bluuebunny/crossref_metadata_2025 huggingface dataset:
Night temperature and flower abortion of glasshouse cucumber (Cucumis sativus L.).
Authors: Lint P.J.A.L. de , Heij G.
Published: June 2020

Plants of the gynaecious cucumber cv. Farbio were planted under glass, about 30 days after sowing, on 13 and 27 December and on 10 and 24 January. Night temperatures of 12, 16 and 20 deg C were compared until 1 April, the day temperature being 21-27 deg . Only 835 of 3600 flowers aborted shortly after opening. The later planted crops showed less abortion than earlier planted ones and the lower the night temperature the higher was the level of abortion. Abortion of the second and third flowers in an axil accounted for 60% of the total, regardless of night temperature. Fruits were picked every 5 days; those with the longest hanging time (i.e. slowest growth) were found primarily in axils just below axils in which all flowers had aborted. Such fruits are known to have a reduced shelf life [see HcA 50, 7105] and quality could thus be controlled to some extent by selective thinning of fruit in these axils. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An alternative approach to the analysis of mixed cropping experiments. 1. Estimation of competition effects.
Authors: Spitters C.J.T.
Published: June 2020

A simple model is introduced to estimate the degree of intra-specific and inter-specific competition and niche differentiation from final biomass data of a set of populations varying in spp. composition and total density. Competition effects can be estimated using addition series. The model is illustrated with results from mixed cropping of maize and groundnut. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Developments in rural areas in relation with developments in land and water management research in the Netherlands. I. Economic development and rural development plans.
Authors: Bijkerk C. , Oostrom C.G.J. Van
Published: June 2020

Since 1900 seven successive stages can be distinguished in the development of agricultural engineering and in land and water management research in the Netherlands. The development process is traced from the introduction of fertilizers during 1900-1930, through mechanisation, improvement of water management and land accessibility, and increase in the size and specialisation of units, to increasing emphasis on the ecological and recreational value of land. The main features of economical development in agriculture after 1945 are disucssed, including changes in production volume, structure and costs, labour input and productivity, and the cost of wages. The influence of land and water management projects on the rise in agricultural productivity is considered, together with the present policy of selective growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of soil pH and ammonium and nitrate treatments on heavy metals in ryegrass from sludge-amended soil.
Authors: Dijkshoorn W. , Lampe J.E.M. , Broekhoven L.W. van
Published: June 2020

Perennial ryegrass was grown in pots on sludge-amended soil adjusted to 8 pH levels ranging from pH 4 to pH 7 and supplied with either ammonium sulphate or calcium nitrate. The chemical form in which N was applied influenced grass accumulations of Mn, Ni, Zn and Cd only when the difference in soil pH between the treatments, resulting from soil and plant factors, had developed to a sufficient extent to affect the availability of the contaminating metals for uptake by grass. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of soil covers on air and soil temperature and on growth and yield of sugar-beets.
Authors: Sibma L.
Published: June 2020

From 1976 to 1979, sugarbeet cv. Monohil was grown in soil screened in various ways with transparent plastic sheet. Soil and air temp. were measured from sowing until some time after emergence. The temp. 7 cm deep in the rows was closely associated with the width of the strips covering the rows. Perforated plastic was less effective. Increasing soil temp. alone did not increase growth or yield of sugarbeet. When the higher soil temp. was combined with a higher ambient air temp. the development of the crop was advanced by 10-14 days. Improvement in the microclimate positively affected DM production during the growing period and final sugar yield. The higher final sugar yields were more often the result of the higher beet wt. than of a higher sugar content. No evidence was found of the effects of high temp. on leaf damage, the number of bolters or changes in DM distribution in any of the experiments. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of applications of sewage sludge and fertilizer nitrogen on cadmium and lead contents of grass.
Authors: Hemkes O.J. , Kemp A. , Broekhoven L.W. van
Published: June 2020

During 5 successive years, 0, 6, 12 or 18 t/ha yr metal-bearing sewage sludge on a DM basis was applied to permanent grassland. Each sludge application was combined with various N treatments. Cd content of the grass increased considerably with increasing amounts of sewage sludge and fertilizer N; Cd content was higher in young than in old grass. The latter also applied to Pb but the increase in Pb content was less and the relation between the supply of Pb and the Pb content of the grass was poor. During the late autumn and winter the increase in Pb content was striking and was probably caused by pollution from the atmosphere. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of fresh water supply on agriculture in the southwest of the Netherlands.
Authors: Boheemen P.J.M. van , Kusse P.J. , Maas C. , Wesseling J.W.
Published: June 2020

Soil water deficits for twelve crops during each summer from 1933 to 1980 were calculated for a 15,000 ha region of southwestern Netherlands, and the chloride load of the drainage ditches, due to the seepage of salt water from the sea, was determined. Water requirements for sprinkling irrigation and for flushing the water courses for quality control were computed. The maximum water requirement for sprinkling and flushing was 3.4 mm day-1. The average increase in crop yields due to sprinkling ranged from
Crop growth models without hormones.
Authors: Wit C.T. de , Vries F.W.T.P. de
Published: June 2020

