bluuebunny/crossref_metadata_2025 huggingface dataset:
Hybrid tea-roses under controlled light conditions. I. The effect of the level of irradiance on the growth and development of seedlings.
Authors: Vries D.P. de , Smeets L.
Published: June 2020

As a basis for breeding cvs adapted to flowering in winter light conditions, the growth of hybrid tea rose seedlings under controlled conditions was studied. Irradiance varied from 4-24 W/m2, day length was 8 h, temperature 21 deg C. Like cvs, the seedlings sometimes aborted the flower bud at low light intensity. With increasing irradiances, the following phenomena were observed: the juvenile period of the seedlings shortened; plants were longer at bud formation, at first flowering and at flower bud abortion; leaf area and the number of petals increased. Leaf number was constant at all irradiances. Flowering seedlings were smaller at bud formation, but taller at actual flowering than blind ones. Blind seedlings had fewer leaves with a smaller area. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Grassland farming and minerals in cattle.
Authors: Kemp A. , Geurink J.H.
Published: June 2020

Data reported earlier by J.A. Keuning [Stikstof (1974) 76, 87] on the mineral composition of grass samples from intensively managed farms in the Netherlands in 1962-1971 are tabulated and discussed in relation to mineral requirements (K, Na, Cl, Ca, P and Mg) of grazing high-yielding dairy cows. The effect of N fertilizer on the nitrate content in grass and other roughages is also considered in relation to the origin and prevention of nitrate poisoning in cattle. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Leaf area determinations in sorghum and maize by the length-width method.
Authors: Arkel H. van
Published: June 2020

5 plant population trials were carried out in 1974 and 1975 with 5 sorghum and 4 maize cv. Each trial was sample harvested several times during the growing period. In 6080 leaves the leaf area was carefully determined and related to its length and width. By regression calculations an examination was made regarding the construction of the best calibration lines for the estimation of the product of length and width from leaf area. Plant population had no significant effect on the regressions. Drawing the regression lines through the origin was sometimes statistically rejected but if the regression lines were forced through the origin in spite of this, the loss of precision was very small. It is therefore concluded that forcing the regression lines through the origin involves an acceptable estimation error. The resulting regression lines which were established separately for each cv. and harvest proved to estimate the leaf area accurately. The values of the regression coefficients varied between 0.65 and 0.77. The lowest correlation coefficient was 0.968, but 55% of all correlation coefficients were >0.990. If data from different harvests were pooled (although not allowable statistically) the highest mean error of estimation of leaf area at any harvesting date was 8.5%. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The forage and grain yield of sorghum and maize as affected by soil moisture conservation, lodging and harvesting losses.
Authors: Arkel H. van
Published: June 2020

The effects of early ploughing (before the start of the dry season) and late ploughing on the grain and DM yields of a forage maize and cold-tolerant forage and grain sorghum crops are reported. It appeared that on a shallow soil no significant effects on crop production could be shown, but on a deep soil with good water-holding capacity, crop yields were increased considerably by reducing soil moisture evaporation in the dry period prior to the growing season. In DM yield forage sorghum outyielded maize, a difference which was accentuated when mechanized harvesting systems were used in lodged crops. Forage sorghum proved to be more lodging-resistant than maize but, even when lodged, was harvestable without too much difficulty. The use of small-plot maize yield trials is considered to have limited applicability to mechanized harvesting systems when presently available Kenyan maize hybrids are used. Lodging was the major limiting field factor for the harvesting of heavy maize crops. The highest net yields recorded for maize and sorghum were 12.0 and 23.7 t DM/ha, resp. The higher yield of sorghum was probably not due to better drought resistance but to lower lodging susceptibility and a longer growing period. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The causes of the lack of self-tolerance of winter rye, grown on light sandy soils. 2. Influences of phytotoxins and soil microflora.
Authors: Scholte K. , Kupers L.J.P.
Published: June 2020

As a result of an investigation into the causes of self-intolerance of rye (i.e. of rye following rye) it could be proved that a number of obvious well-known pathological agents such as nematodes, foot rots and phytotoxins cannot be accepted as important causes. Circumstantial evidence was produced strongly suggesting that the composition of the soil microflora (to a certain extent itself the result of growing this crop in the previous yr) is the main cause. Soil sterilization eliminates self-intolerance. One symptom of self-intolerance is the rapid degeneration of the root system at an early stage of growth. Application of larger rates of N postpones the onset of this phenomenon. The effect of N is indirect. A larger continued uptake of N furthers the potential for compensation of the plant. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Fossil and recent soil formation in lateleistocene loess deposits in the southern part of the Netherlands.
Authors: Slager S. , Jongmans A.G. , Miedema R. , Pons L.J.
Published: June 2020

