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In the area of the biotechnology is fundamental the correct measurement of photosynthetically active radiation (PAR) when is necessary assessing the effect exerted by the light on the productivity of plants and other photosynthetic microorganisms. The commercial PAR sensors available to make these determinations have maximum response peaks in the range between 400 and 700 nm. As a result of this spectral response is common to find multiple nonlinearities that lead to errors and thus to have inaccurate and sometimes unsuitable detectors for several analyzes. Considering this, it is advisable convert the units obtained with different spectrometers into similar units that allow accurate and weighted information. Additionally, the measure obtained from the specific power in the range of measurement calculation PAR, provide additional information to researchers about the ratio of the energy of the photosynthetic efficiency. This article presents the development of a tool that uses a spectrometer with wavelength between 200 to 1100 nm to estimate the extent and irradiance in the PAR range from 400 to 700 nm. The purpose of this work is to improve the quality of information that can be obtained from biological experiments and optimize the data acquisition and processing using software platforms. [ABSTRACT FROM PUBLISHER]

In vitro multiplication of Stevia rebaudiana Bertoni has been described previously in different reference sources. However, the implication of the investigations carried out in the productive scale processes is not informed. The present work was carried out with the objective of establishing a strategy for the in vitro propagation of S. rebaudiana. Studies were carried out on planting, seedling multiplication as well as rooting. The effect of growth regulators at different concentrations was determined in order to increase the production of large-scale seedlings. The in vitro establishment of meristematic apices was achieved with 66.67% explants free of microbial contaminants and 83.33% survival with the use of NaOCl (1% v / v) for 5 min and a previous treatment with Previcure. The treatment with 6-BAP 0.5 + AIB 0.2 mg l-1 was selected for in vitro multiplication, and 76.67% of rooting was achieved with 0.5 mg l-1 of IBA. These results allow to propose a strategy that reduces the time of obtaining apices for the rooting to two weeks. Its approach to a scale production scheme makes it useful for its implementation in the rapid micropropagation of elite clones and the production of plant material of stevia planting on a commercial scale. [ABSTRACT FROM AUTHOR]