Showing papers in "Economic Botany in 1985"

Founder effect in crop-plant evolution

Abstract: Seed-crop plants apparently originated from a limited number of mutants in which seed dispersal was changed from that found in nondomesticated populations. Seed nonshattering in cultivated plants may be controlled by a single gene or a small number of genes. Allopolyploid crop plants were derived from a limited number of interspecific hybridizations followed by chromosome doubling. The consequence of this founder effect is a narrow genetic variability in the crop population compared to its wild progenitor. Natural hybridization between the two is prevented by various isolating mechanisms, and gene flow, if it exists, is apparently more effective in the direction from the cultivated to the wild populations. Founder effect in crop-plant evolution indicates the value and the breeding potential of the genetic variability remaining in its wild relatives.

Potential consequence of plant extinction in the United States on the current and future availability of prescription drugs

Abstract: This paper attempts to answer the question: What is the dollar value that can be placed on a single plant species now growing in the United States, should it become extinct? Based on available botanical and prescription survey data and data on global studies of plants as a source of new drugs for human use, the value of a single species is calculated to be $203 million, and the total value of plant species growing in the United States that may become extinct by the year 2000 AD is calculated to be about $3,248 billion.

Harvest Security and Intraspecific Diversity in Traditional Tropical Agriculture

Abstract: The horticultural strategies of traditional tropical agriculturists center on the preservation of harvest security. In addition to cultivating simultaneously numerous species of crops, traditional tropical farmers also plant multiple varieties of each crop. These cultivars are frequently distinguished on the basis of color, ranging from white to yellow to red to purple. In addition to varying in appearance and taste and in resistance to environmental stresses, the color-based varieties often differ in length of growing season. By practicing multicolored, intraspecific polyculture, the traditional tropical farmer either provides himself several opportunities to secure a complete single harvest and/or staggers his harvest throughout the year and thus, in either case, preserves his lifestyle. Acceptance of Green Revolution technologies by traditional tropical farmers would accelerate if they were offered multiple, high-yielding varieties of staple food crops of varying color and maturation periods.

Selection for perceptual distinctiveness: evidence from Aguaruna cultivars of Manihot esculenta

Abstract: This paper presents evidence that cultivars of manioc (Manihot esculenta) have been selected for combinations of characters that allow them to be perceptually distinguished. This mode of selection is proposed to explain why cultivars are so variable in perceptually salient taxonomic characters unrelated to the use or survival of the plant. This paper reanalyzes published material on manioc and related species and presents new evidence from the inventory of manioc cultivars maintained by the Aguaruna Jivaro of northern Peru. Rogers and Fleming’s (1973) sample of manioc cultivars exhibits 3 characteristics implied by the model of selection for perceptual distinctiveness: high, continuous, and independent variation of nonadaptive taxonomic characters. The inventory of Aguaruna cultivars exhibits 2 additional characteristics predicted by the model: taxonomic characters of this local inventory vary as independently and nearly as greatly as those of the species as a whole. Anthropological evidence is presented to demonstrate that Aguaruna interact with the plants as predicted by the model: Aguaruna identify cultivars using many of the same characters as Rogers and Fleming and they confuse cultivars they regard as similar in stem color, petiole color, and leaf shape. The evidence suggests that procedures used by cultivators to identify cultivars leave their imprint on the plants; crops show the effect of the cultivator's eye as well as hand.

Maize and man in the Greater Southwest

Abstract: In northwest Mexico, along the Sierra Madre Occidental and the adjacent slopes and plains, maize forms the center of a series of cultural traits illustrative of the interrelationships of man and plants. Here more than 20 racial types have been collected. This diversity is related to the variation in climate and soil conditions, to human migrations from the Mesoamerican cultural center to the Greater Southwest area, and to the differential selection by the ethnic groups in the region. The agricultural practices of the farmers are reviewed to illustrate how different aspects of environment, economic needs, food preference, manner of utilization, and ceremonial concepts constitute continuing forces of selection and motivation for introduction of varieties from other areas. It is suggested that color of the grain is utilized as an indicator of physiological characteristics. A phenotypic analysis of more than 600 collections from the area indicates the occurrence of constant intercrossing among maize populations.

