bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionic exchange interrelationships in soils and crops. Ion selectivity in soils.
Authors: Schuffelen A.C. , Middelburg H.A.
Published: June 2020

The relative displacing power of various exchangeable cations in soils depends on the difference between the ion activity in the outside solution and the inside micellar-ion activity of the clay minerals. Theoretical calculations on the relationships between exchange capacity and distribution of ions with different valencies are shown in a graph. Evidence for the presence of Donnan systems is provided by results of chemical studies of temperate, tropical and subtropical soils. The ratio of divalent and monovalent exchangeable cations and the Ca/Mg ratio in soils depend chiefly on the degree of base saturation of the soil colloid. Highly leached acid tropical soils contain more monovalent cations relative to divalent and more Mg relative to Ca than do illuvial, base-saturated soils, indicating that both a valence effect and an effect of activity coefficients play a part in the ion-distribution problem of soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Control of the water-level in faintly sloping areas.
Authors: Van Schagen F.
Published: June 2020

Detailed diagrams and maps are given to supplement the account of water-control methods and installations in central, southern and eastern Holland. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The choice of lucerne varieties in the Netherlands.
Authors: Scheijgrond W.
Published: June 2020

Trials were carried out at 2 stations in the Netherlands in the period 1949-51 to compare the amounts of dry matter and crude protein yielded per ha. by 5 different types of lucerne. The Northern French varieties (Du Puits, Flamande Chartain-villiers and Flamande Flandria) gave considerably higher yields of dry matter and protein than Provence or Italian lucerne. A further trial was carried out in the Netherlands in co-operation with O.E.E.C., in which the performances of varieties from Western, Eastern, Central and Southern Europe, North and South America, New Zealand, India and South Africa were compared. The results are tabulated under the following headings: yield in comparative figures, speed of regrowth after winter, earliness of flowering, degree of infestation by grasses and cold-resistance. The Northern French varieties Du Puits, Flamande Flandria, Flamande Chartainvilliers, Flamande Socheville and Flamande C49, gave higher yields of dry matter and crude protein, regrew more rapidly after winter and were less susceptible to infestation by grasses than the other varieties tested. Their cold-resistance was satisfactory. There were no considerable differences in performance between the Northern French varieties tested.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil- and land classification in the old coastal plain of Surinam.
Authors: Van der Eijk J.J. , Hendriks H.A.J.
Published: June 2020

The old coastal plain consists of isolated, scattered areas of dry or only periodically waterlogged soils. Their total area is 21% of the entire coastal plain. The soils are either sandy loam soils formed on the old offshore bar or silt loam or silty clay soils formed on the old tidal flat. An aerial photograph and a map on a scale of 1: 666, 666 are given and the soils are classified into series. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Sprout uniformity in growing brussels sprouts.
Authors: Kronenberg H.G.
Published: June 2020

The effects of planting distance (60 X 60 or 60 X 30 cm), topping early in the season and pre-picking on the quality (size and distribution of size) of brussels sprouts were determined. The wider planting distance gave the better results. Topping and pre-picking had hardly any influence on crop uniformity in plants spaced at 60 X 60 cm. Combinations of closer planting, topping and pre-picking were always unfavourable. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrogen nutrition of rice plants measured by growth and nutrient content in pot experiments. 3. Changes during growth.
Authors: Dijkshoorn W. , Ismunadji M.
Published: June 2020

Young rice plants cv. IR-5 in flooded sand culture grew better with ammonium than with nitrate as N source; yield differences were initiated by a higher rate of tillering and leaf expansion with ammonium nutrition during the first stage of exponential growth. When complete foliage cover had been obtained and further DM increases were linearly related to growth duration, nitrate was less readily assimilated than ammonium, but growth rate was the same for both forms of N because it was controlled mainly by environment and nutrient supply rather than by leaf area, form of available N or concentration of N in the tissues. Restoration of N supply to an N-depleted culture of well-developed plants showed that ammonium produced an earlier renewal of growth; plants yielded more on a given date than with nitrate although they eventually regained the same rate of linear growth. Plants given nitrate contained more carboxylates than those given ammonium, irrespective of plant age or temporary N shortage. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrate reductase activity and oxalate content of sugar-beet leaves.
Authors: Egmond F. van , Breteler H.
Published: June 2020

Diploid sugar beet was grown in controlled environment at 25/17 deg C in 14-h photoperiods in well aerated, regularly changed nutrient solution containing 6 meq NO3/l. When 6 leaves had been expanded, the total carboxylate content of the oldest leaf (leaf 1) was found to be 5836 meq/kg DM, while that of leaf 6 was only 2312 meq/kg; the difference was mainly due to oxalate content, which was 5236 meq/kg in leaf 1 and 1744 meq/kg in leaf 6. Nitrate-N content was about 50% higher in leaf 1 than in leaf 4. Nitrate-reductase activity fell to very low values as leaves aged. Experiments in which young and old leaf material was mixed, or oxalate at 0-4000 meq/kg DM was added to leaf samples, showed that oxalate had no substantial effect on nitrate-reductase activity. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of local cooling on growth and water content of plants.
Authors: Kleinendorst A. , Brouwer R.
Published: June 2020

