The seasonal changes of evolution of CO₂ from the floor were studied using a mixed forest of coniferous and broadleaf species. The rate of CO₂ evolution (Y) in situ changed considerably with soil temperature (T) throughout the year. On the contrary, soil-watercontent (W) was fairy constant and the mean value was 77% to dry soil. The regression equation between Y (g CO₂-C /m²/day) and T (°C) was log Y =0.029T -0.28. Q₁₀ obtained from field data was 2.0 together with that obtained from soils measured in laboratory. The amount of respiration of plant roots to that of forest floor was 13% in March and 24% in Autumn. It was considered that most of CO₂ evolved from forest floor was due to respiration of soil micro-organisms and animals.
The number of bacteria increased almost proportionally to the amount of glucose added into soil. This indicates that the nutritional minerals such as nitrogen and phosphorus were sufficient in the soil used here. Further, the growth rate at exponential phase was high of 0.71/hr (generation time, 1.4 hr) at 25°C. This shows that the concentration of nutritional minerals in the soil was high enough to support the active growth of the bacteria.
The results of the present experiment suggest that the environmental factors, which control the evolution of CO₂ from forest floor, are soil temperature and water soluble organic carbon, but not soil water and nutritional minerals.

View full abstract

The rate of CO₂ evolution Y (g CO₂-C/m²/day) was studied in situ of the several soils such as naked and farm land. The Y of all soils was strongly controlled by soil temperature T (°C) and increased exponentially with it. But the Y of every soils showed considerable differences even when T showed the same value. For example, when T of all soils was almost the same of 22.5±0.5, there was about sixfold difference between Y of 0.49 in naked land formed on Kanto-roam in Fuchu city and Y of 2.83 in forest land adjacent to the naked land. The differences of the Y were not attributable to the difference of soil water content, microbial number or nutritional minerals.
While, there were large differences in water soluble organic compound expressed in terms of carbon C (mg C/kg dry soil) from the smallest of 3 in naked land to the largest of 89 in farm land formed on alluvial land in Hachioji city. The Y increased linearly with the increase of C upto 50 in every soil, in which the regression equation obtained was Y=0.022C+0.51 at 18±2°C. When C was over 50, the Y was within the range between 1.5 and 1.7.
Namely, in spite of the difference of soil type, human impact and vegetation, it was concluded that the Y could be determined by the two environmental factors in soil of T and C.

View full abstract

The maximum plant surface temperature was measured by an infrared thermometer in a Brasilian desert, Caatinga in March of 1978. The highest temperatures of spikes and stem of Pilosocerus gonellei were 49.2±0.43 and 45.1±0.36, respectively. Stomata of Cactaceae, Neglaziovla and Riccia, did not respond to Abscisic acid applied externally. However, all other plants so far measured responded to the treatment with abscisic acid, suggesting that most of plants grown in Caatinga open their stomata and actively perform photosynthesis under the bright sun light. The measurement of difference in surface leaf temperature between water and abscisic acid treated leaf can indicate the stomatal aperture in the field under the high light intensity.

View full abstract

Effects of solution temperature and oxygen supply into the solution on seedling growth in solution culture were studied, aiming to raising suitable seedlings used for solution culture in high planting density of tomatoes with two trusses.
At low air temperature (6°C), the growth of seedlings grown at high solution temperature (min, 17°C), as represented with stem, leaf and root length, was promoted, compaired to that at low solution temperature (min, 8°C) . There was no difference in number of leaves to the first inflorescence and days to anthesis from sowing. Low solution temperature, however, enhanced the occurrence of abnormal flowers and caused almost fruits to be malformed. Then it is desirable that air temperature should be raised at 10°C andsolution temperature at 12°C.
Aeration into the solution during the period of raising seedlings resulted in increasing top fresh weight, root dry weight and root length. The development of inflorescence, number of leaves to the first inflorescence, days to anthesis and number of flowers in the inflorescence, were hardly affected by aeration. The excess oxygen supply to the solution caused over-growth and malformed fruits such as catf aced and chucked fruits, etc. These indicate that for supplying oxygen into cultural solution in raising seedlings by solution culture in autumn to spring, mechanical aeration is not necessary and diffusing oxygen through the surface of the solution without covering the solution is recommendable.
It is expected that thus raised seedlings develop to plants producing high yield of fruits with high quality over 10 tons, when tomato plants with two trusses are cultured in the planting density of approximately 7, 000 plants per 10 a.

View full abstract