For the simulation of organ formation and assimilate partitioning, information is required on the current level of activities like CO2 assimilation and the growth of various organs, as well as state variables such as leaf and root wt., N content and carbohydrate reserves and exogenous variables like radiation and temp. This information may be retained in auxiliary state variables by considering the dynamic equilibrium between growth of roots and shoots. Auxiliary state variables are not tangible quantities but mathematical artefacts of the simulation program; it is speculated that in real plants similar information may be retained and transferred by the hormonal system. A hormonal system is a communication system and such systems may be analysed either in terms of means (of the hardware used) or in terms of purpose (of the messages transferred). In dynamic models of crop growth, interest should be focused on the latter. Wheat, maize and ryegrass are used as examples. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Feed intake and production in dairy breeds dependent on the ration.
Authors: Korver S.
Published: June 2020

In 2 lactations and the dry period, with a changeover between lactations, Dutch Black Pied (DBP), Holstein-Friesian (HF) and DBP/HF crosses with 50% and 75% HF were offered roughage to appetite and 570 or 2310 kg concentrates per lactation. Energy intakes in the 2 lactations were 21 and 27% lower and roughage intakes 22 and 17% higher for cows given low-concentrates vs. high-concentrates; there was no carryover effect from lactation into the dry period when all cows received the same amount of concentrates. HF cows had higher roughage intakes than DBP by 4-5% but differences were only significant in late lactation. HF cows gave 10.1 and 7.2% (594 and 407 kg) more milk and 7.7 and 3.7% more milk energy than DBP cows in the 2 lactations resp.; this contrasts with a yield superiority of HF cows by 15% (974 kg) in the preceding lactation when concentrates were given according to milk yield. Milk yield was 20% (1250 kg) higher with high- than with low-concentrate; a carryover effect was noted at the beginning of the 2nd lactation. Efficiency of energy conversion to milk yield was significantly affected by ration at the beginning of lactation. Breed x ration interaction effects were not significant for intake or milk yield. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An ideotype of forage maize for north-west Europe.
Authors: Struik P.C.
Published: June 2020

Morphological and physiological characteristics of an ideal genotype are described. High dry-matter yield is required and therefore the ideotype needs to have high crop-density tolerance and efficient photosynthesis. Low susceptibility to pests and diseases is important. A stocky stem would benefit intake, yield and lodging resistance but reduce digestibility and dry-matter content. Selection for root-lodging resistance might reduce whole-plant yield. Improvement of cellular contents is of little importance, but cell-wall digestibility could be improved without strongly affecting yield. To be of high nutritional value, the stover must have sufficient dry-matter content (30-35%) and a moderate level of water-soluble carbohydrates. The ideotype should have an early silking date, a large ear and a slow rate of grain filling. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Rice research and development in West Africa: problems and perspectives.
Authors: Luning H.A.
Published: June 2020

The place of the rice economy in West Africa and its development since the 1960s is considered on and its disappointing performance is reviewed within the context of the area's overall food problems. Rice research and development in West Africa is briefly described and in relation to major agro-ecological zones. Constraints and potentials are discussed and the question as to why returns from rice research are so insignificant is posed. Finally, the perspectives of improved research allocation and productivity in regional rice research are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Estimation of carcass and growth composition in the growing pig.
Authors: Metz S.H.M. , Verstegen M.W.A. , Wilde R.O. de , Brandsma H.A. , Hel W. van der , Brascamp E.W. , Lenis N.P. , Kanis E.
Published: June 2020

In the 1st of 2 experiments to evaluate different methods of estimating body composition in the growing pig, 80 castrated Dutch Large White X Dutch Landrace [male] piglets, from 16 litters and aged 10-11 wk, were assigned to 14 treatment groups involving various combinations of housing system (in metabolic cages, in groups in a calorimeter, or individually in a pen), feeding (ad lib. or 85 or 74% of ad lib.) and weight at slaughter (25, 65 or 105 kg). In the 2nd experiment, 16 [male] and 16 [female] Dutch Landraces from 4 litters born under specific-pathogen-free (SPF) conditions were used. Half the piglets were reared under SPF conditions, and the remainder were suckled by a host sow and reared under normal farm conditions until 6-8 wk of age, when they were placed in groups in calorimeters and were fed an irradiated diet at approx. 80% of the mean intake capacity estimated in experiment 1. Eight pigs were slaughtered at the onset of the experiment, and the remaining 24 at 105 kg body weight. Nitrogen balance was measured frequently during growth, and backfat thickness was measured ultrasonically before slaughter. After slaughter, the carcasses were dissected anatomically and into commercial cuts, and the tissues were analysed chemically. Detailed results are tabulated. In the live animal, ultrasonic measurement of backfat thickness gave the best estimate of body composition (Rsuperscript 2 = 0.6), the residual standard deviation for muscle percentage being 1.9. With increasing percentage of muscle in the carcass, the proportion of protein in the carcass and in the total body increased, and the proportion of chemical fat decreased. The variation in protein percentage was less than that in fat percentage. Regression analysis indicated that the muscle percentage in the carcass can be estimated accurately from a linear combination of percentage of ham + loin and carcass weight, the residual standard deviation being 0.9 and the residual coefficient of variation 1.5-2.0%. Estimates of muscle percentage based on backfat thickness, protein percentage in the carcass and fat percentage were less accurate than the above regression, the coefficients of variation being approx. twice as large. Values of measurements of nitrogen deposition by nitrogen balance and by comparative slaughter differed, the latter technique yielding the more accurate results. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Limits to nitrogen fertilizer on grassland.
Authors: Prins W.H.
Published: June 2020

