PHOTOREGULATORY RESPONSES AND THEIR UTILISATION IN INTENSIFICATION OF PRODUCTION PROCESSES OF PLANTS AND FOR ENERGY SAVING IN PLANT-GROWING

G.A. Odumanova-Dunaeva
Green plants are sensitive to light due to photoactive systems of two types: the photosystems of photosynthesis and the systems of photoregulation. A peculiarity of the systems of photoregulation is their sensibility to extreme low doses of light and at the same time their great efficiency of action caused by regulatory influence on some main processes of vital activity of plants, on processes of photosynthesis, growth and development, including. The study of photoregulatory responses opens new ways for control over the production process of cultivated crops by way of a directed change of terms of their reproductive development and yielding ability.

The classical example of photoregulatory responses, connected with the change of the level of the P130 -phytochrome active form in accordance with regular variations in endogenic sensitivity of plants to light during the day, is the stimulation of reproductive development of long-day plants and supression of the development of short-day plants under the action of the night light breaks by the red light and conversion of this effect by the far-red light.

Our studies conducted with long-day crops of Brassica carinata and wheat, and those of short-day crops Perilla ocymoides showed close relationship between photoregulatory responses and main bioenergetic processes of metabolism, primarily, photosynthesis (Odumanova-Dunaeva G.A., Physiol.rast., v.34, N 2, 1987.USSR).

Long-day crops Brassica carinata start flowering at the day duration not less then 18 hours and their budding is the fastest under continuous illumination. In conditions of the 15-hour day and the9-hour night Brassica carinata remains vegetative. However, if the 9-hour night is interrupted in the middle by the 1–2 hours light interval, the crops change over to the reproductive development. The stimulatoring effect of the night light breaks lacks if in the period of the light break there is no carbon dioxide in the atmosphere and, consequently, photosynthetic assimilation of atmospheric carbon dioxide is excluded.

The development of short-day crops of Perilla ocymoides is suppressed by light breaks for 10–60 minutes in the middle of the night irrespective of the presence of atmospheric carbon dioxide during the light breaks. However, when there is no photosynthetic fixation of CO2 during the breaks, conversion of response by the far-red light is disturbed. An increase of the photosynthesis intensity in the period of light breaks at the begin of the night intensifies their inhibitory action on the development of Perilla ocymoides. Thus at an increased irradiation by the luminescent light in the range of the rising branch of the photosynthesis light curve during the 10-min. breaks at the begin of the 9-hour night (at the 3-rd hour) the formation of reproductive growing points slows down progressively: at irradiation of 4–5 Wt/m2 by a week, at 25 Wt/m2 - by 30–35 days.

During light breaks in the middle of the night, affecting most

Odumanova-Dunaeva, G.A. (1988). PHOTOREGULATORY RESPONSES AND THEIR UTILISATION IN INTENSIFICATION OF PRODUCTION PROCESSES OF PLANTS AND FOR ENERGY SAVING IN PLANT-GROWING. Acta Hortic. 229, 349-352
DOI: 10.17660/ActaHortic.1988.229.38
https://doi.org/10.17660/ActaHortic.1988.229.38

Acta Horticulturae