No description available.

Changes in xylem embolism levels due to drought stress or freezing have been documented for a wide variety of plants. High degrees of tissue water stress which lead to increased levels of embolism are also often cited as factors negatively influencing plant establishment. Embolized xylem elements can potentially lead to restriction of stem water flow, thereby reducing growth. Therefore, this dissertation (5 experiments) was undertaken to determine if certain transplanting practices affect embolism dynamics and plant growth of selected urban tree species. Embolism was estimated based on reductions in hydraulic conductance of harvested stem segments. An initial experiment determined the length of time from tissue harvest to embolism measurement that stem samples may be held in cold storage. Results varied between Fraxinus americana L. (white ash) and Acer rubrum L. x saccharinum L. (hybrid red maple), but data suggested white ash stem samples should not be stored more than one day, especially for between-species comparisons. A greenhouse experiment investigated the growth and embolism levels for container-grown Corylus colurna L. (Turkish hazelnut) seedlings in response to root pruning. Increasing levels of root pruning from 25 to 50% increased embolism, although plant height also increased. There was no fertilizer level x root pruning interaction for embolism. A field-harvest and greenhouse growth experiment investigated the influence of cold storage duration on plant growth and pre- and post-transplant embolism levels. Embolism levels increased with duration of cold storage for Acer rubrum L. (red maple), but not for Crataegus phaenopyrum (L.f.) Medic. (Washington hawthorn). After 15 weeks of growth, however, embolism levels were similar for both species. Growth increased with increased cold storage duration for both species. A field experiment investigated the influence of transplant season and root pruning on plant growth and embolism of Turkish hazelnut and Syringa reticulata (Blume) Hara (tree lilac). Embolism levels just prior to budbreak and days to budbreak were highest for fall-transplanted Turkish hazelnut. Embolism level was unaffected by treatments. No clear relationship between embolism and growth could be determined for either species the first season after transplanting. Other fall-transplanted Turkish hazelnuts, however, had growth reductions that corresponded to increasing embolism levels two years after transplanting. An additional transplanting experiment examined the influence of root severance at transplanting on water relations of red maple. Stem sap flow (in vivo) was reduced within 2 h of harvest, and leaf stomatal conductance was reduced 4 h after harvest. Percent embolism (in vitro) was increased within 24 hr of harvest. Results of these experiments indicate that root pruning, and choice of transplant season can reduce plant growth and increase embolism levels. No clear relationship between embolism and growth reduction was evident. Although embolism dynamics are clearly impacted by transplanting, the implications for transplant success are inconclusive. The role of embolism in transplant success was not clear. / Ph. D.

No description available.

No description available.

No description available.

