bluuebunny/crossref_metadata_2025 huggingface dataset:
Yield-density relations for apple trees on a dwarfing and a semi-dwarfing rootstock.
Authors: Verheij E.W.M. , Verwer F.L.J.A.W.
Published: June 2020

In a planting system trial started in 1962 Golden Delicious trees in low-density plots at 1 100 trees/ha on M.9 and 660 trees/ha on M.2 came into bearing slowly and yields levelled off at about 40 tons/ha. In high-density plots at 3 300 and 2 260 trees/ha on M.9 and M.2, respectively, yields quickly increased to about 75 tons/ha in 1967 and 1968, but thereafter declined; this was associated with more intensive pruning and fruit thinning to restore tree vigour and fruit quality. Yield per unit of growth was initially higher but finally much lower in high-density plots, indicating that fruiting suffered more than growth from competition between trees. Yield per unit of growth was much higher on M.9 than on M.2, especially at high density. Fruit size was slightly better on M.9, and at high density the problems in maintaining fruit size were not as serious as on M.2. Growth control in the high-density M.2 plot became difficult and tree thinning may be advisable. Under the conditions of the trial the optimum density for Golden Delicious on M.9 is probably above 3 000 trees/ha and on M.2 below 2 000 trees/ha. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of defoliation and nitrogen on the regrowth of Rhodes grass (Chloris gayana Kunth). 2. Etiolated growth and non-structural carbohydrate, total-N and nitrate-N content.
Authors: Dovrat A. , Deinum B. , Dirven J.G.P.
Published: June 2020

Data are given on the chemical composition of Rhodes grass cv. Common grown in a heated glasshouse [see HbA 42, 1910]. Plants given high N (8.29 meq/100 g soil) contained about 30% less carbohydrate in the stubble and roots than those given low N (1.43 meq/100g). The carbohydrate content of plants cut every 28 days was generally lower than that of plants cut every 14 days. Amounts of etiolated growth in darkness after cutting were positively correlated with the carbohydrate level in the roots and in the stubble. The percentage of tillers exhibiting regrowth in darkness increased linearly up to about 60% with increase in the amount of etiolated growth. Contents of total N in roots and in stubble were almost double at the high rate of N. Amounts of nitrate as a proportion of total N were about 12% in low-N plants and up to 47% in high-N plants. The nitrate contents of shoots, stubble and roots were negatively correlated with the carbohydrate levels in each of these tissues. The overall difference in carbohydrate level between shoots, stubble and roots was relatively small. It was concluded that Rhodes grass had a limited capacity to accumulate reserve material when grown under conditions favouring rapid growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The action and durability of cetyl alcohol as an evaporation suppressant in soils.
Authors: Kijne J.W.
Published: June 2020

In 4 cetyl alcohol-treated soils, data on the rise in temperature ahead of the wetting front indicated that effect of treatment on the water-conducting characteristics resulted from induced hydrophobicity of the soil particles. Although more water was located near the evaporating surface, the cumulative evaporation from the soil was less than from an untreated soil for a certain period, but thereafter exceeded it. Cetyl alcohol had little effect on the passage of water vapour or water through soil. After 30 weeks the amount of hexadecanol that could be extracted from the soil was less than 7% of the amount originally present.[132.21:954.726]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Crop identification in the Netherlands by means of aerial false-colour film.
Authors: Frinking H.D.
Published: June 2020

The technique gave valid results only for a specified area at a specified time of year. An identification table is given for the major crops in the polder areas of the Netherlands. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Experimental studies on seed production of tropical grasses in Kenya 7. The breeding for improved seed and herbage productivity.
Authors: Boonman J.G. , Wijk A.J.B. van
Published: June 2020

The history and characteristics of the Kitale varieties of Setaria, Chloris, Panicum and Brachiaria are described, as are seed multiplication practices and current breeding work. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Microstructure, soil strength and root development of asparagus on loamy sands in the Netherlands.
Authors: Reijmerink A.
Published: June 2020

Data are presented on the root development of asparagus plants of different ages, in several soil types worked to different depths. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of temperature and radiation on lettuce growing.
Authors: Bierhuizen J.F. , Ebbens J.L. , Koomen N.C.A.
Published: June 2020

Lettuces were planted in the spring at 20 X 25 cm in glasshouses with several temperature regimes and differing light transmission (43-76%), and the effects were determined of air temperature and radiation on the percentage soil cover and yield. With heated, lightly heated and unheated glasshouses the time from planting to almost 100% soil cover was 33, 47 and 54 days, respectively, equivalent to about 600 degree-days. Variations in the total radiation received during these periods were marked. Growth in terms of fresh weight increase was slow initially under all conditions, but when the plants had attained about 60 g fresh weight they grew rapidly, and subsequent fresh weight increases were closely correlated with total radiation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Chromosome numbers in Begonia.3.
Authors: Legro R.A.H. , Doorenbos J.
Published: June 2020