In maize cv. Pioneer 395 grown in controlled environment in Hoagland solution at 20 deg C with 18-h photoperiods, low-temperature treatment of localized parts of the plant inhibited leaf elongation to an extent dependent on the site of cooling. Root temperatures of 5 deg C decreased leaf elongation as a result of water shortage and consequent retardation of cell extension. Plant osmotic potential increased and leaf elongation then resumed. When roots were cooled rapidly to 2-2.5 deg C the lower leaves died as a result of irreversible wilting, but with slow cooling the leaves survived. The response to these low temperatures was considerably less in older than in younger plants. Low temperatures at leaf meristem level directly reduced leaf elongation by acting on cell division and cell extension; the effect tended to increase with time. Local cooling above the meristem temporarily retarded growth by inhibiting carbohydrate translocation (demonstrated using 14CO2), but resulted in an increased concentration gradient which partly offset the effect of temperature. Cell extension was considerably inhibited, cell division probably only slightly. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Studies on the amount and composition of digesta flowing through the duodenum of dairy cows. 2. Sites of net absorption of magnesium and calcium from the alimentary tract.
Authors: Kemp A. , Klooster A. van't , Rogers P.A.M. , Geurink J.H.
Published: June 2020

Two cows were fitted with re-entrant duodenal cannulas, and four with T-piece duodenal annulas. Balance trials were carried out, the cows receiving either a winter ration, or freshly-mown herbage. Direct measurements were made of the flow of digesta, and of the amounts of Mg and Ca in both duodenal and faecal samples. Also indirect measurements were made of these parameters, using polyethylene glycol and chromium sesquioxide indicators. Net Ca absorption was restricted to the intestines, and, at high Mg intake, net Mg absorption was also largely intestinal, though too large an error attached to the indirect measurement of Mg absorption rates for reliable conclusions to be drawn. There was considerable secretion of Ca proximal to the duodenum. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Aspects of agricultural use of potato starch waste water.
Authors: Haan F.A.M. de , Hoogeveen G.J. , Riem Vis F.
Published: June 2020

Disposal of potato starch process water (average N, P2O5, K2O contents, 390, 140, 700 mg/l) on the land results in a high degree of purification. Complete purification is obtained in sandy soils if the rates do not exceed 100 to 150 mm/year. To maintain favourable conditions for biological decomposition of the organic matter the dose should be less than the water storage capacity of the soil. Disposal of the annual amount between a number of sprinkling irrigations is therefore recommended. Application rates can be adjusted to plant nutrient requirements. Optimum adjustment leads to an average yearly application of 25 mm yearly for the normal cropping pattern of the Peat Colonies. If excess supply is accepted the average value can be increased to 60 mm without harmful effects. From a computerized model study of the effect of the utilization of this waste water on farm economic results, the applications of 50 and 100 mm gave the highest returns.[227.7]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Growth of side shoots in brussels sprout plants as influenced by GA3 and defoliation.
Authors: Kronenberg H.G.
Published: June 2020

Field-grown brussels sprouts were either treated once with GA3 at 0-27 mg/plant or were defoliated on 10 fortnightly dates between 25 May and the end of September. GA3 markedly stimulated side shoot growth at most application dates, the maximum effect being obtained with the highest rate applied on 8 June. Defoliation on most dates had little stimulating effect on side shoot growth, but when carried out on 3 August the effect was marked. [For previous related work see HcA 41, 8833.]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Regeneration of bulblets on bulb scale segments of hyacinth in vitro.
Authors: Pierik R.L.M. , Ruibing M.A.
Published: June 2020

Hyacinth bulbs, cv. Pink Pearl, harvested in June were held at 25 deg C for 1-5 months, after which bulb scales were removed for tissue culture in modified basic medium. The length of the holding period had little effect on the number of bulblets that regenerated, but the average bulb weight increased as the holding period lengthened, attaining a maximum with bulbs held until 1-15 October. There were wide differences in regenerative ability and bulblet growth between bulbs of the same harvest and size. The number of bulblets that regenerated was not affected by scale age, but bulblet growth from the older scales (nos. 7-18) was much better than from the younger scales. Regeneration and growth of explants from the proximal parts of the scales was much better than from the distal parts, and 3-cm-long explants gave much better results than shorter ones. Inverting the explants in the culture medium was favourable to regeneration and growth. In further studies on the effects of temperature and light, bulb regeneration was accelerated by raising the temperature, the optimum being 21.6 deg . The greatest number of bulblets/explant, however, was obtained at 13 deg , and the highest bulb weight at 21.6 or 24.8 deg . There were no differences in regeneration and bulblet growth between scales grown in continuous light or in darkness. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of chlormequat on the flowering of the tulip.
Authors: Bragt J. van , Dekker P.H.M.
Published: June 2020

