Search Results

Abstract

The root-regenera ting potential (RRP) of one-year-old Pistacia chinensis seedlings at different growth stages was determined by recording the number of newly initiated roots during the period of 4 weeks after bare-root transplanting into a bottom misting chamber. RRP of intact pistacias was greatest when leaves were fully expanded and the terminal bud was forming (stage III) and lowest when seedlings were in a dormant condition (stages V and VI). However, seedlings disbudded before transplanting and also root cuttings showed two peaks in RRP; one at spring bud break (stage I) and the other at stage III. Removal of buds resulted in decreased RRP at stage I, but had little effect when plants were dormant. Treatments such as thiourea sprays of growing seedlings and chilling of dormant seedlings enhanced bud break and RRP. Potassium indolebutyrate applied to the root system promoted RRP of pistacia seedlings but did not eliminate the seasonal variation of RRP. Potassium indolebutyrate could replace the influence of buds only when seedlings were not in a dormant condition. Sucrose feeding via the stem substantially increased RRP at spring bud break. The results indicate that the dormant condition of buds and the availability of carbohydrates are the factors controlling the RRP of bare root transplanted pistacias.

Sinapine leakage to detect seed germination potential on a single-seed basis in Brassica has been developed as a rapid test. In this test, sinapine leakage predicts that a seed is non-germinable; however, the major source of errors in this method are false-negative (F–)—i.e., the method predicted a seed was germinable because the seed did not leak, and it did not germinate. The sinapine leakage index (SLI) was used to asses the F– for any seed lot by dividing the number of non-germinable seeds that leaked sinapine by the total number of non-germinable seeds. Seed lots including cabbage, cauliflower, and broccoli (B. oleracea L., Captitata, Botrytis, and Italica groups, respectively) were used to examine the F–. The leakage rate as measured by T₅₀, the time for 50% of heat-killed seeds to leak, was linearly correlated to SLI. Cabbage seeds were viewed by scanning electronic microscopy and leaking non-germinable seeds either had cracks or were shrunken. NaOCl pretreatment has been found to increase the rate of sinapine leakage and SLI. The mode of NaOCl was due to high pH altering the seed coat permeability. Chemical analysis was conducted on isolated seed coats for pectin, tannins, hemicellulose, cellulose, phenolic lignin, and cutin. It was found that the higher SLI (more permeable) lots contained lower amounts of cutin, suggesting that cutin may restrict the diffusion of sinapine through the testa.

The shelf life of chestnuts is limited by water loss. Polymeric packages have been used to prevent dehydration, although little specific information is available on the use and design of MA packaging for extending shelf life. To investigate the product response to MA conditions, a range of O₂ levels were generated inside low-density polyethylene (LDPE) packages containing chestnuts. The respiration rate decreased with decreasing O₂ levels below 16 kPa at 0C. A rapid increase in RQ and ethanol were noticed when the chestnuts were exposed to O₂ levels below 1 kPa at 0C, indicating a shift to fermentative metabolism. In a flow-through system, the respiration rate at 0C and the Q10 were measured as 108 nmol·kg^–1·s^–1 and 2.5, respectively. Chestnuts were stored at –2, 0, 5, and 20C in LDPE packages for 6 months and quality was periodically evaluated. Off-flavors were noticed from chestnuts stored in O₂ levels below 1 kPa at 0C on day 38. Chestnuts stored at 0C but at higher O₂ levels were acceptable for 5 months. Chestnuts stored at –2C were still acceptable after 6 months of storage.

Abstract

Root regeneration from root cuttings of both difficult-to-transplant Pistacia chinensis and moderately easy-to-transplant Liquidambar styraciflua was studied in a sphagnum peat medium varying from 0-100% Ca saturation and from 0-50% air filled porosity. Maximum root regeneration of Pistacia root cuttings was obtained at 75% Ca saturation and 30% and 40% air filled porosity, whereas Liquidambar root cuttings regenerated roots best at 25% Ca saturation and at 20% to 40% air filled porosity. Indolebutyric acid applied to the root cuttings greatly increased root-regenerating potential of Pistacia root cuttings but did not affect the optimum Ca and aeration requirement(s). Similarly, indolebutyric acid treatment greatly promoted the root-regeneration potential of Liquidambar root cuttings. Satisfactory root-regenerating conditions of both Ca saturation and air filled porosity for Liquidambar root cuttings were a little broadened by indolebutyric acid (IBA) application.

Pistacia bare root seedlings also required high levels of Ca saturation and aeration for optimum root regeneration. Considerably greater numbers of roots were regenerated in peat having 75% Ca saturation and 20% air filled porosity than in peat having 0% Ca saturation and 5% air filled porosity. Root regeneration was not improved by increasing only the air filled porosity when Ca was low.

