| CPC A01G 7/045 (2013.01) | 6 Claims |
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1. A plant cultivation method that irradiates a plant with a first irradiation light including a blue light and a second irradiation light including a red light and uses gravitational acceleration as an index of tide-generating force, comprising:
during a predetermined period of time, detecting, respectively as minimal clock times, all clock times at which a change of the gravitational acceleration becomes a minimal value, and detecting, respectively as maximal clock times, all clock times at which the change of the gravitational acceleration becomes a maximal value;
calculating, as a reduction amount, a value obtained by subtracting a value of the gravitational acceleration at each of the minimal clock times from a value of the gravitational acceleration at the maximal clock time immediately preceding each of the minimal clock times, for each of the minimal clock times; and
on a basis of a comparison result obtained by comparing the reduction amount at a specific minimal clock time selected from the minimal clock times with the reduction amounts at an immediately preceding minimal clock time immediately preceding the specific minimal clock time and at an immediately following minimal clock time immediately following the specific minimal clock time, controlling the irradiation timing such that at least a part of a period between the specific minimal clock time and the maximal clock time immediately preceding the specific minimal clock time serves as a first irradiation period, in a case where the reduction amount at the specific minimal clock time is greater than the reduction amount at the immediately preceding minimal clock time and greater than the reduction amount at the immediately following minimal clock time, wherein
the first irradiation period during which the first irradiation light is emitted and a second irradiation period during which the second irradiation light is emitted are alternately provided in time series; and
irradiation timings of the first irradiation light and the second irradiation light are determined by using the tide-generating force as the index.
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