J. B. Drossopoulos

FLOWER ANALYSIS FOR PROGNOSIS OF NUTRITIONAL DYNAMICS OF ALMOND TREE

The nutritional fluctuations of almond tree leaves and fruits during their development have been studied to relate the fluctuated nutrient concentrations of these tissues to the nutritional status of flowers. Comparative monitoring for two years in an experimental orchard of almond trees (cv Texas) under integrated production management showed that the analysis of almond tree flowers could be used for the forecast of the elemental dynamics of leaves and fruits of this tree. The values proposed to interpret the elemental analysis of the flowers, under the conditions of this study are: nitrogen (N)=2.8% (± 0.5), phosphorus (P)=0.55% (± 0.10), potassium (K)=2.3% (± 0.2), calcium (Ca)=1.25% (± 0.25), magnesium (Mg)=0.45% (± 0.07), iron (Fe)= 125 ppm (± 25), copper (Cu)=40 ppm (± 8), zinc (Zn)=65 ppm (± 10), and manganese (Mn)=26 ppm (± 4).

DYNAMICS OF NITROGEN AND PHOSPHORUS PARTITION IN FOUR OLIVE TREE CULTIVARS DURING BUD DIFFERENTIATION

Variations of nitrogen and phosphorus levels in reproductive shoots and their leaves of self-rooting olive (Olea europaea) cultivars ‘Amfissis’ (A), ‘Kalamon’ (K), ‘Manzanillo’ (M), and ‘Chalkidikis’ (C) were monitored from the end of harvest until the emergence of the inflorescences. This 90-days period was divided into three sub-periods: before (pre-BD), during (BD), and after (post-BD) bud differentiation. The nitrogen (N)-content in leaves of the reproductive shoots varied between 10–20 mg g−1 and among cultivars the order of decreasing concentration levels was C > K > A > M. The N-content in reproductive shoots varied between 6–14 mg g−1 (K > A > C > M). Patterns of time-course variations are presented. Partitioning of N between leaves and shoots (NL:NS) varied with time, with a ratio between 1.5–2. The fluctuations in the NL:NS ratio over the 90 days showed two distinct phases: during pre-BD either increased (‘Amfissis’ and ‘Chalkidikis’) or remained relatively constant (‘Kalamon’ and ‘Manzanillo’), while during BD and post-BD decreased in all cultivars. The order of decreasing NL:NS ratio among cultivars was K > C > M > A. Phosphorus (P) content in leaves of the reproductive shoots varied between 0.1–2.5 mg g−1, (A > C > K > M). Phosphorus content in reproductive shoots varied between 0.2–1.6 mg g−1, with the highest levels in ‘Amfissis’ compared to the other cultivars. Patterns of P partitioning between leaves and shoots were similar in all cultivars. The PL:PS ratio varied between 0.9–2 (A > C > K > M). The N:P ratio varied between 5:1–20:1 in reproductive shoots and 10:1–35:1 in their leaves, increasing over the examined period. The increase rate of the N:P ratio varied between the three sub-periods, the lowest rate being during BD. The pattern of changes in the N:P ratio was similar in both leaves and shoots and an increase of N:P ratio in leaves was highly correlated with the corresponding increase of N:P in shoots.

Effect of vitamins and inorganic micronutrients on callus growth and somatic embryogenesis from young mature leaves of rose

Abstract The effect of different vitamins and inorganic micronutrients on callus growth and on the induction and proliferation of somatic embryos from young mature, fully expanded leaves of rose (Rosa hybrids L.) was investigated. Expiants were cultured onto a solid Murashige and Skoog (MS) medium supplemented with 3% (w/v) sucrose, 53.5 μM p‐chlorophenoxyacetic acid, 4.6 μM Kinetin, and 0.5 mg L−1 thiamin.HCI in combination with either of eleven different vitamins. Alternatively, expiants were cultured onto a solid medium containing MS macro‐ and micronutrients except for the salts of manganese (Mn), zinc (Zn), iodine (I), copper (Cu), and cobalt (Co), which were added at either the standard MS concentration or at a tenfold increased (Cu, Co) or decreased (Mn, Zn, I) concentration. Embryo maturation and germination took place on a MS medium supplemented with 5.2 μM 6‐benzyladenine and 5.7 μM 3‐indole‐acetic acid. The results indicated that somatic embryogenesis from rose leaves was favored by the addition of nicotinic acid and cystein to the culture medium and the increase of Cu concentration, without reducing embryo maturation and germination.

