Assimilation lighting of butterhead lettuce: an economic evaluation

Application of the Nutrient Film Technique to the cultivation of butterhead lettuce offers an average growth period reduction of 15 %. The possibility to obtain a further reduction using supplementary lighting was studied in two experiments. Both an autumn crop and a winter crop were subjected to a set of 9 light intensities evenly distributed between 15 and 95-mu-mol/(m2.s). The control plot received only natural light. The average number of heads per auction box significantly depended on the light sum only for the winter crop. The combined results of the autumn and winter crops show a linear increase of fresh weight with increasing light sums; the respective harvesting criteria were 392 g/head (420.5 mol/m2) and 240 g/head (250.3 mol/m2). Based on the linear regression equation, the fictitious growth period required to reach the harvesting criterion in both crops was calculated for (a) various levels of supplementary light and (b) a day length of 16 h. Analoguous calculations were performed for a winter crop with a fictitious harvesting criterion of 300 g/head. Maximal growth period reductions were expressed as a % of an average 55-day NFT crop. For the fresh weights of 392 g (autumn), 240 g (winter) and 300 g (winter, fictitious), these were 22.1 %, 61.6 % and 64.6 % respectively. The calculated growth period reductions were valorized using average prices recorded by the Agricultural Economics Institute (L.E.I.). The cost of the lighting installation were established for a 4000 m2 plant. Electricity consumption was charged using the special advantageous rates applied by the public electricity supplier. A cost-benefit analysis indicates that the required investment and operational costs are economically justified only in case of high auction prices (at least 50 % higher than the 1989 L.E.I. average) and/or advantageous electricity rates

Assimilation lighting of Cordyline: an economic evaluation

The commercial value of Cordyline is determined both by its red leaf colour and by the overall plant length. During winter, the growth rate slows down, and at the same time less red coloured leaves are formed. A greenhouse trial was organized to assess the possibility of improving the crop's market value by making use of artificial light. The experimental stand contained Cordyline cv. Prins Albert and received high pressure sodium light supplements from November 1990 to February 1991. Total day length (natural + artificial) was set at 15.5 h. Light intensities and the corresponding temperature increases were measured at crop level. Between 15 and 85-mu-mol/(m2.s), 8 light intensity classes were distinguished; the control plot received only natural light. During the growing period, the plant heights were measured at regular intervals, showing no particular discrepancies among the various classes. The effect of applying light supplements was most evident between the 3rd and 6th week after planting. Both plant length and leaf colouring were evaluated when the plants were transferred to pots. Differences between classes could primarily be attributed to differences in intensity of the light supplement received; the effect of the temperature increases (< 1.5 K) on either parameter was negligible. Plant height and the percentage of red coloured leaves were shown to be exponentially related to light intensity class. Potted Cordyline is valorized according to overall plant height. Calculated financial gain as compared to control was also exponentially related to light intensity class. The costs of providing a light supplement, i.e. luminaire and lamp cost and consumption of electricity, increase almost linearly with increasing light intensity. When electricity consumption is charged according to the special advantageous high tension rates as provided by the public supplier, and taking into account a total day length of 16 h, lighting costs exceed the financial gains from 45-mu-mol/(m2.s) (+/- 3200 lx for high pressure sodium lamps) onwards. The optimum light supplement intensity, this is the intensity with which to achieve maximum financial benefit, was situated at 20-mu-mol/(m2.s) (+/- 1430 lx). However, since the minimum intensity at which sufficient uniformity can be guaranteed with the current luminaire types, is about 25-mu-mol/(m2.s) (+/- 1800 lx), the latter value is put forward as the optimum. Under those conditions, the experimental financial benefits amounted to 37.4 BF/m2

Kunstmatige belichting bij de opkweek van veldsla

A

Nephron Sparing Surgery for De Novo Kidney Graft Tumor: Results From a Multicenter National Study

International audienceNephron sparing surgery (NSS) results in the transplanted population remain unknown because they are only presented in small series or case reports. Our objective was to study renal sparing surgery for kidney graft renal cell carcinomas (RCC) in a multicenter cohort. Data were collected from 32 French transplantation centers. Cases of renal graft de novo tumors treated as RCC since the beginning of their transplantation activity were included. Seventy-nine allograft kidney de novo tumors were diagnosed. Forty-three patients (54.4%) underwent renal sparing surgery. Mean age of grafted kidneys at the time of diagnosis was 47.5 years old (26.1-72.6). The mean time between transplantation and tumor diagnosis was 142.6 months (12.2-300). Fifteen tumors were clear cell carcinomas (34.9%), and 25 (58.1%) were papillary carcinomas. Respectively, 10 (24.4%), 24 (58.3%) and 8 (19.5%) tumors were Fuhrman grade 1, 2 and 3. Nine patients had postoperative complications (20.9%) including four requiring surgery (Clavien IIIb). At the last follow-up, 41 patients had a functional kidney graft, without dialysis and no long-term complications. NSS is safe and appropriate for all small tumors of transplanted kidneys with good long-term functional and oncological outcomes, which prevent patients from returning to dialysis