Initiation Of New Roots Research Articles

Metabolic changes in roots of trifoliate orange [Poncirus trifoliate (L.) Raf.] as induced by different treatments of boron deficiency and resupply

Boron (B) deficiency is one of the major abiotic stresses to citrus. Trifoliate orange, as the most important citrus rootstock in China, is sensitive to B deficiency. B deficiency has serious negative effects on metabolic processes in roots, but whether the hazardous effects can be alleviated to some degree with B resupply remains unclear. The purpose of this study was to investigate the effects of B resupply on metabolites and metabolic pathway in B-starved trifoliate orange [Poncirus trifoliate (L.) Raf.] roots. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the metabolic profiles in roots under different treatments of B deprivation and B resupply. B deficiency induced an obvious enlargement of root tips and significant alterations in metabolites. Changes were also observed in basic or neutral amino acids, several organic acids and carbohydrates of B-starved roots. However, one week of B resupply quickly reversed the changes in the roots with the initiation of new roots across the inflated root tips, and the restored some of metabolites to a normal level, such as proline (Pro), linoleic acid, 6-deoxy-D-glucose and myo-inositol, indicating that these metabolites are very sensitive to B availability. The data suggest that B resupply may contribute to the obvious, although not full, recovery of the root growth by reversing the central metabolite changes. This study provides a new insight into the relationship between root growth and the alteration on metabolites induced by B deficiency and B resupply, which can be expected to make an important contribution to the scientific application of B fertilizer.

Anatomical relations of root formation in strawberry

Anatomical relations of root formation are traced throughout the life cycle of the strawberry plant from the germinating seed up to the runners of the adult plant. Histological picture of the root changes a lot during the development of the plant. First the radicle of the germ grows to a main root, which makes branches into side roots and later adventitious roots are formed on the growing rootstock or rhizome. The anatomy of the different types of roots is also conspicuously different. First tiny branches appear relatively early after germination on the seedling's radicle, but soon the hypocotyl of the seedling thickens and develops side roots, which are already somewhat stronger. During this interval, the first true leaves are formed. The 4th or 5th of them being already tripartite, and the initiation of new roots extends into the epicotylar region of the shoot. The second years growth starts with the development of reproductive structures, inflorescences and runners starting from the axils of the new leaves. Near the tips of the runners below the small bunch of leaves, new root primordia are initiated. The tiny radicle of the germ develops a cortical region of 5-6 cell layers. Cells of the central cylinder are even smaller than the cortical parenchyma and include 3-4 xylem and 3-4 phloem elements as representatives of the conductive tissue. Roots originating from the shoot region are much more developed; their cortical zone contains 17-20 cell layers, whereas the central cylinder is about half as large. In the next year, new roots are formed at the base of the older leaves. These roots differ hardly from those of the last season in size and volume, however, they are recognised by colour and their position on the rhizome. The roots of the last year are dark, greyish-black, and grow on the lower third length of the rhizome, on the contrary, the new ones, on the upper region, are light brown. Roots starting from the shoot or rhizome are, independently from their age or sequence, mainly rather similar in size and diameter, thus being members of a homogenous root (homorhizous) system, i.e. without a main root. Plants developed and attained the reproductive phase develop in the axils of the leaves runners being plagiotropic, i.e. growing horizontally on the surface of the soil. The runners elongate intensely, become 150-200 mm, where some long internodes bear a bunch of small leaves and root primordia on short internodes and a growing tip. Runners do not stop growing, generally, further sections of 15-25 cm length are developed according to the same pattern, with small leaves on the tip. The growing tip of the runners is obliquely oriented, and small, conical root primordia are ready to start growing as soon as they touch the soil. The roots penetrate the soil, quickly, and pull, by contraction, the axis of the runner downwards, vertically, developing a new rhizome. The short internodes elongate a little and start developing adventitious roots. At the end of the growing season, the plantlets arisen on the rooted nods of runners are already similar to the original plants with homogenous root system. On the side of the adventitious roots, new branches (side-roots) are formed. The root-branches are thinner but their capillary zone is more developed being more active in uptake of water and nutrients. The usual thickening ensues later.

