, especially California. With the semiarid climate and abundant sunshine, jujube is an excellent fruit crop for the Southwest. With more media coverage, promotional activities, and research/extension supports, more and more people could be exposed to jujubes
Abstract
Fruit breeders can easily justify the need to improve cold tolerance. Feature articles describing huge losses from winter cold or spring frosts can be found with regular frequency in grower magazines. In addition millions of dollars are spent annually to protect fruit crops from abnormally cold weather.
At the University of Georgia, HORT 3020 (Introduction to Fruit Crops) is a two-credit survey of the botanical characteristics, taxonomy, and production practices of the world's major fruit crops. It is offered via traditional classroom instruction, and as a distance education (DE) course through the University System of Georgia Independent Study program. The DE version of the course is designed to be identical in content, final exam, and grading scale. However, due to the nature of independent study, the end-of-topic evaluations are open-book, written assignments in the DE course, whereas students in the classroom version have closed-book quizzes at the end of each topic. Student performance in the two versions of the course was compared over a 3-year period (May 1998 to May 2001) by analyzing scores on end-of-topic evaluations, final exams, and overall course grades. Students in the DE version had higher scores on end-of-topic evaluations in all 3 years, higher scores on a comprehensive final exam in 2 of 3 years, and consequently higher overall course grades than classroom students in all 3 years. Better performance of DE over classroom students may have been related to 1) qualitative differences in end-of-topic evaluations (written assignments versus quizzes), 2) differences in student demographics (nontraditional students in DE, traditional undergraduates in classroom), 3) the elective (DE) versus required (classroom) nature of the courses, or 4) differences in course duration (1 year for DE, 15 weeks for classroom). Equal or better performance of DE students suggests that survey courses such as Introduction to Fruit Crops can be offered via distance education without compromising learning outcomes.
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.
The IR4 Specialty Crops Program was established to assist in the registration of pest control products for minor uses. The national program, headquartered at Rutgers University and operating through four regions with a network of scientists in every state develops lists of grower needs, prioritizes projects and develops protocols to secure EPA tolerances that lead to labels. Every year IR4 works on pest control products needed by the fruit industry. Pest control products being researched for 2006 include: Insect and disease control in tropical fruit crops: Lepadopterous larvae control in peaches with Avaunt, Danitol, and Spintor: Mite and raspberry crown borer control in blackberry: Weed control in blueberry with Sandea and Spartan: Botrytis and anthracnose control in strawberry.
Regional efforts among research and extension workers in Southeastern fruit crops have evolved from early meetings to write pest control recommendations to more formal interactions such as regional research projects, meetings and publications. For apples, there are currently three individuals in the Southeast working in more than one state. Why regionalize? Similar growing conditions, the need to react quickly to critical issues, intensification within production, broadening of responsibilities and a dramatic reduction in the number of research and extension personnel to address these issues necessitate cooperative efforts. Regional efforts pose special challenges such as increased workloads and greater travel demands, often without increased funding. Conversely, regionalization may enable specialists and researchers to focus their attention on fewer commodities and areas, thus becoming better resources for growers and the industry. In this vein, regional responsibilities entirely within research or extension might be a better option than split appointments encompassing research, extension and, perhaps teaching, within a state. In the future, state lines will become less distinct with research and extension appointments reflecting regional responsibilities. Growers do not care where their information comes from as long as it is available and pertinent to their operations. Regionalization is a positive step for increasingly challenging times.
