The experiment was conducted to investigate the effects of environmental factors on the adventitious root formation of cuttings.
The adventitious root formation of cuttings was affected by environmental factors such as environmental control facilities and rooting media.
Pad and fan system for a greenhouse was more effective for the adventitious root formation of cuttings than air washer cooling system.
It was also ascertained that the rooting medium have influenced on the adventitious root formation of cuttings. It may be necessary to consider the rooting medium as one of the environmental factors.
Intermittent-mist water sprays controlled by electricleaf was very effective in the root formation of cuttings.
The effects of root-promoting substances, e.g. IAA and IBA, on the adventitious root formation were varied due to the environmental control.

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The rate of local lesion growth on leaves of N. tabacum L. Xanthi-nc resulting from tobacco mosaic virus (TMV) infection was varied with condition of light provided to the plants after inoculation. The local lesions on leaf of the plant expanded more under continuous dark than under light, and this enlargement in lesion size corresponded with the increase of virus. These results have led to the assumption that the defense reaction of the plant to TMV infection is closely related to the condition of light provided to the plant after inoculation.

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Absolute humidity control is the most logical approach in the operation of plant test chambers. By making use of the fact that modern installations are near-closed systems and that plants give off copious quantities of water vapor, a simple and effective method of absolute humidity control can be devised. In this the temperature of the air, as it leaves the cooling/condensing heat exchanger in the air flow path, is measured and controlled. The air is then reheated as necessary. A proposal is made for the recapture of some of the energy that is cancelled in the system. Actual data show the adequacy of the method, which gives control of air temperature and dewpoint within 0.1°C with a response time in the order of minutes.

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The mode of diffusion of heat in soil in pot (1/5000 a) during steam treatment by autoclave at 115°C was investigated. In addition, the soil temperature at the center of pot during steam treatment for various periods of time was measured and the effect of these various treatments on soil microorganisms was investigated.
1) Heat diffused innerward in soil drowing nearly cocentric circle, then the soil temperature at the center of pot reached 100°C after continuous steam treatment for 100 min.
2) Soil temperature kept on rising continuously in some degree after stopping steam treatment at the time soil temperature was still below 100°C.
3) Fungi, virus and bacteria in soil at the center of pot were killed by steam treatment for 30 minutes, 60 min and 132 min respectively.

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By analog-simulation, dynamic-characteristic of temperature control system in Phytotron is obtained in many points of several parameters.
Design of temperature control system by means of dynamic-characteristic from these simulations is discussed.
As a result, it is concluded that two way system of temperature control element is nescessary for good dynamic-characteristic; one for good dynamic-characteristic; one for static bias, another for dynamic disturbance.

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Dynamic-characteristic of temperature-humidity control system in Phytotron is obtained by analogsimulation.
Temperature and humidity are not separative in this control system. So, interference of these variables causes complex phenomena. Characteristic of this two variable control system is made clear by examination of analog-simulation.

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The biological effects of cycling in temperature control were examined by using as an index, the characteristics of a rice chloroplast mutant (HO-799) sensitive to low temperature. Temperature control mode for the temperature sensitive initial growing period gave a significant effects on the chlorophyll content. In the temperature range 22-25°C for initial growing period, the cyclic variation of 1°C around the set point gave a noticiable decrease in chlorophyll content than the variation of 0.2°C. While, in higher temperature range 27-29°C, the effect was scarcely observed.
The biological significance on the extent of the cyclic variation around the set point was discussed briefly.

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To analyze the interference of light intensity with the effect of temperature on plant growth and other plant responses, the hypocotyl elongation of cucumber seedlings (Cucumis sativus L. “Aofushinari”) was examined under light intensities of 4, 000, 8, 000 and 12, 000 lux for 8-hour photoperiods at air temperatures of 20, 25, 30, 35 and 40°Cin a growth cabinet. Cucumber seedlings were sown in a plastic container filled with burnt chaff. One day after germination, the seedlings were cultured under their respective light intensities and following results were obtained:
1) Hypocotyl elongation was remarkably affected by light intensity at different temperatures; hypocotyl elongation was inhibited by increased light intensities.
2) The effect of light intensity on the hypocotyl elongation was greatest at 30°C and smallest at 20°C.
3) The optimum temperature for hypocotyl elongation was altered by changing the light intensity; at a light intensity of 4, 000 lux, the optimum temperature was 30°Cand at 8, 000 and 12, 000lux, the optimum temperature was 35°C.
From these results, it is clear that the effect of temperature on hypocotyl elongation of cucumber seedlings is remarkably affected by light intensity. This suggests that much more importance should be attached to light intensity conditions for the exact analyses of the effect of temperature on the plant growth and other plant responses.

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(1) An experimental population of Drosophila virilis was established by the progeny of flies collected at Azumabashi in Tokyo. Twelve iso-female strains were extracted from it. Then, 9 sib-mating lines were made from each strain and they were divided into three groups. One group was composed of 36 sib-mating lines which were female and male pair matings. Three groups were cultured under three kinds of light environments as follows; constant light, periodical light and dark (9L, 3L→D, 9D, 3D→L) and dark with short light (15 min) . Flies were transferred into new vials every day, and eggs laid during 24 hours on the culture medium were scored. Such experimental procedures of three groups were continued simultaneously for 10 days under constant 25°C.
(2) The total number of eggs laid under dark with short light environment was the most and that under periodical light and dark environment was the middle and that under constant light was the least. However, the difference between total numbers of eggs laid for the former 5 days and the latter 5 days was noticed. Under either constant light or dark with short light environments, the difference was about 20 eggs a day, but under periodical light and dark environment, the difference was only 6 eggs a day. From the result, the former two light environments are assumed to be bad for maintaining the regular biorhythm of oviposition and the periodical light and dark environment would be good for it.
(3) The oviposition was remarkably influenced by light environments and it would be accelerated with the short light in the long dark. Female flies, which laid a great number of eggs or very few eggs under a light environment, could not be found among 12 iso-female strains. Some female flies of several strains were short-lived under non-periodical light environments. The total numbers of eggs of 12 strains under three kinds of light environments were arranged in order and the order was preserved significantly under any light environments.

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1) Many flies of Drosophila virilis were collected from the warehouse of a brewery company at Omori in Tokyo, and a cage population was set up with them. After three generations, about 400 female and male flies were sampled from the population, and they were separated and male flies were introduced firstly into a maze apparatus, after that, female flies were introduced into it. They had to choose either light or dark pathway and entered into terminal tubes according to their phototactic activities. About 20 pairs, which were the most photo-positive or photo-negative flies, were taken and two populations were set up with them. From the former photo-positive population, the most photo-positive flies were selected every generation and from the latter photo-negative population, the most photo-negative flies were selected every generation. Such selections for two directions were continued during 30 generations.
2) The photoscore and variance of a foundation population were found to be 5.03 and 12.36, respectively. After about 30 generations of selection, the photoscore and variance of the photo-positive population were estimated to be 4.42 and 11.23, and those of the photo-negative population were estimated to be 8.62 and 6.39, respectively. The lower limit of heritabilities of photo-negative behavior was calculated to be 0.46 and that of photo-positive behavior was calculated to be 0.17
3) The phototactic behavior in Drosophila virilis was assumed to be controlled by polygenic factors as reported in other Drosophila species. However, the photoscore of hybrid flies between photo-positive and photo-negative flies at 30th generation was close to that of photo-negative flies from the mean of both parent flies. These results suggest that polygenes controlling negative phototaxis seemed to be partially dominant.

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