Simulating the soil phosphorus dynamics of four long-term field experiments with a novel phosphorus model

Phosphorus is a nonrenewable resource, which is required for crop growth and to maintain high yields. The soil P cycle is very complex, and new model approaches can lead to a better understanding of those processes and further guide to research gaps. The objective of this study was to present a P-submodel, which has been integrated in the existing Carbon Candy Balance (CCB) model that already comprises a C and N module. The P-module is linked to the C mineralization and the associated C-pools via the C/P ratio of fresh organic material. Besides the organic P cycling, the module implies a plant-available P-pool (P_av), which is in a dynamic equilibrium with the nonavailable P-pool (P_na) that comprises the strongly sorbed and occluded P fraction. The model performance was tested and evaluated on four long-term field experiments with mineral P fertilization, farmyard manure as organic fertilizer and control plots without fertilization. The C dynamics and the P_av dynamics were modelled with overall good results. The relative RMSE for the C was below 10% for all treatments, while the relative RMSE for P_av was below 15% for most treatments. To accommodate for the rather small variety of available P-models, the presented CNP-model is designed for agricultural field sites with a relatively low data input, namely air temperature, precipitation, soil properties, yields and management practices. The CNP-model offers a low entry threshold model approach to predict the C-N and now the P dynamics of agricultural soils.     

The influence of genotype on the effects of impact damage on the accumulation of glycoalkaloids in potato tubers

Summary The effects of impact damage on the accumulation of glycoalkaloids in tubers were studied in a wide range of potato genotypes. Damage, caused by drop tests, resulted in increased glycoalkaloid levels, which sometimes exceeded the toxic limit of 20 mg/100 g fresh weight; there were large differences in levels between genotypes. When the total damage index was high, the severe damage types—shatter cracks and splits—were responsible for the initiation of glycoalkaloid synthesis in stressed tuber tissue, whereas the less severe damage types—bruises and black spot—were not. Genotypes which had the highest shatter crack indices often had the greatest increases in glycoalkaloids. The high correlation between the initial glycoalkaloid level and the increased level after damage showed that selection for low glycoalkaloid potato clones is important.

---

Zusammenfassung Der Einfluss von Stossverletzungen auf die Glykoalkaloide in Knollen wurde an 18 bis 21 Sorten und Zuchtklonen untersucht. Die Knollen liess man von 150 cm H?he (1981) bzw. 100 cm H?he (1982) herabfallen, um Stossverletzungen unterschiedlicher Typen (Schwarzfleckigkeit, Quetschungen, Schlagrisse, Brüche) und unterschiedlicher St?rke hervorzurufen. Der Gehalt an Glykoalkaloiden (α-Solanin und α-Chaconin) wurde an unbehandelten und besch?digten Knollen bestimmt. In unbehandeltem Material wurden wechselnde Glykoalkaloidgehalte aufgefunden (Tab. 1). Die Falltests ergaben grosse Sorten-differenzen hinsichtlich der Verletzungsemp-findlichkeit. Eine Fallh?he von 150 cm verursachte hohe Indizes für die Gesamtbesch?digung (Tab. 2). Unter den einzelnen Besch?digungs-typen waren Brüche und Schlagrisse am h?ufigsten. Der Glykoalkaloidgehalt erh?hte sich signifikant in den Knollen mit Stossverletzungen, und in einer Sorte wurde die toxische Schwelle von 20 mg/100 g Frischgewicht überschritten (Tab. 1). Die Glykoalkaloidbildung war signifikant korrelliert mit dem Schwellenwert in unbehandelten Knollen. Sorten und Klone mit den h?chsten Schlagriss-Indizes zeigten die gr?ssten Zunahmen. Eine zweimalige Fallbehandlung ergab h?here Verletzungsindizes und die Glykoalkaloidgehalte stiegen weiter an. Die Werte schwankten dabei zwischen 4 und 53 mg Glykoalkaloid/100 g Frischgewicht. Drei Sorten/Klone überschritten 20 mg/100 g und drei andere waren nahe an der toxischen Schwelle. Eine Fallh?he von 100 cm bewirkte auff?llig niedrigen Anteile an Stossverletzungen (Tab. 3). Schwere Verletzungenstypen, z.B. Schlagrisse und Brüche, waren hier nicht so h?ufig als weniger schwere, wie Quetschungen und Schwarzfleckigkeit. Der Glykoalkaloidgehalt war verglichen mit demjenigen in unbehandelten Knollen nur geringfügig h?her (Tab. 1). Das Glykoalkaloidniveau der besch?digten Knollen war gut korrelliert mit dem ursprünglichen Niveau, es stand aber weder zum Gesamtindex der Stossverletzungen noch zum Index irgendeines besonderen Besch?digungstyps in Beziehung. Der Grund dafür lag vermutlich in der geringen Anzahl von Verletzungen, insbesondere in der geringen H?ufigkeit von Schlagrissen. Eine zweimalige Fallbehandlung erh?hte signifikant den Gesamtverletzungsindex und die H?ufigkeit der Quetschungen. Dabei ergab sich ein geringer Zuwachs an Glykoalkaloiden mit einer sortenbedingten Differenz von 2–20 mg/100 g Frischgewicht. Der Glykoalkaloidgehalt war jedoch nicht korrelliert mit dem Index der gesamten Stossverletzungen oder, vielleicht mit Ausnahme der Quetschungen, mit dem Index irgendeines besonderen Besch?digungstyps. Die Untersuchung zeigte, dass schwere Stossverletzungen eine Erh?hung des Glykoalkaloidgehaltes in Kartoffelknollen verursachen. Die Pflanzenzüchtung ist ein m?glicher Weg, um die Resistenz gegenüber mechanischen Besch?digungen zu erh?hen, wenngleich stets eine sorgf?ltige Behandlung notwendig ist, um die Besch?digungsh?ufigkeit in der Handelsware zu reduzieren. Die hohe Korrellation zwischen dem ursprünglichen Glykoalkaloidniveau und dem erh?hten Niveau nach der Besch?digungsinduktion zeigt, dass es wichtig ist, Kartoffelklone mit geringem Glykoalkaloidgehalt zu selektieren.

