Apple Seeds Research Articles

The Influence of Abscisic Acid on the Gibberellin Content in Apple Seeds During Stratification

The content of endogenous GA4 and GA7 was determined in apple embryos cultured either on water or in the presence of ABA solution. The embryos were isolated from dormant seeds and from seeds removed from stratification which was effected either in water or in the presence of ABA. The influence of ABA on the decrease of two GAs levels was proved. The relation between the effect of ABA and the stage of stratification is closer in the case of GA4 than GA7. It is assumed ABA to inhibit the gibberellin biosynthesis.

Effects of soil water suction, soil temperature, carbon and nitrogen amendments, and host rootlets on survival in soil of zoospores of Phytophthora cactorum

Zoospores of P. cactorum were added to air-dry soil and recovered periodically on soil-dilution plates. Such inoculum survived longer in relatively dry soil than in wet soil. Temperature at which soil was stored after infestation had little effect on persistence but survival tended to be longer at 10 °C than at 26.7 °C. Adding dextrose or sucrose, and ammonium sulfate, alone or together, had no appreciable effect on fungus survival. Addition of urea, 500 ppm N w/w air-dry soil, shortened considerably the period through which cysts were recovered on dilution plates. This effect was not obtained with urea 250 ppm N. Other common nitrogen fertilizers had no consistent effect on fungus survival. When sprouted apple seeds were planted in soil infested with zoospores, the number of propagules increased substantially and the fungus was recovered for several weeks longer from planted than from non-planted soil. Soil may be infested with P. cactorum more readily by using zoospores than by using other propagules.

Gibberellins and the photosensitivity of isolated embryos from non-stratified apple seeds

The phytochrome system is responsible for the photosensitivity of dormant, isolated apple embryos in culture. Maximum photosensitivity occurs on the second day of culture and it is unaffected by gibberellins (GAs) in concentrations below 10(-4)M. Higher concentrations of GA decrease the photosensitivity.The endogenous quantities of GA4 and GA7 were determined in embryos grown at white light, in darkness and in darkness following an exposure to red light. The GA7 level remained unaffected by the light conditions, whereas the amount of GA4 was three times higher in light or red-light-treated cultures than in the dark grown ones.Similar experiments were done using AMO-1618, an inhibitor of GA biosynthesis, which is also a strong inhibitor of apple seed germination. In this case the level of both GA4 and GA7 was light-independent. These experiments suggest that the phytochrome system participates in the regulation of GAs biosynthesis by mediating one of the last steps of GA4 formation.

Some growth responses of apple seedlings to abscisic acid and growth stimulators

Antonovka seedlings were obtained from the embryos soaked in abscisic acid (ABA) alone, gibberellin A4+7, benzyladenine or the mixtures of these regulators. The inhibitory effect of ABA on the growth of the seedlings was of temporary duration. The height of the 12 week-old seedlings was dependent only on the degree of seed after-ripening and not on the ABA treatment. The growth stimulators studied were unable to overcome the inhibitory effect of ABA observed in the early stages of seedling growth. The growth stimulators did not substitute, for cold treatment of apple seeds which is the only treatment so far known to overcome the dwarf conditions of the seedlings obtained from non-after-ripened embryos. ABA greatly suppressed the early stages of apple seedling growth (up to 6 weeks) during which they resembled physiological dwarfs. The highest concentrations of ABA (2·0 μg ml−1) greatly modified the root system of the seedlings, and produced a larger percentage of seedlings with unbranched roots.

Specific phloridzin glucosidases from seeds and leaves of apple tree

Five enzymatic fractions of β-glucosidase (EC 3.2.1.21) activity were found in stratified apple seeds. Differences in their substrate specificity towards some phenolic β-glucosides were stated. Some characteristics of the enzymes showing the highest and the lowest specificities towards phloridzin are reported. β-Glucosidases of apple tree seedlings were fractionated. In spite of the markedly pronounced specificity of leaves glucosidases towards phloridzin those enzymes were found to be different from the analogous enzymes from the apple seeds.

Shipping Cattle, Not Tropical Soda Apple Seed

This document is WEC 176, one of a series of the Wildlife Ecology and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date: May, 2003.

The isolation of estrone from apple seeds

The presence of estrone in apple seeds was demonstrated by TLC, gas chromatography, and the formation of the acetate derivative. The analyses per 100 g of Red Delicious ( Malus sylvestris) apple seeds revealed an average of 13·0 μg of estrone, and for MacIntosh ( Malus sylvestris) seeds, 10·1 μg of estrone.

