Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation.

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Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light

In this study, a comprehensive review focusing on key strategies of energy saving and climate control technologies for greenhouses is presented. Following the brief and concise assessment of existing greenhouse systems in terms of their role in total energy consumption; cost-effective, energy-efficient and environmentally friendly technologies are analyzed in detail for potential utilization in greenhouses for notable reductions in energy consumption and emission levels. The technologies considered within the scope of this research are mainly renewable and sustainable based solutions such as photovoltaic (PV) modules, solar thermal (T) collectors, hybrid PV/T collectors and systems, phase change material (PCM) and underground based heat storage techniques, energy-efficient heat pumps, alternative facade materials for better thermal insulation and power generation (heat insulation solar glass, PV glazing, aerogel and vacuum insulation panel, polycarbonate sandwich panels), innovative ventilation technologies using pre-heating and cooling (high performance windcatchers) and efficient lighting systems. The findings from the research clearly reveal that up to 80% energy saving can be achieved through appropriate retrofit of conventional greenhouses with a payback period of 4–8 years depending on climatic conditions and crop type.

Renewable and sustainable energy saving strategies for greenhouse systems: A comprehensive review

Current status and recent achievements in the field of horticulture with the use of light-emitting diodes (LEDs)

Improving vegetable quality in controlled environments

Photovoltaic industry has been an important development direction of China's strategic emerging industries since 2012, and more and more attentions have been paid to broaden the domestic demand to solve the problem of overcapacity of China's PV industry. Photovoltaic agriculture, the combination of photovoltaic power generation and agricultural activities, is a natural response to supply the green and sustainable electricity for agriculture. There are several main application modes of photovoltaic agriculture such as photovoltaic agricultural greenhouse, photovoltaic breeding, photovoltaic wastewater purification, photovoltaic water pumping and new type rural solar power station. Photovoltaic agriculture can effectively alleviate the contradiction between more population and less land, powerfully promote the development of controlled environmental agriculture, evidently increase economic benefits of farmers, and significantly improve environment due to emissions reduction in China. In recent years, photovoltaic agriculture has a rapid development in China due to powerful support policies, flourishing controlled environmental agriculture, policy-oriented rural electrification and promising electric machinery for greenhouse. Therefore, photovoltaic agriculture provides new opportunity for China's photovoltaic industry, thus not only to solve the dilemma of overcapacity for China's photovoltaic industry effectively, but also to accelerate the development of modern agriculture in China. However, the more theoretical researches and practical exploration must be conducted to optimize the combination of photovoltaic power generation and agricultural planting. And the unified standards must be established to standardize the design and scale of projects of photovoltaic agriculture. Also, photovoltaic enterprises need to produce widely applicable photovoltaic products for agricultural production and farmers’ life.

Photovoltaic agriculture - New opportunity for photovoltaic applications in China

The study was designed to determine the possible relationship between Brassica oleracea var. italica seedlings stored at 2°C in the dark for seven and fourteen days, respectively, and the level of certain antioxidant parameters in particular organs. A parallel objective of the experiment was to determine if the reaction of seedlings to low temperature might be persistent in fully developed plants until harvest time. After 14 days of chilling a significant increase in the glutathione content was observed in the seedling leaves in comparison to the non-chilled plants. During vegetation in field conditions this effect was maintained in leaves up to the stage of formation of flower buds. At harvest the highest content of glutathione was demonstrated in broccoli heads, obtained from plants, which were previously chilled in the seedling phase for two weeks. Peroxidase activity in broccoli seedlings increased each year of the three-year study due to the duration of the cooling time, whereas in the case of catalase the changes were not so distinct. At harvest time the activity of both enzymes in the leaves and flower buds fluctuated according to the particular year of study.

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The effect of seedling chilling on glutathione content, catalase and peroxidase activity in Brassica oleracea L. var. italica

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The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits

