Comparison of some selection procedures and objectives in faba beans (Vicia faba L.). II. Selection for crude protein content

Summary Starting with two heterogeneous F₂ populations, each based on 20 cross combinations, different types of selection were applied for four consecutive selection cycles. Three of the selection procedures involved crude protein content (CP) and are presented in this paper. They were selection for high CP (HP), selection for low CP (LP) and independent culling levels selection for high CP and an index for seed yield per plant (ICL). For ICL-selection the attention is focussed on CP in this paper.For all three selection procedures, predicted and realized responses were calculated and expressed as percentage of a corresponding random population. The selection intensities (i) differed over selection procedures and generations. Differences in i between HP and LP within generations were mostly of minor interest. The response to HP-selection was slightly higher than to ICL-selection, but this may be due to the higher selection intensity exerted with the former method.HP-and LP-selection showed some remarkable differences, which were interpreted as a tendency towards partial dominance of high over low protein content. The total response to HP-selection gradually increased, whereas LP-selection yielded the total response largely after only one cycle of selection. The predicted response showed a tendency towards overestimation in the case of HP-selection and to underestimation in the case of LP-selection.Selection for high protein yield through CP seems to be feasible, although improvement of yield stability may eventually be more necessary. As no consistent correlation, either positive or negative, between SYP and CP could be detected, selection for either of these characters may be considerd independently of selection for the other one.     

A field study evaluation of Petrifilm™ plates as a 24-h rapid diagnostic test for clinical mastitis on a dairy farm

Clinical mastitis is one of the most common and expensive diseases of dairy cattle. To make an informed treatment decision, it is important to know the causative pathogen. However, no detection of bacterial growth can be made in approximately 30% of all clinical cases of mastitis. Before selecting the treatment regimen, it is important to know whether the mastitis-causing pathogen (MCP) is Gram-positive or Gram-negative. The aim of this field study was to investigate whether using two 3M Petrifilm™ products on-farm (which conveys a higher degree of sample freshness but also bears a higher risk for contamination than working in a lab) as 24-h rapid diagnostic of clinical mastitis achieved results that were comparable to the conventional microbiological diagnostic method.     

Modelling recreational visits to forests and nature areas

Besides their ecological and production function, the social function of forests and nature areas is becoming more and more important However, data, norms, and planning tools for this social function are limited. This makes it difficult for policy makers to do justice to this function, especially in the Netherlands, where spatial claims for different functions often exceed the available amount of land. In this paper we describe the development of a GIS-based planning tool for the recreational function of forests and nature areas. The tool focuses on the number of visits that may be expected. Besides the size of destination areas also the quality of the areas is taken into account. This quality is assessed using GIS-data on e.g. land-use, relief, noise, and the density of walking and cycling opportunities. Airline distances, as well as road distances (for cars) between residential areas and destination areas are calculated using GIS-analysis. The number of trips generated by a local population is then divided over the available areas within a pre-set range, taking each destination's quality and distance into account. The tool is suited not only for predicting present numbers of visits, but also for simulating the effect of new areas being developed, residential as well as natural. Also it can indicate residential areas where the local supply of forests and nature areas is wanting. Preliminary results for the city of Breda are presented.     

Profitability of bovine somatotropin administration to increase first insemination conception rate in seasonal dairy herds with heat stress

A dairy farm simulation program was used to estimate the economic value of increased conception rate at first insemination (FCR) as a result of one administration of bovine somatotropin (BST) per lactation. Further, the economically optimal BST administration period in a year was investigated. Typical conditions in Florida were assumed, including reduced milk production and conception rates in the summer and early fall due to heat stress. Administration of a single dose of BST ($6 per dose) per lactation was incorporated into a timed AI protocol for first insemination at 61 days after calving. Increases in FCR of 0, 4, 8, and 12 percentage points (PP) were compared including changes in prices, fertility, and seasonality of cow performance. No direct effect of BST on milk production was assumed. With default inputs and an increase in FCR of 4 PP, the optimal administration period was February through June which resulted in a small gain in profitability of $0.80/slot/year. Typically, one administration of BST per lactation to increase FCR was profitable in the cooler winter and spring, but not the hotter season. The use of BST in the cooler winter and spring resulted in increased seasonality of herd performance and demographics. When no seasonality in milk production was assumed, administration of BST was profitable throughout the year when FCR increased at least 8 PP. In conclusion, increases in FCR were most profitable during the cooler season of the year when basic conception rates were already greater than in the hotter season.     

