Abstract
Urban Horticulture is a new area of scientific horticulture concerned with functional uses of plants to maintain and improve urban environments. “Functional uses” means that plants are used not only for beauty and ornamentation, but also as screens against wind, headlights, and unpleasant views, to influence climate, perhaps to reduce noise and combat forms of air pollution, for essential food and variation in human diet, and to improve the human psyche in densely populated areas. The constituent audiences for urban horticulture are people who utilize plants, primarily in landscape situations, including landscape maintenance and parks personnel, landscape architects, arborists, highway planters, nursery contractors, members of plant societies, and amateur horticulturists.
Abstract
Horticultural crops play an important role in meeting the needs of man for vitamins and minerals. The serious problem of calorie-deficient diets can be relieved by many horticultural crops, although most of the world’s food energy is derived from grains. It is generally accepted that the most serious problem of underfed people in the less developed countries is one of protein-calorie malnutrition, particularly in infants, young children and pregnant and lactating women (1, 6). What part do horticultural crops play or what part might they play in closing the protein gap?
Abstract
A consistent preference by the meadow vole, Microtus pennsylvanicus, for the roots of certain inbred carrot lines and hybrids observed in field plantings suggested the possibility of using these animals to evaluate carrot breeding material for nutritive value and culinary quality. In a preliminary field test, 50 carrot lines representing the full range of feeding damage were planted in a confined feeding experiment. Lines showing no damage and severe damage were selected for controlled feeding trials and further evaluation.
In laboratory ad libitum feeding tests, all carrot diets were inferior to control diets. There was no relationship between vole preference and the nutritive value of the carrots as measured by the growth response of weanling voles. However, vole preference showed a significant positive correlation with the sucrose content of the roots while a significant negative correlation was found between preference and total reducing sugars. Neither growth response nor vole preference was correlated with crude fiber, protein, or total carbohydrates. No correlation was found between taste panel scores for overall rating of carrot samples and ad lib. feeding indexes by the voles.
Fruits and vegetables are rich sources of the micro mineral elements and vitamins often lacking in diets based on cereals, grain legumes, and starchy roots and tubers, but void of animal products. When embarking on a breeding program to improve nutritional compounds, the way the fruit or vegetable is consumed in mixed diets must be considered. To alleviate nutritional problems, the nutrients must not only be present in the plant parts consumed, but also absorbed efficiently in the body. In some cases, it may be necessary to modify compounds to improve absorption as well as increase the concentration. Breeding to improve nutritionally related traits can be approached in a manner similar to that for other traits; i.e., identification of genetic variability, selection for enhanced levels using either individual phenotype or family mean values, and testing for field performance. In addition to improving amount and availability, avoidance of undesirable correlated responses due to genetic or physiological linkages between the trait of interest and other traits deleterious to either plant growth or the consumer is critically important during selection. The growing number of molecular marker-based linkage maps should prove especially useful for identifying genes of interest and employing marker-aided selection. When insufficient variability for amount or type of compound is present in the gene pool, strategies using transgenic plants may be useful.
Carrots contribute ≈14% of the total Vitamin A to the human diet in the United States due to the presence of the provitamin A carotenoids α- and β-carotene. We have described a recessive gene (rp) that inhibits carotenoid biosynthesis in carrot by 93%, resulting in whitish-yellow roots. The rp mutation is also associated with relatively high levels of a tocopherol (Vitamin E, 0.61±0.15 mg α-tocopherol/100 g FW). Vitamin E is a powerful antioxidant that must be obtained from the diet. The biosynthesis of a tocopherol in carrot has not been studied in any detail; however, the rp gene may provide clues as to its mechanism. The production of carotenoids and tocopherols is biosynthetically linked by their common precursor, geranylgeranyl diphosphate (GGDP). GGDP is converted into phytoene by phytoene desaturase to produce carotenoids and combined with homogentisic acid to produce tocopherols. Carotenoid and tocopherol profiles for various carrot genotypes are presented alongside a model describing the potential relationship between root carotenoids and tocopherols in carrot. The presence of significant amounts of tocopherols in carrot could significantly raise the nutritional profile of this vegetable.
Sweetpotato resin glycosides were purified by HPLC methods. Most allelopathic potential could be explained by these compounds. Fifty percent inhibition (I50) of seed germination was obtained for redroot pigweed at 160 ppm, for velvetleaf at 13 ppm and for prosomillet at 11 ppm. Seed of the congeneric species I. purpurea was not sensitive. Growth of yellow nutsedge was drastically reduced, the I50 for shoot growth was 30 ppm, for number of roots 36 ppm, and for total root length 19 ppm. The glycosides accounted for approximately half of the total fungicidal activity of all extract fractions when tested on Fusarium oxysporum pv. batatae. At 2 mg per ml, the glycosides inhibited hyphal growth by 31%. This concentration is less than 10% of the glycoside concentration in dry periderm tissue of `Regal'. The purified glycosides were incorporated into a meridic diet for diamondback moth larvae. All observed antibiosis was caused by the glycosides; the LD50 was 7.2 mg per ml diet. At that concentration the surviving larvae showed a weight decrease of 46%.
The origins, demise and current status of some common misconceptions about the role of fruit and vegetables in human nutrition are discussed. Most, but not all, of the misconceptions were held by the public. The early widespread belief that tomatoes were poisonous was gradually overcome, and today the tomato is one of the most versatile and widely used foods in the diet. Recent reports suggest that consumption of tomatoes and tomato products has the potential to reduce the risk of certain cancers. Our current awareness of the potential of spinach in nutrition and health evolved from an early misconception that its only important nutritive value was as a source of iron. The connection between foods from the nightshade family and arthritis and the connection of cherries and gout relief are discussed briefly. The misconception that a wide variety of fruit and vegetables was not needed in the human diet was rejected long ago. Today fruit and vegetables are considered essential for their intrinsic nutritive value and for their potential health functionality because of the phytochemicals they contain.
The authors are grateful to Dr. Masahiro Mii, Faculty of Horticulture, Chiba University, for his advice and critical reading of this manuscript. This research was supported by Diet and Cancer Prevention: Exploring Research Technology, Miyazaki
Abstract
A laboratory procedure for assaying Lycopersicon spp. for resistance to the tobacco hornworm Manduca sexta (L.) is described. Results from this procedure, which employed excised foliage from greenhouse grown plants and first instar hornworm larvae from a colony maintained in the laboratory on artificial diet, were similar to those obtained with intact plants, with field collected hornworm larvae, and with field grown resistant plants. The Lycopersicon hirsutum f. glabratum accessions PI 134417 and LA 407 were highly resistant to M. sexta. Resistance was manifest as a significant reduction in larval survival and in weight gained by survivors over a 72 hour period. The interplant variation in larval weight gains within accessions was highly significant, suggesting that most of the accessions tested were segregating for resistance to M. sexta.
We present the decision case titled “One Size Does Not Fit All” developed for use in a capstone experience in the College of Agriculture and Natural Resources. The decision case requires an oral and written presentation of a solution to a problem posed in the case. Students work in small groups comprised of students with many majors within the college. The case study is based on the recent NRC report titled “Pesticides in the Diets of Infants and Children,” and the perceptions of the public concerning pesticides, baby food, and children. We outline how this case study was developed, the support material supplied to the students, and the experiences and observations that we have made as a result of using this case study. In addition, we outline how this case study could be modified to address other questions related to pesticides and food safety in a classroom setting.