---

Résumé L'influence des endommagements par impacts sur les glycoalcalo?des dans les tubercules a été étudiée sur 18–21 variétés et clones de sélection. Les différents types d'endommagements (noircissement interne, meurtrissures, cavernes et fissures) ainsi que leur gravité sont analysés après une chute des tubercules d'une hauteur de 150 et 100 cm, respectivement en 1981 et 1982. La teneur en glycoalcalo?des (α-solanine et α-chaconine) est déterminée dans les tubercules n'ayant subi aucun traitement et dans les tubercules endommagés. Une grande variété de teneurs en glycoalcalo?des est observée dans les tubercules non endommagés (tabl. 1). Les tests d'impacts ont montré des différences variétales importantes, quant à la sensibilité à l'endommagement. La hauteur de chute de 150 cm a causé des indices d'endommagements élevés (tabl. 2). Les fissures et les cavernes sont les types d'endommagements les plus fréquents. La teneur en glycoalcalo?des augmente de fa?on significative dans les tubercules endommagés et pour une variété, le seuil de toxicité de 20 mg/100 g de poids frais est dépassé (tabl. 1). La réponse dans la formation de glycoalcalo?des est correlée de fa?on significative à la teneur initiale, dans les tubercules non endommagés. Les variétés et clones qui présentaient le plus grand nombre de cavernes ont eu les augmentations les plus fortes. Les traitements comprenant deux chutes ont donné les indices d'endommagements les plus élevés et des teneurs en glycoalcalo?des encore plus importantes. Celles-ci variaient entre 4 et 53 mg/100 g de poids frais. Trois variétés/clones ont dépassé les 20 mg pour 100 g et trois autres étaient très proches de ce seuil de toxicité. La hauteur de chute de 100 cm a conduit à des niveaux d'endommagements beaucoup plus faibles (tabl. 3). Les types d'endommagements graves, c'est-à-dire les cavernes et les fissures, furent moins fréquents que les autres types d'endommagements moins graves: les meurtrissures et le noircissement interne. Il n'y eut qu'une légère augmentation des teneurs en glycoalcalo?des, comparée à celles des tubercules non endommagés (tabl. 1). Le niveau de glycoalcalo?des dans les tubercules endommagés est fortement correlé au niveau initial, mais n'est pas lié à l'indice total d'endommagements ni à l'indice d'un quelconque type d'endommagement. Ceci est probablement d? au faible niveau d'endommagement et notamment à la faible quantité de cavernes. Les traitements comprenant deux chutes ont donné un indice total d'endommagements plus élevé avec davantage de meurtrissures. La teneur en glycoalcalo?des a légèrement augementé, avec des différences variétales de 2–20 mg/100 g de poids frais. Toutefois, les glycoalcalo?des ne furent pas correlés à l'indice total ou à l'indice d'un des types d'endommagements, excepté peut être les meurtrissures. Cette recherche montre que les endommagements graves par impacts provoquent l'augmentation des teneurs en glycoalcalo?des dans les tubercules de pomme de terre. La sélection des variétés est un moyen pour augmenter la résistance des tubercules à l'endommagement, bien que des précautions dans les manutentions sont nécessaires pour réduire les fréquences d'impacts des pommes de terre de commercialisation. La forte corrélation entre le niveau initial de glycoalcalo?des et son augmentation après endommagement montre que la sélection des clones à faible teneur en glycoalcalo?des est importante.

