Non-random foraging in certain bird pests of field crops

Two systems of bird-crop interactions were studied to explain the between- and the within-field variation in the foraging pattern of bird pests in agro-ecosystems. Weaverbirds and munias select rice fields with greater vegetation complexity and not based on the resource status. Within a selected area the concentration of feeding birds was greater close to vegetation cover and decreased non-linearly with increase in distance. Certain structural features and earhead characters of rice plants predisposed particular varieties for intense grain predation by birds. In the parakeet-sunflower system the extent of damage among plants within a field was closely linked to the foraging pattern of parakeets. The extent of achene predation by parakeets was influenced by certain structural features of sunflower plants and not the resource load of each plant. Selective feeding on sunflower plants was governed by the predator vigilance pattern; parakeets prefer to feed on plants that offered better field of vision. The results suggest that the observed pattern of foraging by bird pests in agro-ecosystems is non-random and is dependent on factors favouring predator avoidance behaviour and not on resource maximization.     

Basic loci in cultivation of certain crops in the past and modern times

Summary In 1968 H. Brücher asked: Gibt es Genzentren? He proposed a negative answer, but was wrong. The geographical distribution of the majority of crops is not even over all parts of their areas. There are loci of great abundance and regions of small plantations. The abundance of individuals in the large plantation is a factor favouring the display of genetic variability (an increase of the mutation number). The variability of ecological conditions, the antiquity of cultivation and the possibility of interspecific hybridization in such loci promote genetic variability; but a uniformity of ecological conditions and strong selection (natural or artificial) can eliminate new genotypes arising and preserve the homogeneity of the initial populations. Therefore loci of great genetic variability (Genzentren) exist only in conditions favourable for agriculture (with weak natural selection) and in conditions of a primitive consumer agriculture (without strong artificial selection). Loci of genetic variability can be observed in the following regions of a past or existing plantation abundance: in the ancient primary regions of domestication of certain plants; in the regions of ancient large scale cultivation around the primary domestication centers; and in the secondary loci of abundance in conditions favourable for agriculture where certain crops migrated from their primary cultivation regions. Certain loci of abundance (ancient and modern) have no noticeable genetic variability in their different crops, which are relatively uniform there. Such loci of abundance without genetic variability are either disposed at the periphery of the area of the particular crop, with worse natural conditions than in the rest of the area (control by strong natural selection), or are new loci of abundance in conditions of commercial agriculture (control by regular plant-breeding).All loci of polymorphism (Genzentren) are undoubtedly a temporary historical phenomenon. The absence of regular plant breeding was an indispensable condition for the rise of genetic variability loci in the regions of plantation abundance of certain crops. In modern times plant breeding becomes an inevitable component of commercial agriculture. Thus new loci of abundance have no great genetic variability and ancient centres of polymorphism of different crops now go to ruin, giving place to plantations of the few best varieties. Loci of genetic variability are now a relic of the past, while loci of abundance with the few best varieties conform with the economics of modern world agriculture, which aspires to cultivate each crop in the regions where its production cost will be lower and to avoid areas with an expensive product.