In the younger, Weichselian (Wurm, Wisconsin) loess deposits in the south of the Netherlands there is a horizon with fossil pedotubules (filled animal burrows). These pedotubules, 3 mm ( plus or minus 1 mm) in diameter, unbranched, without preferential orientation, are most abundant in the zone extending from about 30 cm above the decalcification boundary (situated 2-3 m below the soil surface) to some decimeters below it. They are rare in the B3t horizon of the overlying Hapludalf. Their lower extension boundary occurs some 2 m below the decalcification boundary. These tubules result from fossil animal activity followed by decalcification, mainly of a Boelling soil surface. A loess layer some 2 m thick was probably deposited in the post-Boelling period; the lower part of this layer has a lamellae spot zone. Micromorphological evidence shows that the lamellae spot zone was originally at the actual soil surface. Consequently a geogenic origin of the lamellae spot zone rather than a pedogenic origin seems likely. Soil formation subsequently intensified the textural differences. It is suggested that the post-Boelling loess was free of calcium carbonate at the beginning of the Holocene and was deposited non-calcareously or was decalcified synsedimentarily. In Western Europe, loess soils formed from Pleistocene deposits probably matured earlier in the Holocene than has been assumed hitherto. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Herbage quality in Rhodes grass (Chloris gayana Kunth). 2. Intra-variety variation in yield and digestibility of plants of similar heading date.
Authors: Boonman J.G.
Published: June 2020

20 clones of similar heading date and selected from within Rhodes grass cv. Masaba were assessed at 3, 6 and 9 wk of regrowth. Lengthening the period of regrowth increased yield of DM and yield of DOM, but decreased digestibility in vitro of leaf, stem and whole-sward samples and leaf:stem ratios. Clonal effects were also significant for these characters except for leaf digestibility and leaf:stem ratio. No significant clone X regrowth period interactions were observed. Stem and leaf digestibility fell by 0.20 and 0.17 units daily, resp., while leaf:stem ratio dropped to 1.1 at 9 wk regrowth which coincided with initial heading. At this stage whole sward digestibility had fallen to 53, at a rate of 0.22/day. Leaf digestibility was always higher than that of stem. Clones differed significantly in digestibility showing a 5-unit range which had no relation to leaf:stem ratios. The 7 clones best in digestibility were among the 9 lowest in herbage yield. The ranking for yield of DOM did not differ from that for yield of DM, which showed a range of 1.38-2.45 t/ha. It is concluded that potential genetic gain in digestibility and leaf:stem ratio is offset by a corresponding decline in herbage yield. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Mixed cropping experiments with maize and groundnuts.
Authors: Mutsaers H.J.W.
Published: June 2020

Experiments were carried out during 3 seasons in the Yaounde area, Cameroon, in order to evaluate maize/groundnut mixtures compared with pure stands. Both crops had similar growth duration. Total grain/seed yields of both crops combined were lower for mixtures than for pure maize, but mixtures were found to be advantageous over pure stands in terms of relative yield total (RYT): in the Sept.-Dec. season of 1975 an av. of 6% more area would have been needed in pure stands to attain the same yield of each sp. as in the mixtures. In the March-July season of 1976 this was 16%. The results are discussed in terms of limiting factors. Results of a 3rd experiment suggest that the mixtures reduce the risk of supra-opt. population density compared with pure maize under severely limiting N availability. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Hybrid tea-roses under controlled light conditions. 3. Flower and blind shoot production in the glasshouse of seedlings selected for flowering or flower bud abortion at low irradiances in a growth room.
Authors: Vries D.P. de , Dubois L.A.M. , Smeets L.
Published: June 2020

Seedlings of hybrid tea roses, previously selected in a growth room for flowering or flower bud abortion at low light intensities were grown in a greenhouse for periods of at least 14 months. Previously flowering seedlings whether grown on their own roots or on a rootstock yielded more flowers, particularly in winter, than previously aborting ones. This was due to a lower percentage of blind shoots and a tendency to produce more shoots. It was shown that selection for better winter performance under glass could be made in young seedlings. [For part 2 see HcA 48, 7528.] (Abstract retrieved from CAB Abstracts by CABI’s permission)
The crude protein production of grassland and the utilization by milking cows.
Authors: Kemp A. , Hemkes O.J. , Steenbergen T. van
Published: June 2020

An attempt was made with experimental data of various origins to quantify the intake of N from pasture grass by milking cows during the grazing period. It was also demonstrated how much of this N was removed by secretion in the milk as well as the conc. of N in the faeces and in the urine remaining on the pasture after grazing. From a fertilizer application to the pasture of 450 kg N/ha yr an equal conc. was taken up by the herbage. Of this herbage N about 75-80% remained on the pasture after grazing. The conc. remaining on the grassland increased sharply with increasing N rates and this went parallel with an increasing intensity in the N circulation in the system soil-plant-animal-soil and a rising NO3 content in the surface layer of ground water. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Available phosphorus in poultry. 2. Effect of phosphorus in diet on performance of chicks, bone composition and strength, and calcium and inorganic phosphorus in blood plasma.
Authors: El Boushy A.R.
Published: June 2020