     

Effects of pulsation rate and viscosity on pulsation-induced taste enhancement: new insights into texture-taste interactions

Oral stimulation with high-tastant concentrations that are alternared with low-tastant concentrations or water rinses (pulsatile stimulation) results in taste intensity ratings that are higher than continuous stimulation with the same average tastant concentration. This study tested the combined effects of taste pulsation rate and viscosity on pulsation-induced taste enhancement in apple juice. According to a tastant-kinetics hypothesis, less pulsation-induced taste enhancement is expected at enhanced pulsation rates in the high-viscous proximal stimulus compared to lower viscous stimuli. High-concentration sucrose apple juice pulses and low-concentration sucrose apple juice intervals were alternated at different pulsation periods (pulse + interval in seconds) every 2.5 s (period length = 5 s) or every 1.25 s (period length = 2.5 s). Pulsed stimuli were presented at two viscosity levels by the addition of pectin (0 and 10 g/L). Sweetness intensities of pulsed stimuli were compared to a continuous reference of the same net but nonalternating sucrose concentration. Sweetness ratings were higher for pulsatile stimuli than for continuous stimuli. In low-viscous stimuli, enhancement depended on the pulsation period and peaked at 5 s periods. In high-viscous stimuli, the same enhancement was observed for both pulsation periods. These results contradict a tastant-kinetics hypothesis of viscosity-induced taste suppression because impaired tastant kinetics by viscosity would predict the opposite: lower pulsation-induced taste enhancement for viscous stimuli, especially at higher pulsation rates. Instead, these observations favor an explanation based on perceptual texture-taste interactions, which predict the observed independence between viscosity and pulsation rate.     

Tundra plants protect the soil surface from UV

In the Arctic, seasonal ozone depletion is resulting in periods of enhanced UV-B radiation at ground level while regional climate change is associated with increasing temperatures. These changes are likely to alter plant distribution, biodiversity and morphology, which may have knock-on effects for microbially driven biogeochemical cycling and other soil processes. Our study examined the transmission of solar UV radiation through arctic tundra plants using a portable UV radiometer and the DLR-biofilm biological UV dosimeter. A strong negative correlation was found between vegetation cover and UV transmission to the soil surface. Penetration of UV to the soil beneath tundra plants varied depending upon plant morphology, being greater through low creeping plants than cushion plants, grasses or mosses. UV transmission to the soil surface beyond the foliage edge also varied with plant morphology and the presence of flowers.     

CEREBRAL VENTRICULAR SIZE IN DEVELOPING NORMAL KITTENS MEASURED BY ULTRASONOGRAPHY

To evaluate the age of fontanelle closure of normal kittens and the size of their lateral ventricles, 50 ultrasonographic examinations using the bregmatic fontanelle as an acoustic window were made. Seven kittens, laboratory animals, were included in the study. To verify the location of the lateral ventricle, two of the kittens were sacrificed as neonates. In one of them ink was injected prior to autopsy into one lateral ventricle under sonographic guidance. In a longitudinal study of five of the kittens, the skull depth and the depth of the central part of the lateral ventricle reproduced in a longitudinal view could be measured up to the age of about 5 months. During that period, the skull depth increased from a median value of 1.95 cm (1.92-1.98) in a seven-day-old cat to 2.58 cm (2.52-2.59) in a 154-day-old cat, while the afore-mentioned ventricle values increased from 0.3 mm to 1.1 mm.     