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Zusammenfassung H. Brücher stellte 1968 die Frage: Gibt es Genzentren? Er verneinte sie zu Unrecht. Die geographische Verbreitung von Kulturpflanzen ist im allgemeinen innerhalb ihrer Areale ungleichmäßig. Gebieten mit hoher Anbauhäufigkeit stehen solche mit geringem Anbau gegenüber. Die hohe Individuenzahl umfangreicher Anbauflächen stellt einen begünstigenden Faktor für die Entfaltung der genetischen Variabilität dar (Steigerung der Zahl der Mutanten). Sie kann in diesen Gebieten durch die Vielfalt ökologischer Bedingungen, ein hohes Alter des Anbaues und die Möglichkeit zu interspezifischen Hybridisationen noch gefördert werden.Durch eine strenge natürliche oder künstliche Auslese können neu entstehende Genotypen eliminiert und dadurch eine genetisch relative Einförmigkeit der Ausgangspopulationen erhalten werden. Daher sind Gebiete mit einer großen genetischen Variabilität (Genzentren) nur dort anzutreffen, wo günstige Anbaubedingungen für die jeweilige Art herrschen (geringe natürliche Selektion) und wo eine primitive Landwirtschaft mit wenig intensiver künstlicher Selektion praktiziert wird. Die Lage derartiger Mannigfaltigkeitszentren kann für eine Art in Zusammenhang mit natürlichen, historischen oder ökonomischen Veränderungen wechseln. Sie waren und sind gebunden an Gebiete der Inkulturnahme von Arten, an diesen benachbarte Regionen mit einer alten und umfangreichen Kultur der Art oder an sekundäre Anbauzentren mit günstigen Anbaubedingungen, in die sich Kulturarten aus den Primärzentren ausgebreitet haben.Bestimmte alte oder rezente Häufigkeitszentren besitzen bei manchen Kulturpflanzen keine bemerkenswerte genetische Variabilität. Das trifft entweder für die Peripherie des Kulturareals mit ungünstigen Anbaubedingungen und strenger natürlicher Selektion oder für jüngere Anbauzentren zu, in denen die Arten unter regulärer Kontrolle durch die Pflanzenzüchtung großflächig für kommerzielle Zwecke kultiviert werden.Alle Genzentren sind zweifelsohne ein temporäres historisches Phänomen. Das Fehlen einer Pflanzenzüchtung war die notwendige Bedingung für ihre Entstehung in den Anbauzentren bestimmter Arten. Heute ist die Pflanzenzüchtung eine unerläßliche Voraussetzung für eine leistungsfähige Landwirtschaft. Daher haben neuere Anbauzentren keine große genetische Variabilität, alte Mannigfaltigkeitszentren werden zerstört und durch den Anbau weniger, hochwertiger Sorten ersetzt. Genzentren sind heute ein Relikt der Vergangenheit, während genetisch verarmte Anbauzentren mit einer geringen Zahl leistungsfähiger Hochzuchtsorten den Bedingungen der modernen Landwirtschaft, die die einzelnen Kulturpflanzen für den Weltmarkt dort erzeugt, wo es aus ökonomischen Gründen optimal möglich ist, entsprechen.

     

Active attachment ofAzospirillum brasilense to root surface of non-cereal plants and to sand particles

The rhizosphere bacteriumAzospirillum brasilense Cd adsorbed strongly to light-textured and heavy-textured soils, but only slightly to quartz sand. Bacterial attachment to sand particles was mediated by a network made up of various sizes and shapes of fibrillar material. Inoculation of sand with an aggregate-deficient mutant resulted in no detectable fibrillar formation. Rinsing or agitating the sand, colonized by the wild-type and the mutant, had a greater effect on the mutant than on the parental strain. We propose that bacterial fibrils are essential for anchoring ofA. brasilense to sand. A. brasilense Cd was capable of efficiently colonizing the elongation and root-hair zones of tomato, pepper, cotton and soybean plants as well as of wheat plants. All inoculated plants demonstrated: (i) larger amounts of a mucigel-like substance on the root surface than non-inoculated plants, and (ii) fibrillar material which anchored the bacterial cells to the root surface. These fibrils established also connections between cells within bacterial aggregates. On non-water stressed soybean roots, mostA. brasilense Cd cells occurred as vibroid forms. Whereas, those on roots of water-stressed plants.(wilting) were cyst-like. A lower rhizosphere bacterial population was observed on water-stressed plants. When water stress conditions were eliminated, cells reverted to the vibroid form. A concomitant increase in the bacterial population was observed. We suggest that cyst-like formation is a natural response forA. brasilense Cd in the rhizosphere of water-stressed plants.     

Effects of the angle of inclination of traps on the numbers of large Diptera caught on sticky boards in certain vegetable crops

The angle of inclination of the surface on which flies prefer to land in vegetable crops was studied in field plots and in field-cages using one-sided sticky traps aligned in one plane but orientated in eight directions. The four Delia species studied, D. antiqua, D. floralis, D. platura and D. radicum, preferred to land on horizontal surfaces, indicating that they are likely to be trapped in largest numbers on traps with a horizontal trapping surface, such as water traps. This trend was even more pronounced with the Syrphidae. In contrast, greatest numbers of the carrot fly, Psila rosae, were caught on the lower surface of traps inclined at 45° to the vertical. The advantages of using traps inclined in this way for trapping P. rosae are that more flies are caught on such surfaces, the sticky trapping compound is protected from the adverse effects of rain, and the traps are highly selective.

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Résu,é L'angle d'inclinaison de la surface sur laquelle les mouches préfèrent atterrir dans les cultures de légumes a été examiné dans la nature, dans des parcelles et dans des cages, en utilisant des pièges englués sur un côté, alignés dans le même plan, mais orientés dans 8 directions. Les 4 espèces de Delia étudiées: D. antiqua, D. floralis, D. platura, D. radicum, ont préféré atterrir sur des surfaces horizontales, ce qui implique qu'elles sont probablement prises en plus grand nombre sur des pièges avec une surface de capture horizontale, comme des pièges liquides. Cette tendance est encore plus prononcée chez les Syrphidae. A l'opposé, de nombreuses mouches de la carotte, Psila rosae, ont été capturées sur la face inférieure de pièges inclinés de 45°. Il est avantageux d'utiliser des pièges inclinés de cette façon contre P. rosae parce que, d'une part ils sont très efficaces, d'autre part le produit actif est protégé de la pluie et enfin, le piège est très sélectif.