2. In 2 trials, medium heavy laying hens were crossed with White Cornish (Hybro) cocks to produce 2160 male chickens which were kept in batteries and given a diet with 0.3, 0.5 or 0.7% available phosphorus. Bodyweight, growth and feed intake of chickens 3 or 7 weeks old increased with increasing amounts of available P. Efficiency of feed conversion did not differ at 7 weeks old but was improved in chickens given 0.7% P at 3 weeks. Calcium and inorganic P in plasma and breaking strength, ash and P in the tibia increased with increasing P in the diet. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Two methods of preparing thin sections of wet soil from sediments in a marine intertidal zone in the Oosterschelde (the Netherlands).
Authors: Kooistra M.J.
Published: June 2020

Thin sections of immature marine sediments in the intertidal zone were prepared by replacement of the soil moisture by acetone, or by freeze drying, prior to embedding and sectioning. Replacement sections were of good quality and did not show artificial cracking. However preparation was time consuming and both salts and humic substances were removed by the acetone. Freeze dried sections were of poorer quality, but satisfactory. Artificial cracking was apparent. Preparation time was shorter but few salts were removed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrate poisoning in cattle. 3. The relationship between nitrate intake with hay or fresh roughage and the speed of intake on the formation of methemoglobin.
Authors: Geurink J.H. , Malestein A. , Kemp A. , Klooster A.T. van 't
Published: June 2020

For part 2 see NAR/B 48, 238. 3. In 40 feeding experiments during about 5 years dry or lactating Friesian cows weighing 415 to 670 kg and 3 to 8 years old were given diets of hay, grass pellets, turnips or freshly mown grass in 2 meals daily. During experiments blood from the jugular vein was sampled every 15 min. Cows were induced to increase nitrate intake by being given at least 4 meals of roughage rich in nitrate before blood was sampled. There was a positive relation between nitrate intake and methaemoglobin per cent of total Hb but there were differences within and between different roughages in formation of methaemoglobin. With similar nitrate intake and speed of intake, more Hb was converted into methaemoglobin with hay than with freshly mown grass. That was related to the speed at which the nitrate taken with the roughage was released in the rumen as a substrate for the rumen flora. When hay was soaked in distilled water 80% of the nitrate in the cells diffused into the water within 20 min. With turnip and grass chopped to about 1 cm, 30% of the nitrate diffused into the water within 20 min. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of dietary levels of calcium on performance of pullets and layers, physical characteristics of the egg, and calcium and phosphorus in plasma and bone.
Authors: El Boushy A.R. , Papadopoulos M.C.
Published: June 2020

From 16 weeks old 432 chickens of a medium-heavy strain were given diets based on maize, soya bean oilmeal and barley with 1.5, 3.7 or 5.0% calcium and about 0.8% phosphorus. Diets supplied metabolizable energy 12.12, 11.35 or 10.96 MJ/kg. After a laying phase at 23 weeks old when they reached 50% production, chickens given 5.0% Ca weighed significantly less and tended to eat more than those given 1.5 or 3.7% Ca. Ca in plasma did not differ among groups but inorganic P was greater in those given 1.5% Ca than in others. During the laying period of 22 weeks egg production was greatest with 3.7% Ca. Feed intake, egg shell thickness, relative density of egg shell and proportion of shell increased with increasing Ca in the diet. Egg weight, albumen index and yolk index did not differ among groups. Tibial ash and breaking strength of tibia increased with increasing Ca in the diet. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrate poisoning in cattle. 5. The effect of tungsten on nitrate formation by rumen microbes.
Authors: Korzeniowski A. , Geurink J.H. , Kemp A.
Published: June 2020

Sodium tungstate added to rumen fluid depressed the nitrate reductase activity of rumen microbes. The rate of nitrite formation in rumen fluid fell by about 86% if 20 mu mol of Na2WO4 were added per litre. At 100 and 500 mu mol/l no nitrite accumulation was observed. This inhibition was overcome by molybdenum. Experiments in cows confirmed these in vitro findings. Tungsten is suggested as a promising preventative of nitrite intoxication in ruminants. [For Part 3 see VB 50, abst. 5179.] (Abstract retrieved from CAB Abstracts by CABI’s permission)
Broiler growth response from practical low-protein diets supplemented with urea and diammonium hydrogen phosphate.
Authors: El Boushy A.R.
Published: June 2020

In an experiment with 480 Hybro chickens initially 1 day old, 6 starter diets were given to appetite for the first 4 weeks: (A) 23.5% crude protein, rich in essential amino acids; (B) 20.6% crude protein, containing essential amino acids to meet requirements; (C) B + 1% urea; (D) B + 0.5% urea; (E) B + 2.2% diammonium hydrogen phosphate (DAP); (F) B + 1% DAP. The finisher diets were: (A) 20% crude protein; (B) 18% crude protein with essential amino acids to meet requirements; (C) B + 0.7% urea; (D) B + 0.35% urea; (E) B + 1.5% DAP; (F) B + 0.75% DAP. Adding 1% urea or 2.2% DAP to the starter diets decreased growth and feed conversion significantly, whereas 0.5% urea or 1.1% DAP had no significant effect on growth and feed conversion, compared with control A. Adding 0.7 or 0.35% urea to the finisher diets decreased growth and feed conversion compared with diet A. Whereas the diet containing 0.75% DAP gave better results than that containing 1.5% DAP, there was no significant effect on growth, compared with group A. At 7 weeks of age, low concentrations of urea or DAP did not produce results that differed significantly from control diet B as far as feed conversion was concerned, but they were not comparable to control diet A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ear development and formation of grain yield in winter wheat.
Authors: Darwinkel A.
Published: June 2020

