Autoradiographic Examination of Meristems of Intact Boron-deficient Squash Roots Treated with Tritiated Thymidine

Intact roots of boron-sufficient squash (Cucurbita pepo L.) plants, plants entering boron deficiency, and plants recovering from boron deficiency were exposed to tritiated thymidine at the end of the treatment period to label the replicating DNA of root tip cells. Using histological sections, autoradiographs of intact root meristems were prepared. The labeling pattern in +B root tips revealed the presence of a well defined quiescent center. The ability of root tip cells to incorporate label is correlated with the total root elongation during the −B treatment period. A greater amount of total root elongation during boron deficiency and recovery reflects the fact that root tip cells have retained their ability to synthesize DNA and enter mitosis for a longer time. In roots recovering from boron deficiency, cells of the quiescent center were seen to play no part in the recovery process in roots treated for as long as 20 hours in a −B nutrient solution. They were inactive before, during, and after the −B treatment. Cessation of mitosis occurs as early as 6.5 hours after boron is withheld from the nutrient solution while DNA synthesis can occur for as long as 20 hours after withholding boron. It was concluded that boron is essential for continued DNA synthesis and mitotic activity. The absence of boron results in the cessation of mitosis and DNA synthesis within 20 hours from the time boron is withheld.     

Effect of light intensity and plant size on rate of development of early boron deficiency symptoms in tomato root tips

Young tomato plants (Lycopersicon esculentum Miller, cultivar Rutgers) grown in solution culture at 27° at 2 light intensities with adequate boron (0.1 mg/l) and treated with these 2 intensities in the absence of adequate boron developed root boron deficiency symptoms. The typical deficiency symptoms of decreased root elongation, increased depth of brown color and decreased RNA content of tips developed more rapidly at high than at low light intensity, and plant size influenced results. Plants supplied with adequate boron did not exhibit deficiency symptoms.     

Genetic variation in the response of pea (Pisum sativum L.) to high soil concentrations of boron

In a greenhouse experiment nine current Australian cultivars of pea were grown to flowering time under five levels of soil boron (0, 10, 20, 30 and 40 mg kg^–1) applied to the soil. This study was conducted to identify the genetic range in tolerance to boron within the group and to identify specific responses which may be utilised as selection criteria in a breeding program. Significant differences in response to increasing levels of boron were found between cultivars for dry-weight yield, and boron concentrations were lowest in shoots of the most tolerant cultivars. Of the other parameters measured, emergence was not affected but plant height and the number of nodes were reduced and the severity of symptom expression increased at the higher boron treatments. Symptom expression was the most efficient observation for predicting the response of cultivars, as determined by dry-weight yield and concentration of boron in shoots, and it was found that the correlation coefficients between symptoms and the latter two measurements were r=–0.78 (p<0.01) and r=0.81 (p<0.01), respectively. Early Dun, Dundale, Alma and Maitland were the more tolerant of the cultivars and these happen to be the most widely grown cultivars in southern Australia.     

Enzymatic activity of a soil profile in the Sudan Gezira

Summary In preliminary work in the enzymatic activity of a semi-arid Gezira soil microbes were counted and urease, dehydrogenase, and Catelase activities were measured in five soil horizons from 0 to 72 inches depth. Urease and dehydrogenase activities of unamended soil from all horizons appeared to be better indicators of biological status than catalase activity. Biological activity was marked in the top soil (0–2 inches) — the zone of grass root activity — but decreased gradually to reach a low level in deeper horizons.     

Nitrogen-induced boron deficiency in lucerne

Summary In a glasshouse experiment with a boron deficient soil the application of nitrogen was found to decrease the boron concentration and boron uptake by lucerne (Medicago sativa). Without added boron, nitrogen applications killed the lucerne, probably by inducing severe boron deficiency. With added boron, the lowest rate of nitrogen application increased lucerne yield but further additions depressed yields. The effect was due to a physiological interaction rather than an effect of the nitrogen on the availability of the boron in the soil.     