Effect of nitrogen fertilization on distribution profiles of selected macronutrients in oriental field‐grown tobacco plants

Abstract As nitrogen (N) fertilization is considered incompatible with oriental tobacco agricultural practice, we studied the influence of N fertilization [no fertilization or ammonium nitrate (NH4NO3) fertilizer applied at either 50 or 100 kg N ha‐1], the growth stage (plant age) and the stalk position (basal, middle, and upper) on the macronutrient phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) concentration distribution in leaves of the oriental tobacco cv. Myrodata Agriniou. The distribution profiles of leaf P showed an increasing trend from the lower to the upper nodes in all treatments during the vegetative stage up to the fruit set while almost uniform profiles were detected after that. Leaf K, Ca, and Mg accumulation profiles showed decreasing trends from the base to the top over the season. All of the examined macronutrients were accumulated in the lower leaves of the higher fertilized plants late in the season. Leaf dry matter accumulation increased by N fertilization and plant ...

The Effects of Light on Callus Growth and Somatic Embryogenesis from Lavandula vera and Teucrium chamaedrys: A Preliminary Study

SUMMARY In order to investigate the effect of light on the tissue culture of lavender (Lavandula vera L.) and wall germander (Teucrium chamaedrys L.), leaf explants from greenhouse-grown plants were inoculated on a Murashige and Skoog (MS) medium (1) supplemented with 1 mg L−1 2,4-D and 2 mg L−1 kinetin and incubated either (i) continuously in the darkness for 6 weeks or (ii) first in the darkness for 0–5 weeks and then under illumination (150 μmol mr−2 s−1, 16 hour light/8 hour dark photoperiod). Lavender callus growth was improved under increased incubation in darkness while somatic embryogenesis was remarkably reduced under the same conditions. Incubation in darkness did not affect the growth of wall germander cultures, but improved somatic embryogenesis. Moreover, a possible participation of boron in the effect of light on somatic embryogenesis for both species was indicated.

Distribution profiles of selected micronutrients in oriental field‐grown tobacco plants as affected by nitrogen fertilization

Abstract In an attempt to investigate nitrogen (N)‐fertilization which is considered incompatible with oriental tobacco agricultural practice, the influence of N‐fertilization (no fertilization or ammonium nitrate fertilizer applied at either 50 or 100 Kg N ha‐1) the growth stage (plant age) and the stalk position (basal, middle, and upper) on the micro‐nutrient concentration distribution in leaves of the oriental tobacco cv. Myrodata Agriniou was studied. All investigated factors affected, I) the leaf micro‐nutrients concentrations and leaf dry matter of field grown tobacco plants in the following order of decreasing strength: N‐fertilization level > growth stage > leaf position and ii) the stem micro‐nutrients concentrations and dry matter accumulation in the order: stalk position > growth stage > N‐fertilization level. Both N‐fertilization level and growth stage were positively correlated with dry matter accumulation, but negatively with zinc (Zn) and copper (Cu) accumulation. In addition, N‐fertilizat...

In vitro studies of ABA and ethephon induced abscission in olive organs

SummaryDetached reproductive shoots of olive (Olea europaea L. cv. Konservolia) were basally fed continuously with solutions of 25 ppm (0.10 mM) or 50 ppm (0.19 mM) abscisic acid (ABA) and 25 ppm (0.17 mM) or 50 ppm (0.32.mM) (2-chloroethyl)phosphonic acid (ET) individually or in combination, four weeks before full bloom. Leaf and flower abscission were counted along shoots at 24 h intervals over a 120 h period. A lag period of 72 h was needed for the first abscission of both organs in the control (water). By 120 h leaf abscission in control remained low (about 15%), although flower abscission was four-fold higher (about 60%). All treatments with growth regulators reduced the lag period for the first leaf and flower abscission to 48.h. Individual ABA or ET applications resulted in a very low leaf abscission at 48 h treatment. The effect was increased by increase in both concentration and application period, attaining maximum values after 120.h (60–95%). The combination of ABA and ET at both levels showed ...