Gibberellins and Other Growth Hormones in Apple Seeds

SummaryNew methods for the complete extraction of gibberellins and other hormones from freeze-dried seeds, and for the partial purification and resolution of the extracts on cellulose columns, are described.The presence of gibberellins A4 and A7 in developing apple seeds has been confirmed by thin-layer and gas-liquid chromatography. Bioassay of partially purified extracts in the lettuce hypocotyl test showed that gibberellins first appeared in the seeds about 5 weeks after full bloom, increased to a maximum concentration at 9 weeks and subsequently decreased again, disappearing completely by the time the seed was mature.The rapid build-up of gibberellins was preceded by the appearance of an unidentified hormone, highly active in the Avena mesocotyl assay, which reached its peak concentration 6 weeks after bloom. A second unidentified hormone with similar biological properties reached its highest concentration 13 weeks after bloom, at the time when gibberellins were fast disappearing.It is pointed out tha...

Studies on abscisic acid in apple seeds

Abscisic acid (AbA) was found to be present in non-stratified apple seeds. The evidence is based on chromatographic behaviour, fluorescence, UV-spectrum and growth inhibition in a wheat-coleoptile straight-growth test.The AbA level, as measured by this bioassay, falls considerably with progressing stratification; after 3 weeks of after-ripening no AbA could be detected in the seeds.The longer the period of stratification, the higher was the concentration of synthetic AbA necessary to inhibit germination.

Identification of cholesterol and progesterone in apple seeds

Cholesterol and progesterone were identified in apple seeds by the use of thin-layer and gas chromatography and the derivatives of the hormones. The analyses per 100 grams of apple seeds revealed an average of 385.0 μgrams of cholesterol and 50.0 μgrams of progesterone.

Apple Fruit-Set: Evidence for a Specific Role of Seeds

An extract of immature Wealthy apple seeds, containing substances with gibberellin activity, was applied to unpollinated blossoms of the same variety, resulting in the production of mature seedless fruits. The implications with respect to the normal process of fruit-set are discussed.

Identification of Gibberellins A4 and A7 in Immature Apple Seeds

FOR many years, plant physiologists have attempted to isolate and identify the growth substances which control plant growth. Many early attempts failed, largely because of the minute quantities of these compounds present in plants. Recently, microtechniques such as thin-layer chromatography have greatly stimulated interest in their identification.

GROWTH INHIBITION PRODUCED BY LEAF EXTRACTS FROM SIZE-CONTROLLING APPLE ROOTSTOCKS

Dilute alkali extracts of leaves from size-controlling rootstocks inhibited the growth of stratified apple seeds. Correlation coefficients of −0.9140** and −0.7292* exist between the vigor of the rootstocks and the respective growth of apple and wheat seedlings in the leaf extracts. The crude extract was chromatographed in isopropanol:ammonia:water (10:1:1). Two zones of growth inhibition were detected using a watercress bioassay. These zones were at 0 to 0.1 and 0.4 to 0.5 Rf units. The amount of growth made by the watercress was in the same ratio as the known vigor of the rootstocks M.II, M.VII, and M.IX. Measurement of the rate of indoleacetic acid oxidation showed that the material at an Rf 0.4 to 0.6 affected IAA breakdown. The more dwarfing rootstocks stimulated the oxidation of IAA. The significance of the results are discussed in relation to the dwarfing of apple rootstocks.

Study of the metabolism of exogenous tryptophane in the apple-tree and the estimation of bound tryptophane in apple and pear seeds

Seeds of apple and pear trees were found to contain 0-5–0-7% tryptophane expressed per dry weight. The hydrolyzate of the seeds contained tryptophane demonstrable microbiologically. Exogenous tryptophane applied to apple-tree shoots toward the end of the vegetation season gives rise to a new compound. Its RF in isopropanol : ammonia : water (10 : 1 : 1) was found to be 0.08, in butanol : acetic acid : water (4:1:5) 0.25.

Biology and Control of the Apple Seed Chalcid in North Carolina

Biology and Control of the Apple Seed Chalcid in North Carolina

The After-ripening of Dormant Apple Seeds in Relation to Auxin Content

1. Experiments were carried out to clarify the mechanism of after-ripening and germination of apple seeds from the viewpoint of natural growth substances. The apple veriety “Jonathan” was used for both germination and Avena tests. 2. Germination tests of intact seeds and excised embryos showed that embryos and intact seeds required about 35-day and 77-day stratifications, respectively, for maximum germination. 3. The embryo contained an unidentified acidic growth-promoter at the outset which increased rapidly as a result of stratification. The breaking of embryo dormancy apparently coincided with the increase in activity of this acidic growth-promoter. 4. A growth-promoter was found to occur in both stratified and non-stratified endosperm, but the production of the growth-promoter was much higher in stratified endosperm. The relationships between the production of growth-promoter in the endosperm, afer-ripening, and embryo germination is not clear. 5. Seedcoats were found to contain both a strong growth-inhibiting substance and a growth-promoting substance. During stratification the growth-inhibiting substance decreased and the growth-promoter increased. After 77-day stratification, ether extracts showed a striking promotion of the elongation of Avena coleoptile. Germ-inhibition was apparently dependent on the inhibitor, but the possible associations between after-ripening of the embryos and fluctuations in natural growth-substances in seedcoats is not clear.