Tulip bulbs, cv. Apeldoorn, that had been stored at 5 deg C for 12 or 18 weeks before planting on 9 November, 15 December or 17 January were forced at 15 or 19 deg under continuous light, and chlormequat at 0-16 g/pot was applied to the soil when the shoots were about 3 cm above the soil. The number of days to flowering and the flowering duration were not affected by chlormequat, but stem length at flowering time and finally, and the lengths of the lowest and highest internodes and of the perianth were all reduced in proportion to the amount applied. Later planting shortened the period to flowering as well as stem length, and forcing at 19 deg had similar effects when compared with 15 deg . Storage for 18 weeks also shortened the period to flowering, but stem lengths were longer than those in bulbs stored for 12 weeks; in addition, the effect of chlormequat on the length of the highest internode was enhanced. The response to the various treatments in terms of length of the different organs was in the order forcing temperature > chlormequat > planting date > storage period. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Gibberellic acid flower formation and stem elongation in Silene armeria.
Authors: Wellensiek S.J.
Published: June 2020

Several selected S. armeria lines differing in their reaction to GA3 were treated with GA3 at various concentrations under short-day (SD) or long-day conditions. With SD treatment one application of GA3 at high concentration (10 000 p.p.m. or greater) induced flower formation in certain lines. Stem elongation increased with GA3 concentration and with plant age and was much greater on flowering plants than on non-flowering ones. [For previous related work see HcA 41, 4400.]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of chopped hay on feed intake, rate of eating and rumination of dairy cows.
Authors: Voskuil G.C.J. , Metz J.H.M.
Published: June 2020

The effect of chopped hay on feed intake, eating rate and rumination time was studied. Relations between these variables were evaluated. Ten pregnant cows at the end of lactation were given 3 kg concentrates daily and chopped or unchopped hay to appetite. Chopping the hay did not significantly affect intake of hay or total ruminating time. Duration of rumination/kg hay was significantly less when chopped hay was given. Chopping the hay also significantly reduced the number of boli/day. Daily intake of hay was positively correlated with duration of rumination. When long hay was given, a higher eating rate was associated with a longer rumination time; with chopped hay there was no significant relation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of nitrogen on the root and shoot development of Lolium multiflorum var. westerwoldicum.
Authors: Schuurman J.J. , Knot L.
Published: June 2020

Westerwolds ryegrass was grown in tubes on artificial soil profiles at N rates equivalent to 25, 50 or 100 kg/ha with a water table maintained 70 cm below the soil surface. Average results/plant after 13 weeks at low and high N were: DM yield of tops 5.0 and 14.6 g, water consumption 2660 and 4850 cm2, DM yield of roots 1.4 and 3.4 g, total length of all primary roots 2589 and 3374 cm, number of primary roots 103 and 161, number of secondary roots in topsoil 63 and 83 and in subsoil 71 and 83, and total root surface area 1084 and 1736 cm2.
ADDITIONAL ABSTRACT: L. multiflorum plants were grown on sandy soil in asbestos tubes with an inner diameter of 15 cm, and 75 cm high, and supplied with 25, 50 or 100 kg N/ha. The soil water level was maintained at 70 cm below soil level. Top growth 8 and 13 weeks after sowing was progressively enhanced by the 2 higher rates, weight increments amounting to at least 72 and 188 %, respectively. These growth increases were accompanied by augmented water consumption, as well as root growth and numbers. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of soil compaction at various depths on root and shoot growth of oats.
Authors: Schuurman J.J. , Boer J.J.H. de
Published: June 2020

The effect of a loose topsoil of 23-63 cm depth overlying a dense subsoil of 35-75 cm depth on root and shoot development was compared with the effect of a homogeneous column of loose soil of 98 cm depth. Shoot weights and, to a large extent root weights, were similar during early growth, but, at later stages, they were higher in the heterogeneous soil columns. Throughout growth, root weights were greater in loose topsoil of the heterogeneous soil columns than in the corresponding layer of the homogeneous columns. Total root weights were higher in the homogeneous columns up to May 23rd, but, at later dates they were higher in the heterogeneous columns. Decreases in root weight at the boundary zone between the layers were mainly due to decreased root branching and, secondarily, to decreased root number. Rooting depth in the dense subsoil increased with increasing thickness of the topsoil, and probably with increasing depth of the water table. Shoot/root ratios at later growth stages were highest for the heterogeneous columns with thin top-soil layers, indicating the presence of favourable growing conditions despite restricted root development. This was confirmed by water consumption data. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The performance of surface and subsurface drainage on heavy clay soils in Yugoslavia.
Authors: Groot J.M.
Published: June 2020

