Periderm and cortex tissues of 14 genetically diverse sweetpotato [Ipomoea batatas (L.) Lam.] clones were grown under low stress conditions and analyzed for their content of scopoletin ((7-hydroxy-6-methoxycoumarin) and scopolin (7-glucosylscopoletin). A wide range of concentrations of both compounds was found in both tissues. The two compounds were tested in vitro for their biological activity (concentration-activity relationships) using several bio assays: germination of proso-millet (Panicum milliaceum L.) seed; mycelial growth of the sweetpotato fungal pathogens Fusarium oxysporum Schlecht. f. sp. batatas (Wollenw.) Snyd. & Hans, F. solani (Sacc.) Mart., Lasiodiplodia theobromae (Pat.) Griffon & Maubl., and Rhizopus stolonifer (Ehr. ex Fr.) Lind; and growth and mortality of diamondback moth[Plutella xylostella (L.)] larvae on artificial diet. The glycoside scopolin showed little activity, except moderate inhibition of F. oxysporum. The aglycone scopoletin inhibited seed germination and larval growth; however, at much higher concentrations than were measured in the tissues. Mycelial growth of the four pathogenic fungi, however, was inhibited at concentrations occurring in some sweetpotato clones.
The world produces adequate food for everyone, but unequal distribution has created a gap between the countries that produce more food than they consume and those countries with deficit production. About 815 million people suffer from hunger and malnutrition, mostly in the developing world. By 2020, the developing world is expected to face the overwhelming challenge of a 97.5% increase in population; moreover, developing countries will face serious challenges with the trend of a major shift in population from rural to urban areas, where 52% of the people will live in megacities—all asking for more food, land, and infrastructure. According to the World Health Organization, an estimated 334 million children in developing countries are malnourished. In 2020, one out of every four children in these countries will still be malnourished. It is recognized that modern agriculture must diversify production and achieve sustainable higher output to supplement food security. In order to reduce pressure on cereals as well as to improve human nutrition through the consumption of other nutritious crops, diversification in cropping patterns can provide better options. The increased production and consumption of fruits and vegetables, with their wide adaptation and providers of important nutrients (especially vitamins and minerals), offer promise for the future. Fruits and vegetables as food and diet supplements are gaining momentum in most countries. In addition, recent experimental evidence has shown the growing importance of fruits and vegetables in the prevention of noncommunicable diseases. Further, horticulture would play an important role in urban and peri-urban agriculture and development.
Abstract
It is a pleasure to be introducing this symposium to provide an appreciation of the real interest that NASA has in using plant systems for life support in space. The symposium is directed toward providing details on what is planned, and what is actually underway, in this effort. It is a program that has been titled CELSS, Controlled Ecological Life Support System, and involves a tremendous breadth of horticultural areas—areas that can require the expertise of nearly everyone in horticulture, as suggested in Fig. 1. The project must start with plant propagation, probably tissue culture propagation, and involve all aspects of environmental optimization of growth, breeding of adapted cultivars, nutrient, possibly nutrient film, feeding techniques (NFT) and automated nutrient recycling, contaminant control in the atmosphere, pathogen control in the nutrient solution, precise growth modeling for regulation of the system, maximization of harvest index to reduce inedible portions, efficient food processing, balanced diets, and complete recycling of all wastes. The expertise of all types of horticulturists is needeed if this project of NASA is to be successful.
Students are often unable to relate the vegetables and fruits consumed as a snack or part of a meal to the plant parts discussed in botany class. Therefore, an exercise was developed for an introductory horticulture course to increase a student's awareness of botany in everyday life. Fresh produce was brought in from local gardens, grocery stores, or farmers markets. Vegetables and fruits were selected that are consumed for their roots, stems, leaves, flower, fruit, and seeds. As each vegetable or fruit was introduced, students named the plant and plant part. As each part was identified it was “dissected” to show the taxonomic features. The different fruit types, i.e., berry, hesperidium, pepo, drupe, and pome were explained. Students were encouraged to taste all vegetables and fruits as they were prepared. Most students sampled the produce as it was passed around the group. Students easily recognized much of the produce, i.e., carrots, asparagus, tomatoes, peas, oranges, and broccoli. The second part of the exercise exposed students to vegetables and fruits that were unfamiliar. Most of the students had little exposure to the more exotic fruits and vegetables that are now available. New vegetables and fruits that students said they would add to their diet include jicama, pomegranate, and star fruit.