Anatomical relations of root formation in strawberry

Anatomical relations of root formation are traced throughout the life cycle of the strawberry plant from the germinating seed up to the runners of the adult plant. Histological picture of the root changes a lot during the development of the plant. First the radicle of the germ grows to a main root, which makes branches into side roots and later adventitious roots are formed on the growing rootstock or rhizome. The anatomy of the different types of roots is also conspicuously different. First tiny branches appear relatively early after germination on the seedling's radicle, but soon the hypocotyl of the seedling thickens and develops side roots, which are already somewhat stronger. During this interval, the first true leaves are formed. The 4th or 5th of them being already tripartite, and the initiation of new roots extends into the epicotylar region of the shoot. The second years growth starts with the development of reproductive structures, inflorescences and runners starting from the axils of the new leaves. Near the tips of the runners below the small bunch of leaves, new root primordia are initiated. The tiny radicle of the germ develops a cortical region of 5-6 cell layers. Cells of the central cylinder are even smaller than the cortical parenchyma and include 3-4 xylem and 3-4 phloem elements as representatives of the conductive tissue. Roots originating from the shoot region are much more developed; their cortical zone contains 17-20 cell layers, whereas the central cylinder is about half as large. In the next year, new roots are formed at the base of the older leaves. These roots differ hardly from those of the last season in size and volume, however, they are recognised by colour and their position on the rhizome. The roots of the last year are dark, greyish-black, and grow on the lower third length of the rhizome, on the contrary, the new ones, on the upper region, are light brown. Roots starting from the shoot or rhizome are, independently from their age or sequence, mainly rather similar in size and diameter, thus being members of a homogenous root (homorhizous) system, i.e. without a main root. Plants developed and attained the reproductive phase develop in the axils of the leaves runners being plagiotropic, i.e. growing horizontally on the surface of the soil. The runners elongate intensely, become 150-200 mm, where some long internodes bear a bunch of small leaves and root primordia on short internodes and a growing tip. Runners do not stop growing, generally, further sections of 15-25 cm length are developed according to the same pattern, with small leaves on the tip. The growing tip of the runners is obliquely oriented, and small, conical root primordia are ready to start growing as soon as they touch the soil. The roots penetrate the soil, quickly, and pull, by contraction, the axis of the runner downwards, vertically, developing a new rhizome. The short internodes elongate a little and start developing adventitious roots. At the end of the growing season, the plantlets arisen on the rooted nods of runners are already similar to the original plants with homogenous root system. On the side of the adventitious roots, new branches (side-roots) are formed. The root-branches are thinner but their capillary zone is more developed being more active in uptake of water and nutrients. The usual thickening ensues later.

Molecular identification of proline‐rich protein genes induced during root formation in grape (Vitis vinifera L.) stem cuttings

ABSTRACTVegetative reproduction relies on the initiation of new plant organs in response to environmental changes. The rapid formation of roots, and ultimately whole plants, from stem cuttings of grape (Vitis vinifera L.) provides a useful system to investigate the physiological and molecular basis of organ initiation during vegetative reproduction. In the present study the differential RNA display technique was employed to identify two genes, VvPRP1 and VvPRP2, that are induced in stem cuttings of grape during rooting. Each of these genes encodes a distinct type of proline‐rich protein that is related to different groups of putative cell wall proteins, and their expression is rapidly induced in stem segments within 6 h after severing. Further, each gene's transcript becomes most concentrated in the basal portion of the stem segment in the region of new root formation. Induction of these genes is not significantly enhanced by indole‐3‐acetic acid (IAA) treatment, and the expression of the VvPRP1 gene, but not the VvPRP2 gene, is wound‐inducible. These results suggest that these VvPRP genes play an important role in the initiation of new roots on grape stem cuttings, perhaps by altering the cell wall mechanical properties to enable root emergence.

