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C.R. Rom

Annual shoot and trunk xylem growth increment of `Starkspur Supreme' in the 1984 NC-140 uniform rootstock trial was studied of 10 selected rootstocks representing a range of tree sizes. Shoot growth was measured weekly from budbreak through harvest in each of four seasons. After 11 seasons of growth, whole trees were cut, placed in water containing diffuse fuschin dye for 30 to 60 min during mid-day. After that, a section of trunk (10 to 15 cm long) was excised at 25 cm above the graft union. Trunk xylem thickness and percent of water transport active xylem were measured. Shoot length during the study was related to both the duration and rate of growth; however, growth duration contributed more to variation among stocks. In all stocks, it appears that almost all xylem translocated water and that there was very little “plugged” or active xylem. There were no differences among stocks for the relative percentage of active xylem. Annual xylem increment width varied with stock. The vegetative growth of these trees will be discussed relative to the production efficiency of scions on these stocks.

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M. Ahmedullah and C. R. Rom

Roots of one year old grape cvs. Concord, White Riesling, Grenache and Semillon were frozen to 0, -5, -10, -15 and -20°C in a programmable freezer. The tops were protected from cold by insulating them. For survival test, 4 plants of each cv. were planted in the greenhouse and their growth observed. Differential thermal analysis (DTA), using a computer attached to a programmable freezer was performed on roots. To aid in the interpretation of DTA, triphenyltetrazolium chloride (TTC) was performed. Hardiness determinations were based on DTA, TTC and the survival tests. DTA patterns representing exothermic response showed an exotherm associated with extracellular free water in tissue which appeared at about the same temperature range for all cvs. This is not associated with hardiness. Additional minor exotherms related to hardiness appeared at lower temperatures than the extracellular water exotherm. Their location differed from one cv. to another. Based on these tests, Concord roots appear to be hardier than other cvs. with important but minor differences in the hardiness of other cvs.

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M. Ahmedullah and C. R. Rom

Roots of one year old grape cvs. Concord, White Riesling, Grenache and Semillon were frozen to 0, -5, -10, -15 and -20°C in a programmable freezer. The tops were protected from cold by insulating them. For survival test, 4 plants of each cv. were planted in the greenhouse and their growth observed. Differential thermal analysis (DTA), using a computer attached to a programmable freezer was performed on roots. To aid in the interpretation of DTA, triphenyltetrazolium chloride (TTC) was performed. Hardiness determinations were based on DTA, TTC and the survival tests. DTA patterns representing exothermic response showed an exotherm associated with extracellular free water in tissue which appeared at about the same temperature range for all cvs. This is not associated with hardiness. Additional minor exotherms related to hardiness appeared at lower temperatures than the extracellular water exotherm. Their location differed from one cv. to another. Based on these tests, Concord roots appear to be hardier than other cvs. with important but minor differences in the hardiness of other cvs.

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Yan Shi and C.R. Rom

Fifty apple cultivars and 30 Malus species were evaluated for resistance to four isolates of bitter rot pathogens, Colletotrichum gloeosporioides and C. acutatum, in controlled conditions. Fruit were wound-inoculated by placing 0.1 ml of inoculum (106 conidia/ml) into puncture wounds (2 mm in diameter), and intact fruit were inoculated by spraying with inoculum. Inoculated fruit were incubated at 25 to 28C for 2 weeks. `Golden Delicious' (susceptible) and `Red Delicious' (resistant) were used as controls. Diseases were quantified by measuring lesion diameter, and disease severity was objectively rated. Relative lesion diameter and severity rating were calculated as [X × 100/RD – 100] and (X – RD) × 100/7 (X = parameter of given cultivar or species, RD = parameter of `Red Delicious') to determine relative resistance. Conclusions were as follows: 1) different levels of resistance were identified in apple cultivars and Malus species and also were detected within `Golden Delicious' and `Red Delicious' types; 2) `Jonagold', `Oregon Spur II', `Spartan', `Melrose', `Red Cort', `Jonafree', `VPI-9', and `Red Delicious showed good relative resistant; 3) M. halliana, angustifolia, prunifolia, sylvestris, and fusca were more resistant than `Delicious'; 4) M. angustifolia was immune to two isolates of C. acutatum.

