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Margaret Pooler and P.W. Simon

Garlic (Allium sativum L.) is an obligate apomict which reproduces almost exclusively by means of division of underground cloves or by propagation of topsets. The occurrence of viable, sexually-derived garlic seeds is rare. In order to assess the factors that limit garlic seed production, variables that affect flower initiation and development were studied. The effects on flowering of daylength, growing temperature, bulb and plant cold storage conditions, and cultivar were examined by observing flower development in plants grown under controlled greenhouse conditions. Correlations between isozyme markers and flowering, fertility, and morphological markers will be presented for a diverse collection of garlic clones, including six sexually-derived garlic plants.

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Karim H. Al-Juboory

Shoots of greenhouse-grown Pothos were surface disinfested and explanted on modified Murashige and Skoog (MS) medium. Later they were treated with pulsed XeCl excimer laser radiation for 30 sec. Cultures treated with 12 or 25 pulses of excimer laser radiation showed only 23% and 10% contamination, respectively, versus 75% control. Inaddition, we demonstrated that pulsed XeCl excimer laser radiation affected the subsequent growth and regenerability of in vitro plants. The reason for this increased growth needs further investigation. Both BA and TDZ were important for increasing the number of shoots generated from a microshoot as well as inducing shoot organogenesis from Pothos callus. Of the 50 rooted ex vitro plants from this experiment only 30% were variegated like parental clone. The others were either pure green or albino, suggesting chimeral segregation.

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Joanne Logan and Michael J. Searcy

Peach production in Tennessee has suffered a decline in the past decade due to late and severe spring freezes. East Tennessee is an area of diverse topography. It may be possible to use topoclimate exposure to ameliorate the low temperatures in spring and therefore lessen the damage to peach buds. Exposure also may also influence the accumulation of chill units and growing degrees, therefore affecting the stage of peach bud development when the freeze occurs. Five automated weather stations were located in topoclimatically different areas of a peach orchard in Dandridge, Tennessee, from September, 1990 to May, 1991. Hourly chill units (base 6.1 °C) and growing degrees (base4.4 °C) were calculated. Twigs from peach trees close to each weather station were forced every three days to determine the date of completion of rest. Hourly freeze data were collected from each weather station. Preliminary results on the effects of topoclimate on spring freeze characteristics, accumulation of chill units and growing degrees, and peach phenology will be presented.

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Margaret Balbach

Introductory Horticulture at Illinois State University is approved for inclusion in the University Studies Program. This program is comprised of courses whose content is considered of general importance to the educated layperson, rather than to the specialist in the field. Departments may use the University Studies Program as a means of attracting students to the field. This has been done with fair success with Introductory Horticulture. Because the course must provide personal enrichment, be broad in scope, offer a systematic design for further learning, and assure a breadth of knowledge and understanding, this course has been designed to focus on the economies of the various horticultural industries, how they are related to the socioeconomic history of the various regions of the country and how the marketing of horticultural products and enterprises affects the personal life of individuals. Acceptance of this approach has been two-fold: first: student evaluations are positive, a steady enrollment has been maintained, and the course has steadily provided 10% to 15% of new Horticulture students, and second: the University Studies review committee has twice affirmed the “tenure” of Introductory Horticulture in spite of increasingly stringent guidelines that discourage many traditional science courses.

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Judith A. Abbott and Louis A. Liljedahl

Sonic vibrational characteristics of intact apples are related to flesh elasticity which is, in turn, related to firmness. Firmness changes in Golden Delicious and Delicious apples were followed during accelerated ripening and under storage conditions. Firmness was measured by Magness-Taylor puncture force and by compression of tissue cylinders (modulus of elasticity and rupture strength) for comparison with sonic vibrational characteristics of intact apples. Influences of apple temperature, size, shape, and skin on sonic spectra were investigated. Sonic resonant frequencies were significantly correlated with destructive firmness measurements and decreased as storage time increased. Sonic amplitudes were not closely related to firmness. Regression equations incorporating sonic data and size were developed to predict Magness-Taylor force. Use of sonic vibrational characteristics is proposed as a rapid nondestructive method for firmness sorting of apples.

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Rex H. Warland

During this presentation, several basic issues related to survey research will be introduced and illustrated. First several issues related to sampling will be considered. These will include how to determine sample size, where to obtain a sampling frame, how to compute error rates, and how to estimate costs associated with sampling. Mail surveys, telephone surveys, and face-to-face interviews will then be described and compared. The state of the art of these methods will be discussed, the costs associated with each method will be reviewed, and the advantages and disadvantages of each method will be described. Response rates will also be discussed. Next we will briefly review the kinds of information that can and cannot be obtained from a survey. Several principles concerning question wording, question order, and question context will be introduced. The presentation will conclude with a few suggestions about the linkages between surveys and statistical analysis.