Cloning and characterization of an actin depolymerizing factor gene from grape ( Vitis vinifera L.) expressed during rooting in stem cuttings

Vegetative propagation relies on the formation of new roots on cuttings. We investigated the molecular basis of this process by using differential RNA display to identify genes that are induced in stem cuttings of grape ( Vitis vinifera L.) during the rooting period. In this paper, one of these genes, VvADF, is characterized in detail. Based on sequence analyses, this gene encodes an actin depolymerizing factor (ADF) protein with significant identity to ADF proteins from various plant species. The VvADF gene is preferentially expressed in the roots and stems of grape plants, and its expression is rapidly induced in stem cuttings within 6 h after severing. Interestingly, the location of preferential VvADF expression shifts from the upper stem segment to the lower stem segment within the first 4 days. This corresponds to the location and timing of root emergence on the stem cuttings. Further, we found that cuttings treated with auxin (IAA) exhibited enhanced induction of VvADF during the first 48 h, suggesting that VvADF is an auxin-responsive gene during this period. The VvADF gene is weakly induced by wounding, but this does not contribute significantly to its increased expression in cuttings. These results suggest that the VvADF gene plays an important role in the initiation of new roots on grape stem cuttings, perhaps by modifying the organization of the actin cytoskeleton in cells that undergo changes in division or morphogenesis during root emergence.

Potential for enhancement of root growth and nodulation of soybean co-inoculated with Azospirillum and Bradyrhizobium in laboratory systems

The potential enhancement of root growth and nodulation in vegetable soybean (AGS190) was studied with application of Azospirillum brasilense (Sp7) and A. lipoferum (CCM3863) co-inoculated with two Bradyrhizobium japonicum strains (TAL102 and UPMR48). Significant root growth stimulation and nodulation were observed in Azospirillum as well as during its co-inoculation with Bradyrhizobium. Nodule formation is linked with the initiation of new roots; nodules were almost absent even in Bradyrhizobium inoculated plant due to the absence of new roots development in clipped rooted seedlings. Total root length, root number, specific root length, root dry matter, root hair development and shoot dry matter were significantly increased by Azospirillum alone and its co-inoculum. Co-inoculated plants significantly influenced the number of nodules and its fresh weight. A. brasilense seemed to perform better in root growth and nodule development compared to A. lipoferum.

Staining roots to determine root growth potential ofPinus taeda

SYNOPSIS Root growth potential (RGP) consists of two components: elongation of existing roots and initiation of new roots. Currently, RGP is determined on planting stock from which any “white roots” present at the start of the test are removed. This study compared RGP defined with an alternative staining technique for root marking and also determined the impact of staining on seedling performance after planting in the field. Staining of roots with neutral red, safranin-O, or methylene blue allowed for easy identification of the new roots during indoor root growth potential studies or field experiments. Roots are marked best by dipping in a 1% water solution of methylene blue for 15 seconds, removal of excess stain by placing roots within moist paper towels for 10 minutes, and then rinsing under running water for 1 minute. Results obtained using a stain to initially mark roots prior to RGP tests indicate that measurements of roots using the destructive method may result in an underestimation of new root growth.