The somatic chromosome numbers are presented of 34 spp. of African, Asiatic and American origin. Many spp. had not previously been investigated cytologically. [For part 2 see HcA 42, 1737.]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrogen nutrition of rice plants measured by growth and nutrient content in pot experiments. 4. Role of the water regime.
Authors: Dijkshoorn W. , Ismunadji M.
Published: June 2020

[116.17.012:145.911].Available N in a flooded soil under rice was assessed by measuring N uptake by the plants. During flooding the supply of NH4 was unchanged but NO3 rapidly denitrified. When applied to a dry soil NH4 was nitrified but flooding caused the denitrification of NO3 to occur and the supply of N was roughly halved. A change in soil pH towards acidity (to pH 4.5) was sufficient to check nitrification and the loss of N from NH4 applied before flooding. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A comparison between ammonium and nitrate nutrition of young sugar-beet plants grown in nutrient solutions at constant acidity. 1. Production of dry matter, ionic balance and chemical composition.
Authors: Breteler H.
Published: June 2020

Diploid sugar beet was grown in nutrient culture with ammonium and nitrate N in solutions kept at constant pH by automatic titration. Since plants given nitrate N yielded only 12% more than those given ammonium N, the effects of form of N on plant chemical composition could be determined. The excess of cations in the plant (C-A) was >3 times as great in plants given nitrate as in those given ammonium. The acidity evolved into the culture medium was a good measure of ammonium uptake, whereas with nitrate the amount of alkalinity evolved was unrelated to and small in comparison with the amount of nitrate absorbed. The rate of H+ production decreased during darkness and that of OH- decreased during or just after the dark phase. Levels of soluble carbohydrates in plants given nitrate were over twice as high as in those given ammonium. Data are given on levels of 6 organic acids, K, Na, Ca Mg, P, S and Cl. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some experiments on supply of ions to the absorbing root surface.
Authors: Wiersum L.K.
Published: June 2020

In solution culture experiments with tomatoes, lowering the N, P, K and Ca concentration resulted in a higher relative rate of nutrient uptake, as did restricting the transpiration rate. In sand culture experiments on the effect of N concentration, N at 83 or 103 mg/l resulted in well grown plants but N at 48 mg/l in small plants. In another similar experiment in dry or moist air K uptake was less at the lower transpiration rate, but plant growth was little affected. Data are also tabulated on the relative rates of uptake and percentage utilization of the total supply of N, P and K in sand and solution culture. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Land use planning in the Lower Mesopotamian Plain - a problem analysis.
Authors: Aart R. van
Published: June 2020

The Lower Mesopotamian Plain in Iraq comprises a total area of 5.5 million ha. of which 4.4 million ha. is cultivable. The present area under cultivation in any one season is estimated at 2.6 million ha. The history of land use is described. Agricultural production has declined and land use practice has changed from annual (mainly winter) cultivation to a system of fallow land rotation. This extensive system of land use is the result of water-logging, and salinity resulting from unreliable irrigation combined with inadequate drainage. Future policy for land use is outlined. It is stressed that social and organizational aspects play an important role in the process of land use planning.
ADDITIONAL ABSTRACT: [175.567]Throughout the centuries a general decline in agricultural prosperity and an overall shift in land use practice from annual, mainly winter, cultivation to a system of fallow land rotation is noted. This extensive system of land use is mainly the result of waterlogging and salinization due to unreliable irrigation coupled with inadequate drainage. Future policy is discussed in terms of soil and water resources, farming system, cropping intensity, cropping pattern, size of the farm area, social and organizational aspects. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Polyester casts for the study of the pore structure in soils.
Authors: Rogaar H.
Published: June 2020

The system of voids occurring in natural soils (a river levee soil, a river basin soil, and a bottom sediment of the river Rhine containing mudworm burrows) was studied by impregnating moist samples with polyester resin and washing out the soil material after the resin had hardened; a cast of the pore structure was thus obtained. The cast and stereo photographs obtained from a preliminary experiment with modelling clay (to test the reliability of the method) suggested that the method would allow good qualitative interpretation. In the basin soil, the existing meadow grass vegetation was mainly responsible for the cavities observed in the upper horizons, but in the unripened subsoil, the system of cavities was derived from the former swamp vegetation. The levee soil contained abundant voids whose origin was not easily attributed to a single specific cause. The ped structure of both soils was clearly expressed by the planes in the casts, representing the voids along ped faces. Burrowing activity was clearly shown in casts from a pot experiment and from Rhine bottom river sediment. The method offered prospects for soil hydrology studies. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Factors affecting the herbage iodine content.
Authors: Hartmans J.
Published: June 2020

