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  • Author or Editor: George C. Martin x
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Abstract

3-CPA when applied to peach moves slowly, accumulating in the margins and veins of leaves, and the epidermal and sub-epidermal layers in the fruit and the micropylar end of the ovule. Equal degrees of fruit thinning resulted when fruit or leaves alone were treated with 3-CPA. Treating both leaves and fruit resulted in an additive thinning effect. Uniform spray coverage is emphasized to obtain uniform thinning results.

Open Access

Abstract

Embryo germination of olive (oleo europaea L.) was inhibited by 10 ppm abscisic acid (ABA); no embryo germination effects were found with treatment of gibberellins (GA3 or GA4+7) or 6-benzylamino purine (BA). Whole seed germination was reduced by 100 ppm GA3. Only ABA was found in extracts of olive seed tissues. Young developing embryos contained up to 600 ng/g fresh weight ABA which declined to nondetectable amounts at seed maturity. ABA was not detected in endosperm plus seedcoat until seed maturity, then at 8 ng/g dry weight. In early stratification, no ABA could be detected in any seed tissues. It seemed evident that embryo tissues were more sensitive to ABA as seed maturity approached, and by then seed germination may be prevented by ABA at 8 ng/g dry weight found in endosperm and seedcoat.

Open Access

Abstract

The determination of sugars and sugar alcohols in horticultural crops is time-consuming and often difficult because of interfering substances. The quantitative deteimination of the individual sugars in a sample has until recently been very difficult. The work of Sweeley and co-workers (2), on the formation and subsequent gas chromatography of trimethylsilyl (TMS) ether derivatives of carbohydrates and related polyhydroxy compounds, has made it possible to determine individual sugars quantitatively.

Open Access

Xenia and metaxenia are phenomena dealing with the effects that pollen from different sources have on certain characteristics exhibited by seeds and fruits in a variety of species. A review of dictionaries, textbooks, and the scientific literature reveals that there is widespread confusion with regard to the nature of these phenomena and how they are to be distinguished. This discussion will attempt to clarify the boundary between these related phenomena by examining both the origins of the terms and our present understanding of the metabolism and anatomy involved. From this perspective, we contend that xenia applies to pollen effects as exhibited in the syngamous parts of ovules, that is, the embryo and endosperm only. Metaxenia applies to such effects found in any structure beyond the embryo and endosperm, this is, in tissues which derive wholly from mother plant material. Metaxenia then encompasses effects found in seed parts such as the nucellus and testa as well as those found in carpels and accessory tissue.

Free access

Xenia and metaxenia are phenomena dealing with the effects that pollen from different sources have on certain characteristics exhibited by seeds and fruits in a variety of species. A review of dictionaries, textbooks, and the scientific literature reveals that there is widespread confusion with regard to the nature of these phenomena and how they are to be distinguished. This discussion will attempt to clarify the boundary between these related phenomena by examining both the origins of the terms and our present understanding of the metabolism and anatomy involved. From this perspective, we contend that xenia applies to pollen effects as exhibited in the syngamous parts of ovules, that is, the embryo and endosperm only. Metaxenia applies to such effects found in any structure beyond the embryo and endosperm, this is, in tissues which derive wholly from mother plant material. Metaxenia then encompasses effects found in seed parts such as the nucellus and testa as well as those found in carpels and accessory tissue.

Free access

Abstract

Spur buds of apricot were sampled at intervals from late July, 1968, until bloom in 1969, and from 1 month after bloom until the end of September. The samples were freeze-dried and then extracted with 80% methanol. The extracts were partitioned into 4 phases: water, neutral ethyl acetate, acidic ether, and acidic butanol, and then bioassayed for auxins, inhibitors and gibberellins. Although an inhibitor and gibberellin-like activity were present in the extracts, no consistent auxin-type activity was found. The end of rest was correlated with a decrease in the level of inhibitor and gibberellin-like activity, with the inhibitor increasing again towards anthesis. The onset of rest in May, 1969, was correlated with a decrease in inhibitor and increase in gibberellin-like activity. The inhibitor was present in scales and floral parts of buds, while gibberellin-like activity was confined mainly to the floral parts.