The effect of N fertilizer on seasonal response of predominantly Lolium perenne grassland, sward quality and productivity, herbage nitrate content and soil mineral N was studied in cutting trials lasting 1-6 years. At an assumed marginal profitability of 7.5 kg DM/kg N applied, the av. opt. annual N application on sand and clay soils was 420 kg/ha. At this rate, herbage nitrate content did not exceed 0.75% NO3 and accumulation of soil mineral N was minimal. At annual N rates exceeding 500 kg/ha sward quality deteriorated and productivity decreased the following year. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Competition between a maize crop and a natural population of Echinochloa crus-galli (L.) P.B.
Authors: Kropff M.J. , Vossen F.J.H. , Spitters C.J.T. , Groot W. de
Published: June 2020

In a field experiment, competition between maize cv. LG 11 and a naturally established weed population dominated by E. crus-galli was studied. At the av. E. crus-galli density of 100 plants/msuperscript 2, the yield of maize was reduced to only 18% of that of the weed-free control. This yield reduction strongly varied with years and the observed variation was probably related to differences between crop and weed in date of emergence. Experimental results were compared with the results of a simulation model for competition for light and water in crop-weed associations. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of ambient temperature and feeding level on slaughter quality in fattening pigs.
Authors: Verstegen M.W.A. , Brandsma H.A. , Mateman G.
Published: June 2020

To study the effect of ambient temperature on lean and fat in the carcass after fattening at a constant feeding level of 93 g/kg0.75 (1170 kJ metabolizable energy/kg0.75) or at equal rate of gain or in free feeding conditions 7 trials with fattening pigs were made each at 2 different degrees of coldness. One level was at 2 K below thermoneutrality (M) and the other at 6 K below thermoneutrality (C). Constant coldness relative to thermoneutrality was obtained by lowering temperature by 1 K kg weight increase. The growing period was between 25 and 60 kg or from 60 to 100 kg. At 60 kg or 100 kg pigs were slaughtered and dissected. After the constant feeding level the lower temperature resulted in a small increase in lean-to-fat ratio as a result of less fat. Feeding to an equal rate of gain or freely at 2 different temperatures resulted in fatter carcasses for the colder-housed pigs than for the constant feeding level. The carcasses after free feeding were associated with an increased fat content in the colder-housed pigs. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of feeding level on milk production of sows during four weeks of lactation.
Authors: Kempen G.J.M. van , Geerse C. , Verstegen M.W.A. , Mesu J.
Published: June 2020

During 2nd lactation, 12 Dutch Landrace X Norwegian Landrace sows suckling 7-9 piglets were kept in farrowing crates in calorimeters and given a 21.4% protein diet at 2.5 kg (ME about 800 kJ/kg0.75) or 4.8-6 kg (ME about 1500 kJ/kg0.75) daily. The diet was reckoned to supply requirements for milk production at the higher intake but not at the lower intake. Weight loss in days 4-25 of lactation averaged 10 and 28 kg for sows with high and low energy intakes, resp. From day 10 onwards, sows on the low energy intake gave less milk but with higher concn. of total solids, fat and protein than sows on the high intake. Yields of energy and protein were significantly higher in sows on high intakes only after day 15 of lactation. The daily gain of piglets was lower with the low energy intake; daily milk intake by piglets was higher, but energy intake per kg piglet gain was lower, with the high energy intake. Age of piglets had a significant effect on milk needed for gain. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of housing systems on the energy balance of laying hens.
Authors: Ketelaars E.H. , Arets A. , Hel W. van der , Wilbrink A.J. , Verstegen M.W.A.
Published: June 2020

In each of 2 experiments 192 medium large laying hens (Warren WSL), of 19 to 27 and 29 to 42 weeks old, respectively, were put in 2 respiration chambers in cages and on wire floor in the same environmental conditions. Production performance and utilization of energy were estimated. Feed conversion (feed intake in kg/eggs produced in kg) was slightly lower in the cage system as a result of a greater egg weight. Hens in cages had a greater growth rate. With about the same energy intake in experiment 1 and a lower in experiment 2 the better performance in cages can only be explained by a possibly slightly better utilization of the energy and in particular by a lower requirement of maintenance energy in cages. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Factors influencing the productivity of irrigated crops in southern Peru, in relation to prediction by simulation models.
Authors: Versteeg M.N.
Published: June 2020

