Shoot production in cut roses with reference to breeding for winter flowering

Summary In 62 clones of cut roses the numbers of flowering and blind shoots were recorded from February 1975 to January 1976. On average about 25 shoots were harvested per plant, of which 27% were blind. No significant correlation was found between the average numbers of flowering and blind shoots. Progenitors for winter flowering roses should be selected among clones that combine a constant total shoot production with a low percentage of blind shoots.     

Introgression of leaf blight resistance from Allium roylei Stearn into onion (A. cepa L.)

Summary Segregation analysis in BC₁ and F₂ progenies from interspecific hybrids between Allium roylei and A. cepa demonstrated that leaf blight resistance is conditioned by one single dominant gene from A. roylei. This gene, designated Bs ₁ , was unlinked to the genes Pd ₁ and Pd ₂ determining downy mildew resistance. The prospects of exploiting A. roylei as a source for disease resistances in onion breeding are very promising.     

The uncertainty in forecasting trends of forest soil acidification

A Regional Soil Acidification Model (RESAM) has been developed to gain insight in long-term impacts of deposition scenarios on forest soils in The Netherlands. Model predictions of such large-scale environmental effects of acid deposition require extrapolation of site specific data to large geographical regions. The major aim of this study is to quantify the uncertainty in model response to a given deposition scenario, due to uncertainty and spatial variability in data. Furthermore, the uncertainty analysis was performed to determine which additional data will most likely improve the reliability of predictions. An efficient Monte Carlo technique was used in combination with regression analysis. The analysis was restricted to one forest soil ecosystem: a leptic podzol with Douglas fir, subject to a reducing deposition scenario. The investigated output variables were pH, Al/Ca ratio and NH₄/K ratio in the root zone, which are generally used as indicators of forest soil acidification and of potential forest damage. Statistical analyses showed that in most cases the relation between the parameters and model output can be satisfactorily described by a linear regression model. The uncertainty contribution of various parameters depends on the considered output variable, soil compartment and time. The uncertainty, as measured by the coefficient of variation, appears to be high for the NH₄/K and Al/Ca ratios, whereas it was relatively low for the pH. Results show that the uncertainty in the depositions of SO_x, NO_x, and NH_x in a receptor area and the uncertainty in the parameters and variables determining the nitrogen and aluminium dynamics contribute most to the resulting uncertainty of the considered model output.     

Pre-determination of survival rate of apple and pear scions after X-ray treatment

Summary A simple method is described which makes it possible to pre-determine the survival rate of dormant scions of woody crops such as apple and pear after X-ray treatment.During early spring irradiated scions were kept on water in a warm glasshouse and the buds were left to sprout. It appeared that the relation between X-ray dose and percentage of buds surviving on the scions after 3–4 weeks was similar to the relation between dose and the percentage of irradiated grafts surviving after two growing seasons in the field. In sofar the dose at which 50% survival occurs is presumed to be the most efficient one, the method enables speedy determination of the most effective dose of X-ray treatment.     

Analysis of fat-soluble vitamins. XIX. Collaborative studies on the chemical assay for vitamin D concentrates

In 1971, a chemical method for the assay of vitamin D in concentrates containing only vitamin D was collaboratively studied by 14 laboratories, using 6 different samples from 2 European manufacturers. On the basis of these results, the laboratories were divided into 2 groups: 5 with significant laboratory biases of greater than or equal to 2%, and 9 laboratories with nonsignificant bias. The 9 laboratories were subdivided into 2 groups which differed significantly as to reproducibility within laboratories. The reproducibility between laboratories, expressed as a standard deviation in per cent with 95% confidence limits, was 1.2% (confidence range 0.6-7.3) and 4.7% (confidence range 2.4-29.3) for 3 and 6 laboratories, respectively. A second collaborative test was performed in 1974, using 12 vitamin D resin samples in oil from 3 United States manufacturers, to compare 2 chemical vitamin D assay methods (with and without maleic anhydride) and to compare results from the chemical and biological methods; 9 laboratories participated in the chemical method study and 3 in the rat bioassay study. The correlation of results of the chemical method including maleic anhydride treatment and the rat bioassays was satisfactory. The reproducibility of the chemical method was about the same as that in the first collaborative test.     

Radionuclides in lung diagnostics: a new approach. Summary of the first results

With a 99mTc-labelled aerosol an inhalation (ventilation) image of the lungs was obtained. A lung perfusion image was obtained with 99mTc-labelled macro-aggregates. The data from the gamma camera were stored in a computer and the inhalation-perfusion (I/P) ratio was calculated for the total lung as well as for one half, another selected region, and a local (pixel) area. In the anaesthetised dog in sternal recumbency, the I/P ratio decreased from the cranial to the caudal lung regions. Hence in the dog gravity is not the only determinant of the I/P ratio distribution, as it is assumed to be in man. Position and anaesthesia appeared to influence the distribution of I/P ratios within the lung.     

Parameterization and calibration of a model to simulate effects of feeding level and feed composition on growth of Oreochromis niloticus (L.) and Oncorhynchus mykiss (Walbaum)

A dynamic model to simulate growth of the African catfish. Clarias gariepinus (Burchell), was parameterized and calibrated for Nile tilapia. Oreochromis niloticus (L.), and rainbow trout, Oncorhynchus mykiss (Walbaum). The model predicts fish weight and fat percentage from the amount and composition of the feed and water temperature. The major factor determining the efficiency of feed conversion is the proportion of energy provided by protein oxidation, which is positively related to the protein feeding level and the protein/energy ratio of the feed. The model predicted fresh weight of the herbivorous Oreochromis niloticus in independent experimental data with a mean deviation of -2.1% (range -23% to +37%) of observed values (fish weights 10-40 g), For the carnivorous Oncorhynchus mykiss, this value was 4.8% (range -21% to +24%, 50-800 g), Options for further improvement of the model are discussed. We conclude that the structure of the model applies to a broad range of fish species and feeding schedules, provided that both feed and fish are characterized by a set of specific parameters.     

Uptake,distribution and metabolic fate of 3H-triforine in plants. II. Long-term experiments

Uptake of ³H-triforine by tomato and barley seedlings from soil with a high organic matter content was much less efficient than from aqueous suspensions, even though the period of exposure was much longer—at least 1 week (“long-term treatment”) vs 1 day (“short-term treatment”). After transplanting to fresh soil, part of the label in the roots was lost probably by desorption. Distribution of label in tomato shoots was as irregular as after short-term treatment; label was virtually confined to the leaves which expanded before about 14 days after cessation of the treatment. In shoots of barley seedlings which were pretreated in an aqueous suspension of ³H-triforine for 1 day before being subjected to a long-term soil treatment, almost all radioactivity present could be ascribed to uptake during the pretreatment phase. The distribution pattern strongly resembled that obtained after short-term treatment, hardly any label being found in leaves which unfolded after the pretreatment phase. Rates of conversion of ³H-triforine in barley shoots depended to some extent on whether or not seedlings were transplanted to fresh soil after 1 week.