Auxin Applications Affect Posttransplant CO2 Exchange Rate and Growth of Bare-rooted Vinca [Catharanthus roseus (L.) G. Don] Seedlings

Uprooting and transplanting seedlings can cause root damage, which may reduce water and nutrient uptake. Initiation of new roots and rapid elongation of existing roots may help minimize the negative effects of transplant shock. In this study, seedlings with four true leaves were transplanted into diatomaceous earth and the plants were transferred to a growth chamber, where they were treated with NAA (0, 0.025, 0.25, and 2.5 mg·L-1; 36 mL/plant). The effects of drenches with various amounts of 1-naphthaleneacetic acid (NAA) on the posttransplant CO2 exchange rate of vinca [Catharanthus roseus (L.) G. Don] were quantified. Whole-plant CO2 exchange rate of the plants was measured once every 20 minutes for a 28 day period. Seedlings treated with 0.025 or 0.25 mg·L-1 recovered from transplant shock more quickly than plants in the 0 and 2.5 mg·L-1 treatments. Naphthaleneacetic acid drenches containing 0.025 or 0.25 mg·L-1 increased whole-plant net photosynthesis (Pnet) from 10 days, dark respiration (Rdark) from 12 days, and carbon use efficiency (CUE) from 11 days after transplanting until the end of the experiment. The increase in CUE seems to have been the result of the larger size of the plants in these two treatments, and thus an indirect effect of the NAA applications. These differences in CO2 metabolism among the treatments resulted in a 46% dry mass increase in the 0.025 mg·L-1 treatment compared to the control, but shoot-root ratio was not affected. The highest rate of NAA (2.5 mg·L-1) was slightly phytotoxic and reduced the growth rate of the plants.

Pin Cherry Sucker Regeneration After Cutting

Abstract Root suckers arising after cutting 10 yr old pin cherry in eastern Quebec were studied. Most suckers emerged during the first 2 yr and only a small proportion emerged after 3 or 4 yr. The number of suckers forming a clone was highly variable and was probably influenced by the degree of interspecific competition affecting this shade-intolerant species. No clonal variations were observed in the diameter of parent roots producing suckers, or in the initiation of new roots around the base of suckers up to 5 yr old. Annual growth of sucker basal diameter differed among clones and also within a clone. The oldest suckers had the greatest rates of basal growth. Results from this study indicate that cutting will not prove effective as a mean for controlling pin cherry during cleaning treatments, but will help to maintain dense pin cherry browse for white-tailed deer or moose. North. J. Appl. For. 14(3):117-119.

Evaluation of root mortality by biochemical analysis

Abstract The development and turnover of root systems is a dynamic process. Continuous initiation of new roots and the senescence of others occur simultaneously. Dead root skeletons persist in soil, are difficult to identify by visual examination, and throw much uncertainty on root evaluation by optical counting. In contrast, actively metabolizing constituents such as root protein, enzymes and coenzymes are know to decay very rapidly in senescing roots and provide therefore a potential as indicators of root viability. From this background, root length, phosphorus (P) uptake per unit root as well as biochemical root constituents were studied in pot experiments with maize as dependent on plant age. Root dry weight and root length increased considerably with root age. In contrast to this, the P uptake rate together with protein nitrogen (N), ATP and phosphatase activity decreased with root aging. Phosphorus uptake rate and root protein showed similar patterns of change, suggesting that protein N may be promising as an index of root activity.

Growth Dynamics of the Cotton Plant during Water‐Deficit Stress

AbstractInformation on the differential growth response of roots and shoots to water‐deficit stress will better describe root growth within the soil for purposes of modeling plant growth and assessment of drought resistant traits. Our aim was to investigate leaf expansion and changes in root elongation for field and growth‐chamber cotton (Gossypium hirsutum L.) during drought. Plants were grown in rhizotron containers and subjected to 6 d of water‐deficit stress followed by 6 d of recovery and compared with a well‐watered control. The stress period commenced when the plants were 55 to 65 d old. Leaf expansion was more sensitive to stress than root elongation, with curtailed growth after 2 d of withholding water compared with 6 d with roots. Stress reduced root elongation and root volume. About 85% of visible roots showed elongation growth under conditions of adequate water, which was reduced by stress to 50%. Small (0.30 mm mean diam.) roots were more abundant and gave the greatest cumulative length, but grew less on a mean length basis than medium roots (0.62 mm mean diam.). The rate of root growth increased during recovery, consisting of regrowth from stalled roots and followed later by initiation of new roots. Medium roots contributed the most to root volume initiated during recovery. Most growth for both root sizes occurred in the lower zone of the soil, where water was more available. Root size and position of roots within the soil profile are important factors to consider when studying root growth response to water‐deficit stress.

