Contribution of roots and hyphae to phosphorus uptake of mycorrhizal onion (Allium cepa L.)—A mechanistic modeling approach

Phosphorus uptake by plant roots and arbuscular mycorrhizae (AM) hyphae can be described based on morphological and physiological uptake characteristics and parameters affecting P transport in the soil to the uptake surface. The current study aimed to quantify the relative contribution of hyphae and roots to P uptake of onion and to investigate the associated mechanisms using a mechanistic simulation model. Onion was grown in a growth chamber under controlled conditions at five levels of P supply with (M) or without (NM) AM. Uptake by onion roots and AM hyphae was simulated separately using a nutrient‐uptake model, which was developed for roots. Model parameters describing P transport in the soil, as well as morphological and physiological uptake characteristics of roots and hyphae were derived from soil and nutrient‐solution experiments. The model fairly described P uptake of M and NM plants at the highest level of P supply (28 µM P in soil solution) where roots and hyphae contributed nearly equally to P uptake of M plants. However, at lower P levels (≤0.41 µM P), hyphae accounted for nearly the whole P uptake whereas roots hardly explained any uptake. The effectiveness of AM hyphae at low P supply was well explained by their favorable morphological and physiological uptake properties. Hyphae were characterized by a diameter of 3 × 10^–4 cm, a K_m of 0.25 µM, and a C_min of 0.04 µM, values that are about 200, 40, and 10 times lower, respectively, compared to those of roots. Not more than 60% of the uptake at lower levels of P supply could be explained by the sum of predicted uptake of roots and hyphae suggesting that hyphae and roots may have used mechanisms additional to those described by the model to mobilize P. This work demonstrated that mechanistic models can be useful tools to study the role of AM in P uptake of plants, although reliable estimation of model parameters, especially physiological uptake properties of AM, is still limiting this approach.     

N-arylamidines and N-arylimidates of substituted acetic acids and their insecticidal and acaricidal properties

The synthesis of N-arylamidines and N-arylimidates of substituted acetic acids is described. Those amidines and imidates possessing a phosphorus ester as substituent showed insecticidal and high acaricidal properties. By contrast, their precursors were ineffective.     

Bewertung von Pyrus-Arten auf Befall mit Birnengitterrost (Gymnosporangium sabinae Dicks.)

Zusammenfassung Birnengitterrost breitet sich in nicht kommerziell genutzten Anlagen zunehmend aus, vor allem dort, wo Pflanzenschutzmaßnahmen unterbleiben. In unserer Untersuchung wurde nach alternativen Lösungen gesucht, den Befall zu minimieren. Dazu wurden Pyrus-Arten und -Hybriden ohne Pflanzenschutz angezogen und der natürliche Befall bewertet. Die Arten Pyrus korzhinskyi, P. betulifolia, P. cordata und die Hybride P. salicifolia Pendula zeigten den geringsten Befall. Sie könnten als Züchtungsausgangsmaterial eingesetzt werden. Ebenso scheint eine Prüfung als Park- oder Landschaftsgehölz sinnvoll.     

Prevalence of endotoxemia in healthy postparturient dairy cows and cows with abomasal volvulus or left displaced abomasum

Left displaced abomasum (LDA) and abomasal volvulus (AV) occur most commonly in postparturient dairy cows. Our main hypothesis was that endotoxemia occurred more frequently in the peripheral blood of cows with LDA or AV than in healthy cows because increased luminal pressure in AV or LDA, or the presence of a hemorrhagic strangulating obstruction in AV, may have injured the abomasal mucosa, thereby facilitating translocation of luminal endotoxin into the circulation. Therefore, our main objective was to compare the prevalence and magnitude of endotoxemia in healthy postparturient cows with the prevalence and magnitude of endotoxemia in cows with AV and LDA. We examined 60 adult dairy cows in early lactation that were diagnosed with AV (n = 15) or LDA (n = 15) or were healthy on physical examination (control group, n = 30). Jugular venous blood was obtained from cows in all 3 groups, and right gastroepiploic venous blood was obtained during surgical correction of AV and LDA immediately after repositioning of the abomasum. Platelet-rich plasma endotoxin concentrations were measured with a chromogenic limulus amoebocyte lysate assay. Endotoxin was detected in jugular vein plasma in 50% (15/30) of control cows; however, the prevalence of endotoxemia was significantly lower (P < .05) in cows with AV (7%, 1/15) or LDA (20%, 3/15). Endotoxin was detected simultaneously in right gastroepiploic and jugular vein plasma in only 1 cow with LDA and 0 cows with AV. Contrary to our hypothesis, we conclude that endotoxemia is infrequently present in postparturient dairy cows with AV or LDA.     

Past,current and future drivers for the development of decision support systems in forest management

The potential for development in decision support for forest management is set by decision theory, available technology and methods. Demands for decision support are emerging from contemporary challenges and problems of forest management which act as stimuli for the science community. Objectives and approaches in forest management as well as technologies have been changing throughout history. Accordingly, the demand for tools to support planning and decision-making has evolved. In this contribution, the authors review the historic development of decision support systems (DSS) for forest management and discuss past, current and future drivers. Based on evidence from scientific literature, case studies in the frame of the Forest Management Decision Support Systems (FORSYS) action, as well as experiences of the authors some hypotheses about the future of DSS are drawn. It is shown that in the past, the drivers evolving from forest management as well as decision support technologies have influenced the way of how models and methods have been applied as well as how DSS architectures have been designed. It is concluded that in the future, the challenges for DSS development will increase, as the complexity of decision-making processes and the related models will compete with the user demands which ask for simplicity.     

Holocene forcing of the Indian monsoon recorded in a stalagmite from southern Oman

A high-resolution oxygen-isotope record from a thorium-uranium-dated stalagmite from southern Oman reflects variations in the amount of monsoon precipitation for the periods from 10.3 to 2.7 and 1.4 to 0.4 thousand years before the present (ky B.P.). Between 10.3 and 8 ky B.P., decadal to centennial variations in monsoon precipitation are in phase with temperature fluctuations recorded in Greenland ice cores, indicating that early Holocene monsoon intensity is largely controlled by glacial boundary conditions. After approximately 8 ky B.P., monsoon precipitation decreases gradually in response to changing Northern Hemisphere summer solar insolation, with decadal to multidecadal variations in monsoon precipitation being linked to solar activity.     

Concentration profiles and safety of topically applied betulinic acid and NVX‐207 in eight healthy horses—A randomized,blinded, placebo‐controlled,crossover pilot study

The naturally occurring betulinic acid (BA) and its derivative NVX‐207 show anticancer effects against equine malignant melanoma (EMM) cells and a potent permeation in isolated equine skin in vitro. The aim of the study was to determine the in vivo concentration profiles of BA and NVX‐207 in equine skin and assess the compounds’ local and systemic tolerability with the intent of developing a topical therapy against EMM. Eight horses were treated percutaneously in a crossover design with 1% BA, 1% NVX‐207 or a placebo in a respective vehicle twice a day for seven consecutive days with a seven‐day washout period between each formulation. Horses were treated at the neck and underneath the tail. Concentration profiles of the compounds were assessed by high‐performance liquid chromatography in the cervical skin. Clinical and histopathological examinations and blood analyses were performed. Higher concentrations of NVX‐207 were found in the skin compared to BA. Good systemic tolerability and only mild local adverse effects were observed in all three groups. This study substantiates the topical application of BA and NVX‐207 in further clinical trials with horses suffering from EMM; however, penetration and permeation of the compounds may be altered in skin affected by tumors.