Potential growth of Medicago sativa, potatoes, Chloris gayana and maize in the irrigated desert of S. Peru was determined and important growth-influencing factors were identified for each crop. The data were related to results from simulation models developed at Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Stratified sampling compared with two-phase stratified cluster sampling for timber volume estimation.
Authors: Stellingwerf D.A. , Lwin S.
Published: June 2020

Two sampling methods were compared on orthophotos (scale 1:10 000) of a rectangular 12 855-ha area of intensively managed Norway spruce forest in Upper Austria. Trees other than spruce >40 yr old were ignored. 'Method 1' used stratified cluster sampling to determine the area proportion of spruce in the total area: 2 clusters of 5 circular 0.05-ha photo plots were randomly selected within each of 8 rectangular sub-blocks in each of 72 blocks into which the area was 'stratified' (systematically divided). Vol. was determined by 2-phase sampling: (i) 2 clusters were randomly selected in each block, and the % crown cover of spruce was determined in each photo plot; (ii) one photo plot was selected in each block (all crown cover classes being represented) for subsequent vol. determination on 72 plots in the field. 'Method 2' used areas of mature spruce on forest management maps, which were copied on to the orthophotos and then divided into 2 nearly equal strata of higher and lower density whose areas were measured by planimeter. Ten field plots were located in each stratum and enumerated in order to determine the s.d. of each stratum and hence the number of additional random field plots required; the total number of field plots was 55. The 2 methods required the same number of man-days (36), method 1 requiring less office work and more field work and computation. If the sampling intensity was reduced, method 1 became less time-consuming than method 2 (except in the field) for the same vol. error. However, method 2 with sampling errors only in vol., is preferred over method 1 which has sampling errors in both area and volume. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Optimization of a forest road network.
Authors: Wijngaard P.J.M. , Reinders M.P.
Published: June 2020

A new planning model was developed that does not specify parallel road networks as in existing models (e.g. Larsson's). The new model, based on the 'travelling salesman' algorithm, consists of 2 complementary models for flat and broken terrain which are reproduced in the synopsis together with Larsson's model. Software (written in FORTRAN 77) was developed for these models, incorporating a database management system (an existing commercial program) for program variables. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Biological evaluation of the effect of processing conditions on feather meal amino acid digestibility.
Authors: Papadopoulos M.C.
Published: June 2020

Feathers were autoclaved for 30, 50 or 70 min without addition or with 0.4% sodium hydroxide or 0.4% proteolytic enzyme. Groups of 7 young male chickens were given feather meal as their only feed in 3 doses at intervals of 3 h. Excreta were collected during 36 h from the first intake of feather meal. Amino acid concentrations in ileal digesta were estimated 2.5 h after the last intake of feather meal and plasma amino acids were estimated 1 h after the last intake. There was considerable variation in true digestibility between individual amino acids ranging from 36% for aspartic acid to 87% for isoleucine. Mean true digestibility of lysine was 49, histidine 53, methionine 63 and cystine 49%. Amino acids were increased in the ileum and decreased in plasma as processing time of the feather meal was increased. It was concluded that quantitative digestibility estimations by excreta analysis of the individual amino acids have to be used for evaluation of quality of feather meal. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Description of methods and experience of 'in vitro' multiplication of potatoes in the Netherlands.
Authors: Marinus J.
Published: June 2020

In this synopsis of a fuller report, techniques for the multiplication of plantlets in vitro and their subsequent storage are described, with information on factors influencing growth and storage, and tuber formation by plantlets grown in soil. [See also 'In vitro' multiplication of potatoes; description of methods and experience in the Netherlands. CABO, Wageningen, Netherlands (1985) 21pp.] (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of temperature during different stages of development on growth and digestibility of forage maize (Zea mays L.).
Authors: Struik P.C. , Deinum B. , Hoefsloot J.M.P.
Published: June 2020

Growth and digestibility of forage maize were studied when it was exposed to low (18 degrees C day/12 degrees night) or high (30 degrees /24 degrees ) temperatures during the following periods of development: from sowing to the 8-leaf stage; from the 8-leaf stage to grain set; during grain filling. Organic matter digestibility values ranged from 69.5 to 74.1 and differences were caused by differences in cell-wall content and in cell-wall digestibility. Differences were greatest around anthesis but declined thereafter. High temperatures during the period from 8-leaf stage until grain set were most effective in reducing the digestibility. Final amounts of indigestible cell wall were similar for all treatments. Amounts of cellular contents varied only slightly. Amount of truly digestible cell wall was reduced by high temperatures during vegetative growth. Differences in proportion or digestibility of plant fractions resulted only in small differences in whole-plant digestibility. Temperature affected digestibility much less than it affected yield. High temperatures were needed for a prolonged period to obtain a noticeable reduction of digestibility. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The use of physical characteristics for predicting nutritive value in breeding material of tall fescue (Festuca arundinacea Schreb.).
Authors: Wijk A.J.P. van , Paul C.
Published: June 2020