SEED DORMANCY IN ROSA AS A FUNCTION OF CLIMATE

THE SEEDS of many plants are known to be dormant at maturity, and to require a period of exposure to low temperature to enable them to germinate under subsequent suitable conditions. In Rosa, and in several other rosaceous genera, this lowtemperature after-ripening is widely regarded as a fixed and characteristic prerequisite to further development of the embryonic plant. Joseph (1929) pointed out that rosaceous seeds require low temperature stratification to prepare them for germination. Haut (1938) found that apple, cherry, peach and pear seeds must be after-ripened before germination will occur. Crocker (1927) reported that seeds of temperate-zone roses germinate well only following a period at low temperature, and Crocker and Barton (1931) determined the after-ripening requirements of hybrid and species rose seeds, as well as those of several other rosaceous seeds. The ubiquitous nature of the low-temperature after-ripening requirement of rosaceous seeds is apparently unquestioned in recent literature, with the exception of a report by Calvino (1930) stating that hybrid rose seeds grown at San Remo, Italy, germinated readily with no prior low-temperature treatment. This report was accorded little significance, and the results were logically explained by Crocker and Barton (1931) by supposing that the seed were inadvertently exposed to winter temperatures sufficiently low and prolonged to allow afterripening to occur. More recently, however, there have been unpublished reports from southern France, and from some of the inland valleys of California, claiming successful germination of hybrid rose seed without resort to low-temperature treatment. These reports have been partially substantiated in this laboratory by the collection or import of seed from several localities, and in the course of the investigation it has become apparent that the dormancy of hybrid rose seed of a given genetic origin may vary widely from year to year, and from one region to another. The present paper deals with the quantitative aspect of the dormancy, and with the relationship between the dormancy and the pre-harvest climatic environment. MATERIALS AND METHODS.Temperature data were obtained in the experimental field from shielded maximum and minimum registering thermometers. Sunlight data were calculated from the Local Climatological Data of the U. S. Weather Bureau station at Portland, Oregon. This station is

The Apple Seed Chalcid, Its Distribution and Potentials as a Pest of Apples in North Carolina1

The Apple Seed Chalcid, Its Distribution and Potentials as a Pest of Apples in North Carolina1

Studies of Fruit Development in Relation to Plant Hormones: I. Hormone Production by the Developing Apple Seed in Relation to Fruit Drop

Measurements of the rate of fruit drop and the hormone content of the seeds, made at weekly intervals on three varieties of apple, have shown that periods of very active hormone production are invariably associated with periods of low fruit drop. On the basis of these and other observations, an hypothesis is proposed to account for the periodicity of fruit drop. It is suggested that, throughout its development, the fruit possesses an inherent tendency to separate from the spur but that, at certain periods, it is prevented from doing so by hormonal stimuli emanating from the developing seeds. Two such stimuli have been demonstrated, at 3–4 weeks and 7–10 weeks after petal-fall respectively, both of which are associated with particular developmental stages of the endosperm. In addition the existence of a third, as yet undetected stimulus at the time of fertilization, is postulated.

Growth-Inhibiting and Growth-Promoting Substances in Relation to the Dormancy and After-Ripening of Apple Seeds

Recent work has suggested that the dormancy shown by the seeds and buds of many temperate zone plants may be due to the action of specific growth-inhibiting substances The experiments described were designed to test this hypothesis, with particular reference to apple seeds which will not germinate until they have been after-ripened at a temperature just above freezing point for 60-70 days. Extracts made from different parts of the seed were tested by observing their effects on the growth of isolated sections of young oat coleoptiles under standardized conditions. These tests showed that the outer layers of freshly harvested apple seed do, in fact, contain relatively high concentrations of a growth-inhibiting substance, which disappears during the after-ripening process. Low temperature treatment, however, does not appear to be essential for the disappearance of the inhibitor, though it may be essential for the production of growth-promoting substances which appear in the embryo towards the end of the after-ripening process. In addition, it is suggested that moist conditions are necessary for the leaching out of growth-inhibiting substance from the seed coat.