The soils of the Sava River basin (Yugoslavia) have a permeable topsoil of about 0.3 m depth, which overlies an impermeable subsoil. During rainfall, horizontal flow through the topsoil occurs. Appropriate formulae for steady and non-steady flow have been derived, which, together with field observations on field accessibility, have permitted the determination of drainage requirements. In selecting the best drainage system the projected mechanization of agriculture in the area has been considered. Partly for this reason, partly because it provides better drainage during reclamation and in the first year of cropping, and partly for long-term economic reasons (initial costs are higher), subsurface drainage (1.0-1.2 m depth and 15 m drain distance) is preferred to surface drainage. Factors determining peak discharges of field drains are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Selective ion uptake in the initial phase and root surface potentials.
Authors: Grobler J.H.
Published: June 2020

A discussion with 28 references. (Abstract retrieved from CAB Abstracts by CABI’s permission)
X-rays applied to the study of the pore structure in soils.
Authors: Rogaar H. , Thiadens R.A.H.
Published: June 2020

X-ray radiography, which has proved to be a useful tool in tackling palaeontological, geological and soil mechanical problems, is shown to be useful as well in the study of the pore structure in soils. The advantages of X-ray radiography, some limitations and the necessity to combine this technique with others are discussed. The method is useful in the field of soil research as well as in education. In illustration, radiographs of subsoil samples of a marsh and three polder soils of the Wash area (Norfolk, England) are added. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Availability for ryegrass of cadmium and zinc from dressings of sewage sludge.
Authors: Dijkshoorn W. , Lampe J.E.M.
Published: June 2020

In pot trials, perennial ryegrass was grown in soil treated with sewage sludge containing 370 ppm Cd, 4940 ppm Zn and 450 ppm Pb or with equivalent amounts of Cd and Zn as sulphates. Levels of Cd and Zn in herbage in sewage sludge treatments were only about half as high as where the sulphates were used, and unlike in water culture did not increase progressively in subsequent cuts. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A simple worst case analysis for estimation of correct scanning rate in a micrometeorological experiment.
Authors: Stigter C.J. , Lengkeek J.G. , Kooijman J.
Published: June 2020

After a review of confusing literature debates, a simple way is demonstrated to estimate influence of sample frequency on means of scanned meteorological variables in a field of maize. For a high time-constant thermometer the influence of high scanning rates is demonstrated to be low in relation to chosen approximations of the true mean by a lower scanning rate. For a very low time-constant thermocouple psychrometer and a low time-constant air movement meter the influence of several lower scanning rates is demonstrated to be low in comparison with a chosen approximation of the true mean by a relatively high scanning rate. As no Fourier analysis is applied in this simple method, definite assessment of aliasing errors is in theory only approximated, although other results point into the direction that such an analysis would not change much the error examples given. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of the phosphorus and calcium content of feeds on growth, feed conversion and slaughter quality, and on the chemical, mechanical and histological parameters of the bone tissue of pigs.
Authors: Kempen G.J.M. van , Kerk P. van de , Grimbergen A.H.M.
Published: June 2020

In a 2 X 4 factorial experiment on 96 individually housed pigs, 2 calcium/phosphorus ratios (1.3 and 1.9) and 4 phosphorus levels (0.4, 0.5, 0.6, 0.7% total P) were tested. The influence of the treatments on growth, feed conversion and slaughter quality was measured. The experiment showed the 1.3 Ca/P ratio to be more favourable than the 1.9 ratio. A P content of 0.6% was sufficient for good growth and favourable feed conversion. The quality of the bone tissue, for which the specific response resistance to distortion and breaking was used as a standard, was close to maximum when P in the feed was 0.6%. The strength of the whole bone, measured as the bending moment for distortion and breaking, was greatest when P was highest; mineralization of the bone also showed a further increase when the P content in the feed increased from 0.6 to 0.7%.During the experiment only a few cases of leg weakness were noted; these occurred throughout all the experimental treatments. On the basis of the results, the P and Ca requirements for optimal growth and feed conversion for the modern Dutch pig are 0.6% and 0.78%. More of these minerals in the feed may, however, increase deposition in the skeleton. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Application of analog and numerical models to investigate the influence of drainage on workability in spring.
Authors: Wind G.P.
Published: June 2020

Models of non-steady unsaturated moisture flow were used to calculate moisture conditions in a top soil from natural rain and evaporation data for 23 years. The calculations were made with 5 drainage depths and 3 drainage intensities using an analog model. The number of days when the soil was workable and the first workable day showed large variations over the years. Drainage depth had a pronounced effect on workability but drainage intensity had hardly any effect. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Aldrin, heptachlor and beta -hexachlorocyclohexane to dairy cows at three oral dosages. 1. Residues in milk and body fat of cows early and late in lactation.
Authors: Vreman K. , Tuinstra L.G.M.T. , Hoek J. van den , Bakker J. , Roos A.H. , Visser H. de , Westerhuis J.H.
Published: June 2020