In pot and field experiments, N application somewhat increased the I content of the harvested crop, although I concentrations in the herbage decreased considerably (diluting effect of increased dry matter yields). Herbage I contents were not consistently affected by chemical fertilizers which produced no yield response. I contents were up to 13 times higher in dicotyledenous pasture species than in grasses. I contents varied between grass species and to less extent between varieties of a single species. Contrary to earlier New Zealand data, good quality grasses were lower in I content than medium-value and inferior grasses. Small I dressings were less effective than larger amounts in terms of percentage return in the harvested crop; residual effects in later cuts were always small. The effectiveness of I dressings depended on soil type and tended to be lowest on soils of low natural I content.
ADDITIONAL ABSTRACT: Studies were with ryegrass in pots and pastures. N dressing increased I uptake by the crop but reduced the I content considerably because of the diluting effect of higher DM yields. Dressing with fertilizers which did increase yield did not affect herbage I content consistently. Dicotyledonous species in pasture had I contents up to 13 times that of grasses. The I content of grasses varied over a 2-fold range but variation was smaller in a given species. Good quality grasses had a lower I content than inferior grasses. Smaller I dressings gave a smaller percentage return in the crop than larger amounts; the efficiency depended on soil type and tended to be less for soils with the lowest natural I content. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Grain growth and distribution of dry matter in the wheat plant as influenced by temperature, light energy and ear size.
Authors: Spiertz J.H.J.
Published: June 2020

The response of wheat plants during the post-flowering stage to temperature, light intensity and ear size was studied in controlled environments. Within the range 15-25 deg C, increase in temperature increased the growth rate of grains, but the duration of post-flowering development of the plant was very much shortened, with the result that higher temperatures resulted in lower grain yields. Increase in light intensity from 92 to 147 cal/cm2 day had a more positive effect on grain weight than an increase from 147 to 175 cal/cm2 day. Removal of spikelets from the ear increased 1000-grain weight but not sufficiently to compensate for the reduction in the number of grains/ear. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Aspects of potassium and magnesium uptake by oats.
Authors: Schuffelen A.C.
Published: June 2020

Data from a range of experiments with oats in water culture indicated that the occurrence of Mg deficiency had only a slight direct relationship with solution acidity. It was calculated that about 3% of the total mechanism for the uptake of K and Mg consisted of a specific mechanism for Mg uptake, 30% of a specific mechanism for K uptake, and 67% of a common mechanism. It was not clear whether one or more systems were involved. At very low K concentrations the specific K uptake mechanism could also take up Na. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of temperature and nitrogen on growth, photosynthesis and accumulation of non-structural carbohydrate in a tropical grass, Panicum maximum var. trichoglum.
Authors: Wilson J.R.
Published: June 2020

After an initial growth period on half-strength Hoagland solution at 25 deg C, plants of P. maximum var. trichoglume were transferred to N-free nutrient solution and an equal number were kept on half-strength Hoagland solution. Plants from both N treatments were grown under constant temperatures of 15, 20, 25, 30 or 35 deg . Leaf net photosynthetic rate, RGR and NAR/unit leaf area were affected to a similar relative extent with change in temperature or N, thereby precluding accumulation of very high percentages of total non-structural carbohydrates (% TNC). At low temperature and low N, changes in % TNC were inversely related to relative leaf area growth rate and also to some extent with dark respiration rate. In high-N plants, reduction in % TNC at higher temperatures was probably accentuated by the use of constant day/night temperatures. The influence of temperature on % TNC in low-N plants was slight. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of temperature and light on the growth of young brussels sprout plants.
Authors: Kronenberg H.G.
Published: June 2020

In 1-year trials young brussels sprouts plants from cuttings or seed were grown in a growth chamber at temperatures between 9 deg and 25 deg C and harvested after 4, 8 or 12 weeks after receiving varying amounts of total radiation. Plants from cuttings grew best at 21 deg and those from seeds at 17 deg . The optium radiation after 4 weeks was 33,000 J/cm2. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Osmotic pressure of the soil solution: determination and effects on some glasshouse crops.
Authors: Ende J. Van den , Koornneef P. , Sonneveld C.
Published: June 2020

In a factorial experiment, calcium sulphate, sodium chloride and potassium nitrate were added to a loamy sand soil in various quantities. The experiment was carried out in an unheated glasshouse. The salt status of the soil was determined with the aid of different method of aqueous extraction. The results were correlated with the osmotic pressure of the soil solution. A close correlation was obtained with the conductivity of the saturation extract. Crop yields were correlated with the conductivity of the saturation extract and with the osmotic pressure of the plant sap. The correlation with the conductivity of the saturation extract was generally highest. With tomatoes, a clear relationship was found between the conductivity and the incidence of blotch on the fruits. In lettuce, there was a clear relationship between conductivity and the occurrence of tipburn. The yield reduction of some crops was significantly greater after the application of sodium chloride than after potassium nitrate. Apparently, this was caused by specific ion effects. The desirable salt level, the salt distribution in the soil and the determination of the osmotic pressure of the soil solution for routine soil-testing purposes are discussed. The curvilinear relationship between the salt level of the soil and the incidence of tipburn may be explained by the calcium uptake of the crop. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Plant density of year-round chrysanthemums.
Authors: Hoeven A.P. van der , Mol C.P. , Steen J.A. van der
Published: June 2020