Physical characteristics, milling resistance and leaf flexibility were estimated in 123 varieties of tall fescue (Festuca arundinacea) on cutting dates in June and September. Milling resistance gave an indication of physical structure of the whole plant and corresponded with crude fibre content. Milling resistance and leaf flexibility were inter-related. Correlation coefficients in June between digestibility in vivo and crude fibre, milling resistance and leaf flexibility were -0.59, -0.56 and -0.35, respectively. Corresponding values for September were -0.62, -0.29 and -0.13. Milling resistance could be applied as an objective, relatively simple and low-cost laboratory method for predicting voluntary intake of tall fescue. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Adaptation of the AFRC wheat phenology model for Dutch conditions.
Authors: Reinink K. , Jorritsma I. , Darwinkel A.
Published: June 2020

The AFRC model describes the phenology of the wheat plant in relation to its environment in terms of the effect of temp., vernalization and photoperiod on development. In 1976-79 four sowing date experiments were carried out in which the developmental stages were scored at regular time intervals. Two of these experiments, containing 35 sowings of 1 cv. over 2 seasons, were used to evaluate and improve the model. Variation in prediction of anthesis was used as a measure of the 'success' of the model. The unchanged AFRC model predicted anthesis with a coeff. of variation of 5.0%. After several parameter changes this was reduced to 2.8%. When the adapted model was used to predict all developmental stages scored in all 4 experiments, it gave good results for anthesis and maturity. Coeff. of variation were high for stages before stem elongation. Exclusion of extreme sowing dates improved the results of the model. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Factors influencing glassiness in lettuce.
Authors: Maaswinkel R.H.M. , Welles G.W.H.
Published: June 2020

Glassiness, a physiological disorder occurring in greenhouses between November and February under low natural light conditions, is probably due to an imbalance between water uptake and transpiration. Eight greenhouse experiments were carried out during winter. Experiments with soil-grown plants showed that soil compaction and nitrogen supply were negatively correlated with the amount of glassiness whereas the amount of nightly outgoing radiation (from inside the greenhouse) was positively correlated with glassiness. Studies using the nutrient film technique showed that the positive effect of nitrogen was probably due to higher salt concentration rather than a specific effect of NO3-. Clear cultivar differences were observed with Dalida, Mistra and Rolinda showing less glassiness than Renate, Amanda Plus and Decisco. High soil compaction, high plant temperature, tolerant cultivars and higher total salt concentration could all be used to reduce glassiness. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A study of soil variation in podzols in the Netherlands.
Authors: Hootsmans M.J.M. , Wallis de Vries M.F.
Published: June 2020

Variation in 31 soil characteristics was studied in a 100-ha area with a nested random sampling method and a 400-m transect. Apart from water-table, no characteristics or combinations thereof could be mapped accurately with a sampling distance of 50 cm. Wet and dry podzols were distinguished, distributed in a fine-grained pattern of small units (less than 4 msuperscript 2). (Abstract retrieved from CAB Abstracts by CABI’s permission)
The digestion of grass and alfalfa silages in the forestomachs and intestines of sheep.
Authors: Kies A.K. , Bruchem J. van , Hof G. , Boer H.
Published: June 2020

Digestion of cell wall constituents (CWC) and crude protein (CP) were estimated in wethers fitted with dorsal rumen sac and small intestine cannulae and given grass or lucerne silage (containing in DM 12.9% and neutral detergent fibre (NDF) 60.2% and CP 19.1% and NDF 48.8%, respectively) with daily DM intakes 46.5 and 49.0 kg0.75. Highest rate of emptying of reticulo-rumen was for grass silage. Fractional rate of emptying of liquid phase for cows given grass silage was 5.7% per h compared with 4.9% per h for cows given lucerne silage. Rates of emptying of particulate phase were similar for both silages. Frequency of rumen contractions was higher for grass silage than for lucerne silage. CWC of lucerne silage were less digestible than those of grass silage. Degradability of dietary CP in reticulo-rumen for grass and lucerne silage was 64 and 87%. Digestibility of CP in the small intestine was lower for lucerne silage than for grass silage. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Sorghum-rice intercropping, a security system for the poorly drained soils of southern Sudan.
Authors: Bontkes T.E.S.
Published: June 2020

In parts of southern Sudan, sorghum production varies greatly from year to year due to the occurrence of floods in some years. These floods are caused by a combination of high rainfall within a short period, poorly drained soils, and varying micro-relief. To improve the reliability of food production, a sorghum/rice intercropping system was tested in 1980 and 1981 on an area prone to such flooding. In these experiments sorghum proved to produce good yields at the expense of rice on areas which had been little flooded, whereas on waterlogged areas sorghum produced little while rice gave good yields. It may therefore be concluded that intercropping of rice with sorghum offers a good possibility to offset the loss of sorghum in wet years. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Analysis of food quality perception processes.
Authors: Steenkamp J.E.B.M. , Wierenga B. , Meulenberg M.T.G.
Published: June 2020