Nitrogen-fixing bacteria of the genusBeijerinckia in South African soils

Summary In contrast to the ubiquitous distribution of the nitrogen-fixing bacteria of the genusAzotobacter which can be encountered in all soils with suitable pH, the nitrogen-fixing bacteria of the genusBeijerinckia seem to be restricted to the tropics.All attempts to isolateBeijerinckia from north-european soils have so far failed. The conditions underlying this peculiar phenomenon are not clearly understood. The selective action of low soil pH, low temperature, frost resistance, etc. cannot be responsible for the absence ofBeijerinckia from temperate zones.In an earlier paper¹³ it was emphasized that the presence ofBeijerinckia is almost invariably connected with the occurrence of laterites, tropical Red Earths or latosols. As these soil types are almost restricted to the tropics, this may be the reason why the genusBeijerinckia is mainly confined to tropical regions.It was also suggested in that paper thatBeijerinckia might also occur in lateritic soils — fossil or developed under particular climatic conditions — outside the tropics.The present paper gives the first evidence of the occurrence ofBeijerinckia in lateritic soils outside the tropics in South Africa. ThereBeijerinckia occurs abundantly in the lateritic soils of the Mistbelt, but it occurs also — although more sporadically — in soils as far south as Cape Town (lat. 34° S.). Hence, non-symbiotic nitrogen fixation may occur in some of these soils which are too acid to containAzotobacter.     

Licht- und elektronenmikroskopische Untersuchungen von Entwicklungsstadien der FlechteEndocarpon pusillum unter Kulturbedingungen

The lichenEndocarpon pusillum Hedw. was cultivated under laboratory conditions on agar, silica gel and soil substrate. Selected developmental stages of the life cycle (germination, contact between the symbionts, cortex, squamule and perithecia development) were studied by light and scanning electron microscope.—It could be shown that the spores had no rigid spore walls with germination colpies and the spore cells which are in contact with the substrate were formed directly into germination tubes.— Further studies showed that the initial contact between the components was thigmotropic and both the form and the gelatinous matrix around the algal cells play an important role in this process. — The development of the cortex occurs under reduced moisture conditions resulting in a reduced algal reproduction. The thickness of the cortex was dependent on light intensity during cultivation. The cortex originated from hyphae, which developed beyond the algal layer and were combined to a tight network.—Fruiting bodies with spores and hymenial algae were only formed in cultures on soil substrate.

Frau Prof. Dr.Elisabeth Tschermak-Woess zu ihrem 70. Geburtstag gewidmet.     

Method for the biological monitoring of hexahydrophthalic anhydride by the determination of hexahydrophthalic acid in urine using gas chromatography and selected-ion monitoring

A method for the determination of hexahydrophthalic acid, a metabolite of hexahydrophthalic anhydride, in human urine has been developed. The urine was worked-up by liquid—solid extraction, esterified with boron trifluoride—methanol, and analysed by capillary gas chromatography and selected-ion monitoring. Hexadeuterium-labelled hexahydrophthalic acid was used as the internal standard. The precision was 4% at 0.7 μg/ml and 5% at 0.07 μg/ml. The recovery of the acid for the overall method was 101% at 0.07 μg/ml of urine (with a coefficient of variation of 4%) and 95% at 0.7 μg/ml (coefficient of variation 2%). The limit of detection was 20 ng/ml urine.     

The effect of age on nitrogen stress and its relation to leaf nitrogen and leaf elongation in a grass

Summary Nitrogen stress inLolium rigidum was measured 5 times during the 8 weeks following emergence.Symptoms of nitrogen deficiency appeared when the stress was greater than 40 per cent. Stresses lower than this were accurately estimated either by the concentration of total nitrogen, or free ninhydrin nitrogen in the youngest fully expanded leaf, or by a leaf elongation index.Each of these estimators could be used for diagnosis of nitrogen stress with a single calibration curve, respectively, over the following minimum periods after emergence: total nitrogen — 6 weeks; free ninhydrin nitrogen –4th to the 8th week; leaf elongation — 4th to the 9th week.Preliminary calibration tables are given for the symptom-free range of nitrogen deficiency.     