Spider-type chrysanthemums on 2 commercial holdings were grown at densities of 40, 54, 60, 64, 70 or 80 plants/m of bed and at 27, 32, 40, 48, 54 or 60 plants/m of bed. In both cases the beds were 1.25 m wide. As density increased the average number of flowers/stem and the percentage of first quality grade stems decreased. During the winter months the quality of flowers from closely planted beds was noticeably poor and cropping was delayed and not uniform. A spacing of 40-50 plants/m would seem suitable for commercial use. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The relationship between plant quality and yields of glasshouse tomatoes.
Authors: Spithost L.S.
Published: June 2020

The results of experiments on tomato plant raising methods for early cropping under glass showed that the quality of the planting material as assessed by the subsequent crop yield was largely determined by size. A further study of growing methods on 55 nurseries showed that in all cases the plants used for December planting for the early 1969/1970 crop were too small. Multiple regression equations showed that for crops harvested before 18 April, 1970, plant size influenced earliness more than yield. In addition, the higher the plant nitrate content the later was the date of the first pick and the higher the Na content the lower the yield. (Abstract retrieved from CAB Abstracts by CABI’s permission)
67Cu for metabolic studies in milk cows.
Authors: Binnerts W.T. , Kapteyn J.C. , Lindner L.
Published: June 2020

Primarily because of its half-life, the longest-lived radionuclide of copper, 67Cu (half-time 61.7 h), is often the isotope of choice for application in metabolic studies. However, large-scale production of 67Cu is cumbersome. The 67Cu used in this study was produced in a cyclotron by exposing a zinc target to a beam of accelerated protons. Radiochemical purification was achieved by solvent extraction, electroplating and ion-exchange, in that order. The resulting dilute acidic solution contained no measurable activity apart from 67Cu and 64Cu. After the injection in cows, the 64Cu component of the preparation of radiocopper could be used during the first days of the experiment for external radioassay of the liver. The 67Cu could be followed in metabolic products for over 3 weeks. It is concluded that the isotope 67Cu in batches of about 100 mu Ci can very well be used for metabolic excretion studies even on large animals. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Photosynthesis and sink size: an explanation for the low productivity of grass swards in autumn.
Authors: Deinum B.
Published: June 2020

In glasshouse and field trials, axillary tillers of Italian ryegrass cv. Milamo were cut at weekly intervals or shaded and photosynthesis was measured in the youngest fully expanded leaf of main shoots; similar measurements were made on fertilized irrigated perennial ryegrass plants spaced at 5 plants/m2. Photosynthesis was stimulated to the high level characteristic of leaves from reproductive plants with reduced stomatal and internal diffusion resistances and lower soluble carbohydrate content and it was suggested that axillary tillers under stress acted as sinks for assimilates. It was concluded that the lack of sinks and poor light penetration into the area of leaf development were the main causes of poor production by vegetative grass crops in late summer and autumn. Various methods of improving DM production by increasing photosynthetic efficiency of individual leaves and creating sinks are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Morphological and physico-chemical aspects of three soils developed in peat in the Netherlands and their classification.
Authors: Dinc U. , Miedema R. , Bal L. , Pons L.J.
Published: June 2020

In an oligotrophic soil formed in Sphagnum peat, an oligotrophic soil formed in Sphagnum-Eriophorum peat and a mesotrophic soil formed in Carex peat, the first and second soils contain a variable but rather large amount of histons, but the histon content of the third soil is low. Fungons are characteristic of the first soil, occur in small amounts in the second soil and are practically absent from the third soil. Decomposition by the soil fauna (as evidenced by faecal pellets) is slight in the first soil and is effected mainly by Oribatid mites, but in the second soil decomposition by Oribatids is considerable, by earthworms moderate, and by Enchytraeids sporadic. In the third soil, which contains some mineral material, the considerable decomposition by the soil fauna is effected by dipterous larvae and earthworms and to a lesser extent by Oribatids. In all the soils the rubbed fibre content and physico-chemical data agree with the change in the nature of the soil material with depth. In the first soil hemic material changes into fibric material, in the second soil the practically sapric soil material in the top 7 cm changes into hemic and fibric material, and in the third soil sapric material occurs down to 51 cm and then changes into hemic material. The classification of the three soils by the US Soil Taxonomy system, the Dutch system and the FAO-UNESCO system is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of sward age on nitrate accumulation in ryegrass.
Authors: Darwinkel A.
Published: June 2020

Two indoor trials were done with Italian ryegrass (Lolium multiflorum) and perennial ryegrass (Lolium perenne) to obtain more information about the nitrate-accumulating process of a new-sown grass sward. With an abundant NO3 supply for Italian ryegrass, NO3 accumulation in herbage decreased during 5 successive cuts after sowing, because of increasing NO3 conversion. In the same way the NO3 content in DM in perennial ryegrass was more in the first cut after sowing than in old plants from a pasture 5 years old. After sowing, a considerable part of the assimilate produced was used for stubble and root growth. With older swards these assimilates were increasingly retained in herbage, which is rich in organic N and to a lesser extent in stubble and roots, which are poor in organic N. Because of this, NO3 conversion is restricted in a new-sown grass sward and reaches a maximum in old sward of a permanent pasture, which almost exclusively produces herbage. Consequently nitrate is more apt to accumulate in new-sown grass than in old pasture. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Light and heavy element detection in thin sections of soils with the ion microprobe mass analyzer (IMMA).
Authors: Bisdom E.B.A. , Henstra S. , Jongerius A. , Brown J.D. , Rosenstiel A.P. Von , Gras D.J.
Published: June 2020