The ‘Spartacus’ F1 sweet pepper was grown in a plastic tunnel on rockwool during 2006-2008. A fertigation technique was used for water and fertiliser application. The tunnel was divided into two parts covered with different plastic films. The first part of the tunnel was covered with a film that transmitted less light than the film covering the second part. In both parts of the tunnel, the plants were divided into two groups. One group of plants was fertilised with just nitrate nitrogen (100% N-NO3) and the other one with three forms of nitrogen (N-NO3:N-NH4:N-NH2 in a ratio of 50:13:37). Fruits were harvested mature green and red. Concentrations of nitrate and ammonium ions as well as total nitrogen and free amino acids were analysed in the plant material. Nitrate and nitrite reductase activities were also investigated, and dry matter content and soluble sugars were also determined. Higher light intensity increased nitrate concentration in red pepper fruits but decreased ammonium ion content. These tendencies were not as obvious in green fruits. In most cases, red fruits fertilised with three nitrogen forms accumulated more nitrates than those fertilised with N-NO3. This observation was similar in the case of green fruits. In most cases, pepper fruits accumulated more ammonium ions in the case of N-NO3 fertilisation than when three forms of nitrogen were applied, but the differences were not always statistically significant. Higher nitrate reductase activity was observed in the case of better light conditions as well as mixed nitrogen fertilisation in red pepper fruits. No differences were observed in the case of nitrite reductase activity between fruits harvested from various treatments in red and also green fruits, with some exceptions. The green fruits of pepper had higher nitrate reductase activity than the red ones. It can be summarised that various light conditions influenced the nitrogen metabolism of pepper fruits as well as the different nitrogen forms applied with fertilisers.

The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits / Wpływ Zróżnicowanych Warunków Świetlnych I Formy Azotu Nawozowego Na Metabolizm Azotu W Owocach Papryki

The aims of this study were both the qualitative and quantitative analysis of chromium accumulation in the shoots of Callitriche cophocarpa. This globally distributed, submersed macrophyte exhibits outstanding Cr phytoremediation capacity in an aquatic environment. Cr was applied separately for 7 days at two stable forms as Cr(VI) and Cr(III), known from their diverse physicochemical properties and toxicities. The maps of Cr depositions in young leaves, mature leaves, and stems were obtained by micro X-ray fluorescence spectroscopy (μXRF). The detailed analysis of XRF maps was done based on Image-Pro PLUS (Media Cybernetics) software. Cr was accumulated either in trichomes or vascular bundles in respect to the element speciation and the plant organ. The concentration of Cr significantly increased in the following order: Cr(VI) mature leaves < Cr(VI) young leaves = Cr(VI) stems < Cr(III) young leaves ≤ Cr(III) mature leaves ≤ Cr(III) stems. The observed differences in distribution and accumulation of Cr were correlated with the different reduction potential of Cr(VI) by particular plant organs. The reduction of Cr(VI) is considered the main detoxification mechanism of the highly toxic Cr(VI) form. The unique L-band electron resonance spectrometer (L-band EPR) was applied to follow the reduction of Cr(VI) to Cr(III) in the studied material.

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Accumulation patterns of Cr in Callitriche organs—qualitative and quantitative analysis

BACKGROUND Plant transformation with rol oncogenes derived from wild strains of Rhizobium rhizogenes is a popular biotechnology tool. Transformation effects depend on the type of rol gene, expression level, and the number of gene copies incorporated into the plant's genomic DNA. Although rol oncogenes are known as inducers of plant secondary metabolism, little is known about the physiological response of plants subjected to transformation. RESULTS In this study, the physiological consequences of rolB oncogene incorporation into the DNA of Dionaea muscipula J. Ellis was evaluated at the level of primary and secondary metabolism. Examination of the teratoma (transformed shoots) cultures of two different clones (K and L) showed two different strategies for dealing with the presence of the rolB gene. Clone K showed an increased ratio of free fatty acids to lipids, superoxide dismutase activity, synthesis of the oxidised form of glutathione, and total pool of glutathione and carotenoids, in comparison to non-transformed plants (control). Clone L was characterised by increased accumulation of malondialdehyde, proline, activity of superoxide dismutase and catalase, total pool of glutathione, ratio of reduced form of glutathione to oxidised form, and accumulation of selected phenolic acids. Moreover, clone L had an enhanced ratio of total triglycerides to lipids and accumulated saccharose, fructose, glucose, and tyrosine. CONCLUSIONS This study showed that plant transformation with the rolB oncogene derived from R. rhizogenes induces a pleiotropic effect in plant tissue after transformation. Examination of D. muscipula plant in the context of transformation with wild strains of R. rhizogenes can be a new source of knowledge about primary and secondary metabolites in transgenic organisms.

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Anna Kołton

Papers

The effect of seedling chilling on glutathione content, catalase and peroxidase activity in Brassica oleracea L. var. italica

The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits

The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits / Wpływ Zróżnicowanych Warunków Świetlnych I Formy Azotu Nawozowego Na Metabolizm Azotu W Owocach Papryki

Accumulation patterns of Cr in Callitriche organs—qualitative and quantitative analysis

Response of physiological parameters in Dionaea muscipula J. Ellis teratomas transformed with rolB oncogene.