A study was made to investigate ways in which consumers perceive the quality of food products and a model of the quality perception process was developed. Consumers used intrinsic (colour and appearance of product) and extrinsic (price and brand name) factors to determine rating of a product on quality aspects that cannot be evaluated at point of purchase (such as taste). The model was used on 13 foods and a high score for a food quality variable (nutritive value, energy content, additives and sensory quality) indicates that this quality is perceived as important. Energy content of meat, cheese, minced meat, margarine and meat products is perceived as most important indicator of quality. A high score for additives in jams, canned and jarred vegetables indicates that these products are perceived as poor quality. (Abstract retrieved from CAB Abstracts by CABI’s permission)
From conventional to integrated agriculture.
Authors: Vereijken P.
Published: June 2020

Conventional agriculture aims mainly at a maximum financial return. This had both positive and negative consequences. The paper indicates that conventional farming systems with their predominantly agricultural aims cannot adequately meet the complex of environmental and social aims. It is necessary to find farming systems which pursue a broader aim than the simply agroeconomic one. This new direction, which embraces various aims in the field of economics, employment, environment, nature, landscape, quality of food and well-being, is called 'integrated farming'. A new and appropriate technology needs to be developed on the basis of this integrated vision of agriculture. The paper discusses the research and development at the farm level being carried out at the experimental farm at Nagele in the Netherlands. The first results show that an integrated approach can result in considerable reduction of inputs without loss of income for the farmer. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Culling of sows and the profitability of piglet production.
Authors: Brake J.H.A. te
Published: June 2020

This discussion considers work on (1) the effects on piglet production of culling rate, energy intake of the sow, ages at 1st mating and 1st farrowing, and age at weaning, (2) the effects of CR and farrowing rate on the length of the reproductive cycle, and (3) the development of a sow productivity index for use as a guide to culling. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Crown shyness: a parameter for ageing in Piptadeniastrum africanum.
Authors: Offermans D.M.J.
Published: June 2020

The aging of P. africanum within the forest followed a well-defined pattern which was determined from large-scale aerial photographs taken over Tai and Banco National Parks, South Ivory Coast. The main parameters of this pattern were branch orientation, crown stratification, depth of foliage and crown shyness (a phase of declining vigour considered useful for aging the senescent stages of P. africanum). (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of tiller length and age on herbage quality of hybrid Pennisetum canopies.
Authors: Warndorff M. , Dovrat A. , Kipnis T.
Published: June 2020

Whole plants were sampled every 10 or 11 days from field-grown P. americanum X P. purpureum canopies which were cut at intervals of 3 or 6 weeks. Tillers of varying lengths were analysed for in vitro dry matter digestibility (IVDMD). During the growing period, average whole tiller digestibility decreased, as did differences between tillers of different lengths. In 42-day-old herbage, no difference in IVDMD was found between 10 and 70 cm tillers. The decline in digestibility with time was attributed to (1) the appearance of tall tillers and (2) the detrimental effects of low light intensities on tillers growing deep in the canopy. Results suggested that it is doubtful whether tiller length or other morphological or physiological traits can be used to predict herbage digestibility, and that in breeding for better digestibility selection for stem digestibility per se should be more promising than selection for reduced stem growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Multiplication of seed potatoes by tuber formation in leaf axils of stems derived from single-bud stem cuttings.
Authors: Marinus J.
Published: June 2020

Single-node cuttings of 3 cultivars were planted in such a way that the buds were some centimetres above the soil surface. Some of the plants were grown under long-day conditions, the others under short days during stem growth, this being favourable to tuber formation in normal plants. Stems growing from the buds showed abundant tuber formation in the leaf axils of Jaerla (early) and Bintje (mid early), especially under short-day conditions, but fewer tubers were formed in Alpha (late). This cultivar formed many thickened branches instead of tubers under short-day conditions. Under long days Jaerla and Bintje formed many above-ground tubers, whereas half of the cuttings of Alpha did not form tubers. When planted, above-ground tubers produced good yields. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of seasonal radiation and daylength shifts on growth and development of spray carnation. 1. Vegetative growth.
Authors: Klapwijk D.
Published: June 2020

Studies are reported on 32 successive plantings, from September 1982 to July 1984, of the cv. West Pink grown in containers under glass. The relative growth rate of the shoots was markedly affected by the season. The minimum rate was about 2%/day in December; it increased linearly to almost 9% in mid-summer and decreased linearly again thereafter. Leaf initiation rates showed the same pattern with a minimum of 0.09 and a maximum of 0.24 leaf pairs/day. Stem elongation was also characterized by 2 linear functions, with a minimum of about 0.1 cm/day in winter and a maximum of slightly less than 0.5/day in summer. The effect of season on flower growth between initiation and full bloom was similar to that on fresh weight and leaf initiation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some aspects of gas bubble disease in African catfish (Clarias gariepinus Burchell 1822).
Authors: Boon J.H. , Ooms M.R. , Wensing T. , Huisman E.A.
Published: June 2020