Growth characteristics of aquatic macrophytes cultured in nutrient-enriched water: II. Azolla, Duckweed, and Salvinia

Abstract: Seasonal growth characteristics and biomass yield potential of 4 small-leaf, floating, aquatic macrophytes cultured in nutrient nonlimiting conditions were evaluated for central Florida’s climatic conditions. Biomass yields were found to be 10.6, 11.3, 16.1, and 32.1 t (dry wt) har−1 yr−1, respectively, for azolla (Azolla caroliniana), giant duckweed (Spirodela polyrhiza), common duckweed (Lemna minor), and salvinia (Salvinia rotundifolia). Operational plant density was in the range of 10–80 g dry wt m−2 for azolla, 10–88 g dry wt m−2 for giant duckweed, 10–120 g dry wt m−2 for common duckweed, and 35–240 g dry wt m−2 for salvinia. Specific growth rate (% increase per day) was maximum at low plant densities and decreased as the plant density increased. Results suggest that small-leaf, floating plants may not be suitable in monoculture biomass production systems because of low biomass yields, but they may be suitable for inclusion in poly culture systems with larger aquatic plants. The high N content (crude protein = 20–33%) of small-leaf,floating plants suggests the use of biomass as animal feed.

Plants used for reproductive health in Oaxaca, Mexico.

Abstract: The use of herbal remedies for the treatment of reproductive health problems and the management of reproduction is still nearly universal in many indigenous communities throughout modern Mexico This paper describes the medicinal plants and related substances used for childbirth, fertility regulation, and the treatment of reproductive disorders in a bilingual Chinantec-Spanish speaking township in highland Oaxaca The discussion focuses on how the group’s ideas about reproduction and reproductive physiology influence their selection of these plant species

Native crop diversity in Aridoamerica: Conservation of regional gene pools

Abstract: Scholars have seldom considered the native crop diversity in northwest Mexico and the U.S. Southwest as resources of the same cohesive ecological and cultural region. The term Aridoamerica is introduced to describe this overlooked center of plant domestication and diversification, which is distinct from centers of Mesoamerica and the Mississippi Valley. To understand why certain of its landraces are unique, the systematic relationships and gene-pool relations of crops found prehistorically and protohistorically in Aridoamerica are reviewed. Signifcant crop/ weed introgression continues where indigenous agriculture persists, but native fields are being rapidly abandoned or converted. In planning in situ and ex situ conservation efforts to maintain this diversity, both cultural factors and plant population genetics must be considered.

Subsistence benefits from the babassu palm (Orbignya martiana).

Abstract: Stands of babassu palms (Orbignya martiana) occupy an area of Brazil estimated at nearly 200,000 km2, concentrated in the states of Maranhao, Piaui and Goias. Babassu’s cryptogeal germination, establishing the apical meristem of the plant below ground for its early growth and development, enables it to survive human disturbance, making the palm an integral part of shifting cultivation and pastoral farming systems. People obtain a multitude of products from babassu throughout the palm’s life cycle: leaves are used widely for thatch, basketry, and construction; trunks for palmito and bridges; the fruit for feed, oil and, charcoal. As many as 450,000 subsistence-level households rely on the sale of babassu kernels, used in a regional vegetable oil industry, for an important share of their cash incomes. Deforestation pressures and technological innovation toward an industry based on mechanical processing of whole babassu fruit threaten to reduce benefits the palm provides to the region’s rural poor. Understanding how babassu is used by rural families who depend upon it will help to make current efforts at “domesticating” the palm and whole-fruit processing more responsive to human needs.

Ethnobotany of the Naranjilla (Solanum quitoense) and its relatives

Abstract: One of my former students, who happens to be here tonight, some time ago suggested that instead of giving one of my interesting, humorous and entertaining talks I should use the occasion to say something significant, if not profound. That was a difficult assignment, but I did give it some consideration. I thought of speaking on the food problems of the world, but I decided against it for two reasons. First, I think that as economic botanists you should be well aware of the problems and that you also realize that we are in a position to offer some solutions. Maybe a single individual can do very little, but collectively I think we could have an impact. The second reason is that I feel that after eating the way we have tonight, it would be embarrassing to say more than I already have on this subject. So I am going to compromise. I hope the subject is neither too light nor too ponderous and hence suitable for the occasion. I thought that I would try to convey to you, by using some of my own research, why I find ethnobotanic research so fascinating and how it may at times take some unusual turns. I used the word ethnobotany in my title although I realize that this is an economic botany meeting. Perhaps I should try to distinguish between ethnobotany and economic botany. Ethnobotany may be defined as the study of plants in relation to people. Obviously it is a very broad field, including many, if not all, aspects of botany, and many other disciplines as well. Economic botany, on the other hand, usually concerns such subjects as the production, distribution and consumption of plants useful to people. Some (for example, Maheshwari, 1983) would limit ethnobotany to the use of plants by "primitive" human societies; economic botany, therefore, would concern plants and modern human societies. I, however, would prefer to think of ethnobotany as comprising both fields, and that perhaps economic botany is then a subdivision of ethnobotany that is involved where money becomes an important consideration. At the same time I feel we might also think of it as botany in the service of humankind today.