Exploratory pot experiments on sensitiveness of different crops to sodium: D. Barley

Summary The effect of sodium on barley has been investigated by means of three pot experiments, of which one was on a humic sandy soil and two on an artificial soil complex (dusarit/quartz-sand mixture).In two of these experiments the effect of sodium — as nitrate of soda — was studied by comparison with calcium nitrate. At low potassium levels sodium was found to excercise a positive effect, but with an ample supply of potassium no differences between the effects of the two nitrate fertilizers were observed.In the third experiment a wide variation in the potassium and sodium levels was introduced by the application of these elements adsorbed to dusarit, all treatments receiving nitrogen in the form of calcium nitrate. Little influence was exercised by the total level of monovalent ions (10, 20 and 40 per cent respectively, of the adsorbed bases). Three-quarters, or possibly seven-eights of the potassium was found to be replaceable by sodium without causing significant changes in the yields of grain and straw.From a survey of the available literature it cannot yet be concluded whether the importance of sodium for barley is limited to a beneficial effect resulting from its mere replacement of potassium, when too little of the latter is available, or whether this importance may be regarded as essential in the sense that sodium has a yield-increasing effect, even in the presence of a sufficiency of potassium.     

Determination of plasma fatty acid composition in neonates by gas chromatography

Total fatty acids in plasma of neonates have been analysed as their methyl esters by gas chromatography. They were separated on a capillary column coated with a SP-2380 stationary phase. As little as 100 μl of plasma is used for the analysis. The extraction procedure was performed with dichloromethane—methanol (2:1) and fatty acids were methylated with boron trifluoride—methanol. The quantification of fatty acids is based on an internal standard method. Absolute values (μg fatty acid per 100 μl plasma) are given together with relative values (%). At a signal-to-noise ratio of 3, the detection limits for flame ionisation detection are between 0.08 to 0.51 ng. The high sensitivity and precision permits the effective determination of the fatty acids in neonate plasma.     

Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field

Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013–2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha^-1 year^-1 (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q₁₀ ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013–2014 and 2014–2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013–2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014–2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration.     

Boron deficiency inPinus radiata D. Don and the effect of applied boron on height growth and nutrient uptake

Summary Severe dieback observed inP. radiata D. Don plantations during dry years in Southeastern Australia was found to be due to boron deficiency. Borax applied in spring (August 1982) at rates of 50, 100 and 150 kg ha^–1 resulted in a marked increase in foliar B and an alleviation of B deficiency symptoms. During the dry summer following the application of borax no further dieback was observed and height growth of fertilized trees was significantly improved. Correction of B deficiency enhanced the uptake of P by the trees.     

The preparation of microtome sections of unaltered soil for the study of soil organisms in situ

Summary A new technique for study of small soil organisms in situ in unaltered soil is described.The soil samples are cooled in a refrigerator at — 10°C to kill the animals. A small portion taken from a frozen soil sample, is slowly immersed in a solution of gelatin. When the specimen is infiltrated with gelatin and the whole cooled it is fixed in formalin to enable it to withstand treatment with hydro-fluoric acid for removal of sand grains. Subsequently the specimens are immersed in gelatin solution for a second time after which the specimens are affixed to wooden blocks which can be clamped in the microtome. Before sectioning, the embedded specimen affixed to the wooden block is hardened in methylalcohol after which it is possible to cut sections 7,5–10µ thick.The most satisfactory staining procedure proved to be the quadruple staining method of Johansen. By this method nematodes, fungi, bacteria and amoebae are easily distinguishable from the soil particles.     

