A GIS-based plant prediction model for wetland ecosystems

An existing non-spatial model for the prediction of response of wetland plant species on ecological factors has been transformed into a GIS-based prediction model which produces spatial output at the landscape scale. The input, spatial patterns of the ecological factors, were constructed with geostatistical spatial interpolation (kriging). With this GIS-based model the spatial patterns of presence and absence of 78 wetland plant species are predicted for an area with wetlands in the Netherlands of approximately 500 square kilometers. The GIS-based model has been validated, and the estimated uncertainty of the input has been propagated through the model. At the species level the output shows spatially coherent and non-random patterns. The validation is affected by the propagation of input errors through the model. The number of valid predictions declines approximately 10–20% when 95% confidence intervals are used in the validation. This study shows that it is feasible to use a geostatistical interpolation method to construct spatial patterns of ecological factors on a landscape scale and to use these patterns as input for a GIS-based prediction model. The added uncertainty on the input values however, affects the number of valid predictions of the model.     

A COMPARATIVE STUDY OF PAPER AND OIL AS CARRIERS OF CHROMIUM SESQUIOXIDE ADMINISTERED TO GRAZING STEERS TO DETERMINE THEIR FAECAL OUTPUT

Two steers excreting similar quantities of organic matter daily were grazed at pasture during the summer of 1961. The four experiments each involved a preliminary period of five days dosing with Cr₂O₃ to reach a fairly constant excretion. The steers received a daily dose of Cr₂O₃ either in oil suspension or in shredded paper. The carriers and steers were interchanged for each trial. For two of the trials each steer in turn was harnessed every other day and all its dung collected in a bag. Total faecal excretion of organic matter was measured from the bagged steer and estimated from the Cr₂O₃ concentration in a composite sample made up from all dung pats voided during the ten-day collection period. In the other two trials the steers were not harnessed and each dung pat was separately sampled and analysed for Cr₂O₃ in the organic matter. The average recovery of Cr₂O₃ in the first two trials was 99·1 (oil) or 94·4% (paper). Calculating the faecal organic matter excretion from the concentration of Cr₂O₃ in the faeces and the quantity given daily overestimated it by 3·5 to 8·0%. There was no significant difference between shredded paper and oil as carriers of Cr₂O₃ for estimating the quantity of organic matter excreted. There were 37% and 22% less variation between dung pats in Cr₂O₃ concentration when this was administered in shredded paper than when given in oil suspension.     

The genetic system for reaction of field beans (Phaseolus vulgaris L.) to infection by three physiologic races of Colletotrichum lindemuthianum

Genetic resistance to race alpha of C. lindemuthianum in the nine varieties of beans studied can be accounted for by dominant alleles at either of two loci, which are unlinked and which behave as duplicate factor loci in the classical sense. A similar system of loci governs reaction to races beta and gamma, with evidence favoring multiple allelism and dominance of alleles conferring susceptibility in certain instances in the case of beta. In addition, for reaction to races beta and gamma, there are distinct systems of complementary factors, again with multiple allelism at the beta loci. Finally, there is genetic linkage between genes of the duplicate factor set governing reaction to gamma and genes of the duplicate factor set, and complementary factor set conditioning reaction to beta. The genes that are members of the set(s) pertaining to any one race alone are independent of each other in a linkage sense.Paper based on work conducted by the senior author in partial fulfilment of requirements for the Doctor of Philosophy degree at Michigan State University and supported by the Rockefeller Foundation.Formerly Rockefeller Foundation Student in Crop Science, now Director, Instituto Nacional de Investigaciones Agricolas, Veracruz, Mexico; Professor of Crop Science, Michigan State University; and Research Pathologist, Crops Research Division, Agricultural Research Service, USDA.     

Triple-cross hybrid kale

A triple-cross method is described as an alternative to the double-cross method for the production in kale of 100 per cent hybrid seed. This new method would reduce the labour involved and improve yields in the early stages of seed multiplication. These advantages would justify slightly lower yields of forage from triple-cross hybrids than from double-crosses.     