Transplanting is a common practice for many horticultural crops and some field crops. Recently, transplanted oilseed rape (Brassica napus L.) crops have been reported to be sensitive to zinc (Zn) deficiency. However, Zn nutrition in transplanted field crops has not been investigated in detail. The objectives of this present research were to investigate whether transplanting increases external Zn requirements of transplanted oilseed rape, and the mechanisms of root function, growth and Zn uptake after transplanting including rhizosphere modification capacity by plant roots. The second objective was to examine the relative effects of root pruning and transplanting on Zn responses of oilseed rape, and the third objective was to determine external and internal Zn requirements of transplanted oilseed rape for diagnosing and predicting Zn deficiency. An experiment on a low Zn sand (DTPA extractable Zn 0.14 mg kg-1) was set up to determine whether transplanted oilseed rape had a higher Zn requirement than that of direct-sown plants. Low Zn supply depressed shoot dry weight, however, root growth was relatively more strongly suppressed than shoots. Maximum root dry weight required much higher external Zn for transplanted plants compared to direct-sown plants, whilst shoot dry weight required a similarly low external Zn supply. In addition, transplanted plants were sensitive to zinc deficiency during the early post-transplanting growth, and the response weakened as the plants recovered from root injury or transplanting stress. However, the transplanted plants also experienced root pruning before transplanting and so in this experiment the higher Zn requirement could have been due to root pruning or transplanting or both. A further experiment was undertaken to determine the comparative external Zn requirements of direct-sown and transplanted plants in well-stirred chelate-buffered solution culture where a rhizosphere effect on plant availability of Zn forms is absent and the effects of poor root-soil contact on post-transplanting growth are minimized. In solution culture at the same level of Zn supplied, direct- sown plants produced higher shoot and root dry matter and greater root length than those of transplanted plants. However, since a higher external Zn requirement was found for transplanted plants in buffered solution culture than for direct- sown plants, it was concluded that the higher Zn requirement was not related to decreased rhizosphere modification, to greater demand for Zn or to poor root-solution contact, but rather to the time required for transplanted plants to recover from transplanting and root injury. The recovery of root function in solution culture was more rapid than that in soil culture and expressed as a higher Zn requirement for shoot as well as root growth. It suggested that the delay in root recovery in soil culture was due to slower absorption of Zn from the soil after transplanting than was the case in solution culture. Chelate-buffered nutrient solution culture and harvesting plants successively at 5 day intervals until 25 days after transplanting was used to examine the mechanisms of the recovery of root growth and function. In this experiment, the external Zn requirement of transplanted plants was investigated with unpruned or pruned root systems. Plants with unpruned root system and sufficient Zn supply exhibited faster recovery from transplanting than those with pruned root system plants. The results suggest that root pruning impaired Zn uptake by plant roots and slowed down the root and shoot growth after transplanting. Increased solution Zn partly alleviated the effects of root pruning and presumably this is a major reason why transplanted oilseed rape had a high external Zn requirement. However, root pruning also appeared to impair water uptake, and may have suppressed shoot growth through sequestering carbon for new root growth and through decreased phytohormone production by roots. Since rapid root recovery of transplanted plants is essential for successful of growth in the field, Zn application to the nursery bed was explored as a starter fertilizer to stimulate root growth after transplanting. The objective of this experiment was to determine whether increasing the seedbed Zn would stimulate new root growth of transplanted oilseed rape, and therefore would alleviate the need for increased external Zn for post-transplanting growth. Results showed that adequate Zn concentration in the seedbed promoted the post-transplanting growth by stimulating the new root growth especially increased root length, and also hastened the recovery of root systems. However, high Zn concentration at transplanting still had a more dominant effect in stimulating the new root growth of oilseed rape after transplanting. The final experiment was set up using rhizobags with three rates of Zn supply and unpruned or pruned root systems. The purpose of this study was to investigate the chemical change in the rhizosphere and non-rhizosphere or bulk soil and its relationship to the recovery of root function after transplanting, and also to identify and quantify the organic acids in soil extracts of direct-sown and transplanted plants. The rhizosphere soil pH was lower than that of non-rhizosphere soil, and the decrease of soil pH was suggested as the mechanism of the increase of Zn availability and mobility in the rhizosphere soil. Direct-sown plants were more efficient in utilizing Zn than those of transplanted plants especially compared to those of plants with pruned root system. Zinc deficient plants excreted higher concentration of organic acids particularly citric acid, suggesting this was a mechanism of Zn mobilization and Zn uptake by roots of oilseed rape. The main implications of the present study for the management of Zn nutrition of transplanted crops were: the need to increase the Zn application to crops in the nursery and at transplanting compared to direct-sown plants; the possibility that external requirements of other nutrients will be greater in transplanted crops also requires further consideration; and in cropping systems where transplanting is practised, greater attention should be given to the avoidance of root damage during the transplanting.