SOIL TEMPERATURE AND ROOT GROWTH

Soil temperature affects both the rate and thoroughness with which a plant root system permeates soil. Root system expansion is a function of two temperature-dependent processes, growth and development. Growth processes, like cell elongation, increase root length and diameter. Development controls duration of growth and initiation of new roots and reproductive organs. Interpreting root temperature responses requires an understanding of how development and growth interact. Soil temperature affects growth of root system components, initiation and branching, orientation and direction of growth, and root turnover. Genotypic differences in root response to soil temperature exist between and within plant species. In natural soil profiles, root system expansion is affected by seasonal patterns of soil temperature. As soil warming advances downward, progressively deeper soil layers become suitable for root growth. In temperate regions, soil temperature often limits the rate of rooting-depth increase and the maximum depth attainable. A simple temperature-based model to predict rooting depth with time indicates that rooting depth may follow the downward progression of a particular isotherm, which has sometimes been observed in the field.

The effects of drought and subsequent rehydration on the structure and vitality of Zea mays seedling roots

Drought was induced in Turface and vermiculite-grown seedlings of Zea mays L. by withholding water. Despite a 34-day drought period, the roots of stressed plants increased in dry weight by continued elongation of existing roots and initiation of new roots. A differential response to desiccation, with respect to structure and cell vitality, was observed along the root axes. In apical regions (terminal 20 mm) of seminal roots, all cell layers typically remained alive. In midlength regions (half way between the apex and base), the epidermis died in both control and treatment plants. The cortex of control roots displayed some distortion, but most of the cells were alive; the cortex of stressed roots displayed severe collapse and death of the majority of these cells. In basal regions (20 mm distal to the kernel), cells of the outer cortex were sclerified and less susceptible to collapse. Cells of stelar tissues retained their normal shapes and vitality. Upon rehydration, the root systems of stressed plants resumed growth by elongation of existing seminal, adventitious, and lateral roots and, in some cases, also by emergence of previously dormant lateral root primordia. The root systems' capacity for recovery diminished with increasing stress. Key words: drought, roots, Zea mays L., exodermis, hypodermis.

ウンシュウミカンの花芽分化に及ぼす環状はく皮と温度条件

The effects of ringing with or without hand defoliation on vegetative growth, flower bud differentiation, and physiological changes in young, container-grown satsuma mandarin (cv.Okitsu Wase) on trifoliate orange were investigated. Comparisons were made between trees grown under different temperatures in a growth chamber and those grown in the field. A ring of bark, 3 mm wide was removed 5 cm above the bud union. The wound was wrapped with a vinyl tape to prevent drying and to enhance callus development.1. Ringing in mid-June, after the spring growth flush ceased root growth within several days. After the ringing wound healed, new roots developed but the onset of the summer flush was delayed and shoot growth was depressed. Ringing in early September, after the summer flush stopped, not only depressed root growth, but it also prevented the initiation of new roots even though the girdles callused over. The absence of new roots is attributed to the lower air temperature in autumn. The autumn flush of new growth did not occur on treated trees.2. Potted trees were ringed in either mid-June, late July, or mid-September. Ringed and non-ringed trees were defoliated, and then transferred to a 25°C growth chamber at intervals of 1.5 months. Number of flowers and vegetative shoots which emerged after defoliation was observed. Defoliation in mid-June of non-ringed control trees required new growth over 10 days. When trees were defoliated in late July, bud break occurred within several days.However, trees required more days again in mid-September, and the maximum of 20 days in late October for bud break after defoliation. Trees ringed in mid-June and defoliated in late July, mid-September, or late October required 15, 9, and 17 days, respectively, to initiate regrowth. Ringed trees in July or September caused regrowth similar to that of non-ringed trees. Trees defoliated in early December, girdled in July or September, and held at 25°C produced many flowers, whereas those ringed in June produced few flowers.3. Trees, ringed on 1 September, and non-ringed trees were held at 15°, 20°, and 25°C in growth chambers or planted in the open field. The girdle produced more callus and healed faster at 25°C than at 20°C; no callus formed at 15°C. When trees at 25°C were defoliated in early December and kept at the same temperatures, bud break was delayed compared to those which were transferred to lower temperatures. Non-ringed trees held at 25°C produced few flowers, whereas ringed trees bloomed profusely. With or without girdles, trees kept at 15° and 20°C produced many flower buds; girdled trees kept at all temperatures had more flowers per sprouting node than did non-girdled ones.4. Analysis of leaves from non-girdled trees growing in the field and from those girdled on 1 September revealed that the sugar content in all samples increased in autumn. The in-crease is attributed to the low air temperatures. After ringing, leaf starch content increased to over 20% (dry weight basis) and then decreased. Nitrogen content decreased linearly until the wound callused over and then the level increased. The C/N ratio increased until the wound healed and then decreased. Transpiration resistance of the leaves was temporarily greater on ringed trees; the upward movement of the transpiration stream was, therefore, slower until the girdle healed.

