The influence of light spectrum on morphogenesis of orchid germs in vitro

The aim of the study is to reveal growth and developments specificities of orchid (Cymbidium hybridum F1) germinant in vitro cultured early in the ontogenesis in relation to various light spectra. Chromatic and achromatic luminous tubes (Philips, TLD 18 W) were used as lighting sources. 4 light patterns were tested: control group - colorless (white) light WL; group 1 - WL with addition of red WL+RL, group 2 - WL and blue WL+BL, group 3 - WL and green WL+GL. The authors showed that during C. hybridum F1cultivation in type breeding ground, morphometric growth indexes of root and leaf and wet weight of germs raised with the increase of red light part in PAR (photosynthetically active radiation) flux, thought stem length was twice bigger under the mix of colorless and green light, and also blue light addition to achromatic emission aided the reduction of germ parameters, in contrast with control group. Growth characteristics of plants, cultivated under photoculture conditions, can be adjusted by light with varied spectral content

The influence of the LED lighting on structural-functional parameters of lettuce plants

Comparative studies were conducted on morphofunctional parameters of lettuce (Lactuca sativa) plants cultivated with the use of supplementary lighting from different light sources - LED lamps, high-pressure mercury arc lamp (HPM) and high-pressure sodium arc lamp (HPS). The work showed that morphofunctional parameters of lettuce were significantly higher with LED lighting, in comparison to plants cultivated with HPM illumination, and main parameters of leaves grown under LED were barely discernible from the samples grown under HPS lighting. We observed accelerated transfer into reproductive period during HPM lighting, what can lead to quality degradation of the product. Considering the approximate values of leaf character range in experiments with HPS and LED lighting and greater energy efficiency of LED, light emitting diodes are obviously more promising for supplementary illumination in protected ground conditions

Photomorphogenesis of wheat sprouts with LED irradiation of different intensities

Definition of the growth and development characteristics of plants in varied light conditions is a key factor for the creation of highly efficient light facilities for plant cultivation. Experimental research was conducted using an LED irradiation facility with photosynthetic photon flux densities ranging from 0 to 261 lmol m2 s1 and a continuous spectrum with maxima at 445 and 600 nm. Under the maximum photosynthetic photon flux density (261 lmol m2 s1) wheat germs demonstrated diminishing leaf surface with high values of specific leaf area, enhanced pubescence of ground tissues, increases in the number of stomata on the upper epidermis and palisade, and an increase in the thickness of the leaves as well as an increase in carotenoids but a decrease in the chlorophyll aþb/carotenoids relation. It was revealed that the optimum level of photosynthetic photon flux density for the referred spectrum was in the range from 82 to 100 mmol m2 s1, which may enable a reduction of irradiance under specific conditions during early development with no harm to the plants while minimizing energy consumption during cultivation