Effect of Medium Composition and Explant Source on the Distribution Profiles Selected Micronutrients in Mistletoe Tissue Cultures

Abstract In order to study the pattern of in vitro accumulation of selected micronutrients in mistletoe (Viscum album L.) callus cultures, we inoculated leaf and stem explants on a Murashige and Skoog (MS) medium supplemented with different combinations of plant growth regulators at various concentrations. The accumulation of manganese (Mn), zinc (Zn), copper (Cu), and boron (B) in mistletoe callus cultures was significantly affected by both plant growth regulator (PGR) treatment and explant source, as well as their interaction. However, neither of these factors affected Fe accumulation in a statistically significant sense. The average concentration of iron (Fe), Mn, Zn, and Cu in vitro was higher in stem‐derived callus cultures than in leaf‐derived calli, and much higher than in mistletoe plants and in mistletoe hosts, such as fir, oak and chestnut. For stem‐derived calli and with the exception of B, application of 4.65 µM potassium (K) was superior to other PGR treatments leading to the maximum in vitro accumulation of the selected micronutrients. Except for B, the accumulation of micronutrients in stem‐derived callus cultures was highly correlated with dry weight concentration; a high positive correlation was also observed among Fe, Mn, Zn, and Cu concentration, while B accumulation was slightly negatively correlated with the other micronutrients. On the contrary, in leaf‐derived cultures, a high positive correlation was observed only between Mn and Cu concentration. The concentration of the selected micronutrients fluctuated during a total incubation period of 10 weeks on MS + 4.95 µM α‐naphthylacetic acid (NAA), with an increasing trend after the eighth week (B concentration being again an exception). Finally, the addition of ascorbic acid to the culture medium generally promoted micronutrient accumulation, in particular Mn and Cu in stem‐derived cultures and Fe, Zn, and B in leaf‐derived calli. This effect was correlated with an increase in total free phenolics substances, and further discussed in view of various plant antioxidant systems in vitro.

Studies on the Physiological Function of In Vitro Produced Antioxidants from Sage (Salvia officinalis L.): Effects on Cell Growth and Metabolism

SUMMARY We investigated the effect of antioxidant phenolic compounds produced by sage (Salvia officinalis) callus cultures on some physiological parameters of the producing cells. Although cultures demonstrated a continuous growth during an incubation period of five weeks, the cell dehydrogenase activity, the cytochrome c oxidase activity and the respiration of isolated mitochondria declined. An analysis of meth-anolic extracts derived from the callus pieces indicated that the accumulation of phenolic compounds was correlated with mitochondrial activity, although the antioxidant activity (Fe+2 reduction) of the extracts was independent from any other physiological parameter. These results might elucidate some aspects of the physiological function of in vitro produced phenolic antioxidants from sage.

Oxygen transport by Apium nodiflorum

Summary Apium nodiflorum is a partially submerged aquatic plant able to oxygenate its substrate. This work focuses on the elucidation of the process by which A. nodiflorum oxygenates the substrate, and whether this ability differs during ontogenesis. Young, mature and aged whole plants were examined for the pattern of their process. The contribution of the various plant organs to the increase of the dissolved oxygen concentration in the substrate under hypoxic conditions was also evaluated. Young, mature and aged plants required different amounts of oxygen. When facing hypoxia, young and mature plants elevated their substrate dissolved oxygen concentration. In contrast, aged plants oxygenated their substrate poorly. Changes in dissolved oxygen concentration, both under light and dark conditions, presented no statistical differences at any plant age. An internal oxygen transfer may take place within the plant, apparently without the release of oxygen into the substrate. Thus, it is the existence in petioles of an outer air transport pathway, similar to that of rice, that makes A. nodiflorum plants capable of facing hypoxic conditions in their substrate. This pathway is absent in stems. This fact explains the phenomenon of aged plants poorly oxygenating their substrate, since it is their stems that are inserted into the medium and not their petioles.