Studies on Mg,B, and Zn deficiencies in acid ‘Wilder’ soil of California

Summary A greenhouse study of some aspects of infertility of an acid soil of California, namely the ‘Wilder’ soil, was undertaken. Experiments with white-rooted radish showed that the soil when limed to near neutrality with CaCO₃ indicated deficiencies of boron and magnesium. When sweet corn was used as a test crop, zinc deficiency was exposed in limed soil. The plant tissue tests and morphological observations corroborated this. The apparent decrease in zinc content in sweet corn in presence of the added phosphate was taken to be a dilution effect. The work was carried out in Department of Soils and Plant Nutrition, University of California, Davis.     

Boron and Coumaphos Residues in Hive Materials Following Treatments for the Control of Aethina tumida Murray

In the search of alternatives for controlling Aethina tumida Murray, we recently proposed the BAA trap which uses boric acid and an attractant which mimics the process of fermentation caused by Kodamaea ohmeri in the hive. This yeast is excreted in the feces of A. tumida causing the fermentation of pollen and honey of infested hives and releasing compounds that function as aggregation pheromones to A. tumida. Since the boron is the toxic element in boric acid, the aim of this article is to assess the amount of boron residues in honey and beeswax from hives treated with the BAA trap. For this aim, the amount of bioaccumulated boron in products of untreated hives was first determined and then compared with the amount of boron of products from hives treated with the BAA trap in two distinct climatic and soil conditions. The study was conducted in the cities of Padilla, Tamaulipas, and Valladolid, Yucatan (Mexico) from August 2014 to March 2015. The quantity of boron in honey was significantly less in Yucatan than in Tamaulipas; this agrees with the boron deficiency among Luvisol and Leptosol soils found in Yucatan compared to the Vertisol soil found in Tamaulipas. In fact, the honey from Yucatan has lower boron levels than those reported in the literature. The BAA treatment was applied for four months, results show that the BAA trap does not have any residual effect in either honey or wax; i.e., there is no significant difference in boron content before and after treatment. On the other hand, the organophosphate pesticide coumaphos was found in 100% of wax samples and in 64% of honey samples collected from Yucatan. The concentration of coumaphos in honey ranges from 0.005 to 0.040 mg/kg, which are below Maximum Residue Limit (MRL) allowed in the European Union (0.1 mg/kg) but 7.14% of samples exceeded the MRL allowed in Canada (0.02 mg/kg).     

Boron in Relation to Membrane Function in Higher Plants

The capacity for absorption of phosphate was shown to be reducedin Zea mays and Vicia faba suffering from boron deficiency;addition of 10^–5 M boron rapidly restored this capacity.Root tips of normal plants also responded to the addition ofboron during a short pretreatment period prior to the determinationof phosphate absorption. Comparable effects of boron on theabsorption of chloride and rubidium ions were also demonstratedin Zea mays. Specific inhibition of ion uptake by auxins maybe relevant to the mechanism of the impaired ion transport seenduring boron deficiency. The KCl-stimulated adenosine triphosphatase (ATPase) of theroots of Zea mays was also studied, with a view to examiningthe effect of boron deficiency on the activity of the enzyme.Boron-deficient roots had a reduced ATPase activity which couldbe rapidly restored by the addition of 10^–4 M H₃BO₃ 1h before extraction of the enzyme. The results suggest that the activity of specific membrane componentscan be directly influenced by boron. Possible mechanisms wherebythis control is exercised include direct interaction of boronwith polyhydroxy components of the membrane and the elevationof endogenous levels of auxins. The evidence presented stronglysupports the view that boron plays an essential role in theregulation of the functions of higher plant membranes and thatthe ATPase is a possible component of the transplant process.     