Abstract

Rooting of stem cuttings of Bougainvillea cv. San Diego Red, Ceratonia siliqua L., Chrysanthemum morifolium Ramat. cvs. Golden Anne and Mandalay, Euonymus japonica L. cv. Yellow Edge, Euphorbia pulcherrima Willd. cv. Eckspoint C-1 Red, Hedera helix L., Trachelospermum jasminoides [Lindl.] Lem., Juglans hindsii (Jeps.) Jeps., Pistacia chinensis Bunge, and Salix laevigata Bebb. is greatly promoted by basal dipping in H₂SO₄ prior to applying indolebutryic acid. Pre-treatment with NaOH results in considerable increase of rooting of cuttings of Rhododendron (Pericat) cv. Sweetheart Supreme, Bougainvillea, Liquidambar styraciflua L., Osmanthus heterophyllus G. Don cv. Ilicifolius, and Pinus radiata D. Don.

Abstract

Leaves of spinach (Spinacia oleracea L.) from N fertilized and unfertilized plots were harvested at different stages of maturity, and analyzed for nitrate and nitrite at harvest and after storage at 10°C for 5, 10 or 15 days. Leaf nitrate-N increased with time in plants sidedressed with 340 kg N/ha, but decreased in unfertilized spinach. Leaves harvested at market maturity accumulated 5-fold more nitrite-N when held at 10°C for 15 days than immature leaves. N fertilization increased nitrate accumulation at harvest, and nitrite accumulation after 15 days at 10°C.

A protocol was developed for production of transgenic iris plants (Iris germanica L. `Skating Party') from regenerable suspension cultures via Agrobacterium-mediated transformation. We tested a series of selection agents, and identified hygromycin and geneticin as the most suitable for selecting transformed iris cells. Suspension cultures of iris were cocultured for 3 days with A. tumefaciens LBA 4404(pTOK233) carrying an intron-interrupted uidA (GUS) gene encoding β-glucuronidase, and hpt (hygromycin) and nptII (geneticin) selectable marker genes. Hygromycin- or geneticin-resistant calli having GUS enzyme activity were identified and used to induce plant regeneration. More than 300 morphologically normal transgenic iris plants were obtained in ≈6 months. About 80% of the transformants were GUS-positive and NPTII-positive (paromomycin-resistant). Integration of transgenes into the nuclear genome of iris plants was confirmed by Southern blot analysis. We have, therefore, developed an efficient A. tumefaciens-mediated transformation system for Iris germanica, which will allow future improvement of this horticulturally important ornamental monocot via genetic engineering.

Abstract

A calcined shale potting medium is useful to obtain intact root systems free of substrate. Root system structure and shape is retained with minimal damage upon removal from this medium.

Abstract

Avocado (Persea americana Mill.) fruit from various locations in California were analyzed for oil and subjected to taste tests every 2 weeks throughout the fruiting season over a period of 5 years. Oil content at acceptable taste differed among cultivars, and the 8% requirement was too low to serve as a good maturity standard for many cultivars. While the date of acceptable taste of fruit grown at the same location was not significantly different from year to year, it varied significantly among and within the widespread avocado production areas. Dry weight, which was highly correlated with increasing oil content, was evaluated as a maturity index. The dry-weight analysis with a microwave oven was much easier than determining oil content. The average dry weight at 8% oil (the existing legal standard in California) was 19.4% for ‘Bacon’, 19.1% for ‘Fuerte’, 19.8% for ‘Hass’, 18.9% for ‘Pinkerton’, and 18.4% for ‘Zutano’ fruit. Dry weight at acceptable taste was 20.0% for ‘Bacon’, 21.0% for ‘Fuerte’, 22.8% for ‘Hass’, 20.0% for ‘Pinkerton’, and 20.2% for ‘Zutano’.

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] has the potential for increased use as a turfgrass species due to its low maintenance and water conservation characteristics. This study was conducted to estimate diversity and relationships among naturally occurring buffalograss genotypes based on the nuclear genome, using sequence-related amplified polymorphism (SRAP) markers. The 56 genotypes studied represented five ploidy levels collected from diverse geographic locations in the North American Great Plains. In addition, blue grama [Bouteloua gracilis (H.B.K.) Lag. Ex Steud.] and perennial ryegrass (Lolium perenne L.) were included as outgroups. Twenty-five combinations of forward and reverse primers were used. Ninety-five intensively amplified markers were scored and used to infer diversity and relationships among the genotypes. All buffalograss genotypes were discriminated from each other with similarity values ranging from 0.70 to 0.95. Principal component analysis (PCA) suggested that the 56 genotypes could be reduced to 50 due to high similarity levels among some of the genotypes. The distance between buffalograsses, blue grama, and perennial ryegrass were consistent with current taxonomical distances. This research indicates that SRAP markers can be used to estimate genetic diversity and relationships among naturally occurring buffalograss genotypes.