Ergänzungen zum Nachweisverfahren Des Y-Virus in der Kartoffelknolle

Zusammenfassung Der Nachweis des Kartoffel-Y-Virus im Gewebeanschnitt von Licht- und Dunkelkeimen stimmte überein und war im Vergleich zum Anschnitt des Kronenendes in den Herbst- und Wintermonaten sortenweise ungünstiger. In kéimenden Kartoffelknollen nach Winterlagerung und 3-w?chiger Vorkeimung bei 20 C hatten Verwundungen keinen Einflu? auf die Virus-aktivit?t; sie war in isolierten Kronenendestüken gegenüber ganzen Knollen erh?ht. Die Virusaktivit?t nahm in Kartoffelknollen w?hrend des Vegetationsablaufes mit fortschreitender Entwicklung bis zum Eintritt der Keimruhe st?ndig ab.

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Summary In supplementary experiments for the identification of the Y virus in potato tubers (Nienhaus: 1960, 1961/62) the question arose as to which was the most reliabie test for virus Y,viz. rubbing the leaf of the A₆-test plant with the cut surface of a sprout or with the surface of a section cut from the rose end of the tuber. The inhibitory effect of expressed sap from sprouts produced in light or darkness on the development of local lesions in leaves of A₆ averaged 93% and 94%, when two volumes of sap were mixed with one volume of virus suspension. The sprouts of theAckersegen, Capella, Dt. Erstlinge andMaritta varieties were particulaly rich in inhibiting material (Table 1) No differences in the number of local lesions occurred when cut surfaces taken from different parts of infectious sprouts produced in light or darkness were tested (Table 2), but in six varieties tested the virus activity in autumn and winter was usually higher in the cut surface of the rose end than in that of the sprouts grown in light. It was very low in the rose end of tubers after unusually long storage (Table 3). When the tubers were wounded before a 3 week's storage at 20°C, after the end of the dormant period in spring no activation of the virus was found, but the activity was higher in isolated pieces of rose end than in whole tubers (Table 4). The virus activity decreased in growing tubers during the vegetation process and in prematurely harvested tubers during subsequent storage at 20°C. There is assumed to be an inactivating process with increasing ripening of the tubers; this process becomes retrograde again when the dormant period is broken during winter storage (Table 5).

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Résumé Dans des essais complémentaires d'identification du virus Y dans le tubercule de la pomme de terre (Nienhaus; 1960, 1961/62), nous avons recherché lequel des deux tests permettrait de démontrer avec plus de certitude la présence du virus Y: la friction du limbe de la plante test A₆ avec la coupure d'un germe ou avec celle au sommet du tubercule. L'action inhibitrice des jus exprimés de germes développés à la lumière et dans l'obscurité sur l'apparition de lésions sur les feuilles de la plante test A₆ atteignait les moyennes respectivement de 93 et 94% en cas de mélange de deux tiers de jus de germes avec un tiers de suspension de virus. Les germes des variétésAckersegen, Capella, Dt. Erstlinge etMaritta étaient particulièrement riches en substance inhibitrice (Tableau 1). En frictionnant les feuilles avec des coupures à différentes régions des germes infectieux développés à la lumière et dans l'obscurité, il ne fut constaté aucune différence du nombre de lésions (Tableau 2). Cependant, chez 6 variétés étudiées, il fut observé qu'en automne et en hiver, l'activité du virus dans la coupure au sommet du tubercule souvent etait plus grande que dans celle du germe développé à la lumière. Mais l'activité dans la coupure au sommet du tubercule était extrémement basse si les tubercules avaient été conservés pendant un temps excessivement long (Tableau 3). Si les tubercules étaient blessés avant un stockage de trois semaines à 20°C, au printemps aprés la fin de la dormance, aucune activation du virus dans le tubercule n'était démontrée, mais l'activité dans des morceaux de sommet isolé, était plus grande que dans le reste du tubercule (Tableau 4). Dans le tubercule en développement, l'activité du virus diminuait pendant la phase terminale de la végétation: dans les tubercules récoltés trop t?t, il en était de même durant un stockage prolonge à 20°C. Il est supposé qu'à mesure que le tubercule m?rit, il se déroule un processus d'inactivation, lequel régresse à son tour après interruption de l'état de dormance pendant le stockage d'hiver (Tableau 5).