The relationship of air supersaturation in the rearing water to gas bubble disease in African catfish was studied. The fish were susceptible to the disease, but less so than trout and carp. Clinical characteristics are described. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Fuelwood scarcity and forest policy on Santo Antao, Cabo Verde.
Authors: Briel J. van den , Brouwer R.
Published: June 2020

In spite of massive reforestation, local people in Cape Verde face increasing shortages of fuelwood. This is caused by conflicting objectives of the reforestation project, which is aimed primarily at erosion control, and restrictive legislation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of wet vs. dry by-product ingredients and addition of branched-chain volatile fatty acids and valerate to dairy diets. I. Feed intake, milk production and milk composition.
Authors: Visser H. de , Tamminga S.
Published: June 2020

A feeding trial was carried out with 56 dairy cows during 1st 18 weeks of lactation. Rations consisted of 40% grass and maize silage (in a 50:50 ratio) and 60% concentrates based entirely on by-products (beet pulp, maize gluten feed and brewers' grains) and were offered ad lib. 60% (on DM basis) of concentrates were given either ensiled (WET) or dehydrated (DRY). Half of the cows receiving WET or DRY diets also received an additive containing approx. 80 g of calcium salts of iso-butyrate, 2-methyl butyrate, 3-methyl butyrate and valerate. No significant effects of additive on feed intake, milk yield and milk composition were found. Feed, energy and protein intake and milk protein production were significantly lower after feeding WET diet compared with DRY diet. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of redox processes on soil acidity.
Authors: Breemen N. van
Published: June 2020

Redox processes due to alternating aerobic and anaerobic conditions may give rise to strongly acidic or alkaline soils and waters. First, oxidized chemical components tend to be more acidic or less alkaline than their reduced counterparts. Second, and more important, redox processes often lead to the simultaneous formation of acidic (or potentially acidic) and alkaline substances with different mobility (dissolved or gaseous versus adsorbed or solid), so that one of the two substances can be exported, leaving a more acidic or more alkaline residue. Examples of acidification or alkalinization processes in wetlands based on these principles are: (1) formation of acid sulfate soils (transformation of seawater sulfate and sedimentary iron to immobile potential acidity (FeS2) and mobile alkalinity (HCO3-), followed by oxidation of FeS2 after the alkalinity has disappeared), (2) alkalinization of periodically flooded acid sulfate soils (formation of dissolved ferrous sulfate during reduction, and oxidation of the ferrous sulfate to ferric oxide and sulfuric acid at the soil surface, followed by drainage of the acid floodwater), (3) ferrolysis (immobilization of seasonally reduced ferric iron as exchangeable Fe2+, and removal of replaced bases by drainage, followed by oxidation of Fe2+ -clay to H+ -clay), and (4) soil alkalinization in closed depressions (reduction of sodium sulfate to sodium (hydrogen) carbonate and volatile H2S). (Abstract retrieved from CAB Abstracts by CABI’s permission)
Proton adsorption mechanism at the gibbsite and aluminium oxide solid/solution interface.
Authors: Hiemstra T. , Riemsdijk W.H. van , Bruggenwert M.G.M.
Published: June 2020

Titration curves of a synthetic pure crystalline gibbsite suspension have been made at three NaCl levels. The synthesized gibbsite is characterized by TEM, TGA and X-ray diffraction. The overall BET surface area and the surface area of the edges of the hexagonal crystals are determined. The surface structure of gibbsite is discussed. The surface charge ( sigma 0)-pH data are analysed with a recently proposed one-step charging model for proton adsorption (one-pK model). Analysis of the data suggests that the singly coordinated surface hydroxyls are probably the dominant reactive surface group. Considering these groups as reactive only the titration data could be fitted well with the one-pK model if it is extended with pair formation. Only two adjustable parameters are needed, the Stern layer capacitance and the pair formation constant. Analysis of titration data of aluminium oxides, as presented in recent literature, showed that all sigma 0-pH curves could be described rather well with one and the same set of two parameters, the capacitance of the Stern layer and the pair formation constant. The difference in proton adsorption behaviour between different aluminium (hydr)oxides is mainly caused by differences in the site distribution and the site densities of the aluminium (hydr)oxides involved. The results suggest that pair formation should be taken into account. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Environmental factors in cauliflower curd initiation and growth.
Authors: Booij R.
Published: June 2020

In 1982, 1983 and 1984, seedlings of the cultivars Delira and Elgon were transplanted on several dates during the summer. The number of days between transplanting and curd initiation varied between 25 and 46 and was not related to the transplanting date. The date of curd initiation was correlated with the mean temperature in the period after initiation of the 19th leaf. At higher temperatures, curd initiation was delayed. The initiation date for Elgon tended to be a few days later than that for Delira. The final number of leaves (all initiated before curd initiation) was best correlated with mean maximum day temperature in the period between initiation of the 19th leaf and curd initiation. The variation in duration of curd growth was less than the variation of the period between transplanting and curd initiation. The duration of curd growth could be explained as well by the date of curd initiation as by a temperature-time product or by the mean irradiance. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Relationship between cropping frequency, root rot and yield of silage maize on sandy soils.
Authors: Scholte K.
Published: June 2020

