This document discusses how light affects plant growth and development, including its intensity and duration, and how plants adapt to varying light conditions.
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[...] In the absence of gb, the stems are very short and no ST movement is observed. If we inject gb, there is elongation of the stems and ST movement. Between 7 and 14 days after the last gb injection, stem growth and heliotropic movement are reduced by 35%. Therefore, we understand that the elongation of the stem is primary in the phenomenon of heliotropism. The change in orientation of the plant is explained by a difference in growth rates (Growth Rate or GR) on the West and East sides of the plant. [...]
[...] 3.2.1 Impact of light intensity on leaf thickness Researchers conducted an experiment on 5 rose plants, placing them all in different light conditions. They set the daily average radiation dose (DAR for Daily Average Radiation) to 800µmol photons/m².s. Also, using shading fabrics, they placed the 5 rose bushes in conditions where they received respectively and of the DAR. The plants were maintained in these conditions for 4 months before being analyzed. For plants and we observe, by electron microscopy, that they possess 2 to 3 layers of hypodermal cells. [...]
[...] Leaves placed in more intense lighting conditions would therefore be thicker. By studying this phenomenon more precisely, and especially by analyzing the dry masses and specific surfaces (m²/kg) of the leaves, researchers found that the dry mass of the plants decreased as the light intensity decreased and the specific surface increased as the light intensity decreased.Figure 3-10). A high light intensity therefore implies small thick leaves, while a low light intensity results in large thin leaves. Figure 3-10 : Graphs of specific surface area and dry mass rate of leaves as a function of light intensity. [...]
[...] Figure 3-8 : Leaf cross-sections of the 5 rose plants viewed under electron microscope, the black bars representing 50µm). Figure 3-9 : Graphs of the leaf surface area and dry mass rate as a function of light intensity. Figure 4-1 : Result of different lighting conditions on the date of first ovulation in mares. Figure 4-2 : Evolution of the progesterone rate over time in mares subjected to natural photoperiod or short or long treatment, the corresponding peaks to ovulations. [...]
[...] and ZAMSKI, E. The Phototropic Pulvinus of Bean Phaseolus vulgaris L.-Functional Features.Plant Biology vol no p. 584-594. - KUTSCHERA, Ulrich et BRIGGS, Winslow R. Phototropic solar tracking in sunflower plants: an integrative perspective.Annals of botany vol no p. 1-8. - LINCOLN, G. A. et GUINNESS, Fiona E. Effect of altered photoperiod on delayed implantation and moulting in roe deer.Reproduction vol no p. 455-457. - MARTINET, L., MONDAIN-MONVAL, M., et MONNERIE, Régine. [...]