Vegetationsschwankungen in einem Melico-Fagetum

Summary Following the dry year of 1959 considerable damage was done to a number of beeches in a Melico-Fagetum wood in the Drübel area near Brilon (Sauerland). The effects of this damage coupled with the subsequent removal of the affected trees were studied over an 8-year period with a permanent quadrat and revealed the following vegetation cycle: pure or almost pure beechwood — dying or cutting down of single beeches and with it an opening up of the tree canopy — an increase in the abundance and flowering of wild strawberry (Fragaria vesca) and other lightloving species — an increase in the density and growth of sycamore (Acer) and ash (Fraxinus) saplings — a decrease in the amount of wild strawberry and indeed of other light-loving species too because of the increasing shade — development of beech seedlings into young trees under the shadow of the other shrubs and trees — probably a sycamoreash-beech stand — probably a pure or almost pure becchwood again.

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Zusammenfassung Das Dürrejahr 1959 verursachte in einem Melico-Fagetum des Drübels bei Brilon erhebliche Schäden an mehreren Buchen. Diese Schäden und die folgende Abholzung der erkrankten Bäume lösten, wie 8jährige Untersuchungen in einem Dauerquadrat ergaben, folgenden Vegetationsyklus aus: Reiner oder fast reiner Buchen-Hochwald — Absterben bzw. Schlag einzelner Buchen und damit Auflockerung der Baumschicht — Vermehrung bzw. Blüte der Walderdbeere und anderer lichtliebender Arten — Verdichtung und schnelles Emporwachsen des Ahorn- und Eschen-Jungwuchses — Abnahme der Erdbeere, wohl auch anderer licht-liebender Arten infolge wieder zunehmender Beschattung — Heranwachsen von Buchen-Keimlingen zu Jungpflanzen, und zwar im Schatten der anderen Sträucher und Bäume — voraussichtlich Ahorn-Eschen-Buchen-Bestand — voraussichtlich wieder reiner oder fast reiner Buchen-Hochwald.

     

The use of carbon isotope ratios to evaluate legume contribution to soil enhancement in tropical pastures

Soil carbon distribution with depth, stable carbon isotope ratios in soil organic matter and their changes as a consequence of the presence of legume were studied in three 12-year-old tropical pastures (grass alone —Brachiaria decumbens (C₄), legume alone —Pueraria phaseoloides (C₃) and grass + legume) on an Oxisol in Colombia. The objective of this study was to determine the changes that occurred in the¹³C isotope composition of soil from a grass + legume pasture that was established by cultivation of a native savanna dominated by C₄ vegetation. The¹³C natural abundance technique was used to estimate the amount of soil organic carbon originating from the legume. Up to 29% of the organic carbon in soil of the grass + legume pasture was estimated to be derived from legume residues in the top 0–2-cm soil depth, which decreased to 7% at 8–10 cm depth. Improvements in soil fertility resulting from the soil organic carbon originated from legume residues were measured as increased potential rates of nitrogen mineralization and increased yields of rice in a subsequent crop after the grass + legume pasture compared with the grass-only pasture. We conclude that the¹³C natural abundance technique may help to predict the improvements in soil quality in terms of fertility resulting from the presence of a forage legume (C₃) in a predominantly C₄ grass pasture.     

Influence of waterlogging and lime or organic matter additions on the distribution of trace metals in an acid soil

Summary A study has been made of the influence of waterlogging on the distribution of trace metals between the various reservoirs in which they are held in a soil. Selective extractants have been used to remove metals held in 4 ways: soil solution and exchangeable; specifically adsorbed by inorganic sites; adsorbed or chelated by organic sites; adsorbed onto oxide surfaces.Waterlogging over a period of 16 weeks resulted in the release of both manganese and iron from the organic — and oxide — bound reservoirs to the soluble, exchangeable and inorganic reservoirs. Addition of both 1% dried grass (as an actively decomposing organic material) and 1% CaCO₃ to the soil resulted in an acceleration of the metal redistribution.For manganese, selective extraction methods accounted for the distribution of all the metal in the reservoirs studied. In the case of iron however, there appeared to be some release from a reservoir not being extracted.