The pattern of grain production of a winter wheat crop and the effect of plant density and time of tiller emergence on grain yield/ear were studied. At harvest, ear size and ear components were ascertained and were discussed in relation to ear growth and ear development during the prefloral and postfloral growing period. Detailed information was obtained on the productivity of ear-bearing tillers and their contribution to final grain yield. Shoot productivity decreased in denser crops; ears were smaller because spikelet differentiation, grain set and grain filling were inadequate. The date that the tiller emerged largely determined its subsequent grain yield. With later tiller initiation and emergence fewer ears were produced. Moreover, these ears were smaller because spikelet initiation, spikelet differentiation, grain set and grain filling were reduced. At low and moderate plant densities, the grain yield of the early-emerged tillers only slightly lagged behind that of main shoots and max. grain yield could be achieved at moderate plant densities. It was concluded that in cereal farming, high and stable grain yields are aims to be achieved. These can be best achieved by having moderate plant densities and applying correct treatments for good crop growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Chemical element detection in thin sections of soils with the Laser Microprobe Mass Analyzer (LAMMA 500).
Authors: Bisdom E.B.A. , Henstra S. , Jongerius A. , Heinen H.J. , Meier S.
Published: June 2020

Components from thin sections of soils developed on weathered granite were analysed with the Laser Microprobe Mass Analyzer. Fragments of thin sections were mounted on sandwich grids, and perforated with the laser from the edges inwards (laser milling), using the laser light at grazing incidence. Laser-induced mass spectra of secondary titanium compounds and other constituents in the weathered granite were obtained in this manner. Positive and negative laser desorption mass spectra were recorded with such a speed and accuracy that in spite of the relatively large volume of analysed materials, minute changes in composition could be detected over very short distances. This allowed total chemical element analysis of spots in which titanium compounds concentrated during weathering, giving information on changes in purity of amorphous and semi-crystalline materials at such sites. Characteristic analysis possibilities of the Ion Microprobe Mass Analyzer (IMMA), Laser Microspectral Analyzer (LMA) and Laser Microprobe Mass Analyzer (LAMMA 500) are compared. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Quality of herbage at different latitudes.
Authors: Deinum B. , Beyer J. de , Nordfeldt P.H. , Kornher A. , Ostgard O. , Bogaert G. van
Published: June 2020

In a cooperative experiment, yield and herbage quality of timothy was measured during the uninterrupted growth of the 1st cut at 6 lat. (51-69 deg N). Rate of production was greatest at Tromso (69 deg N), apparently because of the long day and rapid reproductive development. Digestibility of OM declined faster at higher lat. because stem development proceeded faster and less leaf DM was produced. At the same morphological stage, digestibility of the whole crop was better at higher lat. because of the better digestibility of the cell walls from the stems. It was concluded that rate of lignification could not keep pace with the rapid rate of stem development. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of season on early tomato growth and development rates.
Authors: Klapwijk D.
Published: June 2020

Successive batches of tomato plants were raised throughout two years under ideal conditions in a glasshouse, and the intervals between sowing and the attainment of different stages in vegetative and reproductive growth were determined. The relationship between the season and the growing period was a simple one. There was a linear increase in the duration of the growing period between 21 September and 21 December, and a linear decrease between 21 December and 21 March. In the third season, from 21 March to 21 September, the growing period remained practically constant. The pattern of the relationship between the season and the growing period was maintained over a range of temperatures and light levels. Growth data from the literature for carnations, roses, radishes and lettuces under glass could be described in the same way. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Tomato plant growth as affected by horizontally unequal osmotic concentrations in rock-wool.
Authors: Cerda A. , Eysinga J.P.N.L.R. van
Published: June 2020

Tomato plants, cv. Moneydor, were grown in rockwool in a split-root system with equal or different osmotic concentrations. Fruit yield was negatively correlated with the mean electrical conductivity (EC) of both parts of the system. In treatments with two different EC values in the root zone, root development was better in the part with the low EC, and water uptake was higher. Nutrient concentrations showed an increase in the part with the low EC when differences in EC between both parts were 4 mS/cm [4 mmho/cm] or more. A possible explanation is that solutes move through the roots from the part with high to the part with the low osmotic concentration. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Alkane-grown yeast in relation to selenium in broiler diets.
Authors: Boushy A.R. El , Binnerts W.
Published: June 2020

In a trial, 1080 male chicks, 15 per cage, were given a basal diet low in selenium or diets with 12.5 or 25% of G-yeast grown on alkane-type hydrocarbons. All diets were supplemented with vitamin E 10 and antioxidant 100 mg/kg and each diet was supplemented with Se at 0.1, 0.25, 0.5, 0.75 or 1 mg/kg. There was a significantly negative linear effect of yeast on bodyweight, weight gain and a significantly positive linear effect on feed conversion efficiency up to 7 weeks of age, indicating that the G-yeast caused a depression in comparison with the control. The supplements of Se did not increase weight gain or feed conversion efficiency but increased contents of Se in breast and leg muscle at 7 weeks. The contents of Se in muscles of the broilers on the basal diet were rather high, presumably because of a carry-over from the hen via the egg. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of pH on copper toxicity to hydroponically grown maize.
Authors: Lexmond T.M. , Vorm P.D.J. van der
Published: June 2020