Open Access

Abstract

A sample of freeze-dried apricot buds collected during December, 1968, and January, 1969, was extracted with 80% methanol. The extract was partitioned into 3 phases: water, neutral acetate, and acidic ether. The acidic ether phase contained most of the inhibitor that was present in the methanolic extract. Thus, further purification and identification was done with this fraction exclusively.

The similarity of Rf values of abscisic acid and of the apricot bud inhibitor when TL-cochromatographed using 10 different solvent systems, the equal retention times of their methylated derivatives when gas chromatographed, the congruency of their ultraviolet light spectra, and their inhibition of growth of apricot seedlings indicate that the apricot bud inhibitor is similar, if not identical, to abscisic acid.

Open Access

Abstract

Fruit-bearing olive (Olea europaea L.) shoots were exposed to more than 100 ethylene (C2H4) treatments to determine if C2H4-induced abscission varied between leaves and fruits in response to manipulation of treatment concentration, duration, and total amount of exogenous C2H4. Nearly three-quarters of the treatments induced greater fruit abscission than leaf abscission on a percentage basis. The potential for optimization of C2H4-induced fruit abscission relative to leaf abscission was examined by calculating the fruit-to-Ieaf (F:L) abscission ratio. Of the treatments inducing at least 75% fruit abscission, the dose range of 150 to 370 μmol C2H4 gave ratios up to 13.3; however, results were highly variable and closely dependent on the interaction of concentration and duration. Response surfaces were created to depict this interaction. Desirable levels of fruit abscission occurred at durations > 30 hr and concentrations > 2 to 3 μl·liter−1. However, excessive leaf abscission occurred at durations of 24 to 48 hr, depending on concentration. Acceptable F:L ratios were found for about 30% of the surface, with the highest ratios occurring for treatments of 3 to 5 μl·liter−1 for 28 to 34 hr.

Open Access

Abstract

The presence of gibberellin A29 (GA29) in extracts of pericarp of immature prune, was established by combined gas chromatography-mass spectrometry (GC-MS). Another gibberellin (GA) in the extract was determined by GC-MS to be a di-hydroxy A9 derivative different from any of the 46 GAs of known structure. An inhibitor of wheat coleoptile elongation present in pericarp and seeds was tentatively identified as abscisic acid (ABA), based on Rf values on thin-layer chromatograms (TLC) and retention times of the methyl ester on gas liquid chromatographic (GLC) columns.

Open Access

Fruit removal force (FRF) and percent leaf drop (LD) of fruit-bearing olive (Olea europaea L.) shoots were examined 120 hours after being sprayed with ethephon at 600 mg·liter-1 and held under controlled-environmental conditions analogous to those found in the field in California at harvest time in mid-October. FRF was not significantly affected by solution pH, but FRF of all treated shoots was significantly lower than that of the untreated controls. Only at pH 5 was percent LD significantly greater than that of the controls, but, of the shoots treated with ethephon, the lowest percent LD occurred at pH 3. Percent LD after treatment with ethephon at pH 3 was not affected by application time, but FRF was significantly less than the controls' when shoots were treated at 7 am or 12 pm but not at 5 pm or 10 pm. Adding NAA to the ethephon solution raised FRF and adding BA lowered FRF compared to ethephon alone. Adding NAA or BA did not mitigate percent LD significantly. Adding BA advanced anthocyanin production in fruit. Ethephon penetration of rachides was ≈70% that of petioles. Correlation between ethephon penetration of petioles and percent LD was greater than that between penetration of rachides and FRF. Correlation was significant for both tissues only in the 12 pm pH 3 treatment; correlation was also significant for petiole penetration and percent LD at pH 5. Autoradiographic studies of the 14C-ethephon penetration showed no pH effect, greater penetration into petioles than rachides, and that radioactivity was limited largely to intercellular spaces, with accumulation in vascular bundles, especially xylem. Regardless of treatment, FRF and percent LD are negatively correlated (r 2 = 0.615). Mean results to be expected using ethephon as an olive harvest aid under these conditions are an FRF of ≈3 N and a percent LD of ≈15%. The desired low FRF and percent LD were obtained by applying ethephon alone at pH 3 at 7 am. Raising ethephon solution pH does not increase harvest effectiveness. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon), naphthalene acetic acid (NAA), 6-benzylaminopurine (BA).

Free access