Previous research with the scanning electron microscope (SEM)-energy dispersive X-ray analyzer (EDXRA) and the electron microprobe analyzer (EMA), showed that the detection of light elements in thin sections of soils was problematic or even impossible. Consequently initial experiments were performed with the ion microprobe mass analyzer (IMMA). These preliminary investigations were carried out on a piece of root material in soil (containing both light and heavy elements) which has a 'clayey' appearance and is known as a clayified root (Parfenova et al., 1964). The presence of heavier elements in this sample was investigated by SEM-EDXRA prior to IMMA analysis. The results with the ion microprobe mass analyzer showed that all chemical elements could be analyzed in the plant fragment. Also much higher elemental detection sensitivities were found with IMMA as compared to SEM-EDXRA and EMA. This even allowed ion imaging of trace elements. High-quality ion images of both light and heavy elements could be obtained in much shorter exposure times than with SEM-EDXRA and EMA techniques. Furthermore by analysis of fragmentation ('fingerprint') spectra additional information was obtained with respect to the chemical binding of the analyzed elements. Due to these preliminary results IMMA offers full possibilities for microchemical analysis in situ of all important elements in soil specimens. This technique considerably increases possibilities in soil micromorphology. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The concept of matric flux potential applied to simulation of evaporation from soil.
Authors: Shaykewich C.F. , Stroosnijder L.
Published: June 2020

Two simulation models of evaporation were based respectively on (a) soil matric flux potential and (b) soil hydraulic conductivity and water potential. Mathematical analysis showed that the former method gave a lower and more accurate estimate of soil water movement in unsaturated soil, and therefore of evaporation from the soil. The difference between the accuracy of the two methods tended to be greatest in soils of coarse texture. The matric flux potential method required less computer time than the other method did. (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. 1. Influences of foot rots and nematodes.
Authors: Scholte K. , Kupers L.J.P.
Published: June 2020

In an 18-yr rotational experiment on a light sandy soil, rye, grown after rye, showed a depression in grain yield of 30% and in straw yield of 10%, compared to rye following other crops (oats, maize, potatoes or rape). Investigation into the causes of this reduction in yield made it highly probable that neither nematodes nor foot-rot fungi were the main causes. Rye grown after rye seems to take up less N from the soil than in any other sequence.
ADDITIONAL ABSTRACT: In an 18-year rotational experiment on a light sandy soil in the Netherlands, yields of seed and of straw from rye following rye were reduced by 30% and 10% respectively, compared with yields from rye following other crops. Investigation showed that it is highly improbable that either nematodes or foot rot fungi are the causes. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Aldrin, heptachlor and beta -hexachlorocyclohexane to dairy cows at three oral dosages. II. Residues post partum in milk and body fat of cows fed on pesticides in the dry period.
Authors: Vreman K. , Tuinstra L.G.M. Th. , Bakker J. , Hoek J. van den , Roos A.H. , Visser H. de , Westerhuis J.H.
Published: June 2020

The 9 cows used in the preceding trial [see DSA 39, 2470] were allocated during the dry period (approx. 8 wk) to 3 levels of aldrin, heptachlor and beta -hexachlorocyclohexane ( beta -BHC) mixed with the concentrate ration. The daily dosages/cow were (i) 0.5, (ii) 1 or (iii) 2 mg of each pesticide. Because the date of parturition could only be predicted roughly, the dry period/cow varied resulting in large differences in total doses for cows within a group; mean total dose of each pesticide was (i) 26, (ii) 56 and (iii) 87 mg/cow. The pesticide levels in milk fat after parturition did not only represent the effect during the dry period because the cows had also been dosed with pesticides late in the preceding lactation. Aldrin and heptachlor residues in milk fat were below the detection limit of 0.01 mg/kg and content of beta -heptachlor epoxide was
The effect of relative humidity on incompatibility and fertility in Brassica oleracea L.
Authors: Marrewijk N.P.A. van , Visser D.L.
Published: June 2020

During 1976, nine self-incompatible Brussels sprout clones and one self-compatible cabbage clone, homozygous for their S incompatibility alleles, were placed in growth rooms at 50, 80 or 95% relative humidity, about ten days before flowering. Self and cross pollinations were performed using pollen ripened in the same environment, or from clones grown in the glasshouse at 65-80% relative humidity. Assessments of pollen-tube penetration indicated that humidity does not affect incompatibility, although pollen ripened at 95% relative humidity showed lower fertility. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Genotype X environment interactions with lettuce (Lactuca L.) in relation to the development of genotypes for growing under poor energy conditions.
Authors: Eenink A.H. , Smeets L.
Published: June 2020

