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Henry R. Owen and Louis H. Aung

A relationship between ovary size at anthesis and final fruit diameter of 12 tomato (Lycopersicon esculentum Mill.) cultivars with a range of fruit sizes, shapes, and maturation rates was determined. `Fireball', `Michigan/Ohio Hybrid', and `New Yorker' produced nonfasciated, spherical fruits of intermediate maturation rate and showed a significantly higher correlation between ovary diameter at anthesis and final fruit diameter than `Small Fry', `Roma VF', `Early Cascade', `Campbell 1327', or `Ponderosa'. A linear regression of final fruit diameter at maturity on ovary diameter at anthesis of the cultivars was highly significant (r2 = 0.92**; ÿ = 22.5X - 0.3). Continuous root application of 0.01 μm BA to seedlings of `Fireball' significantly delayed anthesis. A single foliar application of 0.37 mM NOA to `Fireball' plants at the appearance of the first inflorescence significantly increased ovary diameter on the first inflorescence, but decreased ovary diameter on the second inflorescence. Treatment with NOA altered final fruit shape but not final fruit diameter. Single foliar applications of 0.1 mM GA stimulated stem and peduncle elongation but did not affect fruit size. Chemical names used: ß-naphthoxyacetic acid (NOA), N6-benzylaminopurine (BA), gibberellic acid, (GA).

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Lisa C. Berg and Henry R. Owen

Nicotiana tabacum callus growth (fresh weight) was measured after culture in the light (16-hour photoperiod) or in darkness for four different culture media, differing in iron chelate type or concentration. All media contained MS basal medium supplemented with 30 g·L–1 sucrose, 2 mg·L–1 IAA, 0.2 mg·L–1 KIN, and 7 g·L–1 agar, pH 5.8. Three of the media contained iron-metalosate (Albion Laboratories), an organic iron chelate, at 100, 200, and 400 micromolar concentrations, and the fourth medium contained 100 μm Fe-EDTA. Twenty-five culture tubes were prepared for each of the 4 different media concentrations and 2 light treatments (8 treatments total). A 1-cm3 callus explant was used for each treatment and cultured for 56 days at 20°C. About 20-fold increases in callus fresh weight were observed for cultures incubated in light or in darkness. In addition, callus growth was not significantly affected by iron chelate type, suggesting the potential utility of this organic chelator in tissue culture media to alleviate potential problems of light-induced EDTA instability and subsequent IAA inactivation. These cultures are being maintained to examine the influence of iron chelate type on organogenesis.

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Henry R. Owen and A. Raymond Miller

A comparison of pretreatment, fixing, and staining methods for root tips of Fragaria × ananassa (2n=8x=56), a polyploid species with small chromosomes, was made to facilitate chromosome counting. Three pretreatments (8-hydroxyquinoline, α-bromonaphthalene, and p-dichlorobenzene), three fixatives (Farmer's, Carnoy's, and Newcomer's), and five stains (acetocarmine, lacto-propionic orcein, leucobasic fuchsin, altered carbol fuchsin, and alcoholic hydrochloric-acid carmine) were examined in a factorial design to determine which treatment combination produced the best chromosome preparation. Field propagated runners were grown in sand under greenhouse conditions with supplemental lighting to produce root tips for late morning collection. The treatment combinations of α-bromonaphthalene or 8-hydroxyquinoline, Farmer's fixative, and altered carbol fuchsin, or the combination of α-bromonaphthalene, Farmer's fixative, and alcoholic hydrochloric-acid carmine produced the most intensely-stained and well-defined preparations.

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Henry R. Owen and A. Raymond Miller

A factorial combination of pretreatments, fixatives, and stains was examined to identify the best available method for staining the chromosomes of strawberry (Fragaria × ananassa Duch. `Chandler') root-tip cells. Three pretreatments (a -bromonaphthalene, p -dichlorobenzene, and 8-hydroxyquinoline), three fixatives (Farmer's fluid, Carnoy's fluid, and Newcomer's fluid), and five stains (acetocarmine, alcoholic hydrochloric-acid carmine, altered carbol fuchsin, lacto-propionic orcein, and leucobasic fuchsin) were tested. Pretreatment with either a -bromonaphthalene (saturated aqueous) or 8-hydroxyquinoline (2 mm) for 5 hours at 14C, overnight fixation in Farmer's fluid, hydrolysis in 1 n HCl (15 minutes at 60C), and staining with altered carbol fuchsin produced chromosome preparations superior to other treatment combinations. Treatment with a-bromonaphthalene, Farmer's fluid, and alcoholic hydrochloric-acid carmine (2 days at 25C) also produced acceptable chromosome preparations.

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Lynze Greenwood, Janice M. Coons, Henry R. Owen, Lisa Ferguson and Ronglin Wang

Lettuce (Lactuca sativa) is one of the most important U.S. fresh-market vegetables with year-round consumption. For winter markets, lettuce is produced in the southwestern states with plantings in early fall when soil temperatures are high. Seed germination of lettuce, however, is inhibited by soil temperatures over 25 °C. The objective of this study was to test the emergence and growth of five lettuce cultivars using two seedlots produced in winter or summer to provide information for improving stand establishment at high temperatures. Seeds of five cultivars (`Empire', `Parris Island Cos', `Waldmann's Green', `Prizehead', and `Dark Green Boston') produced in Yuma, Ariz., during summer or winter months were used. Seeds were planted in a greenhouse mix in plastic trays and grown in a growth chamber at 23, 25, 30 and 35 °C. After 4 weeks, number of emerged plants, number of leaves, height, fresh weight, dry weight, and leaf area were measured. At lower temperatures (23 and 25 °C), more plants emerged and plants developed more rapidly than at higher temperatures (30 and 35 °C). More plants emerged of `Empire' and `Parris Island Cos' than of `Waldmann's Green' or `Dark Green Boston'. Growth varied greatly for the different cultivars. At 35 °C, only `Empire' winter seed emerged. At other temperatures, summer seed lots generally were better than or equal to winter seedlots. This information suggests that seeds developed during the summer are more vigorous at emergence than those developed during the winter.