Three separate experiments were conducted to determine the influence of depth of transplanting on the size and shape of head of crisp-head lettuce. A hotbed experiment was conducted in the winter of 1950-1951. A greenhouse experiment was conducted in the spring and early summer of 1951. A final experiment, which was a modification of the other two, was conducted in the field in the early summer of 1951. The variety of lettuce used was Imperial 44 for all three experiments. The lettuce was seeded in a seed flat and transplanted to Bird-10 Vita-Bands 1 ½ inches by 1 ½ inches in size. The plants were then transplanted into the growing areas at shallow, medium, and deep transplanting depths. The hotbed and greenhouse experiments were inconclusive in their results but were of value in giving practice and growth information which made the field experiment more satisfactory in results. The results of the field experiment showed that deep transplanted lettuce produced heads more conical, more compact, and more curly leaved than lettuce transplanted medium or shallow. The core length of deep transplanted lettuce was shorter than the core of shallow or medium transplanted. The heads from all three transplanting depths were the same in height but were significantly different in width. Heads from the deep transplanted plants had the narrowest width and were definitely more concial than the shallow or medium transplanted. The heads from the three transplanting depths weighed the same, which indicated the deep transplanted heads were smaller because they were more firm. The shape of head was influenced by the added mechanical pressure of the soil around the plants. The compactness of head and conical shape of the deep transplanted plants appeared to be the result of soil pressure around the plant. Very compact heads, as observed on the deep treated plants, are undesirable where the lettuce is to be used as a garnish or in a sandwich because it is difficult to remove a leaf intact from such a head. The results of this experiment indicates that deep transplanting of crisp-head lettuce should be avoided, and that the more shallow the plants are transplanted the more desirable the size and shape of the heads will be. / Master of Science

Use of soil amendments at planting is one of the time-honored traditions in horticulture, although their effectiveness has been questioned by many. Recently, humate and humate-based products, generally known as biostimulants, have been marketed to increase transplant success. In this study, three experiments were conducted to examine the effects of soil amendments and biostimulants on post-transplant growth of landscape trees. The first experiment, conducted in a greenhouse, determined the effects of several biostimulant treatments (granular humate, water-soluble humate, liquid humate, liquid humate+ = humic acid, hormones, and vitamins) and fertilizer levels (low, medium, high) on the growth of container-grown Corylus colurna L. (Turkish hazelnut) seedlings. Biostimulants did not increase top growth compared to control treatments, but root growth was increased by granular humate at a medium fertilizer rate. The second experiment examined the effects of biostimulants (granular humate, water-soluble humate, liquid humate+) on the post-transplant root growth and sap-flow of landscape-sized balled and burlapped Acer rubrum L. (red maple) grown in root observation compartments (rhizotrons). Biostimulants did not increase root growth over control treatments, but sap-flow was increased. The third experiment, conducted in the field (Groseclose silt loam soil) investigated the effects of soil amendments (peat, and compost) and biostimulants (granular humate, and liquid humate+) on the post-transplant growth of Crataegus phaenopyrum (Blume) Hara (Washington hawthorn) and red maple transplanted bare-root, and grown under combinations of irrigated vs non-irrigated and fertilized-at-planting vs non-fertilized-at-planting regimes. Hawthorn controls generally had less top growth than the other soil treatments as a whole. No soil treatment was higher than control for top growth of red maple. However, root growth of red maple was highest in the peat-treated trees. Stem diameter and dry mass for the control and compost treatments were higher than the biostimulant treatments in irrigated plots, but no differences were observed in non-irrigated plots. Granular humate-treated trees resulted in higher stem diameter and dry mass than the liquid humate+-treated trees in non-irrigated plots. There were no effects of fertilizer, or irrigation on growth after two growing seasons for either species. / Master of Science

No description available.