     

Purification and characterization of a thiol amylase over produced by a non-cereal non-leguminous plant, Tinospora cordifolia

A 43 kDa α-amylase was purified from Tinospora cordifolia by glycogen precipitation, ammonium sulfate precipitation, gel filtration chromatography, and HPGPLC. The enzyme was optimally active in pH 6.0 at 60 °C and had specific activity of 546.2 U/mg of protein. Activity was stable in the pH range of 4-7 and at temperatures up to 60 °C. PCMB, iodoacetic acid, iodoacetamide, DTNB, and heavy metal ions Hg²⁺ > Ag⁺ > Cd²⁺ inhibited enzyme activity while Ca²⁺ improved both activity and thermostability. The enzyme was a thiol amylase (3 SH group/mole) and DTNB inhibition of activity was released by cysteine. N-terminal sequence of the enzyme had poor similarity (12-24%) with those of plant and microbial amylases. The enzyme was equally active on soluble starch and amylopectin and released maltose as the major end product.     

Thiamin biofortification of crops

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Hydrocarbon-and rubber-producing crops

Agricultural production of rubber and other hydrocarbons in the United States may be compatible with increased food and fiber production if entire plants are harvested and processed for fiber, protein, and carbohydrate as well. Thus, procedures and criteria have been established for the preliminary evaluation of plant species as potential multi-use hydrocarbon-producing crops. Previously, 106 species representing 44 families and 81 genera were evaluated. Now an additional 100 species representing 13 additional families and 60 additional genera have been evaluated, and some of these species also offer promise as future crops. Several Labiatae are high in natural rubber (NR) content;Pycnanthemum incanum (Mountain Mint) andTeucrium canadense (American Germander) were evaluated as promising species. Three Compositae,Cacalia atriplicifolia (Pale Indian-Plant),Solidago graminifolia (Grass-leafed Golden-rod), andSolidago rigida (Stiff Goldenrod) were also evaluated as promising species for NR.Campanula americana (Tall Bellflower, Campanulaceae) has potential as a source of both oil and NR.Euphorbia dentata (Euphorbiaceae ) does not produce NR but is very high in protein and oil contents.Sassafras albidum (Sassafras, Lauraceae ) is of interest for its rapid growth rate in combination with a high oil content. A few other species offer some promise.     

覆盖作物的生态效应

评述了农田生态系统中主要覆盖作物在减少土壤损失、降低表土迳流、增加土壤养分、减少NO3^-I淋溶、减轻水质污染及病虫草防除中的作用与效应,讨论了覆盖作物管理对农业持续发展的影响。     

Future utilization of cereal crops

Estimates made on the uses for cereals (corn, wheat, oats, barley, sorghum, rice, and rye) in 1975 are based upon a number of assumptions. If those made in this article are approached, the pattern of cereal use will be much the same as it is at present.     

Utilization of commercial oilseed crops

The United States is a major producer of many different types of oilseeds, but the predominant one is soybean, that remarkable legume whose meal and oil serve many animal feed, human food, and domestic industrial product needs. More than half of the soybeans and the products produced from them are exported. The 16 mill MT of soy meal processed and fed in the United States in 1981 constituted 88% of the total oilseed meal, 71% of the high-protein feeds, and 48% of total processed feeds. Of the total soy protein available, less than 5% goes into human food products such as meat extenders, simulated meats, baked goods, dairy product analogs, dietary foods, infant foods, and fermented food products. Less than 1% of soy protein in the United States is used in industrial products, mainly as a binder for pigmented paper coatings. Of the total soy oil available, about 95% is consumed in food products such as margarines, salad oils, and cooking oils. About 5% of soy oil is applied to nonfood uses such as alkyd paints, plasticizer/stabilizers for vinyl plastics, soaps, eraser factices, and many other lesser uses. Other major oilseeds produced in the United States include cottonseed, flaxseed, peanut, safflower, and sunflower. Corn oil is produced in significant quantities as a by-product of the corn starch industry. The oilseed crops having the greatest oil productivity are peanut and sunflower. However, sunflower meal has certain deficiencies for feed and food uses. If the United States is to draw upon oilseed crops as significant contributors to feed, food, industrial products, and agricultural fuel needs, greatly improved productivity will be needed either from new oilseed crops or from improved varieties of present commercial crops.