Pigeon pea is an important food crop for the Puerto Rican diet, as well as the economy. Pigeon pea ranks fourth in production among edible legumes in production worldwide. It can be consumed dried or as a vegetable (fresh, frozen, or canned). Canned, frozen, and dried peas are commonly used when fresh peas are no longer available. Due to the preferred flavor of fresh pigeon pea, it commands a higher market premium, selling for more than twice the price of the dried product. Although there is a great demand for this vegetable in Puerto Rico, virtually no research has been done on fresh pigeon pea postharvest physiology and its overall keeping quality. Baseline data on pigeon pea physiology, including respiration and ethylene production rates, soluble solids, titratable acidity, color reflectance, chlorophyll content, and responses to ethylene are presented here in order to establish the optimum storage temperature. Using this information, fresh pigeon pea consumption could increase locally, and exporting opportunities for shipping pigeon pea to alternative markets could be expanded.
Squash and pumpkins (Cucurbita sp.) are important contributors of beta-carotene to the diet. Consumers of tropical pumpkin and butternut squash (both C. moschata Duchesne) prefer a deep orange mesocarp color. Color intensity is related to carotene content. Among the five domesticated Cucurbita species, C. moschata and C. argyrosperma Huber have a close relationship. In crosses between these two species, fertile F1 plants can be easily obtained when using C. argyrosperma as the female parent. This research studied the relationship between and within C. moschata and C. argyrosperma by sequencing three genes in the carotenoid biosynthesis pathway and generating gene trees. Genotypes used in the study differed in flesh color from very pale yellow to dark orange. In some cases, haplotypes were associated with a particular mesocarp color. Further study of these types of associations may improve our understanding of color development in Cucurbita. The frequency of single nucleotide polymorphisms (SNPs) in the sequenced fragments was low. There were more SNPs and more heterozygotes among C. moschata accessions than among C. argyrosperma accessions. Haplotypes of the outgroups (C. ficifolia C.D. Bouché and C. maxima Duchesne) were always distinct from C. moschata and C. argyrosperma. These later species had both distinct haplotypes and shared haplotypes. Haplotypes shared among species tended to be maintained in the same branch of the phylogenetic tree, suggesting either gene flow between the species or a common ancestral gene. Both explanations suggest a close genetic and evolutionary relationship between C. moschata and C. argyrosperma.
The horticulture industry continues to show interest in using stabilized organic wastes as a component of container media. Vermicompost, also known as worm-worked waste or worm castings, is one of these materials of interest and can be produced from a number of organic wastes, including manure wastes. One issue that has not been addressed is the uniformity of vermicomposts produced from wastes of different sources. Are all vermicomposts created equal? The uniformity of vermicompost is important for growers to consider when using as a medium amendment. This research project investigated the physical properties of vermicompost 1) from different sources of wastes and 2) from a single waste source sequentially sampled over time. The first stage determined the physical properties of vermicompost from beef manure, hog manure, and peat-based media used by two earthworm growers. There were significant differences between the four vermicomposts in bulk density, air volume, percent air volume, percent volumetric moisture, total porosity, and water holding capacity. The second stage involved determining the physical characteristics of vermicompost produced from beef manure collected at the Illinois State University Research Farm from cattle receiving a consistent diet through the year. Manure was collected bimonthly. There was no difference in vermicompost bulk density among the samples. There were significant differences in air volume, percent air volume, percent volumetric moisture, total porosity, and water holding capacity. These changes in vermicompost physical characteristics must be quantified for growers to accurately predict performance as a growth medium amendment.