The effect of pH on Cu toxicity in maize cv. Capella was studied in 3 sol. culture experiments of different design. Raising the pH intensified the toxic effect of Cu which reduced root growth and enhanced association of Cu2+ ions with physiologically essential sites in the roots when competition from protons was lowered. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Concentrate feeding and ruminal fermentation. 1. Influence of the frequency of feeding concentrates on rumen acid composition, feed intake and milk production.
Authors: Malestein A. , Klooster A.T. van't , Counotte G.H.M. , Prins R.A.
Published: June 2020

1. Four cows with rumen cannulae were given 12 kg concentrates daily in 2 equal portions at 0800 and 1530, in one portion of 12 kg at 0800 or in 4 portions of 3 kg each at 0800, 1100, 1400 and 1700 h. Every period lasted 2 weeks. In addition to the concentrates hay was provided at 0900 and 1630 h and was adjusted so that the daily remainder was at least 1 kg. In 1978 experiments were made with concentrates low in starch and sugars (LSS) (23%) and in 1979 with concentrates high in starch and sugars (HSS) (50%). In 1978 when total DM intake, milk production and milk fat content of each milking were estimated daily, the trend in pH and concentration of L-lactic acid in rumen fluid were estimated on the last day of the preliminary period (2 X 6 kg) and on the 1st, 7th and 14th days of the experimental periods (1 X 12 kg and 4 X 3 kg). In 1979 the same estimations were made, but D-lactic acid and volatile fatty acids were also estimated. Compared to 2 X 6 kg concentrates the changeover to daily 1 X 12 kg or 4 X 3 kg concentrates did not result in significant differences in DM intake nor in milk or milk fat production. Within types of concentrates there was hardly any difference in lowest rumen pH between frequencies of concentrate feeding. When HSS concentrates were given pH in rumen fluid tended to be lower than with the LSS concentrates. With 2 X 6 kg HSS concentrates, pH in rumen fluid was for a short time lower than 5.5. Lactic acid concentrations in the rumen fluid reached maximum within 1 h after concentrate feeding and L-lactic acid was 6.5, 5.0 and 2.0 mmol/litre, respectively, for 1 X 12, 2 X 6 and 4 X 3 kg LSS concentrates. For HSS concentrates the values were 4.5, 2.5 and 1.0 mmol/litre. When the HSS concentrates were given maximum concentration of D-lactic acid in rumen fluid were 2.5 to 3 times the L-lactic acid concentration. When lactic acid was not increased D- and L-lactic acid concentrations were similar. At 0800 h the molar ratio of volatile fatty acids (C2:C3:C4) as a percentage of total volatile fatty acids (VFA) in rumen fluid was 62:22:15 and changed gradually to 56:24:20 at 1900 h. Differences in VFA between frequencies of concentrate feeding were small. Total concentrations of VFA did not vary between treatments. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of some trace elements on urea hydrolysis in soils.
Authors: Daif M.A. , Beusichem M.L. van
Published: June 2020

The application of Fe, Cu or Zn at 20 mu g g-1 soil to eight Spanish soils resulted in 7-20% inhibition of urease activity. The inhibitory effect was most pronounced in light-textured soils, and Cu was the most effective metal. These elements did not inhibit microbial production of urease in two soils. Cu, but not Zn and Fe, markedly retarded urea hydrolysis and reduced the loss of urea-N by ammonia volatilisation in a loamy sand. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of the roughage/concentrate ratio on nitrogen entering the small intestine of dairy cows.
Authors: Tamminga S.
Published: June 2020

The effect of different roughage:concentrate ratios on N entering the small intestine was studied in groups of 2 to 5 cows with a rumen fistula and re-entrant cannulae at the beginning of the small intestine. In 3 series there were 10 treatments in which DM intake ranged between 3.8 and 15.7 kg daily; the proportion of long roughage in the diet was from 29 to 81%. The apparent digestibility of organic matter (O), crude fibre (XF) and nitrogen-free extracts (XX) was 76, 69 and 81%, respectively. The proportion of the digestion taking place in the stomach was 59, 94 and 76%. A larger proportion of the apparently digestible organic matter tended to be digested in the stomach when there was a larger proportion of long roughage in the diet. The contribution of microbial N to the intestinal N was estimated. From this the efficiency of microbial protein synthesis was estimated and related to the amount of carbohydrates (XF + XX) fermented in the stomach. Per kg carbohydrates fermented, 32 plus or minus 1.5 g microbial N was produced. The percentage of dietary N not degraded in the stomach averaged 30 plus or minus 1.5. Varying the ratio between long roughage and pelleted concentrates seemed to have little effect on the degradation of dietary protein or on the efficiency of microbial protein synthesis. With long roughage in the diet between 29 and 81% there seems little effect of varying the roughage:concentrate ratio on the protein supply in dairy cows. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The antivitamin D factor in roughages.
Authors: Weits J.
Published: June 2020