Phytotoxic effect of Sesbania virgata (Cav.) Pers. On seeds of agronomic and forestry species

Sesbania virgata(Cav.) Pers.is a pioneer species native to South America able to release allelochemicals that affect germination and development of other plant species.The aim of this work was to evaluate the allelopathic effect of S.virgata on the germination and development of co-occurring species from gallery forest and on agronomic species.Two forest native species,Enterolobium contortisiliquum(Vell.) Morong and Sapindus saponaria L.,and two agronomic species(these as control),Oryza sativa L.and Solanum lycopersicum L.were used in the lab and greenhouse assays with seeds and leaf extracts of S.virgata.Agronomic species were more affected than native species when co-germinated with seeds of S.virgata.The germination percentage and speed germination index of the agronomic species were reduced in both in vitro and greenhouse assays.In the same assays,the seeds of native species showed no significant differences in the parameters mentioned.However,the initial growth of the four species assayed was affected,with reduction in plant length and shoot diameter followed by significant reduction in plantlet shoot and root weights.In the assays with irrigation of S.virgata leaf extracts,no significant inhibitory effects on germination were observed for all species.Height and shoot diameter of the native species were not affected by the leaf extracts,nor were fresh and dry weights.However,these parameters increased in the agronomic species as they were irrigated with leaf extracts.Based on our data we conclude that seed leachates of S.virgata affect germination and seedling development of other species,suggesting that its invasive behavior is due mainly to seed allelochemicals.Although with less pronounced effects on native species,allelopathy of S.virgata might also influence Interspecific competition in its natural environment.     

On the inheritance of the dwarf character in Polyantha × Rosa chinensis minima (Sims) Voss F1-populations

Summary The inheritance of the dwarf character was studied in F1-seedling populations arisen from crosses between diploid Polyantha cultivars and the diploid dwarf species R. chinensis minima (Sims) Voss. Dwarfness is controlled by a single dominant gene D. R. chinensis minima and its dwarf descendants are heterozygous for D, while polyanthas are homozygous for d. The origin of R. chinensis minima and its potential for breeding new pot roses are discussed.     

On the transmission of the yellow flower colour from Rosa foetida to recurrent flowering hybrid tea-roses

Summary To transfer the yellow flower colour of R. foetida to Hybrid Tea roses, F₁'s and backcrosses with Hybrid Tea's were produced. In B₁ populations, yellow, recurrent flowering seedlings occurred. Recurrent flowering was controlled by one recessive gene.     

Solute leaching in a sandy soil with a water-repellent surface layer: A simulation

Many sandy soils in the Netherlands have a water-repellent surface layer covering a wettable soil with a shallow groundwater table. Fingers form in the water-repellent surface layer and rapidly transport water and solutes to the wettable soil in which the streamlines diverge. Although several field observations are available, this system has not yet been studied systematically. In this paper, we present a model with a steady-state water flow to which solutes are added as a pulse. The model predicts the flow through the distribution zone and through the finger in the water-repellent surface layer with a closed form solution and transport in the wettable subsoil numerically. Model calculations show that the travel time through the water-repellent surface layer and the thickness and hydraulic conductivity of the wettable soil have the strongest effect on the arrival time of the solute pulse at groundwater level. The calculations also show that, assuming transport in the wettable subsoil to take place in fingers, the travel time is considerably shorter than when the diverging flow in the wettable soil is included.     

The relation between soil acidification and element cycling

Controversy about the contribution of acidic deposition to soil acidification partly arises from different concepts of soil acidification. Differentiating between actual and potential soil acidification has proved to be appropriate for properly identifying and quantifying the natural and anthropogenic sources of protons. Actual soil acidification is primarily manifested by leaching of cations from the soil, regulated by the mobility of major anions. Leaching of HCO₃ ^? and RCOO^? occurs naturally whereas leaching of NO₃ ^? and SO₄ ^2? is mainly caused by land use in agricultural soils and by acidic deposition in forest soils. Potential soil acidification is primarily due to accumulation of atmospherically derived N and S. This potential acid threat is partly realized by mineralization processes after the removal of vegetation.     

Average critical loads for nitrogen and sulfur and its use in acidification abatement policy in the Netherlands

Atmospheric deposition of N and S on terrestrial and aquatic ecosystems causes effects induced by eutrophication and acidification. Effects of eutrophication include forest damage, NO₃ pollution of groundwater and vegetation changes in forests, heathlands and surface waters due to an excess of N. Effects of acidification include forest damage, groundwater pollution, and loss of fish populations due to Al mobilization. Critical loads (deposition levels) for N and S on terrestrial and aquatic ecosystems in the Netherlands related to these effects have been derived by empirical data and steady-state acidification models. Critical loads of N generally vary between 500 and 1500 mol _c ha^?1 yr^?1 for forests, heathlands and surface waters and between 1500 and 3600 for phreatic groundwaters. Critical loads of total acid (S and N) vary between 300 to 500 mol _c ha^?1 yr^?1 for phreatic groundwaters and surface waters and between 1100 to 1700 mol ha^?1 yr^?1 for forests. On the basis of the various critical loads a deposition target for total acid of 1400 mol _c ha^?1 yr^?1 has been set in the Netherlands from which the N input should be less than 1000 mol _c ha^?1 yr^?1. This level, to be reached in the year 2010, implies an emission reduction of 80–90% in SO₂, NO _x and NH₃ in the Netherlands and of about 30% in neighboring countries compared to 1980 emissions.