Kura clover (Trifolium ambiguum): Legume for forage and soil conservation

Abstract: Kura clover (Trifolium ambiguum) is a perennial legume adapted to many temperate regions where grassland agriculture is of importance. Previous and widespread adoption of this species has not taken place because of problems associated with inoculation and subsequent nitrogen fixation. A commercial inoculant is now available that has proven to be effective in a number of trials. With an extensive root-rhizome complex, Kura clover may find use as a forage, for soil conservation purposes, and in forage crop improvement programs. Kura clover establishes very slowly, however, and seed supplies at the present time are very limited. Widespread use of this species will, therefore, proceed slowly.

Forest-product trade in a lowland Filipino village

Abstract: Forest-product use among nonforest dwelling cultural groups in Southeast Asia is not well known, particularly in contrast to what is known about indigenous forest-product collectors. A case study in one lowland Filipino village in Leyte, Philippines, revealed that over half of village households depend upon 8 species of commercially valuable rattan and 8 species of timber as a primary source of livelihood, and that all village households collected forest-products for supplementary and emergency income. The future of the rattan and timber trade on Leyte is seriously threatened by agricultural encroachment and intensive collecting pressures in the absence of forest management.

Numerical analysis of allozyme variation inCucurbita pepo

Abstract: Cucurbita pepo, represented by cultivated forms of squash, pumpkins, and ornamental gourds, is a morphologically diverse species. Although several classifications of the cultivars have been proposed, none has been fully accepted. In an attempt to clarify the systematics of theC. pepo cultivars, allozyme variation was assayed. Twelve loci representing 6 enzyme systems (GOT, IDH, MDH, PER, PGI, and PGM) were screened. Seven of the loci were polymorphic. Electrophoretic data were collected for 50 accessions representing 14 commercial cultivars and a landrace from Mexico. Statistical analyses of the allozyme data revealed a biochemical basis for characterizing cultivars that agrees with morphology. Principal component analysis and cluster analysis revealed a major subdivision within the species above the level of cultivars. Genetic identities among groups of cultivars were much lower than those usually found among conspecific populations for outcrossing plants, possibly reflecting the influences of populational subdivision, drift, and selection particular toC. pepo.

Indian almond (Terminalia catappa), salt-tolerant, useful, tropical tree with “nut” worthy of improvement

Abstract: Native to the East Indies, commonly grown in India, casually planted for shade and ornament throughout the tropics, the Indian, or tropical, almond (Terminalia catappa) is still not fully appreciated nor utilized as a multipurpose tree Fast-growing, to 80 ft, the tree flourishes with little or no care, exposed to coastal winds and salt spray It furnishes timber of excellent quality, bark suitable for tanning, and dyes from both wood and bark The seed kernel is delicious and wholesome without processing, though the bulk of the abundant crop is wasted through ignorance of an easy mode of extraction and lack of selection and propagation and promotion of strains with large kernels

Allozyme differentiation in theCucurbita pepo complex:C. pepo var.medullosa vs.C. texana

Abstract: Two interfertile species ofCucurbita, the wildC. texana and the domesticatedC. pepo (var.medullosa), were hybridized to elucidate the genetic basis of inter-specific differences in isozyme phenotypes. Presented here are descriptions of phenotypes associated with 6 enzyme systems (GOT, IDH, MDH, PER, PGI, PGM). Genetic interpretation for 6 gene loci and 12 alleles is based on F2 segregation data while 10 additional loci and 15 alleles are presumed on the basis of phenotypic variation found throughout theC. pepo complex. A coefficient of genetic identity calculated for single populations of each taxon was within the range that traditionally separates species. However, observations on phenotypes in both taxa leave the taxonomic delimitation of C. texana unresolved. The complexity of banding patterns in some enzyme systems suggests a polyploid origin for the genus Cucurbita.