Effects of Flooding of Soll on Growth, Stem Anatomy, and Ethylene Production of Thuja Orientalis Seedlings·

Flooding of soil for 66 days decreased the rate of dry weight increment and induced stem hypertrophy and abnormal cambial growth in 3-year-old Thuja orientalis seedlings. The rate of dry weight increase of seedlings was reduced largely because of root decay and a decrease in root growth and in initiation of new roots. Diameters of the submerged portions of stems increased as a result of accelerated growth of bark as weil as xylem increment. stem diameters also increased above the water level but alm ost en tirely because of an increase in tracheid production. The xylem of submerged portions of stems was characterised by wide variations in tracheid size (with many largediameter tracheids), lack of arrangement of tracheids in orderly radial rows, and an increased number of xylem rays and large ray cells. Flooding also stimulated ethylene production in stems but did not affect formation of resin ducts in the bark and did not induce formation of compression wood. Ethylene appeared to play a role in regulating cambial growth of flooded plants.

Influence of Genotype and Mineral Nutrition on the Distribution of Growth within Plants of Lolium perenne L. grown in Soil

Genotypes of Lolium perenne were grown with two levels of fertilizer application. Using exponential growth-rates and parameters derived from them, the rate of growth of each genotype was partitioned into the rates of initiation of new roots and tillers, and the growth of the individual roots and tillers after initiation. The growth of the individual roots was further analysed by measuring changes in diameter and length of the main root, and the growth in the branches of the main root. The genotypes varied in their response to additional mineral nutrition. The greater the increase in the rate of shoot growth for a genotype, the greater was its increase in the rate of tiller initiation, the smaller was the increase in the size of its tillers, and the greater was the decrease in its rate of root relative to shoot growth. Within a population of genotypes growing with the same level of mineral nutrition, the greater the rate of shoot growth of a genotype, the greater was the rate of initiation of new tillers and, at a low level of mineral nutrition, the smaller the size of tillers. With a higher level of mineral nutrition, the higher the rate of tiller production, the smaller or larger was tiller size, depending upon environmental factors other than mineral nutrition. At both levels of mineral nutrition, the greater the rate of shoot growth, the smaller was the rate of root growth relative to shoot growth, due to relatively less growth taking place in the branches of the main root.

