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Olle M.,Jogeva Plant Breeding Institute
Acta Agriculturae Scandinavica Section B: Soil and Plant Science | Year: 2012

The objective of this investigation was to examine the effect of restriction of growing medium volume on the level of tipburn in chervil and leaf lettuce. Chervil: The plants were grown in different sizes of rock wool cubes: a. 31 cm 3, b. 64 cm 3, c. 135 cm 3. The incidence of tipburned leaves decreased by increasing the size of cubes. Leaf lettuce: Plants were grown in different sizes of pots: 12 cm pots with capacity of 0.6 L and 8 cm pots with capacity of 0.25 L. The incidence of tipburned leaves increased by decreasing pot size. © 2012 Taylor and Francis Group, LLC.

Olle M.,Jogeva Plant Breeding Institute | Virsile A.,Lithuanian Research Center for Agriculture and Forestry
Agricultural and Food Science | Year: 2013

The aim of this study is to present the light emitting diode (LED) technology for greenhouse plant lighting and to give an overview about LED light effects on photosynthetic indices, growth, yield and nutritional value in green vegetables and tomato, cucumber, sweet pepper transplants. The sole LED lighting, applied in closed growth chambers, as well as combinations of LED wavelengths with conventional light sources, fluorescent and high pressure sodium lamp light, and natural illumination in greenhouses are overviewed. Red and blue light are basal in the lighting spectra for green vegetables and tomato, cucumber, and pepper transplants; far red light, important for photomorphogenetic processes in plants also results in growth promotion. However, theoretically unprofitable spectral parts as green or yellow also have significant physiological effects on investigated plants. Presented results disclose the variability of light spectral effects on different plant species and different physiological indices.

Olle M.,Jogeva Plant Breeding Institute | Ngouajio M.,Michigan State University | Siomos A.,Aristotle University of Thessaloniki
Zemdirbyste | Year: 2012

The aim of the review is to present an overview of the effects of mineral soil, inorganic and organic growing media on the growth, development, yield and quality of vegetables grown under greenhouse conditions. The findings from the literature suggest that the yield of various vegetables tends to be higher for the plants grown in various growing media compared to those grown in the soil. A number of authors have reported that dry matter, sugar, soluble solids, vitamins and carotenoids content in tomatoes; acidity and taste have better marks when grown in soilless culture systems compared to soil. Only very few authors have indicated that soil culture could increase acidity, dry matter, carotenoids and sugar content in tomatoes compared to soilless culture systems. Growth and development of vegetables are enhanced, when plants are grown in inorganic media compared to organic ones. For yield enhancement several authors have recommended growing vegetables in inorganic media (rockwool, sand) rather than organic media. Furthermore, there is a growing body of studies indicating the benefit of mixing organic and inorganic components for vegetable growing media with improved performance in greenhouse production. In most cases, the addition of compost did not change the yields of vegetables grown on organic media. Also it is difficult to draw broad conclusions on the impact of various organic substrates on the chemical composition of vegetables based on the information in the literature. Some inorganic substrates can influence growing medium so that vegetables grow faster, but that may depend on substrate used. As a substrate, zeolite had advantages over perlite, as it increased growth of crisp-head lettuces. As observed with organic media, it is difficult to draw general conclusions on the impact of inorganic media on the chemical composition of vegetables. Results vary with the crop and the chemical composition and availability of elements of the inorganic substrate.

Mander U.,University of Tartu | Jarveoja J.,University of Tartu | Maddison M.,University of Tartu | Soosaar K.,University of Tartu | And 3 more authors.
GCB Bioenergy | Year: 2012

We studied the impact of reed canary grass (RCG) cultivation on greenhouse gas emission in the following sites of an abandoned peat extraction area in Estonia: a bare soil (BS) site, a nonfertilized Phalaris (nfP) plot, a fertilized Phalaris (fP) plot, and a natural bog (NB) and a fen meadow (FM) as reference areas. The C balance and global warming potential (GWP) were estimated by measuring CO2, CH4, and N2O emissions and aboveground and belowground biomass variations. The high CO2 flux from the nfP and fP sites and the low CO2 emission from the BS are due to the enhancement of mineralization by plant growth on planted sites and inhibited mineralization by the recalcitrant C of BS. The NB site emitted 24 kg CH4 ha-1 yr-1, whereas the almost zero CH4 emission from the Phalaris plots and the BS site was due to the high S concentration in peat, which probably inhibited methanogenesis. The N2O flux varied from <0.1 kg on the Phalaris plots and the NB to 2.64 kg N2O ha-1 yr-1 on the FM. The highest yield of RCG was obtained in autumn (13.9 t and 8.0 t dw ha-1 on the fP and nfP, respectively). By spring, the biomass yield on the fP and nfP plot was 12.7 and 7.9 t dw ha-1, respectively. The C balance of nfP and fP plots was negative in comparison to the BS (-3322, -5983, and 2504 kg CO2 ha-1 yr-1, respectively). This indicates that the cultivation of RCG transformed them from a net source of C into a net sink of C. The GWP for the fP and nfP sites was -5981 and -3885 kg CO2 eq ha-1 yr-1, respectively. The BS site had a total GWP of 2544 kg CO2 eq ha-1 yr-1. © 2011 Blackwell Publishing Ltd.

Runno-Paurson E.,Estonian University of Life Sciences | Runno-Paurson E.,Jogeva Plant Breeding Institute | Remmel T.,University of Tartu | Ojarand A.,Estonian Research Institute of Agriculture | And 2 more authors.
European Journal of Plant Pathology | Year: 2010

The characteristics of populations of Phytophthora infestans from organic farms, small conventional farms and large conventional farms were determined from isolates collected in northern Estonia in 2004 and 2005. For the population as a whole 41% were A2; all virulence factors to the 11 R genes from Solanum demissum were found; and more than 70% had high or intermediate resistance to metalaxyl. Isolates from organic farms tended to have more complex pathotypes than isolates from either large or small conventional farms, but there was a higher proportion of metalaxyl resistant isolates from large conventional farms than from small conventional farms or from organic farms. © 2010 KNPV.

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