In field trials at Wageningen in 1979-86, forage maize cv. Dorina was given 100 t cattle slurry/ha and grown in a long (sugarbeet/1 or 2 years barley/potato/maize) or short (potato/maize) rotation, or continuously cropped. Nematicides were applied to each crop in all rotations. The effects of soil treatment with pencycuron, benomyl, metalaxyl or gamma -irradiation were studied in 1986 in pot experiments using soil from the field trial plots for each cropping sequence. Roots were given a healthiness ranking in each year. Yields were 10-20% lower with continuous cropping and a prolonged short rotation. Neither annual applications of slurry nor nematicides reduced the adverse effects of continuous cropping. Continuous cropping stimulated root rot. There was a close negative relation between cropping frequency, incidence of root rot and maize yield. Root rot seemed to be caused mainly by Pythium spp., and seemed to occur more seriously in years when the first half of the growing season was wetter than normal. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Plasma proteins of young African catfish (Clarias gariepinus, Burchell 1822).
Authors: Boon J.H. , Smits J.M. , Wensing T. , Lo E.
Published: June 2020

The effect of feeding level and water supply on the total content of plasma protein (TPP) and fractions of these proteins (PPF) of young African catfish was studied. It was found that TPP can be divided into 4 fractions (PPF I-IV), of which PPF I is predominant. Analysis of the results showed a strong effect of feeding level on TPP and PPF I-IV. There was a positive correlation between TPP and the weights of PPF I-IV, and a negative correlation between PPF I and PPF II. The PPF I fraction might be usable as an indicator for the health status of young catfishes. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Competition between a sugar beet crop and populations of Chenopodium album L. and Stellaria media L.
Authors: Kropff M.J. , Joenje W. , Bastiaans L. , Habekotte B. , Oene H. van , Werner R.
Published: June 2020

In field trials on sandy loam, 5.5 C. album plants/msuperscript 2 and 11 clumps S. media/msuperscript 2 reduced sugarbeet DM by 37 and 21%, resp. Although S. media populations had a much higher LAI, C. album proved the stronger competitor and grew taller than the crop. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of winter wheat cover crop management on first-year Poa pratensis L. and Festuca rubra L. seed crops.
Authors: Meijer W.J.M.
Published: June 2020

In field trials at 3 locations in the Netherlands in 1978-84, P. pratensis or F. rubra was sown simultaneously with a wheat cover crop in Sep.-Nov. or sown in Dec.-Apr. into an Oct. sown wheat crop. Wheat was sown at 110 or 160 kg/ha with between-row spacings of 12.5, 25.0, 37.5 or 50 cm, and given 140 kg N/ha as a single or split dressing. Light interception of several wheat cultivars was measured in concurrent government cultivar trials. Mean seed yield of P. pratensis was lowest with Feb.-Apr. sowing (0.80 t/ha) and highest with Sep. sowing (1.34 t). Mean F. rubra yield was lowest with Sep. sowing (1.26 t) and highest with Oct.-Nov. sowing (1.42 t/ha). Tillering of the grasses ceased if >85% of the solar radiation was intercepted by the cover crop. Grass production was enhanced by using a wheat cultivar with a late-closing canopy, decreased cover crop sowing rate and split application of N. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Modelling to support health programs in modern livestock farming.
Authors: Dijkhuizen A.A.
Published: June 2020

The application of herd health programmes in livestock farming is rarely an all-or-nothing affair. Usually several control measures are available, but none is ideal. The use of models in optimizing the application of herd health programmes is on the increase. Two broad categories of models have been reviewed: (1) statistical/sepidemiological models used for direct evaluation of any programme actually carried out (positive approach); and (2) economic models used for predicting the profitability of specific measures or programmes (normative approach). Priorities for further research in the field of animal health economics are also discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The use of the 'wet workability limit' to predict the land quality 'workability' for some Uruguayan soils.
Authors: Terzaghi A. , Hoogmoed W.B. , Miedema R.
Published: June 2020

In an attempt to predict soil workability, the upper critical moisture content for tillage was determined for some Uruguayan soils, using two laboratory methods developed for Dutch conditions ('upper tillage limit' or UTL, and 'wet workability limit' or WWL). The results obtained showed that the critical point is mainly influenced by the percentage clay and organic matter (OM) in the soil, yielding the linear relationship: UTL = 7.5 + 1.91 x OM (%) + 0.34 x clay (%). The UTL is highly correlated with the moisture content at a range of pF values between 2.0 and 2.7, this being a consequence of the influence of clay and organic matter on the shape of the pF curve. The results obtained by both methods (UTL and WWL) are highly correlated (r = 0.88). Within a certain range of texture, both methods give statistically the same result. (Abstract retrieved from CAB Abstracts by CABI’s permission)