Influences of temperature on effects of growth regulator on hypocotyl elongation of cucumber seedling were analized with the use of bromocholine bromide and gibberellic acid under the controlled temperature in phytotron.
Seeds of cucumber (Cucumis sativus L. “Santo”) were sown in plastic containers filled with burnt chaff. The bottom of the container was kept being soaked in water to moisten the burnt chaff, and sown seeds were incubated at 25°C. One day after germination, each of the solutions of 5 ×10^-3M bromocholine bromide (BCB) and 100 ppm gibberellic acid (GA) which contains 85% of GA₃ was sprayed on cotyledons of the cucumber seedlings. At the same time, the hypocotyl unit was marked; the hypocotyl of each seedling was marked with ink at cotyledonary node and at a distance 1 cm below the cotyledonary node. The treated seedlings were cultured at 20°C, 25°C, 30°C and 35°C respectively. The length of the hypocotyl unit was measured every day.
The elongation of the hypocotyl unit was inhibited by BCB and was promoted by GA under the temperature conditions of 20°C, 25°C, 30°C and 35°C. At the same time, the elongation of the hypocotyl unit was remarkably affected by temperature. The difference between the length of hypocotyl unit of treated seedlings and that of untreated ones was large at higher temperature and was small at lower temperature. While, the ratio of the length of the hypocotyl unit of the treated seedling to that of untreated seedling indicated that the promotive effect of GA on the hypocotyl elongation is small at 35°C, and also indicated that the inhibitory effect of BCB on the hypocotyl elongation is small at 20°C.
These facts suggest that the temperature of envi-ronment should be taken into consideration for the analysis of the effects of the growth regulator.

View full abstract

Leaf temperature was measured under various conditions of air temperature, relative humidity and light with the use of a micro-thermister, which was inserted into the cotyledon of Cucurbita maxima seedling.
Under the condition of 70% relative humidity in darkness, the leaf temperature was lower than the air temperature at air temperatures of 20°C, 30°C, 40°C, but at the air temperature of 10°C, there was no difference between the leaf temperature and the air temperature. The difference between the leaf temperature and the air temperature was larger at higher temperatures.
When the leaf was illuminated by a tungsten lamp with the intensity of 22 mW/cm², the leaf temperature was higher than the air temperature at air temperatures of 10°C, 20°C, 30°C. The difference between the leaf temperature and the air temperature was smaller at higher temperatures. When the air temperature was changed from 30°C to 40°C under the illuminating condition, the leaf temperature once became 40.5°C and fell to 38.5°C and gradually converged to 39°C.
When the relative humidity was changed from 80% to 40% at the air temperature of 40°C under illuminating conditions, the leaf temperature fell from 39°C to 35.5°C and gradually converged to 36.0°C. When the relative humidity was changed from 80% to 40% at the air temperature of 30°C under the same conditions, the leaf temperature fell from 34°C to 32.5°C. Thus, the effect of relative humidity on the leaf temperature was larger at higher temperatures and was scarcely observed at the air temperature of 20°C.
From these results, it could be estimated that the leaf temperature was remarkably affected by air temperature, light, relative humidity, and their combinations.

View full abstract

Rice and soy bean plants were cultivated under the controlled temperature of 30°C, 25°C and 20°C with the use of different root supporters, such as glass wool, agar gel, burnt chaff, quartz sand, sand, water and paddy soil. The interferences of the effects of the root supporters with the temperature effects on plant growth were analized, and following results were obtained.
1) Even under the same environmental condition, each of the root supporters brings remarkable difference in the plant height of rice and soy bean seedlings. The plant height of rice seedlings was highest in sand at 30°C and 20°C, and was also in paddy soil at 25°C. In glass wool, the plant height of rice seedlings was lowest at 30°C, 25°C and 20°C. The plant height of soy bean seedlings was highest in burnt chaff and was lowest in agar gel at 30°C, 25°C and 20°C.
2) There were appreciable differences in the temperature effect on the plant growth among the seedlings of rice and soy bean grown on the different root supporters. The temperature effect on plant height of rice seedlings was largest in glass wool and smallest in sand. The temperature effect on the plant height of soy bean seedlings was. largest in agar gel and smallest in burnt chaff. The temperature effect on dry weight of rice seedlings was largest in agar gel and smallest in burnt chaff. The temperature effect on dry weight of soy bean seedlings was largest in agar gel and smallest in glass wool. From these results, it could be estimated that the different natures of the root supporters resulted in bringing forth the differences in growth of the plant, and it is noticeable that the temperature effects on the plant growth were remarkably affected by root supporters.

View full abstract

The spectral transmission properties of various clear plastic films which were produced for crop protection were examined over the wavelengths from ultraviolet to infrared.
In the plastic films used, the transmission varied drastically in the ultraviolet and infrared regions but not much in the visible one (Figs. 1 and 2.) . Some films were almost opaque in the wavelengths shorter than 350 nm. The transparency in the near ultraviolet region had no direct relation to the film materials such as polyvinyl chloride (PVC), polyethylene (PE) and ethylenevinyl acetate copolymer (EVA) (Fig. 1) .
The infrared transmission, especially in the range of 7-15μ, varied widely with the material of films, i. e. PE films were highly transparent but PVC films were almost opaque, while EVA films were in the middle of PE and PVC films (Figs. 2-6) . There was no substantial difference in the infrared transmission properties among the films of the same material, regardless of the kind of brands (Figs. 2 and 3) .
The transmission in the ultraviolet and visible regions of PVC and PE films was decreased remarkably by the practical use, but it was recovered partially by cleansing them. The infrared transmission was, however, almost no change even if the film was soiled or cleaned (Figs. 5 and 6) .

View full abstract

[in Japanese]

View full abstract

The distinct difference was detected with regard to the appearance of flower color pattern among varieties and strains of Petunia hybrida.
One clone in the variety, Star Dust (blue strain), having a wide variation in the type of flower color pattern was selected, propagated by stem cuttings and used as materials.
During cool season many corollas striped in white in a magenta background put in an appearance and some corollas became white.During hot season many ones starred or colored appeared.
At a constant temperature 25°C in the phytotron, many corollas starred or colored appeared. On the other hand at a constant temperature 18°C many ones striped did.In the poor light condition at an intensity of 73 per cent of the full sunshine, the corollas colored or starred increased, while in the full sunlight the ones colored or starred decreased.From these the main effect of temperature and light intensity on the appearance of flower color pattern was considered to be of high significance.Further the interaction between these two factors was also significantly greater.For example, about 78 per cent of corollas colored appeared in the condition maintained at 25°C and in the poor light.
It may be suggested that the climatic requirement for the variation of flower color pattern appears to be independent of the one for the formation of anthocyanin.

View full abstract