1. To investigate the transfer of aldrin, heptachlor and beta -hexachlorocylohexane ( beta -HCH) from feed to milk and body fat of dairy cows, 9 cows early and 9 cows late in lactation were assigned to groups of 3 and given different daily dosages of a mixture of pesticides: 1 mg, 2 mg or 4 mg each of aldrin, heptachlor and beta -HCH/cow daily for 4 weeks. Milk fat and body fat samples were analysed for pesticide content. Aldrin and heptachlor could not be detected in milk fat or in body fat. Average contents of beta -heptachlorepoxide were below 0.1 mg/kg even for the highest dosage. The beta -HCH and dieldrin contents in milk fat increased rapidly. The ratio of contents between the groups roughly corresponded to that between the dosages. The cows early in lactation did not have less beta -HCH and dieldrin than the cows late in lactation. During the first 14 days after withdrawal the contents of beta -HCH and dieldrin usually decreased by more than half. The average transfer coefficients for cows late in lactation were all below 10% and for cows early in lactation about 3 times as high, because yield of milk fat was nearly 3 times as high early in lactation. The pesticide contents in body fat too increased but did not reach the same level as in milk fat. Cows early in lactation usually had higher contents in body fat than cows late in lactation. An estimate of the average relative mass of beta -HCH and dieldrin in milk fat and body fat is given. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Vegetative propagation of Freesia through the isolation of shoots in vitro.
Authors: Pierik R.L.M. , Steegmans H.H.M.
Published: June 2020

Shoots from the cvs Ballerina, Aurora, Rijnveld's Golden Yellow and Rose Marie, originating from excised flower-buds, were grown in vitro and were induced to form shoots on a modified Murashige and Skoog medium containing PBA and IAA. The greatest number of new shoots/excised shoot was obtained when the medium contained PBA at 5 mg/l and IAA at 0.1 mg/l. The number of shoots formed depended on the cv. tested. Subcultured shoots, grown on a medium with IAA but without PBA, could be rooted easily and viable plants were obtained. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Determination of free ammonium in plant tissue.
Authors: Novozamsky I. , Houba V.J.G.
Published: June 2020

The testing of a gas diffusion ammonia electrode for analysis of free NH4 in plant tissue is described. The method was quick, simple and reproducible if measurements were made within a few minutes of addition of the base to the plant extract. Coefficients of variation were 12.5 and 7.5% with borax buffer and NaOH, respectively, and it seemed that reproducibility was greater at higher pH. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil factors affecting the germination of potatoes left on the field after harvest.
Authors: Boone F.R. , Elst C.J. van der
Published: June 2020

Laboratory tests simulating field conditions with potato cv. Bintje showed that damaged tubers were more susceptible to rotting than healthy tubers and rotting occurred most readily in wetter soils. Crushing tubers resulted in a higher number of sprouts/tuber particularly when tubers were not buried deeply and the ability of uncrushed tubers to grow in loose soil decreased only slowly after 6 weeks. With increased soil compaction, germination decreased and growth of sprouts in the soil was impeded. In well-drained soils with good structure, deeper burial did not reduce germination although the later emergence resulted in weaker plants. It was concluded that soil temperature, soil water content, degree of tuber crushing, tillage operations and weather conditions all influenced tuber survival and that the soil environment immediately around the tuber was more important than overall soil structure. The success of crushing in inhibiting tuber survival was dependent on other factors and it was suggested that increasing the chances of simultaneous rotting and freezing was most promising. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Problem hydromorphic soils in north-east Thailand. 1. Environment and soil morphology.
Authors: Brinkman R. , Jongmans A.G. , Miedema R.
Published: June 2020

The Roi Et soil, a Gleyic Acrisol (FAO, 1974) is one of the main soils on the extensive seasonally wet, low terrace in north-east Thailand. The soil looks poor and produces traditionally low yields of one paddy rice crop/year. With fertilizers and dry-season irrigation, problems of water-logging, surface salinity and acidity caused poor germination and low yields of both rice and dry-season dryland crops. X-ray stereo radiographs, and macro- and micromorphological data indicate that the processes that have taken place in this soil include perforation and homogenization by roots and soil fauna; iron mobilization and redistribution; clay translocation; alteration of clay and formation of secondary silica; and surface slaking alternated with ploughing. The clay translocated appears to be fossil clay. Two stages of iron mobilization under (seasonally) wet conditions are indicated, the later one, with clay alteration, continuing at present. The soil has considerable macroporosity, due to worms and termites, mainly in the subsoil. The ploughpan and the deep subsoil have low porosity. (Abstract retrieved from CAB Abstracts by CABI’s permission)
New forage crop introductions for the semi-arid highland areas of Kenya as a means to increase beef production.
Authors: Arkel H. van
Published: June 2020

A UNDP/FAO Development Project has initiated and aided the establishment of a commercial beef cattle finishing sector in Kenya. The feeding systems developed utilize surplus cattle from rural areas which are fed on rations based on maize silage. The project has now initiated a search for forage crops suitable for cultivation under highland conditions, but more drought-resistant than the presently used maize. It appeared in a trial at 3 sites at 1850-1920 m alt. that new introductions of cold-tolerant sorghum cv. from the high-alt. areas of Uganda and Ethiopia produced consistently good yields which were comparable to, or better than, maize. Some of the high-alt. sorghum cv. were completely free from diseases which are typically encountered when 'lowland' cv. are grown above 1600 m in Kenya. In contrast with maize and sunflower, the new sorghum introductions were highly resistant to lodging. Correlation analysis showed that the unwanted tallness of crops is highly associated with the yield of maize and sunflower, whereas with cold-tolerant sorghum cv. there is scope for selection or breeding of high-yielding material which is shorter. The single highest-yielding entry for cold-tolerant sorghum, sunflower and maize produced 30.5, 29.5 and 26.6 t DM/ha, resp. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Tulip bulb production potentials in Europe.
Authors: Kronenberg H.G.
Published: June 2020

