Size, density, and stomata opening value in leaves of Actinidia deliciosa shoots cultured in three benzyladenine (BA) concentrations (4.4, 44, and 440 µM) during different incubation periods at the end of the multiplication, rooting, and acclimatisation phases were measured. A follow-up of the morphology of both adaxial and abaxial surfaces of the leaves was also performed. The presence or absence of 4.4 µm BA in the culture medium did not affect stomatal size during the multiplication phase, though the increase of the BA incubation period from 30 min to 4h did induce an increment in the stomata transversal axis size. The application of BA (4.4 µM), regardless of the incubation period, increased stomatal density at the end of the multiplication phase. When the concentration of BA was increased in the culture medium during the multiplication phase, a decrease in the stomatal opening took place at the end of the acclimatisation phase.

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Somatic embryogenesis is a powerful technique for forestry improvement programs when implementing multi-varietal forestry. However, it still faces some bottlenecks to be e cient in many forestry species. In this work we have studied the effect of some physico-chemical modi cations at proliferation, maturation and germination stages of Pinus radiata D. Don somatic embryogenesis, as well as the impact of this modi cations on plant conversion, survival, and on the morphology and biochemical pro le (carbohydrate and amino acid analysis) of the resulting plantlets. Given the long culture period needed for maturation and germination in radiata pine, an increase of the plant yield could be very bene cial for its commercial application.A preculture of 14 days without plant growth regulators before maturation seems to be bene cial for the development and germination of somatic embryos. Before germination, a cold storage at 4ºC had no detrimental effect and even increased plant conversion in some embryogenic cell lines. During germination, supplementation of the culture medium with glutamine and a reduction of the sucrose content can improve the greenhouse acclimatization of the plants. Similarly, germinants were demonstrated to be in uenced by the light source: uorescent light enhanced root formation, whereas blue LED light increased the shoot height of somatic plants. Moreover, the highest plants showed lower contents of arginine, asparagine and total carbohydrates. Key MessageModi cation of the physico-chemical environment before or during somatic embryo maturation and germination improves the success of the process.