Effects of Plant-Growth Regulators on Shoot Development and Field Survival of Forest-Tree Seedlings

1. A series of seven experiments, conducted between October, 1942, and October, 1943, involving about 25,000 individual trees and several hundred feet of nursery bed, was undertaken to survey several potential applications to forest-planting practice of the control of top development of seedlings by means of growth regulators. Seedlings of red, loblolly, shortleaf, pitch, and table-mountain pines, red spruce, tuliptree, and white ash were treated in the nursery bed, before storage or before planting. Napthaleneacetic acid, naphthalenemethylacetate, napthalene acetamide, and mixtures of naphthalene compounds with or without indolebutyric acid were applied in various ways. Methods included dipping, soaking, or spraying with water solutions and carrier emulsions of lanolin or commercial wax, and exposure to vapors of the compounds. 2. Nursery-bed treatments were applied for purposes of prolonging dormancy and restricting the amount of shoot growth. The normal surge of leader growth of pine seedlings was not delayed or substantially lessened by concentrations of 200 or 600 mg./l., sprayed on the expanding buds and old foliage. Needle development, once started, could be completely arrested shortly after treatment and "frozen" for the remainder of the season on red and table-mountain pines. Undesirable curving of the new leaders resulted after treatment of table-mountain pine but not of red pine. 3. At the end of the growing season, red pine seedlings which had been sprayed in May with 600 mg./l. naphthalene acetamide had somewhat lower top-root ratio and much lower average dry weight than untreated seedlings. Inhibiting treatments were close to the lethal concentration, for they occasionally killed some of the trees. More than one application during the period of shoot growth of a spray containing 600 mg./l. naphthaleneacetic acid or similar growth regulators resulted in death of most of the seedlings. 4. Red pine seedlings having only one-half to one-third the normal quantity of new foliage, as a result of inhibition by growth regulators, were no more resistant to artificial drought than untreated seedlings. Top pruning of loblolly pine during early spring resulted in significant decrease in resistance to artificial drought and to transplanting during the same summer and therefore did not appear to be a desirable alternative to growth regulators for checking top growth in nursery beds. 5. Vapors and sprays of naphthalenemethylacetate and a mixture of growth regulators were effective in preventing or restricting the development of etiolated shoots of white ash seedlings held until June in unrefrigerated storage. These treatments also stimulated initiation of new roots, but a high proportion of the new roots appeared on the stem. Inhibition of shoots and stimulation of roots were much less distinct in treated trees heeled-in outdoors. Pre-storage treatments with growth regulators did not affect the survival of white ash seedlings planted in May when controls were still largely dormant, but they resulted in higher initial survival and greater root growth of trees planted in June. 6. For 2-year-old seedlings of white ash, a successful pre-storage treatment was naphthalenemethylacetate applied as vapor (0.3 or 0.5 mg./cu. ft. of space for 18 hours at 70⚬ F.) or as a spray (100 mg./l. in dilute commercial-wax emulsion). Similar pre-storage treatments did not improve survival of loblolly or short-leaf pine seedlings. 7. Growth regulators were also applied just before planting in an attempt to improve initial survival by holding back top growth and transpiration while the roots become established. Pre-planting treatments were applied to tops of seedlings of red, shortleaf, and loblolly pines, and to roots, tops, and whole plants of red spruce and tuliptree. Various treatments with 80-1000 mg./l. naphthaleneacetic acid and other compounds failed to improve the field survival of conifers, and usually lowered it. 8. Seedlings of tuliptree dipped in emulsions containing 200 or 400 mg./l. of a mixture of growth regulators just before planting in the spring leafed out more slowly than untreated trees. However, survival was so uniformly high for all treatment groups (planted in May) that no advantage resulted from the prolonged dormancy. Tuliptree seedlings treated with growth regulators showed slight stimulation of root growth in the heeling-in bed and excelled controls in total dry weight by the end of the first season in the plantation. 9. Application of emulsions of lanolin (30-50 gm./l.) or commercial wax to foliage of conifers immediately before planting resulted in higher survival during the spring months. After a long and severe summer drought (1943), the survival of coated seedlings exceeded that of controls in some plantations but not in others.