Twenty genotypes of wild and cultivated species during 1975 and ten genotypes during 1976 were grown in the glasshouse at 10, 14, 17 or 20 deg C, and at two light intensities intended to simulate autumn/winter with good or poor light conditions. Genotype X temperature, genotype X light intensity, temperature X light intensity and three-factor interactions were apparent for plant weight and leaf number, and stability estimates of each genotype for these characters are tabulated. The environmental conditions that could be useful within a selection programme are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of plant density and water supply on wheat production.
Authors: Ryhiner A.H. , Matsuda M.
Published: June 2020

A model is described to predict the DM production of a wheat crop. The photosynthetic rate of the crop surface is calculated from the amount of light and certain influences of the physical environment on photosynthesis, such as crop density, water supply and meteorological conditions. The dominant role of the leaf surface resistance with regard to the final yield to be reached is apparent. Lowering the sowing density at limited water supply will give favourable grain:straw ratio. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An agricultural analysis of rainfall reliability for Cameroon.
Authors: Mutsaers H.J.W.
Published: June 2020

An improvement of Manning's analysis of rainfall reliability is presented. Confidence limits of 20-day rainfall totals are calculated with a simple normalizing transformation. Rainfall distribution within a 20-day period is assessed by simply counting the frequency of occurrence of dry spells exceeding 10 days duration. The joint probability of deficient 20-day rainfall total and dry spell occurrence is estimated. The analysis is applied to two practical examples in Cameroon, including the semi-arid northern area.
ADDITIONAL ABSTRACT: An improvement of Manning's analysis of rainfall reliability is presented. Confidence limits of 20-day rainfall totals were calculated with a simple normalizing transformation. Rainfall distribution within a 20-day period was assessed by simply counting the frequency of occurrence of dry spells exceeding 10 days duration. The joint probability of deficient 20-day rainfall total and dry spell occurrence was estimated. The analysis was applied to 2 practical examples in Cameroon. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A battery-operated circuit for a self-timing leaf diffusion resistance meter.
Authors: Lammers B. , Stigter C.J.
Published: June 2020

A battery-operated circuit is described for use in self-timing leaf diffusion resistance (porometer) equipment. The circuit is based on an earlier successful design with mains power supply, but some modifications have improved the suitability for routine field use of the equipment. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Measurement of the rate of water flow in plants.
Authors: Schurer K. , Griffioen H. , Kornet J.G. , Visscher G.J.W.
Published: June 2020

A non-destructive thermo-electric method is described for the measurement of water flow in the stems of plants such as wheat and potatoes. The 2 temp. sensors are 10 or 20 mm apart. The miniature sensing is made by evaporation techniques. The sensor is suitable for laboratory as well as for field work. Flow rate in the stem can be monitored for several wk at relatively low cost. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Available phosphorus in poultry. 1. Effect of phosphorus levels on the performance of laying hens and their egg quality, hatchability, bone analysis and strength in relation to calcium and phosphorus in blood plasma.
Authors: El Boushy A.R.
Published: June 2020

1. For 6 months 432 medium heavy laying hens were given diets which supplied 0.16, 0.20, 0.40, 0.60, 0.80 or 1.00% available phosphorus. Egg production was greatest by hens given 0.20 or 0.40% P and least by those given 0.16%. Feed intake did not differ among groups. Heaviest eggs, 62.2 g, were laid by hens given 1.00% P. Shell quality, determined from shell percentage, shell thickness and shell index, decreased as P in the diet increased. Hatchability, yolk and white indices of eggs and calcium, P and ash in tibiae of chicks one day old did not differ among groups. Ca in blood of hens did not differ among groups but inorganic P in plasma increased with increasing P in the diet. Ash, Ca and P in tibiae and breaking strength of tibiae of hens increased with increasing P in the diet. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Phytotoxicity of zinc, nickel, cadmium, lead, copper and chromium in three pasture plant species supplied with graduated amounts from the soil.
Authors: Dijkshoorn W. , Broekhoven W. van , Lampe J.E.M.
Published: June 2020

In pot trials, (a) Plantago lanceolata: (b) white clover and (c) perennial ryegrass were grown on an acid sandy soil with added levels of Zn, Ni, Cd, Pb, Cu and Cr as single test elements. The metals were classified for inhibitive metal conc. in the shoots of the plants and in the soil. Ni, Cd and Cu were found to cover a 5-fold range with one exception: Cd in (a) was inhibitive at a 10-fold higher tissue conc. than in (b) and (c). Zn was more efficiently absorbed, but tolerated at a higher soil conc. because it was much less toxic to the tissue. Cr was tolerated at low shoot conc. but at high conc. in the soil because its uptake by the shoots was disproportionally smaller. Differences between plant spp. in response to the soil test levels were illustrated in terms of relative uptake and shoot conc. for toxicity. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Multi-point temperature measuring equipment for crop environment, with some results on horizontal homogeneity in a maize crop. 2. Equipment used.
Authors: Birnie J. , Stigter C.J. , Jansen P.
Published: June 2020

