in in-ground containers

Shade tree production in large, rigid, in-ground containers is a new nursery practice for which scientific data is lacking. The objective of this research was to study the effects of fertilizer and container size on production and nutrient status of shade trees grown in this manner. Whips of green ash (Fraxinus pennsylvanica Marsh), European birch (Betula pendula Roth.), thornless honey locust (Gleditsia triacanthos L. var. inermis Willd.), and hybrid poplar (Populus angulata Ait. × nigra L. var. plantierensis (Simon-Louis) Schneid.) were grown for two seasons (1991–1992) with a blended medium in 38-L and 76-L containers. Each container was placed in another container of equal size previously sunken into the ground Trees were trickle irrigated and fertilized with slow release (SR) or liquid (LIQ) fertilizer, or both (SR + LIQ). Poplar grew very rapidly, resulting in large roots escaping from the containers by September 1991, therefore, results for this species were excluded from the analysis. In both years, top dry weight and trunk diameter of the other three species were significantly greater for SR-treated than for LIQ or SR + LIQ-treated trees. Root dry weight was greater for SR-treated trees only in 1991. SR-treated trees also grew more than field-grown trees, planted within the experimental site as a baseline comparison. Trees grew larger in the 76-L containers than in the 38-L containers (1991 and 1992) or in the field (1991). Key words: In-ground containers, container growing, shade trees, ornamentals, slow release fertilizer, trickle irrigation, nutrition, foliar nutrients