Vitamin D was separated from the rachitogenic substance in dry grass and hay by chromatography [no details]. Fractions of the unsaponifiable residue of the grass fat, with addition of fixed amounts of vitamin D, were tested on rachitic rats, with radiography of the bones as criterion, to ascertain the content of rachitogenic substance. A fraction was obtained which contained all the vitamin D but not the rachitogenic substance. The last was present chiefly in the carotene fraction; the fraction containing xanthophylls was inactive. The method was applied to routine estimation of roughages. In hay dried in windrows or cocks or on tripods the vitamin D content ranged from 1005 to 1375 I.U. per kg., and there was little increase after chromatography, showing the absence of rachitogenic substance. In artificially dried grass the values ranged from 270 to 1150 before chromatography, and from 595 to 1790 after it; the amount of rachitogenic substance was, therefore, considerable. The results were in accordance with the finding of Grant (Abst. 1730, Vol. 24), that carotene is the rachitogenic substance. The rachitogenic substance was not a phytosterol precipitable with digitonin.-E. M. Hume. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Research on varieties on behalf of the registration.
Authors: Nijdam F.E.
Published: June 2020

The procedure by which varieties of field crops in the Netherlands are registered (to establish the breeder's rights o ver, a variety) and entered on the List of Varieties (after field tests) is described.-WJ.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Notes on the water household of the kapok tree Ceiba pentandra (L) Gaertu.
Authors: Toxopeus H.
Published: June 2020

The limiting factor for fruit setting appears to be the length of the period during which the tree stands in full leaf at the beginning of the dry monsoon. In that period there is severe competition for available water between the leaves and the young fruits. The total water consumption of a kapok plantation and its transpiration ratio were compared with data on other plants.-From author's summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of tilth on soil- and air-temperature.
Authors: Van Duin R.H.A.
Published: June 2020

A mathematical treatise based on the assumption that cultivation affects the distribution of heat in depth of the soil which is considered to consist of two homogeneous layers of different thermal properties. The effects of cultivation on soil temperature at different seasons, risks of night frost, energy used in evaporation and transpiration, and the heat flux into soil and air are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Stand development and stem form of the Douglas Fir (Pseudotsuga taxifolia Britt.) in the Netherlands.
Authors: Laar A. van
Published: June 2020

Increment measurements on 65 heavily thinned trial plantations are used to show the development of stands in the Netherlands up to 30 years. Yields compare satisfactorily with Kanzow's yield tables for Prussia (1937), but are considerably below those of Grandjean and Soest [cf. F.A. 15 No. 567]. A taper table was derived from 801 trees measured after felling. At heights below 20 m. the stem forms of Douglas Fir and Japanese Larch, as shown in figures obtained by Schober [cf. F.A. 15 No. 1656], correspond closely with each other, but above 20 m. the former tapers more rapidly. KEYWORDS: Increment \ mensuration \ forests \ Pseudotsuga taxifolia \ Pseudotsuga menziesii \ aggr. form \ stem \ Pseudotsuga taxifolia \ Pseudotsuga menziesii \ aggr. yield \ taper \ tables \ stem form \ s \ yield tables (Abstract retrieved from CAB Abstracts by CABI’s permission)
Recent advances in cereal breeding.
Authors: Lupton F.G.H.
Published: June 2020

The subject is discussed under the headings: (1) comparison of old and modern varieties, (2) requirements for further improvement in yield, (3) breeding for durable disease resistance, (4) combination of increased yield with good grain quality, (5) the expansion of winter barley, (6) improvements in the logistics of breeding and (7) longer-term prospects. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Night temperature and number of nodes and flowering of the main stem of glasshouse cucumber (Cucumis sativus L.).
Authors: Lint P.J.A.L. de , Heij G.
Published: June 2020

Plants of the cucumber cv. Farbio (all-female) were planted on 13 or 27 December, 10 or 24 January and grown at 3 minimum night temperatures, 12, 16 or 20 deg C from planting until 1 April. Node number/stem increased as the night temperature fell. Internodes were longer with later planting and on plants on inner rather than outer rows; these responses could not be related to light intensity alone. The number of flowers/stem was determined by the number of nodes bearing flowers and the number of flowers/node. More flowers/node occurred towards the top of the plant and late planting increased flowering at all nodes; the night temperature had little effect on numbers but these were highest at 16 deg . Earliness to flower of the first flowers/axil and the intensity of flowering both rose with temperature. Flowering was delayed only slightly by later planting. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The price elasticity of milk production in the EEC and the problem of discriminating between model estimates.
Authors: Noort P.C. van den
Published: June 2020