Syftet med denna rapport är att sammanställa fakta kring hur åtgärder före och efter trädflytt kan påverka trädets etablering. Rapporten behandlar även vilken inverkan rotbeskärning har på träd och hur nybildning av rötter kan främjas. Rapporten besvarar frågor kring hur ett träd reagerar på att bli flyttat och hur trädart, växtplats och tidigare åtgärder kan påverka resultatet av en trädflytt. Rapporten besvarar även frågor angående vilka åtgärder som kan genomföras, innan och efter trädflytt, för att förbättra trädets etablering på sin nya växtplats, vilken inverkan rotbeskärning har på det flyttade trädet och hur nybildning av finrötter kan främjas. Rapporten är skriven som en traditionell akademisk rapport och är baserad på litteratur som har samlats in från vetenskapliga artiklar, böcker och uppslagsverk. Vid trädflytt förlorar ett träd stora delar, cirka 90 procent, av sitt rotsystem och drabbas av stressymptom. Ett friväxande, sådd i naturen och icke-rotbeskuret, träd kan förlora ännu större delar av sitt rotsystem. Det är viktigt att undersöka om det är ett plantskoleträd eller ett friväxande träd och även vilken trädart som ska flyttas då det kan ha betydelse för hur lyckad trädflytten blir. Genom att utföra rotbeskärning skapas ett kompakt rotsystem som ger en minskad rotförlust. Rotbeskärning främjar även tillväxten av finrötter i rotklumpen, vilket gynnar trädet vid etablering och ger minskad vattenstress. Ofta genomförs en kronreducering för att reducera obalansen mellan krona och rötter. En måttlig kronreducering, mellan 10 och 30 procent, kan gynna trädet. Om trädet ska kunna etablera sig och överleva flytten måste det övervinna stressymptomen. Om ett träd ska kunna bilda nya rötter och ha tillväxt av grenar och skott behöver trädet ha god vitalitet. Bevattning spelar en essentiell roll för trädets överlevnad och etablering. Mulch kan ge god tillväxt av finrötter och bidra till en förbättrad etablering. Rapportens slutsats är att både förberedande åtgärder och efterskötsel har inverkan på trädets etablering och hur väl trädet klarar av att bli flyttat. En korrekt genomförd rotbeskärning bör utföras, en måttlig kronbeskärning av 10-30 procent av kronan bör utföras, träd ska flyttas under sin viloperiod och träd som flyttas bör ha hög vitalitet. Nybildning av rötter främjas av god markfukt, varm jord, jämn bevattning och att mulch läggs på. / The purpose of this report was to put together facts regarding how the measures before and after tree transplanting can affect the establishment of the tree. The report also dealt with the impact that root pruning might have on trees and how regeneration of roots can be promoted. The report answers questions concerning how tree transplanting affects a tree and how tree species, locality and previous measures can influence the effect of a tree transplanting. The reports also answers a question concerning which measures could be performed, before and after tree transplanting, to improve the tree’s establishment in it’s new locality. The last question that this report answers is what impact root pruning has on the tree and how regeneration of fine roots can be favoured. The report is written as a traditional academic report and is based on literature that was collected from scientific articles, books and encyclopedias. A tree loses a large amount, approximately 90 percent, of its root system during the tree transplanting. This causes stress symptoms in the tree. A tree, sown and grown in nature, that has never been root pruned will lose even larger amounts of its root system when it’s transplanted. It’s important to do investigations before tree transplanting. Investigations should be done before tree transplanting to determine what kind of tree, nursery-grown or grown in nature, and what species is about to be transplanted. Both of these aspects may have an influence on how successful the transplanting is. Root pruning can make the root system more compact which reduces root loss during transplanting. Root pruning also increases the amount of fine roots in the root ball which is beneficent during establishment and also reduces water stress. The high amount of root loss causes an imbalance between crown and roots. The crown is often reduced to correct this imbalance and in this report it was proven that a moderate crown reduction is beneficial for the tree. The tree must overcome the stress symptoms to be able to survive and to establish itself. Trees need good vitality to be able to regenerate roots, shoots and branches. Irrigation plays an important part in the establishment and the survival of the tree. Mulch can promote regeneration of fine roots and contribute to an improved establishment. The conclusion of the report is that both preparatory measures and after care has an impact on the establishment and on how successful the transplanting of a tree will be. A correctly executed root pruning and a moderate crown pruning (10 to 30 percentage of the crown) should be carried out. Trees should be transplanted during their dormant season and trees, that are going to be transplanted, should have high vitality. Regeneration of roots is promoted by having good soil moisture, warm soil, even watering and applying mulch.