The development of tulip growing in Europe (particularly the Netherlands, the UK and Denmark) is discussed in relation to the growth cycle and effects of temperature and radiation. Maps are presented for the dates of shoot emergence (earliness of spring), leaf senescence (earliness of bulb ripening), potential production areas and relative aberrations. The present tulip-producing regions are not distributed evenly over the most suitable growing areas but are concentrated in eastern England and the western part of the Netherlands, indicating that other factors in addition to the growing requirements considered here are decisive. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Determination of leaf area coefficient in sunflower.
Authors: Pereira A.S.R.
Published: June 2020

For studies on the relationship between photosynthetic capacity and yield components in sunflower a method for estimating leaf area was required. To this end use of the leaf area coefficient (LAC), i.e. the quotient area/(length X max. width), was evaluated. It was found that LAC may be a function of leaf position and plant density, depending on the cv. concerned. For the Russian cv. Armavirec, LAC was independent of leaf position and plant density. For the Rumanian hybrid HS 18, LAC was dependent on leaf position but not plant density. For the French hybrid INRA 4701, LAC depended on both leaf position and plant density, but even in this case, it was concluded that LAC can be a useful aid in leaf area estimation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Problem hydromorphic soils in north-east Thailand. 3. Saline-acid conditions, reclamation, improvement and management.
Authors: Brinkman R. , Dieleman P.J.
Published: June 2020

Saline-acid conditions have developed in patches in the irrigated areas on the low terrace in north-east Thailand. There are also traditionally uncultivated, virtually barren, saline-acid strips adjoining higher terrace remnants, in spite of the excess of monsoon rainfall over evapotranspiration. Calculations show that the salts in the shallow groundwater of the low terrace may have originated from rainfall, but that salts in the main rivers are mainly derived from salt beds. The local surface salinity, mainly of NaCl, is caused by continual evapotranspiration during the dry season and locally impeded leaching. The latter is due to a combination of a shallow water-table, slow vertical permeability and in some cases the slight elevation above the normal level of monsoon flooding. The high salt concentrations in and on the soil surface bring originally exchangeable aluminium into solution, which lowers the pH. In extreme cases even some ferric iron is dissolved at the soil surface. Reclamation, improvement and management practices on these soils should include leaching, for example under two rice crops per year; judicious liming, to eliminate most of the exchangeable aluminium but not to exceed the small buffer capacity of these soils; and emphasis on paddy rice, both in the monsoon season, and, irrigated, in the dry season. If, however, dry-season dryland crops are to be grown, physical problems of different kinds may necessitate further land improvement and management practices. These include, principally, lowering and keeping down the water-table, for example by control of irrigation water losses from canals and ditches; ploughing or disking in chopped crop residues with added nitrogen; and locally, chiselling the upper part of a dense subsurface horizon. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of temperature on growth and development of cultivars of radish (Raphanus sativus L. var. radicula Pers.) under summer conditions.
Authors: Nieuwhof M.
Published: June 2020

During 1977, seven cultivars and strains were sown in glasshouses at temperatures of 10, 14, 17, 20, 23 and 26 deg C and harvested at five dates. Maximum leaf and dry-matter production occurred at 20 and 23 deg C, and maximum root growth initially at 20 and 23 deg C, but later at 17 deg C. Cultivar differences in rate of leaf and root growth were observed, and cultivar X environment interactions were apparent for leaf and root growth under summer conditions. The overall order of cultivars for leaf and root weight was similar to that for plants grown under autumn conditions [see PBA 47, 5915]; hence it is suggested that selection of plants for growing in winter could be performed during the summer. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Breeding for early root thickening of radish (Raphanus sativus L. var. radicula Pers.) under poor light conditions. I. Performance of F1 half-sib families at different temperatures in late autumn.
Authors: Nieuwhof M. , Garretsen F.
Published: June 2020

Twenty half-sib families, from early-thickening mother plants selected from four early cultivars in a late-autumn trial [see also PBA 47, 5915], were sown in the glasshouse with their parent types during October 1975, at 10, 14, 17 or 20 deg C. The optimum temperature for root thickening was 14 deg C, and significant differences were observed between families for average root diameter. The earliest families originated from mother plants selected from the early cultivars Rota and Robijn [Ruby]. It is suggested from the results that the autumn selection of plants with early root thickening could be used to obtain families with a shorter growing period under poor light conditions than the parent cultivars, and since the heritability of the breeding value was highest at 14 deg C, selection should be performed at this temperature. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Selection for wide temperature adaptation in Chrysanthemum morifolium (Ramat.) Hemsl.
Authors: Jong J. de
Published: June 2020