Plant growing systems have consistently utilized the standard Earth day as the radiation cycle for plant growth. However, the radiation cycle can easily be controlled by using automated systems to regulate the exact amount of time plants are exposed to irradiation (and darkness). This experiment investigated the influence of different radiation cycles on plant growth, chlorophyll and carotenoid pigment accumulation in kale (Brassica oleracea L. var. acephala D.C). Kale plants were grown in growth chambers in nutrient solution culture under radiation cycle treatments of 2, 12, 24, and 48 h, with 50% irradiance and 50% darkness during each time period. Total irradiation throughout the experiment was the same for each treatment. Radiation cycle treatments significantly affected kale fresh mass, dry mass, chlorophyll a and b, lutein, and beta-carotene. Maximum fresh mass occurred under the 2-h radiation cycle treatment. The maximum dry mass occurred under the 12-h radiation cycle treatment, which coincided with the maximum accumulation of lutein, beta-carotene, and chlorophyll a, expressed on a fresh mass basis. The minimum fresh mass occurred during the 24 h radiation cycle treatment, which coincided with the largest chlorophyll b accumulation. Increased levels of chlorophyll, lutein and beta-carotene were not required to achieve maximum fresh mass production. Environmental manipulation of carotenoid production in kale is possible. Increases in carotenoid concentrations would be expected to increase their nutritional contribution to the diet.
Cowpea, Vigna unguiculata (L.) Walp., is a very important legume in the diet of the population of the Amazon. Although it is autogamous, this species has a cross-pollination rate of ≈10%. Over several years, the mean productivity of cowpea has declined. We suggest that this is linked to a decrease in or an absence of pollinating insects in the fields. The objective of this study is to ascertain the pollinator contribution to cowpea production, as well as to determine the pollination type of the `BR3-Tracuateua' cultivar. In an experimental design, four treatments were compared: no pollination, with flowers in cages to prevent insect visits; open-pollination, with flowers exposed to all visiting insects; self-pollination, with flowers pollinated with their own pollen; and cross-pollination, with emasculated flowers being pollinated manually with pollen from another plant. We observed higher fruit set in the presence of pollinators (83%) than in their absence (77%, caged flowers). However, cross-pollination reduced both the number of seeds per pod and fruit set relative to self-pollination. This result suggests that pollinators have a complementary role in the yield of cowpea, by creating a mixed pollination system where self-pollination dominates.
Japanese beetles (JB), Popillia japonica Newman, are destructive, highly polyphagous herbivores that show a general preference for Rosaceous plants. Choice and nochoice feeding assays were conducted to determine the level of resistance among 10 taxa of Malus spp. Mill. Under no-choice conditions, M. baccata (L.) Borkh. `Jackii', M. × `Hargozam' Harvest Gold and M. transitoria (Balatin) Schneider `Schmitcutleaf' Golden Raindrops were highly resistant, with <2 cm2 leaf area consumed in 24 hours. M. × `Radiant' was highly susceptible, with 7.6 cm2 consumed, and the remaining six cultivars were intermediate. Under choice conditions, eight taxa were resistant with <10% defoliation, M. × `Red Splendor' was intermediate with 26%, and M. × `Radiant' was susceptible with 73% defoliation. Feeding responses to eight individual phenolics were tested in artificial diets over a range from 0 to 100 mm. Phloridzin, phloretin, naringenin, and catechin were all feeding deterrents, whereas quercetin and rutin were feeding stimulants. Chlorogenic acid stimulated feeding at low concentrations and deterred feeding at higher concentrations (i.e., a peak response). Kaempferol had no effect. Analysis of endogenous foliar phenolics showed considerable variation in concentrations among taxa. Stepwise multiple regression analysis identified phloridzin as the only endogenous phenolic that was significantly related to resistance under both choice and no-choice feeding conditions.