Estimates of the price elasticity of milk supply in the EEC were obtained by getting an expert from each country to give a subjective judgement after comparison of the widely varying results obtained with different types of models. Weighted averages based on the expert judgements suggested that a 1% change in milk prices changes EEC milk output by 0.5-0.6% in the short term and 1.3% in the long term. Elasticity estimates for each country are tabulated, and the need for objective methods of discriminating between models and estimates is highlighted. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of root mass of perennial ryegrass (Lolium perenne L.) on the competitive ability with respect ot couchgrass (Elytrigia repens (L.) Desv.).
Authors: Hofman T.B. , Ennik G.C.
Published: June 2020

When 6 perennial ryegrass cv. were planted in sandy soil in a large tray with couchgrass [Elymus repens], the cv. which developed the greater root system were the most competitive. Perennial ryegrass cv. 39 gave low DM yields in monoculture but was the most competitive with couchgrass. There was an inverse relationship between root mass of perennial ryegrass in monoculture and the herbage yield of couchgrass in the mixture. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Redistribution of nutritive elements in a 'Gros Michel' banana plant.
Authors: Vorm P.D.J. van der , Diest A. van
Published: June 2020

A procedure is described and leaf, rhizome and root analyses are presented for a one-year-old vegetative plant of the banana cv. Gros Michel grown under glass in a sandy soil supplied with organic and inorganic fertilizers. Silicon was used as an index element on the presumption that it is not redistributed within a plant. The results indicated that N, S, P, K and Cu were mainly redistributed into young leaves from the old leaves, the rhizome functioning as a circulation pump. In contrast, only small amounts of Mg, Cl, Fe and Zn (and no Ca) were redistributed. Most redistribution of N and S was in the organic, rather than inorganic, form of each element. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of cytokinin and cultivar on shoot formation of Gerbera jamesonii in vitro.
Authors: Pierik R.L.M. , Steegmans H.H.M. , Verhaegh J.A.M. , Wouters A.N.
Published: June 2020

The success of gerbera clonal propagation in vitro, using either capitulum explants or subcultured shoots in trials with up to 28 cvs, depended both on the cv. and on the cytokinin level in the medium. With capitulum explants, shoot formation was very low for some cvs regardless of the level of BA (5, 10 or 20 mg/l) whereas other cvs had individual optimum BA levels. Axillary branching of subcultured shoots differed between cvs and between levels of kinetin (1, 5 or 10 mg/l) in the medium. The optimum level for the highest quality shoots (highest leaf weight/shoot, no leaf malformation and no callus formation) was not always the same as the level producing the highest number of axillary shoots. Results are tabulated for each cv. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Further studies on the effect of fat supplementation of concentrates fed to lactating dairy cows. 1. Effect on feed intake, feed intake pattern and milk production and composition.
Authors: Visser H. de , Tamminga S. , Gils L.G.M. van
Published: June 2020

1. In a 3 X 3 Latin square design 9 cows were given long hay and a concentrate without supplemental fat or with 12% fat (11% tallow and 1% palm kernel oil) mixed with other ingredients or adsorbed on a carrier of Palabora vermiculite. During the 3rd week of treatment milk production was 21.4, 23.5 and 22.6 kg daily, respectively. With both fat-supplemented concentrates, milk fat content increased initially but then decreased sharply and was 3.55, 3.18 and 3.91% in week 3. At the same time protein was 3.19, 3.07 and 3.09%. Feed intake of cows given the fat supplements decreased. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effects of short and long shading, applied during different stages of growth, on the development, productivity and quality of forage maize (Zea mays L.).
Authors: Struik P.C.
Published: June 2020

In 2 field experiments, shading which differed in duration and date of initiation was applied to normal stands of forage maize cv. LG11. Short shading during vegetative development affected leaf area, plant ht., stem thickness and reproductive development but final effects on DM yield and quality were small. Short shading during silking drastically reduced ear size and final ear yield. Although the deleterious effect on ear yield was partly compensated for by higher stover yield, productivity was low after the shading tents were removed. Digestibility was also greatly reduced because production of total DM was affected more than production of partly indigestible cell walls. Short shading soon after silking curtailed cell-wall formation more than DM production and crop digestibility was not adversely affected. Reduction in DM production remained large especially in the ear because of grain abortion. Shading after grain set stimulated the depletion of short carbohydrates in the stover and slowed down the decrease in the cell wall content of the whole crop. Crops shaded for long periods yielded more than expected on the basis of the short treatments. Long shading treatments lasted until final sampling and the earlier a long treatment was initiated, the greater the reduction in yield. The same was true for whole-crop digestibility, except in the earliest shading treatment in which poor vegetative development accompanied poor ear development. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An alternative approach to the analysis of mixed cropping experiments. 2. Marketable yield.
Authors: Spitters C.J.T.
Published: June 2020

The effects of competition on marketable yield are derived from those on biomass by means of the relation between individual plant biomass and harvest index. A method is presented to estimate competition effects and advantage of mixed cropping directly from the data of marketable yield. The effect of spp. composition and population density on the advantage of mixed cropping, measured by the land equivalent ratio, is partitioned into an effect due to better resource exploitation (niche differentiation), a favourable influence of mixed cropping on harvest index and an effect due to density which can also be achieved by growing monocrops at a higher density. The approach is illustrated with the results of an experiment on mixed cropping of maize and groundnuts. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ear formation and grain yield of winter wheat as affected by time of nitrogen supply.
Authors: Darwinkel A.
Published: June 2020