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Ronald W. Moore, K.M. Eskridge, P.E. Read and T.P. Riordan

The concept that greater callus mass will induce competence was investigated. The second most immature nodal segments were removed from heavily fertigatcd greenhouse grown plants. Shoots initiated from those nodes were only cut back to one-third their total length. They were subjected to the following treatments: (1) dicamba from 1μM to 5μM in increments of 1.0; (2) B5 medium salt concentrations from 1/3x to 5/3x in increments of 1/3; (3) sucrose levels from 2% to 10% in increments of 2; (4) casein hydrolysate from 0 to 200mg/l in increments of 50. The experiment consisted of twenty-five different treatment combinations in a central composite rotatable second order design. Explants were placed in continuous cool white fluorescent light at 26°C.

Dicamba, B5 salts, and sucrose had significant effects on callus mass (p<.12), while casein hydrolysate had no notable effects on callus mass (p ≥ .57). It was determined that optimum response occurred at 5/3x concentration of B5 salts, 10% sucrose, and 5.0μM dicamba. White, compact calli were observed in treatment combinations that yielded callus fresh weights of two-hundred milligrams or higher.

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Martin C. Goffinet and Roger C. Pearson

Clusters of Vitis labruscana cv. Concord were grown either in full sun or canopy shade, and either not sprayed or sprayed with 3.4 Kg/Ha chlorothalonil every 2 wk from pre-bloom to veraison. Only sun-exposed, sprayed fruit produced skin russeting. Clusters of the very susceptible V. vinifera cv. Rosette were grown in direct sun, sprayed with chlorothalonil 4 times from bloom to veraison, in the presence or absence of purported anti-russeting agents. Heavy russet occurred in all treatments. Russet initiation was similar in the 2 cvs.: epidermal cells first died beneath spray residue in full sun, a phellogen then arose in the hypodermis, followed by periderm. Epidermal death began in `Rosette' within a wk of the bloom spray, but in `Concord' only after 2-3 wk post bloom and 3 sprays. `Concord' russet generally appeared as patches or scabs, whereas `Rosette' russet ranged from freckles, welts, scabs to large smooth burnished areas. In both cvs., unbroken russet consisted of uniform layers of phellum. New, deeper periderm initials arose beneath checks and cracks which formed as fruit enlarged. In `Concord', but not `Rosette', the daughter cells of each such initial were often enclosed in the original cell wall. In all cases of russet, cell walls in the periderm were suberized and sometimes lignified. Cells also contained much phenolic material.

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Keith T. Birkhold and Rebecca L. Darnell

Partitioning of carbon and nitrogen reserves were examined in two cultivars of rabbiteye blueberries (Vaccinium ashei] differing in their timing of vegetative budbreak relative to floral budbreak. Floral budbreak precedes vegetative budbreak in `Climax', while floral and vegetative budbreak occur concomitantly in `Bonita'. Twenty eight containerized plants from each cultivar were dual labeled in the fall with 105 μCi of 14C02 and 0.6 g of nitrogen enriched with 5% 15N. Plants were grown outdoors throughout the winter and the following growing season. At five dates, beginning 27 days prior to full bloom and ending at fruit maturity, plants were harvested into old shoots, roots, fruit, and vegetative growth.

Fall leaf drop accounted for loss of 12% of applied N and 20% of applied 14C. In the first harvest, approximately 73% of the recovered 15N and 50% of the recovered 14C was in the roots for both cultivars. By fruit maturity, approximately 8% of the recovered 15N was in the fruits, 51% in new vegetative growth, and 41% in old shoots and roots. Approximately 1.2% of the recovered 14C was in fruit, 1.5% in vegetative growth, and 97% in old shoots and roots. Data suggest that differences in the timing of vegetative budbreak between these two cultivars do not influence overall partitioning patterns of reserve carbon and nitrogen.

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Tadeusz Jacyna

Branched (B) and unbranched (UB) one-year-old `Bradford'/`OHFx97' trees were examined at intervals between preparation for bare root harvest and long term storage to determine the extent of mechanical bud damage caused by the various handling steps.

After hand stripping of leaves, digging, transportation to the storage facility, and grading, and tying of bundles, there was a marked difference in the percentage of damaged buds between branched (26%) and unbranched (53%) trees. The B/UB live bud ratio before and after harvest was 1:0.45 and 1:0.26, respectively. This difference may have been due to a various morphological growth pattern which both types of trees had produced.