Masao Yajima

Biodegradation of an s-triazine herbicide, simazine

Abstract Two types of simazine-degrading microorganisms were isolated from soil samples where the herbicide had been spread with the enrichment culture using simazine as the sole carbon and nitrogen source. A fungal strain, DS6F, identified as Penicillium steckii , is the first simazine-degrading fungus ever reported. Simazine was gradually degraded by P. steckii DS6F in the mineral medium containing simazine (initial concentration: 50 mg/l) and 25 mg/l of yeast extract. The rate of simazine degradation was improved when assimilable carbon sources were added into the medium, and the reduction rate of 53% was obtained after 5 days of cultivation at 30°C when glucose was added into the basal medium. The bacterial strain, N5C, identified as Moraxella ( Branhamella ) ovis , was newly isolated and proven to degrade simazine more effectively than strain, DS6F, and 200 mg/l of simazine disappeared almost completely within 5 days at 35°C. M. ( Branhamella ) ovis could also degrade another s -triazine herbicide, atrazine, at the similar reduction rate as simazine.

Naphthoquinones from juglandaceae

Abstract The oligomeric juglones isolated from the barks of Juglandaceae plants, Pterocarya and Juglans , were shown to be 3,3′-bijuglone (8,8′-dihydroxy[2,2′-binaphthalene]-1,1′,4,4′-tetrone and unsymmetrical cyclotrijuglone ( 1,7,16-trihydroxy-5,6,11,12,17,18-trinaphthalenehexone).

Vector locus of an equivalent radius of the root in growing plants

Tree planting on arid land is taken up as one of the measures against global warming prevention. It is important for the tree planting to grasp growth state of the root after planting. To monitor the root advancement, a method measuring electric ground impedance of the root has been presented. By this method, we can know the growth state without digging the soil. To estimate the value of impedance, we introduce a concept of an equivalent radius. In this method, the value of ground impedance is converted to a radius of the disk electrode that has the same value as the object. Moreover, ground impedance of the root is indicated as complex number, which consists of resistance and capacity components of the root. The equivalent radius is also expressed by complex number. We propose the method indicating the change of equivalent radius as growing of the root by means of vector locus. It is demonstrated by the experiments on sunflower and kenaf during one summer that the present method is useful for estimating the growth state of the plant root.

An estimation method of ground resistance of trees growing in different lands

It is important to monitor the growing state of tree roots without digging the soil away from the bottom of the tree. Electrical ground resistance of tree roots indicates the grade of the growing state. The better roots advanced in the ground, the smaller the value of ground resistance becomes. However, ground resistance of the tree is modified by resistivity of the soil. If the growing state of roots is the same in trees growing in different lands, the value of ground resistance of each tree shows different values according to soil resistivity where trees are growing. This disables the comparison of the growth level between different lands, and complicates the estimation of results. In order to make comparison possible between the two without the effect of soil resistivity, the value of ground resistance of the tree is converted to that of a metal disk electrode. Here, if we know the soil resistivity, a radius of the disk becomes to be known. This disk radius is called equivalent radius that can indicate the growth level according to its value regardless of soil resistivity. Using the equivalent radius, we can estimate the growth level of plants growing in different lands evenly. Measured equivalent radii and the ratios to their butt radius of objective trees in West Australia, Hawaii Island, and Japan are summarized in figures.

A measurement method of grounding impedance of a tree

This paper describes a method for measuring the grounding impedance of a tree. Electrode impedance of an electrode using for connection between the measurement circuit and the tree, brings serious error in the measurement. To avoid the effect of the electrode impedance, the four-electrode method known in the impedance measurement methodology, is newly introduced. The hybrid method of the four-electrode method and usual grounding impedance measurement method makes it possible to measure grounding impedance of the tree directly. The experiments of the measurement were conveyed for three materials, zelkova tree, cherry tree, and silk-tree with the girth of 1.7-2.0 meters. Obtained values of impedance were 60-100 O in absolute one, and they showed slight capacitive reactance. It is concluded that the presented method is available for the measurement of grounding impedance of the tree.