33 POSTER SESSION 6 (Abstr. 513-529) Fruits/Nuts/Berries: Breeding and Genetics
Thomas M. Gradziel and Dale E. Kester
Dan E. Parfitt, Chih-Cheng T. Chao, Craig Kallsen, Joe Maranto, and Louise Ferguson
33 ORAL SESSION 2 (Abstr. 392–396) Breeding & Genetics–Fruits/Nuts
Twenty variables were recorded on 15 apricot (Prunus armeniaca L.) genotypes differing in growth habit and blossom time to detect possible associations among morphological and phonological traits. The widest range of variability observed among phenotypes was for fruit size and factors associated with adaptation to local conditions, such as blossom season and yield potential as expressed by number of buds, flowers, and fruits per length of fruiting spurs. The most important morphological traits correlated with fruit weight were tree growth habit, apical and basal diameter of fruiting spurs, and bud and leaf size. Multivariate analysis allowed tree and variable grouping, which might encompass the basic criteria for apricot breeding programs in central México.
R. Neal Peterson
The pawpaw (Asimina triloba) is a new crop in the early stages of domestication. Recently commercialization has become feasible with the availability of high quality varieties. The history of pawpaw varieties is divided into three periods: 1900-50, 1950-85, and 1985 to the present. The history before 1985 was concerned primarily with the discovery of superior selections from the wild but experienced a serious break in continuity around 1950. The third period has been characterized by greater developmental activity. Larger breeding programs have been pursued, regional variety trials initiated, a germplasm repository established, and a formal research program at Kentucky State University (KSU) instituted. Future breeding will likely rely on dedicated amateurs with the education and means to conduct a 20-year project involving the evaluation of hundreds of trees. For the foreseeable future, governments and universities will not engage in long-term pawpaw breeding.
Jenny Knoth, John Frampton, and Ray Moody
The authors gratefully acknowledge Christmas tree growers Dale Taylor and Tom Wright for their maintenance and culture of the field trials. The Nursery and Tree Improvement Program of the South Carolina Forestry Commission and the
`Oconee' is a `Schley' × `Barton' cross from the USDA pecan breeding program and was tested as selection 56-7-72. It first bore in its 5th leaf and yields increased each succeeding year except year 11. Yields exceeded 23 kg/tree in year 10 and 12 and nut quality has been excellent each year. Percentage kernel averaged 56 with 26% (of inshell nut) grading fancy and 2% grading amber. `Oconee' is large with nuts averaging 9.7 g in wt. and 13 cc in volume with 71% 2.54 cm or larger in diameter. After mechanical cracking, nuts are easily shelled into large unbroken kernel halves. `Oconee' will pollinate `Cape Fear', `Stuart', `Desirable', `Kiowa' and `Sumner'. It is pollinated by `Sumner', `Stuart', `Maramek', `Kiowa', `Gloria Grande' and `Forkert'. `Oconee' should make an excellent temporary tree. More years data are needed to assess its merits as a permanent tree.
José Luis León and Enrique Troyo-Diéguez
The high cost of inputs and water deficit in arid lands demand the use of more drought tolerant species into the agricultue. The flora of the deserts offer a variety of fruits and vegetables that may diversify horticulture. `Cimarrón' wild plum tree or “ciruelo cimarrón” (Cyrtocarpa edulis Brand.:Anacardiaceae) is one of the species with potential importance in arid lands. C. edulis is an endemic tree of the meridional portion of the Baja California peninsula, occurring along arroyos and on gentle slopes in sandy soils. The flesh of the fruits is edible, with a slight acid tang, and is used locally. Actual exploitation is based on the fruit harvest in natural dry forest and xerophilous shrubs, where average density is near 100 trees/Ha. There is a growing interest in marketing the dried fruits, especially for the snack industry, hence, the need to develop a breeding program in order to establish it as a reliable fruit crop.