Vicia johannis and wild relatives of the faba bean: a taxonomic study

Abstract: Preliminary taxonomic and agronomic investigation was made of close relatives of the faba bean (Vicia faba) to aid future plant breeding. Cluster analysis of 2 yr’s morphometric data showed thatV. johannis is clearly separable from other members of theV. narbonensis complex. AlsoV. faba was much more distinct from eitherV. narbonensis orV. johannis than they are from each other. Petal colours at anthesis provided a rapid method of field identification forV. faba, V. narbonensis, andV. johannis. The 2 varieties ofV. johannis can also be distinguished by their petal colours: var. procumbens shows a marked colour change at anthesis and var. johannis does not. The geographical distribution of the plant material studied suggests thatV. johannis is found in Turkey and Europe despite being omitted from the major published floras. BothV. johannis andV. narbonensis possess agronomically useful characters of importance to faba bean breeders, including increased frost tolerance and resistance to bothAphis fabae andBotrytis fabae.

Copal and rattan collecting in the Philippines

Abstract: Minor forest products such as rattan and Manila copal have long been an important source of cash income for indigenous forest collectors in Southeast Asia. Focusing on the Tagbanua of Palawan Island in the Philippines, the history and economic significance of forest collecting in the region are described. The paper also documents the growing scarcity of forest products in Palawan and discusses several policy options intended to help preserve rattan and copal resources.

Limitations of a random screen: Search for new anticancer drugs in higher plants

Abstract: The inherent limitations of a random search of higher plants for novel cancer chemotherapeutic agents are reviewed—the National Cancer Institute’s (NCI) Anticancer Screening Program. A graphic summary of plant exploration for the NCI is depicted on a world map showing 58 floristic regions. It is estimated that less than one-half of the world flora is economically feasible for collection. Random screening of approximately 35,000 species has led to guidelines that precluded further screening of all species in 333 genera and another 2,905 species in 1,773 genera. These taxa are reported to represent one-half to two-thirds of the species that characterize vegetation in geographic areas most frequently explored for the NCI. It is estimated that 40,000 untested species of flowering plants are readily available and meet the NCI guidelines for antitumor screening. However, because of apparent diminishing returns from random screening of chemicals in plant genera, it is suggested that a good representation of the diversity in the world flora could be obtained in 10,000 collections, if random sampling follows the phytogeographic outline that is recommended. Modifications to the screening methodology might be geared to an expected point of diminishing returns for discovering novel chemotypes. Additionally, the NCI should continue random screening to increase the development of new anticancer drugs; past screening has generated a tremendous wealth of data. Finally, in this paper, the author proposes to utilize lists representing taxa commonly collected for the NCI to create a manual of worldwide common plants.

Relationships between maize and teosinte of Mexico and Guatemala: Numerical analysis of allozyme data

Abstract: Electrophoresis revealed 153 variants at 19 enzyme loci among 77 accessions of annual teosinte, 1 accession of diploid perennial teosinte, 1 accession of tetraploid perennial teosinte, and 43 accessions of maize from Mexico and Guatemala. One hundred and thirty-three (87%) variants were found within teosinte, and 95 (61%) variants were found within maize. Seventy-four (48%) variants were distributed among both teosinte and maize, whereas 58 (38%) variants were found only in teosinte and 20 (13%) variants were found only in maize. The majority of alleles were found in low frequency. A single allele predominated across maize and teosinte at 11 loci, 3 loci showed similar trends and 5 loci showed greater variability for the predominant alleles among maize and teosinte. Principal components analysis revealed little overlap between maize and teosinte, involving a minority of maize collections and Balsas teosintes. No clear evidence could be seen suggesting recent introgression between maize and teosinte. The collections of maize and teosinte were seen to represent a rich and contrasted array of germplasm.

