ИСТИНА

The characteristics of the time course of gravicurvature of 3-day-old wheat coleoptiles and 7-day-old wheat stems were studied in darkness and under red and red-blue illumination after declination from the vertical at various angles. The experiments showed that the shortest gravitropic transients corresponded to 30° initial angle of gravistimulation (IAG). The time course became longer as IAG increased and with plant age. The effects of unilateral red (660 nm) and red-blue light (660 nm; 470 nm) at PPF = 30 µmol∙m-2∙s-1 on the curvature of 3-day-old coleoptiles were evaluated. Red light did not invoke phototropic bending of wheat coleoptiles as contrasted with the curvature effect of red-blue light. The analysis of experimental data showed that distinctions in the curvature transients under the influence of a gravitropic stimulus or of integrated gravity-light stimuli were not statistically-valid. Data about the gravitropic curvature transients were used to devise a method of determining the acceptable crop rotation rate around the horizontal axis. Approximation of the experimental gravitropic stem bending to a linear dynamic system described by the first-order aperiodic element with a lag allowed the dependence of the amplitude of apex oscillations on the rate of horizontal rotation in the Earth’s field of gravity to be estimated. The calculated lowest deadline rotation rate (DRR) minimizing the gravitropic effects on wheat cultivated inside the ground-based prototype of a spherical space greenhouse called “Hemisphere” was about 1 r.p.h. Rotating the plant growth chamber (PGC) at a rate of more than DRR allowed the effect of gravity on plant orientation inside “Hemisphere” to be eliminated.