Kim D. Bowman
`Cipo' sweet orange [Citrus sinensis (L.) Osbeck] is distinctive among citrus selections because of reduced tree height and procumbent growth habit. Open-pollinated seeds were collected from `Cipo' orange and `Pineapple' sweet orange (C. sinensis) at Riverside, California, and grown under cool greenhouse conditions. Seedlings of `Cipo' were relatively uniform in morphology (including drooping shoot habit) and were presumed to be apomicts derived from nucellar embryos. `Cipo' seedlings were distinctly different from `Pineapple' in several characteristics, including smaller shoot altitude/extension ratios (a measure of uprightness) and broader stem-petiole angles (`Cipo' 1.33 radians; `Pineapple' 0.84 radians). The procumbent habit of `Cipo' appeared to be related to a preference for horizontal shoot orientation rather than a weakness of stem structure. Some increased sensitivity to ethylene was observed in the `Cipo' seedlings. `Cipo' is proposed as a resource for hormone research and a potential parent in breeding for unique tree morphology and reduced tree size.
L.A. Wasilwa, N. Ondabu, G.W. Watani, H. Mulli, S. Kiiru, A. Nyagah, and Kagiri
Several outstanding macadamia trees (Macadamia integrifolia Maiden and Betche, M. tetraphylla L. S. or hybrid of these two species) were selected from orchards established in the 1960s in the central and eastern highlands and evaluated over a period of 10 years. In the thrid year of these evaluations, clones from 30 high-yielding trees (40 to 90 kg) were propagated by grafting and trials were established in the central and eastern highlands. Three to five Hawaiian varieties were included as controls. Each trial consisted of five to 10 trees of each clone. Trees were evaluated for vigor, flowering, age of bearing, and yield. From these tests, a subset of 10 of the most outstanding clones were selected and evaluated in 25 field trials located in the Kenyan highlands. Most these clones started to bear 3 years after transplanting. Three distinct flowering patterns have been observed. Ten years after transplanting, yields ranged between 30 to 60 kg nuts/tree. The macadamia hybrids and M. tetraphylla performed best at the higher elevations (1700–1850 m), M. integrifolia clones performed best at elevations of 1500 to 1750 m. Only two Hawaiian varieties performed well and have been used in the breeding program. Most of the cultivated macadamia trees in Kenya are either M. integrifolia or hybrids. Cultivation of M. tetraphylla in Kenya is no longer recommended.
Gennaro Fazio, Herb S. Aldwinckle, Terence L. Robinson, and James Cummins
The Geneva® Apple Rootstock Breeding program, which was initiated in 1968 by Dr. James Cummins and Dr. Herb Aldwinckle of Cornell University and which has been continued as a joint breeding program with the U.S. Dept. of Agriculture Agricultural Research Service (USDA-ARS) since 1998, has released a new semi-dwarfing apple rootstock which is named Geneva® 935 or G.935. G.935 (a progeny from a 1976 cross of `Ottawa 3' × `Robusta 5') is a selection that has been widely tested at the New York State Agricultural Experiment Station in Geneva, N.Y., in commercial orchards in the United States and at research stations across the United States and Canada. G.935 is a semi-dwarfing rootstock that produces a tree slightly larger than M.26. G.935 is the most precocious and productive semi-dwarf rootstock we have released. It has had similar yield efficiency to M.9 along with excellent fruit size and wide crotch angles. It showed no symptoms of winter damage during the 1994 test winter in N.Y. G.935 is resistant to fire blight and Phytophthora; however. it is susceptible to infestations by woolly apple aphids. G.935 has shown tolerance to replant disease complex in several trials. It has good propagation characteristics in the stool bed and produces a large tree in the nursery. G.935 has better graft union strength than M.9, but will require a trellis or individual tree stake in the orchard to support the large crops when the tree is young. G.935 will be a possible replacement for M.26. Suggested orchards planting densities with this rootstock are 1,500-2,500 trees/ha. It has been released for propagation and sale by licensed nurseries. Liners will be available in the near future.