Rooted cuttings of commercial cvs were grown to flowering at five temperatures and the the number of short days to flowering was recorded. The optimum temperature for rapid flowering varied between cvs. The number of days to flowering at the optimum temperature was not related to the delay in flowering caused by either high or low temperature. In many cvs the delay in flowering at low temperature was accompanied by a similar delay at high temperature. It was concluded that for the character 'time to flowering' genotypes should preferably be selected at low temperatures. If low temperature cannot be realized, only rapidly flowering genotypes should be selected. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some soil morphological effects of earthworm activity; field data and X-ray radiography.
Authors: Rogaar H. , Boswinkel J.A.
Published: June 2020

The effects of the burrowing activity of earthworms on recently reclaimed polder soils were studied in the field and by binocular microscopy and X-ray stereo-radiography. Most observations are from a plot in a grassed apple orchard, some from a permanent pasture. Species involved comprise Lumbricus terrestris, Allolobophora caliginosa, A. rosea, A. chlorotica and L. rubellus. Under grass cover, an A1 horizon is formed, increasing in thickness with time since introduction of the worm population. Under clean cultivated conditions and in strongly compressed wheel tracks, however, development of an A1 horizon is inhibited. The A1 horizon mainly consists of earthworm excreta, which fill most of the burrows. The pre-existing channel structure produced by roots is disrupted by the earthworms. The earthworm activity leads to a marked increase in air permeability of the surface horizon. This may not be sufficient explanation for the previously-reported yield increase of the orchard or the divergence in composition of the grass cover. Several kinds of burrows are distinguished by their shapes and contents, and ascribed to different species or genera. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Herbage quality in Rhodes grass (Chloris gayana Kunth). 1. The effect of heading date on intra-variety variation in yield and digestibility in vitro.
Authors: Boonman J.G.
Published: June 2020

350 selected plants of Rhodes grass cv. Mbarara (early-heading), Masaba (medium-heading) and Pokot (late-heading) were examined for both seed and herbage yield characters, the latter at the stage of initial heading. Within each of these cv. a large variation occurred between individual spaced plants in seed and herbage yield, leaf:stem ratio and OM digestibility in vitro (D-vitro). However, this variation was secondary, as it was largely accounted for by a wide variation in heading date, ranging over more than or equal to 8 wk within a cv. There was a progressive decline in yield characters with every wk of delayed heading. Early-heading plants produced yields of pure germinating seed more than double those of late plants. At the initial-heading stage these plants also had a higher herbage yield, leaf:stem ratio and D-vitro, but a lower content of stem and dead leaf. D-vitro was on average 7.6 units higher in early plants than in plants heading 8 wk later, but the extremes varied as much as 17 units between some early and late. D-vitro of leaf, stem and whole-sward samples fell by 0.07, 0.12 and 0.14 units, resp., with every day of delayed heading. Leaf digestibility and DM content were higher than those of stems. At the initial-heading stage whole-sward digestibility and leaf:stem ratio were higher in Mbarara than in Masaba and Pokot, because Mbarara plants were on the whole earlier in heading. Of those plants, however, which had a common heading date in each of the 3 cv. i.e. which were sampled at the initial-heading stage and on the same day, digestibility and leaf:stem ratios of Masaba plants were above those of Mbarara and, in particular, those of Pokot. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Investigations on a diffusion porometer with a fast humidity sensor.
Authors: Visscher G.J.W. , Griffioen H. , Leeuwen C.H. van
Published: June 2020

A commercially available small humidity sensor with a very fast response was used in an unventilated diffusion porometer to measure leaf epidermal resistance. Measurements over calibrated dummy resistances showed that such a porometer had definite advantages in transpiration measurements in the field. In particular the waiting time before each measurement, necessary to obtain reproducible results with the commonly used LiCl sensor, could be shortened from 2 min to 15 s or even less. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A comparison of the behaviour of some root systems under restricted aeration.
Authors: Wiersum L.K.
Published: June 2020

Using soil-filled plastic cylinders with a controlled atmosphere in contact with the soil surface, the limiting aeration requirements of 5 crop spp. including pea, oats and potato were measured, with O2 diffusion rate values as a parameter. Pea had the highest requirements, oats the lowest, while potato was intermediate. This sequence corresponded rather well with field experience. Shallow rooting as a result of poor soil aeration could restrict the uptake of a number of mineral nutrients. In these experiments, P and K were more often severely restricted than Ca or NO3. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrogen uptake by rice plants from a dry soil at maintained water supply from a greater depth.
Authors: Rehatta S.B. , Dijkshoorn W. , Lampe J.E.M.
Published: June 2020