Ribulose bisphosphate carboxylase/oxygenase (Rubisco) initiates the photosynthetic carbon metabolism;therefore, its activity has been measured in many physiological studies. However, information on in vitro Rubisco activity from leaves of deciduous fruit crops is very limited and the reported activities are suspiciously low. We measured Rubisco activity in crude extracts of leaves of apple, pear, peach, cherry, and grape by using a photometric method in which RuBP carboxylation was enzymically coupled to NADH oxidation. Replacing polyvinylpyrrolidone with polyvinylpolypyrrolidone in the extraction solution significantly increased extractable Rubisco activity. Depending on species, freezing leaf discs in liquid nitrogen followed by storage at –80°C for only 24 hr reduced both initial and total Rubisco activity to 5% to 50% of that obtained from fresh leaves. Initial Rubisco activity from fresh leaf tissues of all species was well correlated with maximum Rubisco activity (Vcmax) estimated from gas exchange; an exception was pear, where initial Rubisco activity was higher than Vcmax. In most cases, initial Rubisco activity was approximately two to three times higher than net photosynthesis.
We have previously demonstrated that a protein of ∼62 kD decreases in response to temperature during the final stages of chilling unit accumulation in dormant peach flower buds (Lang and Tao, 1991, HortSci. 26:733). To further examine proteins that potentially may be associated with endodormancy, floral buds, spurs, and/or shoots were collected during winter from `Anna' apple, various blueberry cultivars, `MidSouth' grape, `20th Century' pear, `Hawthorne' peach, and `Santa Rosa' plum. Soluble proteins were extracted and analyzed by one-dimensional SDS-PAGE. A major protein of ∼62 kD was present in plum, and lesser amounts of one or two similar proteins were found in blueberry, but not in apple or grape. The 62 kD peach protein originally found in buds was also present, in lesser proportions, in peach shoot xylem and phloem tissues, but not in petioles or seeds. Apple exhibited a major protein band at ca. 31 kD that may be a storage protein. The similarities and disparities in protein profiles between fruit crops, as well as changes that occur during winter, will be discussed with respect to dormancy, cold hardiness, and storage compounds.
The reproductive biology of the climbing cacti Hylocereus polyrhizus (Weber) Britt. & Rose, H. undatus (Haworth) Britt. & Rose, H. costaricensis (Weber) Britt. & Rose, and Selenicereus megalanthus (Schum. ex Vaupel) Moran (syn. Mediocactus megalanthus) was studied with the aim of cultivating the cacti in Israel as fruit crops. Flowering in Hylocereus spp. occurred in two to three waves during the summer, whereas in S. megalanthus, flowering was concentrated at the end of autumn. Flowers of all species opened 1 to 1.5 hours before sunset and closed ≈6 hours after sunrise. In the Hylocereus spp., H. polyrhizus and H. costaricensis were self-unfruitful, and cross-pollination with other species led to high fruit set (100%). Hylocereus undatus was self-fruitful, setting fruit with self-pollen. Cross-pollination between the clones of S. megalanthus led to a high fruit set and each clone was self-fruitful. In contrast to H. undatus, S. megalanthus clones could set fruit without pollen vector involvement, although the set was slightly lower than with hand pollination. Pollen source influenced fruit weight. In the self-fruitful species of Hylocereus, fruit obtained by hand cross-pollination with other Hylocereus spp. were significantly heavier than fruit obtained by hand self-pollination. The largest fruit in each of the Hylocereus spp. were obtained by specific cross-combinations within the group. Fruit of S. megalanthus had a lower weight than fruit of the Hylocereus spp. Flowers of all species were visited by day-active honeybees only. Fruit set and fruit weight with open pollination was lower than with hand pollination in Hylocereus spp. Since stigma receptivity and pollen germinability stayed high during anthesis, the low pollination effectivity has to be related to other factors, such as the short bee visits and the absence of specific adaptation by the bees to the flower. In S. megalanthus, fruit set and fruit weight with open pollination were similar to values obtained with hand pollination. This similarity is probably related to the fact that pollen transfer in open pollination is achieved by bee visits and direct transfer of pollen to the stigma, which occurs via physical contact between anthers and stigma during flower closing.
to be indigenous to North American Rosaceous plants and was first reported in the 19th century. Although it attacks a variety of fruit crops, european pears are particularly susceptible to tree damage and death from the disease ( Van der Zwet and Kiel