Curry leaf (Murraya koenigii), perennial, nutritious, leafy vegetable

Abstract: Curry leaf (Murraya koenigii, Rutaceae) is an important leafy vegetable and the leaves are widely used in Indian cookery for flavouring foodstuffs. The leaves have a slightly pungent, bitter and feebly acidic taste, and they retain their flavour and other qualities even after drying. Curry leaf is also used in many of the Indian ayurvedic and unani prescriptions. The plant originated in the Tarai region of Uttar Pradesh, India, and at present it is cultivated in Burma, Ceylon, China, Australia and the Pacific Islands. The crop is usually propagated by seeds. A volatile oil, curry leaf oil, produced from the plant has uses in the soap industry. There is need to conserve the variability in the plant to prevent extinction of desirable types.

Plant utilization: Patterns and prospects

Abstract: Concern for the future of mankind, in a world of expanding human population and increasing demands on the biota, has intensified interest in the greater use of less well-known plants that are presumed to have potential to ameliorate current and predicted shortages of food and other products derived from organic sources. The premise that a wide range of plants is underutilized is examined. Consideration of plant use in hunting-gathering societies and through the development of agriculture places utilization in a different perspective and indicates that man selects from the biota plants that reflect and support his needs in any given cultural context and at any level of technological achievement. The future of agricultural systems and practices is considered. The potential of plants is discussed as an outgrowth of historical trends and predicted changes in the earth’s plant resource base and its genetic diversity, modifications in primary, secondary, and tertiary pools of utilized plants, and advances in biotechnology. The evidence indicates continued humanization of the world, greater management of biotic resources, and increased applications of technology to agriculture, accompanied by a general decline worldwide in species and genetic diversity and increasing simplification and internationalization of the primary and secondary pools of cultivated plants. The direct utilization of wild plants by man will become more limited. Increased use of plants thought to be underutilized is likely to develop largely in relation to new needs and imperatives of mankind.

Chemical constituents and energy content of two milkweeds,Asclepias speciosa andA. curassavica

Abstract: Asclepias speciosa and A. curassavica were evaluated as potential renewable sources of chemicals for use as fuel and/or chemical feedstock. Leaves and stems of both plants were analyzed for acid-detergent fiber, acid-detergent lignin, cellulose and ash. Bomb calorimetry was performed onA. curassavica (leaves 4,590 cal/g; stems 4,219 cal/g; and latex 4,663 cal/g), andA. speciosa (leaves 4,404 cal/g; stems 4,514 cal/g; and latex 9,005 cal/g). Organic carbon inA. curassavica (leaves 41.20%; stems 41.18%; latex 48.03%) andA. speciosa (stems 45.71%; leaves 42.51%; latex 67.30%) were also determined. Major differences between the 2 plant species were in the chemical composition of the latex; A. speciosa latex contained primarily α- and β-amyrin and their acetates, and a small amount of rubber, whileA. curassavica latex is known to contain at least 50% cardiac glycoside.

Plant species evaluated for new crop potential.

Abstract: About 500 plant species from various regions of the United States have been screened previously at the USDA Northern Regional Research Center for their multipurpose, energy-producing potential. Most collections have been from the rich flora of central Illinois. For this report, 92 additional species were collected from southern Illinois and evaluated by criteria previously established at this Center. Plant samples were analyzed for “oil,” “polyphenol,” “hydrocarbon,” and protein. Oil fractions of selected species were analyzed for classes of lipid constituents and were saponified to determine yields of unsaponifiable matter and fatty acids. Hydrocarbon fractions of selected species were analyzed for rubber, gutta, and waxes. Average molecular weight and molecular weight distribution of rubber and gutta were determined. of the 92 species, complete analytical data are presented for 16 selected species. Substantial quantities of oil were obtained fromPhiladelphias coronarius (5.0%; dry, ash-free sample basis),Cacalia muhlenbergii (4.1%),Lindera benzoin (4.1 %), andKoelreuteria paniculata (4.0%). High yields of polyphenol were obtained fromAcer ginnala (33.1%),Cornus obliqua (20.8%), andSalix caprea (20.0%). Maximum yields of hydrocarbon and protein were fromElymus virginicus (0.6%) andLindera benzoin (11.1%), respectively. Data are discussed with respect to species previously analyzed at this Center.

Botanical perspectives of ethnobotany of the Greater Southwest

Abstract: The historical roots of ethnobotany in North America are in the Greater Southwest. Today this region still provides the opportunity to study the biological bases of plant-people interactions and relationships. Various plants of the Southwest are discussed in the contexts of 1) recognition, short- and long-term values, and manipulation of resources, 2) changes in species diversity of edible plants, 3) domestication, and 4) role of archaeological, historical, and contemporary information in ethnobotany.