Details regarding equipment used in obtaining field data on crop environment temp. published earlier [see FCA 30, 5292] are reported. Pt resistance mounting and error analysis, calibration of these resistances and data logger requirements and modifications are dealt with. Equipment details regarding the actual collection of accurately scanned field temp. are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Hybrid tea-roses under controlled light conditions. 4. Combining ability analysis of variance for percentage of flowering in F1 populations.
Authors: Vries D.P. de , Smeets L. , Dubois L.A.M.
Published: June 2020

F1 populations of the hybrid tea-roses Sonia, Baccara, Ilona, Prominent and Zorina were grown in a growth room under 8 W/m2 at 20 deg C with an 8 h day. The inheritance of flowering ability under low irradiance was mainly controlled by additive gene action. Prominent and Zorina had a good general combining ability for flowering under low irradiance. [For part 3 see HcA 49, 5235]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An improved method for the isolation and the quantitative measurement of crop roots.
Authors: Heringa J.W. , Groenwold J. , Schoonderbeek D.
Published: June 2020

The isolation of crop roots from soil samples, making use of the dispersing action of CO2 evolved by the reaction of added oxalic acid on carbonates in the soil was described. The roots were photographed in a thin layer of water against a matt black background, resulting in sharp negative pictures that can be used by a Quantimet image analyser to measure length or other properties embodied in the photographs. The methods were applied in a study of the rooting characteristics of potato crops in a rotation experiment. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Growth analysis and shade experiment with Solanum nigrum L., the black nightshade, a leaf and fruit vegetable in West Java.
Authors: Fortuin F.T.J.M. , Omta S.W.P.
Published: June 2020

The cultivation of S. nigrum was studied in West Java. Growth analysis showed that individual plant weight reached 1070 g 113 days after planting. When fruits and leaves were harvested the total yield was 580 g berries/plant (16.5 t/ha) and 28 g leaves/plant (0.8 t/ha). Picking the leaves influenced plant shape, relative growth rate and net assimilation rate. Shading caused a decline in total plant weight and changes in the distribution of biomass; the production of fruits was strongly affected, whereas the production of edible leaves was not affected by 35-60% shade and only moderately affected by 75-85% shade. Leaves from plants grown in shade were larger and thinner than those from plants in full light. There was no indication that the berries were toxic. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The formation of volatile N-nitrosamines in grass and maize silages.
Authors: Broekhoven L.W. van , Davies J.A.R.
Published: June 2020

Normal grass or maize silage generally had N-nitrosamines 1 mu g/kg. Only in special conditions did maize silage have about 5 mu g/kg. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Results of municipal waste compost research over more than fifty years at the Institute for Soil Fertility at Haren/Groningen, the Netherlands.
Authors: Haan S. de
Published: June 2020

Until about 1950, municipal waste compost in the Netherlands was used principally on agricultural soils (mainly reclaimed cut-over peat and heath soils). Between 1950 and 1970, about equal proportions of compost were utilized in agriculture, horticulture and in amenity areas. Since 1970, amenity areas have demanded more than 90% of the compost. The main producer of municipal waste compost in the Netherlands is the VAM Waste Disposal Company, with a production level of about 100,000 tonnes per year. Its domestic refuse recycling plant recovers about 33% of organic residues suitable for compost production. Microelement contents and Ca and S levels in the compost are high, N, P and K contents and availability are low, and the organic matter content is c. 30% (dry matter basis). Biennial applications of up to 40 t/ha of compost between 1948 and 1975 resulted in large increases in microelement concentrations in crops and especially in soils. The Zn content of crops in a range of compost/soil mixtures increased with increasing compost/soil ratio, and crop growth was greatest in 100% compost. The current tendency in the Netherlands towards large-scale recycling of municipal waste may lead to increased compost production. Because the recreational sector can only absorb limited quantities, this compost would largely be disposed of on agricultural land. In such a situation limits for maximum permissible concentrations of potentially toxic substances in this compost, and maximum permissible application rates, would need to be set: for sewage sludge such limits already exist. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Varietal differences in growth, development and tuber production of potatoes.
Authors: Meyling H.D.G. , Bodlaender K.B.A.
Published: June 2020

In 1967-9, a comparative study was carried out on growth and development in relation to tuber production in 6 potato cv. Differences in productivity were not caused by 1 single growth or development parameter. The intervarietal yield differences were distinctly associated with genetic differences including leaf efficiency and size of the leaf apparatus, rate of stem growth and stem development and the earliness of cv., as well as by weather conditions. Early cv. were characterized by a higher growth rate and favourable DM distribution between June and July. Productivity of the later cv. was especially enhanced by a longer leaf area duration. This was a result of the slower senescence of the foliage during Aug. and Sept. The importance of the relation between stem and tuber growth was more distinct, whereas favourable tuber/stem ratios were independent of the earliness of cv. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An evaluation of the use of chromic oxide, polyethylene glycol and Cr-EDTA as markers for digestive studies along the small intestine of ruminants.
Authors: Bruchem J. van , Wiersma J. , Adrichem P.W.M. van
Published: June 2020