Ocular morphology of the Leatherback sea turtle (Dermochelys coriacea)

Objective The Leatherback sea turtle is the largest extant reptile and the sole member of the family Dermochelyidae. Here, the eye of this critically endangered marine turtle was investigated to determine the anatomy, optics, and optical sensitivity. Animals studied Three Leatherback sea turtles, Dermochelys coriacea. Results The eye is small in proportion to body size of the adult compared to other vertebrates, with prominence of the retractor bulbi and pyramidalis muscles. The nictitans shows extensive folding of the bulbar conjunctiva as an apparent mechanism to increase the surface area for mucus secretion. The intraocular anatomy is consistent with an eye adapted to aquatic vision with minimal curvature of the cornea, a near‐spherical lens, deep ciliary cleft and highly vascularized ciliary body. The optical sensitivity, a measure of the sensitivity to light of a given optical system, is higher than in other marine turtles studied but lower than those found in teleost fish that share a habitat with the Leatherback sea turtle. Conclusions The Leatherback sea turtle shows ocular features that are characteristic of Chelonians with similarities to aquatic mammals. The calculated optical sensitivity suggests that compared to pelagic fishes, for instance, the Leatherback sea turtle eye is not particularly well adapted for vision in dim light even though this species is known to venture into deep, dark waters, and might feed at night.     

Experimental superinfection of a Lesser Malayan mousedeer (Tragulus javanicus) persistently infected with bovine viral diarrhea virus.

A Lesser Malayan mousedeer (Tragulus javanicus), persistently infected with noncytopathogenic bovine viral diarrhea virus (BVDV) type 1f, was experimentally superinfected with a cytopathogenic isolate of BVDV type 1c, which antigenically partially matched the endogenous strain. Within the observational period of 125 days after superinfection, the animal did not demonstrate any clinical signs of the disease and/or significant changes in blood values. Neutralizing antibodies were detected at 35 and 42 days postinfection. The isolate causing the superinfection was found in feces, nasal swabs, and saliva starting from day 29 and at various times postchallenge. Macroscopic or histologic examination did not reveal mucosal disease-like lesions, despite the detection of the cytopathogenic isolate in the salivary gland, rumen, abomasum, kidney, and superficial prescapular lymph node. Results indicate that the cytopathogenic BVDV strain, which was used in the superinfection, persisted in the viremic animal without causing disease within the observation period.     

Aphanomyces pea root rot disease and control with special reference to impact of Brassicaceae cover crops

Abstract

Pea root rot disease caused by the pathogen Aphanomyces euteiches deserves increased attention, since peas are an important cash crop and also improve the N balance in temperate agriculture. However, due to pea root rot it is difficult to cultivate peas as frequently and successfully as desired. In the search for biological measures to overcome this problem, attention has been drawn to the use of Brassicaceae plants as cover crops between main crops, since these can be effective catch crops for nutrients and also exert allelopathic effects. Many species within the Brassicaceae contain glucosinolates (GSLs). Their hydrolysis products, the volatile isothiocyanates (ITCs), have been shown to suppress soil-borne plant pathogens such as A. euteiches. In addition, Brassicaceae biomass releases water-soluble toxic substances such as oxazolidine-2-thione and supplies nutrients and organic matter. Overall, this influences the soil microbial community and the final suppression of pathogens. Due to the unpredictability of the control effect of Brassicaceae biomass incorporation into soil on the pathogen, there is a need to define the mechanisms behind suppression in the field situation. This review focuses on how incorporation of Brassicaceae biomass suppresses A. euteiches under field conditions and the effect on the emerging pea. Different factors influencing the severity of field pea (Pisum sativum L.) root rot disease are also discussed. One conclusion is that suppression of pea root rot depends on the quality and quantity of incorporated Brassicaceae biomass.     

中国为何青睐原木——世界林业专家解析背后深层原因

前言：过去十几年来，中国已跃居全球最大的木材产品进口国行列。1997～2007年，中国木材进口材积总量（圆木当量）翻了四倍，从大约1250万立方米增长到了5200多万立方米，目前已是全球第一的木材产品进口国。原木增长量占据木材产品进口增长的绝大部分。然而，简单地从经济学角度上看，受目前资源短缺、木材价格上涨和不断攀升的运输费用的影响，进口原木并非效益最佳。那么，如何解释中国为什么倾向于进口原木而不是木制品成品呢？