Winter wheat cv. Caribo (1979) or Arminda and Okapi (1980) was provided with an additional N dressing at different stages between tillering and ear emergence after a basal N dose applied at the onset of tillering. The effect of N on ear formation depended greatly on the growth stage at the time of N application. Max. effects on tiller formation and spikelet initiation were achieved when additional N was supplied at the beginning of tillering; on ear number when N was supplied at the onset of stem elongation; on the numbers of fertile spikelets, grains/fertile spikelet and grains/ear when N was applied during stem elongation until flag leaf emergence and on single grain wt. when N was applied at ear emergence. Variations in 1000-grain wt. were small, therefore grain yield/ear as well as yield/unit area was largely determined by grain number. Main shoots outyielded ear-bearing tillers because of a higher grain number. In ear-bearing tillers, grain yield largely depended on grain number, being highest in the older tillers. Grain formation of ear-bearing tillers was more strongly affected by the time of additional N application than that of main shoots. Top-dressings of N applied during stem elongation increased the grain number of ear-bearing tillers considerably, because both the number of fertile spikelets and the grain number/fertile spikelet were higher. In the young late-appeared tillers, the opt. time to apply additional N for grain set shifted to later stages of development. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Scion-rootstock relationships in hybrid tea cut roses on Rosa canina 'Inermis'.
Authors: Vries D.P. de , Dubois L.A.M.
Published: June 2020

In 2 successive years, 11-month-old cut rose clones grown in greenhouses were uprooted in December. Highly significant correlations occurred between the girth at the graft union and the root weight or the number of bottom-breaks, between the root weight and the number of bottom-breaks, and between the number of bottom-breaks and the number of harvested shoots. Plant vigour in clones was mainly determined by the scion. Rootstock-scion relations in rose were similar to those in apples and cherries. The equilibrium between aerial and underground parts in composite plants is discussed. Breeding of rose rootstocks that promote scion vigour under various glasshouse conditions is recommended. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Development of improved wheat genotypes in Zambia using incomplete resistance against rusts.
Authors: Milliano W.A.J. de
Published: June 2020

A low-cost breeding programme was used to develop high-yielding lines within six years. The lines had stable and incomplete resistance to Puccinia graminis, uniform resistance to Puccinia recondita and stable and adequate resistance to various pathogens and pests. Locally selected parental genotypes with incomplete resistance to the Puccinia species were used and crossing was carried out on a large scale with few personnel, using a male gametocide (Ethrel [ethephon]). (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some mechanical properties of aggregates of top soils from the IJsselmeer polders. 1. Undisturbed soil aggregates.
Authors: Dexter A.R. , Kroesbergen B. , Kuipers H.
Published: June 2020

Aggregates were collected from the arable layer at eight sites in the IJsselmeer polders. The compositions of the soils were determined, and measurements were made of porosities, tensile strengths and water stabilities of undisturbed aggregates. Porosity was negatively correlated with the age of the soils since reclamation. Tensile strength of dry aggregates and water stability were both positively correlated with the clay content. The soils had extremely high values of friability. Tensile strength was negatively correlated with porosity. Porosity had no clear influence on water stability. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of energy intake on age at puberty in gilts.
Authors: Hartog L.A. den , Noordewier G.J.
Published: June 2020

From 12 to 38 weeks old 680 Dutch Landrace gilts were given diets to provide 3.0 M, 2.5 M, 2.1 M and 1.8 M (where M = metabolizable energy required for maintenance). At the 2 greater energy intakes 9.3 and 7.7% of gilts had to be culled, compared with 2.4 and 4.7% for the 2 lower energy intakes. Number of gilts with a spontaneous oestrus was not affected significantly by different energy intakes. Mean daily gain and backfat thickness at 99 kg and at 187 days old were increased by higher energy intake (P
Yield responses of winter wheat to plant removal and to wheelings.
Authors: Darwinkel A.
Published: June 2020

In winter wheat cv. Arminda the removal of plants from 2 adjacent rows increased grain yields in 2 rows on either side of the path thus created. This yield compensation was achieved by an increase in ear number/plant, grain number/ear and 1000-grain weight. Yield compensation exceeded 80% if the plants had been removed at an early growth stage (GS); the yield compensation was smaller the later the plants were removed, being 14% after plants had been removed at Zadoks GS 71. The contribution of grain number/ear to yield compensation followed a similar trend to ear number with hardly any effect when plants were removed after GS 51 and GS 32, resp. Frequent passes through the crop with a tractor led to almost total failure of grain production in the wheelings created, but this yield loss was partly compensated for by the increased yields of the rows next to the tracks. When tramlines were used for carrying out the cultural operations, the yield compensation by plants in bordering rows was greater, and consequently the yield loss was smaller. It is estimated that in commercial wheat production the yield losses resulting from cultural operations will be small, usually less than 150 kg grain/ha. (Abstract retrieved from CAB Abstracts by CABI’s permission)