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Curt R. Rom, R.C. Rom and R. Bourne

`Redhaven' trees on 10 rootstocks planted in 1984 were annually evaluated for growth and cropping as part of the NC-140 national cooperative rootstock troial. All trees on Citation have died, 60 % of trees on GF-43 have died and only a single tree of Lovell, Halford, and GF-677 have died. Trees on Damas GF-1869 and GF-655.2 had significantly more root suckers than other trees. Redhaven own-root, Halford and GF-677 were largest in height, spread, canopy volume or TCSA while the smallest trees were GF-43, Damas, and GF-655.2. Damas, GF-43 and GF-655.2 bloomed 3-4 days before trees on Lovell. Fruit on Redhaven own-root matured 4 days before fruit on Lovell while fruit on Halford, GF-677 and GF-43 ripened 2 days later than Lovell. Trees on Halford had the highest annual yield and accumulated yield while GF-655.2, Damas and GF-43 had the lowest yields. Redhaven own-root and Halford had the highest yield efficiencies (kg/cm2TCSA). Trees on Lovell consistently produced the largest individual fruit size.

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Curt R. Rom, Roy C. Rom and James N. Moore

The Arkansas apple breeding program began in 1966 with objectives to develop high quality, dual purpose, adapted cultivars with a range of harvest dates and resistance to spring diseases. The program has two goals: 1) to develop red colored apples which are large, tart, firm and ripen between June and August; and, 2) develop yellow apples as a replacement for `Golden Delicious' which are large, typey, without russet and with a range of maturities from July through September. Apples with commercial potential are AA-18 (red, ripens 1-July), AA-44 (red, ripens 15-July), AA-58 (yellow, ripens 29-Aug.), AA-65 (yellow, ripens 11-Sept.) and AA-62 (yellow, ripens 15-Sept.). Data on time of bloom, harvest, fruit size, and fruit storage tests will be presented.

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J.D. Mcafee and C.R. Rom

Alternative fruit thinners and pesticides are needed for certified organic fruit growers. A transient reduction in photosynthesis has proven to be an effective technique used for fruit thinning. Conversely, pesticides, which reduce Pn may be detrimental to plant growth. This study was developed to measure plant response to foliar applications of various organic acids as potential horticultural chemicals Treatments were applied to vegetative apple trees under controlled environmental conditions to study photosynthetic effects. CO2 assimilation significantly decreased temporarily 3 days after treatment with citric acid. Decreased trends of evapotranspiration were observed for all treatments 1 day after foliar application; however, not significant. Salicylic acid significantly decreased stomatal conductance 1 and 15 days after treatment. Average leaf area was not significantly affected but oxalic acid increased plant stem growth while acetic acid application reduced growth. This model system for screening new and alternative compounds will be a basis to study agents that may have potential to be used as certified pesticides or fruit thinning agents.

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C.R. Rom, H. Friedrich and K. Harper

Higher education curricula should be alert to trends in production and science, and responsive to needs of producers and consumers in our society. A recent trend has emerged nationally and internationally for the production and consumption of certified organic produce which is increasing at a significant rate. Following the creation of the National Organic Program and formal federal regulations for certification which govern production, it has been questioned whether horticulture programs in land grant institutions have adjusted curricula appropriately to train producers, consultants, extension specialists, teachers and research scientists to be engaged in organic production systems. According to USDA statistics, several states in the southern region have significantly fewer certified organic farms and certifying agencies than the northeast, Midwest or western regions. A review horticulture and crops programs at 36 land grant universities (1862 and 1890) in 14 southern region states indicated although several institutions had research and outreach programs for sustainable and organic production, there were only three classes on organic gardening, two classes on organic crops production, and one field-based organic production course that could be identified in existing curricula. It appears that with the growth of the organic industry worldwide that students in programs in the southern region may be under-served in this educational area. Further, it may be questioned whether the lack of production and certifying agencies in the southern region is associated with the lack of science-based education provided by the land grant universities. A recent survey of faculty indicated a perceived need for stand-alone coursework on organic, sustainable, and ecologically-based production systems.

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M.E. Garcia and C.R. Rom

AGRI 1203 “Introduction to Plant Sciences” is a college core requirement for students in the College of Agricultural, Food, and Life Sciences. One of the objectives is accomplished in part by writing a scientific research-review paper (term paper) on a subject of the student's interest. After several semesters of assigning the term paper, it was apparent that students had extensive variation in experience and skills in writing and documenting references. A SOLO was created so that students could develop and practice techniques in reading, understanding, summarizing, and documenting references in a research paper. The SOLO is a self-instructional exercise consisting of three parts: l) a statement of learning objectives, 2) activities on how to achieve the objectives; and 3) exercises to measure mastery level of the exercise's objectives. The SOLO and student and instructor evaluations of the SOLO will be presented and discussed in the poster.

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John R. Clark and Roy C. Rom