Economic prospects for new crops in the Southwestern United States

Abstract: Agriculture in the Southwest is productive but expensive. High yields of traditional crops depend on extensive irrigation. As water costs increase and water availability is reduced, production of traditional crops will decline. New crops with low water use (and consequently lower yields) will be needed if agriculture is to persist in the region. The best candidates will be drought-tolerant species with high value products. Plants producing botanochemicals will probably be favored over those yielding pulp, energy, commodity foods, or fiber.

Traditional preparation and uses of cassava in Nigeria

Abstract: Various methods of cassava preparation are practised by different ethnic groups in Nigeria. These methods involve peeling cassava roots, soaking roots in streams, grating cassava, and pressing grated cassava. Other methods include heating sieved, grated cassava, boiling peeled cassava roots, and pounding boiled or dried cassava roots. The traditional, cassava-based products aregari, fufu, akpu, cassava flour, edible starch, and tapioca. Detoxification of fresh cassava roots is partly achieved through cell rupture during cutting and grating, soaking in running or standing water in earthen pots for 3–5 days, heating, drying, and boiling.

Development of buffalo gourd (Cucurbita foetidissima) as a semiaridland starch and oil crop.

Abstract: Cucurbita foetidissima (buffalo gourd), a semiaridland plant native to the Greater Southwest, has been utilized by humans for thousands of years, primarily as food and medicine. In recent years, buffalo gourd has been the focus of an important domestication program at the University of Arizona. This research has led to 2 main cultural systems, an annual mode for root-starch production, and a perennial mode primarily for seed-oil production. In our paper, over 75 references are analyzed to evaluate the potential of buffalo gourd as an energy, chemical-products, and food crop. Priorities are suggested, including investigation of buffalo gourd as a novel crop for New Mexico's developing fuel ethanol industry.

Co-evaluation of plant extracts as petrochemical substitutes and for biologically active compounds

Abstract: Recent efforts to discover phytochemicals that could substitute for petroleumderived fuels and industrial feedstocks have not given much attention to the potential of these same phytochemicals to provide sources of biologically active compounds The suitability of extraction products made to assess specific plants as potential botanochemical sources has been evaluated for use in screening procedures for evidence of biologically active compounds Screening procedures for antibacterial, antifungal and toxic properties are discussed Screening results are presented for extracts of nearly 80 species of plants from the southeastern United States and southern Great Plains that had previously been evaluated as sources of botanochemicals

Breadfruit fermentation in micronesia

Abstract: Throughout Oceania, pit fermentation of starchy crops was used as means of ensuring a predictable food supply despite the vagaries of drought, cyclonic storms, and warfare. During a 6-mo period, fermentation techniques for breadfruit (Artocarpus altilis) were studied in Micronesia in the islands comprising Majuro, Guam, Belau, Yap, and Ponape. Fermentation techniques were found to vary throughout Micronensia but as a whole to differ significantly from techniques used in Polynesia. We believe the benefits of such food preservation technologies to be significant in facilitating colonization of temporally marginal island environments.

New native crops for the arid Southwest

Abstract: Agricultural production in the arid Southwest is heavily dependent upon water for irrigation. If current trends of water use continue, the amount of water available to agriculture in the year 2000 will only meet approximately 50% of the needs of currently available irrigated crop land. Development of new crops with low irrigation needs is of highest priority. None of the major crop plants of the world is well adapted to arid lands. However, in the Sonoran Desert, more than 375 species of noncultivated food plants have been identified, and approximately 40 of these served as major local food resources for native people in the region. Research and development of new crops must address the issues of water use, productivity, chemical composition, and quality. Domestication of native species that have evolved and became adapted to arid conditions in the Southwest is considered to be a good strategy. Research and development programs on such native, new crops as guayule, jojoba, and buffalo gourd are well underway. New domestication programs involvingCuphea species for medium-chain fatty acids,Lesquerella species for hydroxy fatty acids,Grindelia camporum for resin production, and interspecific hybrids ofBaccharis for landscape plant materials are described. The role of the USDA Agricultural Research Service, state agricultural experiment stations, and industry in the development of new crops is discussed.