In a pot trial in the Netherlands with sunflower and an upland rice cv., multiple-compartment systems with N and water supplied from different compartments were used to demonstrate that plant availability of N from a dry soil horizon was low. The separation of N and water in different soil horizons along with a decreasing input of irrigation water reduced the uptake of N more than the plant DM production was reduced by the decrease in the amount of water supplied to the plants. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The growth of maize in the cool temperate climate of the Netherlands: Effect of grain filling on production of dry matter and on chemical composition and nutritive value.
Authors: Deinum B. , Knoppers J.
Published: June 2020

In a trial in 1975 the effect of grain filling on productivity and nutritive value of forage maize was studied in 3 hybrid cv. Variation in grain filling was obtained by periodic sampling after silking (end-July) of pollinated (fertile) and unpollinated (sterile) crops. Production of DM of fertile and sterile maize was the same until end-Aug. but in Sept. production rate of the sterile crop lagged behind the fertile crop by c. 100 kg DM/ha day, the difference mainly consisting of non-structural carbohydrate. In the fertile crop, carbohydrate mainly accumulated in the ear as starch, but in the sterile crop it was almost completely stored in the stover as water-soluble carbohydrate. In contrast to the fertile crop, cell-wall production in the sterile stem proceeded throughout Sept. Cell-wall digestibility in the stover was not affected by pollination, so because of the smaller yield of non-structural carbohydrate, yield of DM and DOM of the sterile crop were 14 and 17%, resp. less than of the fertile crop at the final sampling. These differences might become greater in the silage. These data collected in the sunny season of 1975 and from the literature suggest that in bright and warm weather yield of sterile maize will greatly lag behind fertile maize, but in adverse conditions (lower irradiance and temp., high plant density, unhealthy leaves) this yield lag would be smaller. So grain filling is important for good production and nutritive value of forage maize in cool regions with little sun, but it is less essential than in brighter and warmer climates. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A tentative approach to the molecular structure of humic acids: The spectral evidence for a derivation of humic acids from plant-borne esters. 2. Infrared and chemical analyses.
Authors: Minderman G.
Published: June 2020

It is suggested that: humic acids are polyesters, originate as monomers in the secondary metabolism of both higher and lower plants, and are formed in an acid environment (including high-moor peat); the formation of humic acids is promoted by desiccation, particularly under alkaline conditions; humic acids exhibit keto-enol tautomerism, can form semi-quinones and therefore stable radicals also, and derive their colour from these radicals. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Regeneration of leaf explants of Anthurium andraeanum Lind. in vitro.
Authors: Pierik R.L.M. , Leeuwen P. van , Rigter G.C.C.M.
Published: June 2020

Leaf explants were cultured on a basic nutrient agar medium to which were added growth substances (adenine, benzyladenine, kinetin, 2-iP [isopentenyladenine], zeatin or 2,4-D) and NH4NO3, (NH4)2SO4 or NaNO3 in various concentrations. The effects of using the surfactant Tween 20 during leaf sterilization and of growing explants in light and/or darkness for 20 weeks were also investigated. There was a strong positive correlation between callus formation and shoot regeneration. Regeneration was optimal under the following conditions: addition of 0.25-1.00 ml/litre Tween 20 during leaf sterilization, adding a growth substance (adenine 0.1 mg/litre, zeatin 1 mg/litre, or 2,4-D 0.08 mg/litre), culture during 16 weeks in darkness followed by 4 weeks of light, and including 206 mg/litre NH4NO3 in the medium. The promoting effect of low levels of NH4NO3 on shoot regeneration in callus was caused by the NH4+ ion and not by the NO3- ion. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A tentative approach to the molecular structure of humic acids: the spectral evidence for a derivation of humic acids from plant-borne esters. 3. Pyrolysis-mass spectrometry.
Authors: Minderman G.
Published: June 2020

Pyrolysis mass spectrometry of humic acids collected from oak forest litter and humus horizons, of esters extracted from oak leaves and of bark extracts indicated a close relationship between plant esters and humic acids. The data support the hypothesis that humic acids can be derived from simple mixed esters formed in the plants. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of protein and energy levels in a constant ratio supplemented with methionine and lysine on performance of layers and on egg quality.
Authors: El Boushy A.R. , Gils L.G.M. van , Papadopoulos M.C.
Published: June 2020

Twenty groups of 36 laying hens in individual cages were fed on one of 5 diets in which the energy:protein ratio was constant. Diets 1 to 5 had crude protein 12.0, 12.9, 14.0, 15.0 and 16.0% and metabolizable energy 8.71, 9.57, 10.27, 11.10 and 11.70 MJ/kg. From 24 to 64 weeks old, egg production of hens given diets 1 to 5 was 71.46, 71.31, 72.51, 71.13 and 69.99%, respectively. Corresponding values of mean egg weight, weekly feed intake and efficiency of feed conversion were 60.51, 60.47, 61.11, 61.02, 61.07 g; 157.16, 147.56, 142.03, 130.37, 126.72 g; 3.674, 3.460, 3.262, 3.031, 3.014 kg feed/kg egg, respectively. (Abstract retrieved from CAB Abstracts by CABI’s permission)