In cows, fitted with a T-shaped cannula in the duodenum and with a re-entrant cannula in the ileum, ileal recoveries were determined of Cr2O3, from impregnated paper and polyethylene glycol (PEG), introduced into the duodenum. The length of the collection periods of digesta was important. The mean transit time of both markers along the small intestine did not differ. In sheep, fitted with an infusion tube into the abomasum and with an ileal re-entrant cannula, PEG was recovered quantitatively over 10-h collection periods. In sheep, fitted with an infusion tube into the abomasum and with 4 T-shaped cannulae along the small intestine, flow rates of digesta in jejenum and ileum estimated with PEG and Cr-EDTA were similar. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrogen and energy balance of a short-rotation poplar forest system.
Authors: Veen J.A. van , Breteler H. , Olie J.J. , Frissel M.J.
Published: June 2020

The mean annual dry matter production of a short-rotation poplar forest in the Netherlands was 14.4 tonnes ha-1 during a 5-year growing period. During the growing period trees took up 542 kg N ha-1 of which 64 % was in the bole and branches. In the 5th year denitrification was measured in undisturbed columns in the field by the acetylene-inhibition technique. An annual denitrification rate of 18 kg N ha-1 was estimated on the basis of the observed N2O profile. The system needed an annual input of 122 kg N ha-1 to balance the nitrogen budget. The energy balance showed that at the present dry matter production the system had a net output of 54 GJ ha-1 year-1. An increase in dry matter production to a maximum of 25 tonnes ha-1 year-1, possible by planting the trees at a higher density, would raise the net energy output to 97 GJ ha-1 year-1, in spite of higher energy inputs associated with fertilizer applications. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The vitamin B₁ content of Dutch wheat and the factors which determine this content.
Authors: Van der Mijll Dekker L.P. , De Miranda H.
Published: June 2020

Vitamin B1was estimated colorimetrically by the method of van der Mijll Dekker (Chem. Weekblad, 1947, 43, 532) in 10 Dutch winter and summer wheats grown for 3 years, 1946-48, on sea clay, sandy sea silt, river clay and sand. Summer wheats varied widely, Van Hoek was high and Koga low. Summer wheat grown on sea clay or sandy sea silt had more than the same varieties grown on river clay or sand. All varieties were richer in 1947 with a warmer, drier summer than in 1946 or 1948. High content tended to be associated with late seeding date. Among winter wheats, Alba had significantly more than Carstens V. Clay soils gave higher values than sandy soils. Weather conditions affected the vitamin B1content, but not as much as for summer wheat and not on silt soils. Seeding date had no influence.-V. R. Jackson. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Annual seed growing of beets.
Authors: Wellensiek S.J. , Verkerk K.
Published: June 2020

Experiments were carried out at Wageningen to develop a practical method of seed production from beet in one year. It was shown that natural cold, affecting plants sown in frames at the beginning of January, had a stronger flower promoting effect than artificial vernalization. Supplementary lighting to extend the photoperiod to 24 hours markedly increased the number of good seed plants. Early sowing plus supplementary light until transplanting with the varieties Egyptische Platronde and Noord-Hollandse Bleekblad increased the percentage of good seed plants, to 96-100%. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Sieve tube disease (phloem necrosis, flagellatosis) of coffee trees. [not specified]
Authors: Stahel G.
Published: June 2020

A review of work done in the thirties. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Development of knowledge about Septoria nodorum Berk. with regard to breeding wheat for tolerance or resistance. [German]
Authors: Bronnimann A.
Published: June 2020

This review of work on S. nodorum [Leptosphaeria nodorum] is presented under the following headings: (1) history, (2) epidemiology, (3) symptomatology and damage, (4) selection methods and variety testing, (5) genetic basis of tolerance, (6) breeding methods and (7) the assessment of the current state of Septoria prevention and of the prospects for further advances. The contribution of the late W. Feekes to this subject is emphasized. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of localized supply of H2PO4, NO3, SO4, Ca and K on the production and distribution of dry matter in young maize plants.
Authors: Jager A. de
Published: June 2020

Roots of treated maize cv. 535 plants were divided between 2 compartments and (a) one root received a complete nutrient sol. and (b) the other 3 a sol. lacking one nutrient. In control plants, all roots received either (c) a complete sol. or (d) a sol. lacking one nutrient. Localizing the supply of a nutrient did not affect DM production rate or the shoot:root ratio. The treatment however did cause a shift in DM distribution within the root system in favour of (a). Except for Ca, this effect was only temporary. The wt. ratio (a):(b) after the period of adaption was highest for nitrate and decreased in the order K > H2PO4 > sulphate, whereas for Ca, (a):(b) still rose at the end of the experiment. Possible explanations for the differences in response are discussed in terms of differences in demand of the roots that are dependent on internal supply and differences in phloem mobility of the nutrient concerned. (Abstract retrieved from CAB Abstracts by CABI’s permission)