     

Unsprouted potato tubers treated with gibberellic acid (GA3)

Summary Tubers (still unsprouted after an eight months' storage period) of the late varietyLibertas with slow growth in youth and few stems were treated with gibberellic acid (GA₃) in 1958 and 1959. Two sprayings gave similar results as dipping for 15 minutes. 25 ppm probably had more effect than 12,5 ppm. During both years the treatment resulted in more and longer sprouts and more stems, although the number of stems is usually less than the number of sprouts. Emergence was not accelerated and in both years yields tended to be lower. In 1958 all yields reached a high level, treatment gave a non-significant lower yield, but there was a greater number of tubers especially in the 25–40 mm seed-class. In 1959 the size and the number of tubers were affected by second growth owing to the unusually dry summer with short spells of rainy weather. In this year presprouted tubers emerged 10 days earlier than treated and non treated, unsprouted seed, which for a long period gave the crop a lead in haulm growth and even a permanent lead in tuber yield.

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Zusammenfassung Von der sp?ten SorteLibertas, die in ihrer Jugend ein langsames Wachstum zeigt und wenig Stengel entwickelt, wurden ungekeimte Knollen (nach 8-monatiger Lagerung) in den Jahren 1958 und 1959 mit Gibberellins?ure (GA₃) behandelt. Eine zweimalige Spritzung ergab zumindest ?hnliche Ergebnisse wie das Eintauchen w?hrend 15 Minuten. 25 ppm hat wahrscheinlich eine bessere Wirkung, wie 12,5 ppm. In beiden Jahren ergab die Behandlung mehr und l?ngere Keime sowie mehr Stengel, obzwar die Anzahl der Stengel gew?hnlich nicht so hoch ist, wie die Anzahl der Keime. Es zeigte sich keine Beschleunigung des Auflaufens, jedoch eine Tendenz für einen geringeren Ertrag in beiden Jahren. In 1958 waren alle Ertr?ge hoch und die Behandlung ergab eine nicht signifikante Ertragsverminderung, jedoch eine gr?ssere Knollenzahl (insbesondere in der Saat-Gr?ssenklasse, 25–40 mm). In 1959 war die Gr?sse und die Anzahl der Knollen infolge des ungew?hnlich trockenen Sommers mit kurzen Regenperioden durch Mehrwüchsigkeit beeintr?chtigt. In diesem Jahr sind die vorgekeimten Knollen um 10 Tage früher aufgelaufen, was den Pflanzen im Vergleich zu den behandelten und nicht behandelten ungekeimten Pflanzgut einen l?ngeren Vorsprung im Krautwuchs und einen dauerhaften Vorsprung in der Knollenbildung gab.

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Résumé Des tubercules non germés (après stockage pendant huit mois) de la variété tardiveLibertas, à lente croissance de début et à petit nombre de tiges, ont été traités à l'acide gibberellique (GA₃) en 1958 et en 1959. Deux pulvérisations donnaient des résultats au moins égaux à ceux d'une immersion de 15 minutes. La concentration de 25 millionièmes est probablement plus efficace que celle de 12,5 millionièmes. L'une et l'autre année, les tubercules traités avaient des germes plus nombreux et plus longs et un plus grand nombre de tiges, bien que le nombre de tiges ne soit généralement pas aussi grand que le nombre de germes. La levée ne fut pas accélérée et il se manifesta une tendance de diminution du rendement. En 1958, toutes les récoltes furent bonnes, le traitement entra?nant une diminution non significante de la récolte mais faisant augmenter le nombre de tubercules (particulièrement dans la catégorie de semenceaux de 25–40 mm). En 1959, la grosseur et le nombre des tubercules furent influencés par croissance secondaire (excroissance) par suite de l'été exceptionnellement sec avec de courtes périodes de pluie. Cette année-là, les tubercules prégermés levèrent 10 jours plus t?t que les plants non prégermés, traités et non traités, de sorte que le développement du feuillage fut supérieur pendant une longue période et que celui des tubercules fut supérieur jusqu'à la récolte.