An ecological investigation of the relation between crop load and some cultural conditions was made for the grapes“Kyoho” (Vitis labruscana Bailey × Vitis vinifera L.) and“Campbell Eary” (Vitis labruscana Bailey) .
(1) Correlation coefficients (γ) between crop load and the sugar content in juice from the fruit, the percentage of dry matter in the fruit and the total dry matter production were -0.821, -0.734 and +0.875, respectively.
(2) For“Kyoho, ”a leaf area of approximately 1200 m² was necessary to produce 1000 kg of fruit (17°Brix) in cultivation by the horizontal overhead training system. The data of the total dry matter production and the dry weight of the fruit, indicate that 42% or more of the total leaf area in the orchard contributes to the production of fruit.
(3) “Kyoho”grown in Ohbu city during the second half of August took about 5 days to increase 1° Brix, but this tendency to increase leveled off in September.
(4) “Kyoho”cultivated by the horizontal overhead training system in Ohbu city had a small crop load, and the gross sugar production for the total area of the orchard was low. However, fruits of excellent quality were produced at a relatively early stage.“Kyoho”cultivated by a modified Munson training system in Mizunami city had an excessive crop load, and the leaf area index was extremely small. As the result, the gross sugar production of the total fruit was large. However, the maturing stage was delayed, and some trees died. An orchard of“Campbell Early”cultivated by a modified Kniffin training system in Aomori had a moderate crop load. In spite of this, there was a large leaf area index and the gross production of sugar was high.
(5) The distribution of light intensity in the orchards and the light-photosynthesis curve for the grape leaves showed that the efficiency for light utilization was very high in the orchard with the modified Kniffin training system, but was low in the horizontal overhead training system.

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The changes of DO conc and the mixing pattern of solution in a growing bed of a hydroponics for tomato were examined in the different growing stages.
The growing bed was 4.0 m × 0.8 m and the solution depth was 7.0 cm. The solution was poured from a corner of the bed into the bed through an aerator for mixing dissolved oxygen and was drained off through an overflow shaft which was placed at the opposite corner. The flow rate was about 150 liters per 10 minutes.
1) The change of DO conc during circulation in the growing bed before planting tomatoes was about the same as at that of the flowering stage of the first cluster, and the DO was well-mixed in the bed at the either case.
2) At the flowering stage of the 5th cluster of the plants, which were planted in two straight rows, the solution tended flow along the bed wall and a part of the solution was drained off immediately, because the roots grown between the two rows were much denser than those in the outsides of the rows. In this case, the DO was not mixed uniformaly. Therefore, the tomato plants at the supplying side of the bed grew better than at the draining side.
3) The root density in the bed was more uniform in the plants planted in staggered row than in those planted in straight, and the supplying solution was successively mixed from the suppling side to the draining side. Consequently, much uniform level of the DO conc and of the growth of the tomato plants could be maintained in the staggered-row planting.

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A mathematical model was presented to evaluate the efficiency of low temperature and photoperiod on flower stalk development in Chinese cabbage. Flower stalk development was found in plants treated with low temperature and longer day length and not observed in any plants untreated with low temperature. The pattern of flower stalk development was fitted to the logistic curve on time after the low temperature treatment. This curve of higher order lag can be estimated by using the asymptote and time of delay in its rise. The equation of asymptote was given by the function of treating duration with low temperature and day length after low temperature treatment. In order to evaluate the delay, equation of the logistic curve was approximated to that of the first order lag having the same asymptote and the same differential coefficient at 63.20 (1-1/e, e is napier's number) of asymptote as those of the logistic curve. The sum of the time constant and dead time of the first order lag curve was used to estimate the time of delay in rise of flower stalk development. The time of delay was given by the function of treating temperature, treating duration with low temperature and day length. Thus, the mathematical model of flower stalk development was represented by an equation of the first order lag as a function of treating parameters of low temperature and photoperiod. From this model, it became clear that log₁₀ PΔT^1/2t_d² is useful as a treating parameter for evaluating the combined effect of the temperature and photoperiod on plant response to those factors, where P, ΔT and t_d are the function of day length, a degree of the subtraction of treating temperature from untreating temperature of 20°C and treating duration with low temperature, respectively.

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The image processing system is composed of a thermal camera with a 8-14 μm band pass filter, video memory with A/D, D/A, IC memory (64 K Byte), and a timingcontroller and computer with 32 kW cores and a 2.5 MW disc memory. Data on the input images is processed by a FORTRAN, JIS 7000. After the processing, leaf distribution and the binary pattern of leaf temperature, respectively, are passed to colour display and to the printer. The temperature determination has an accuracy of about 0.1°C through out the total system after adjustments for leaf reflectence, emissibility and resolution.
Distribution of the leaf temperature in both tobacco and sunflower were measured by the image processing system under various plant environments. Binary images gained by the threshold leaf temperature play an important role in image analysis for plant physiology. We concluded that this image processing procedure is one of the most effective methods for investigating leaf information in plant growth.

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An investigation of simulations of one dimensional distributions of CO₂concentrations in soils was made. For the simulation, the coefficients of CO₂ diffusion in a soil D (x) were required. The relation between the diffusion coefficient (D) and air permeability (K) in this experiment, was found the following equations.
D=0.093 cm²/sec at K≥1.2 cm/sec
D=0.0845K^0.432cm²/sec at K≤1.2cm/sec
As it was very difficult to determine the D (x) of a soil, the D (x) was estimated from the equations above after determining the air permeability K (x) . Then, we made the assumption that the amount of CO₂ generated in a soil is expressed by the following equation
Pco₂ (t) =Ae^{-B (logt/Tm) 2}+C_const
C (l) _pv was the CO₂ concentration at the bottom of a soil, and was calculated by the Pco₂ change with time. C (l) _pc also was the CO₂ concentration at the same place, and was calculated by assuming that the amount of PCO₂ when the CO₂ concentration was determined was constant throughout the experiment.
Comparing C (l) _pv with C (l) _pc, we found that C (l) _pv was about 0.9-1.6 times as great.
Therefore, distribution of the CO₂ concentration could not be expressed as C (x) so far as the parameters in the equation of PCO₂ are concerned. When the CO₂ concentration at the bottom of a soil was taken as 1 (=RC (l) ), and all the CO₂ concentrations in a soil were taken as RC(x) =C (x) /C (l), distributions of the CO₂ concentrations in soils were found to be regular regardless of the parameters in the equations of Pco₂. Therefore, to express the distributions of the CO₂ concentrations, we used RC (x) which denotes the relative concentrations of CO₂.
The distributions determined and those simulated by the expression above agreed very wll. Thus, the one dimensional distributions in a soil could be simulated.

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For the humidity control in wide range, an instrumentation was developed for sensing the humidity with the use of electric capacitance. The probe used was Brady rray BR-101B (Thunder Scientific Corp.) in which the electric capacitance was changed by humidity and temperature. The capacitance was converted to voltage, and equation (4) was presented for calculating the humidity as a function of output voltage and temperature. In this system, it was made possible to measure the humidity in temperature range of 0°C to 40°C by obtaining digital and analog outputs of relative humidity, absolute humidity and saturation deficit. Thus, the humidity was measured in wide range, especially in lower temperatures with reliable characteristics, and the humidity control in lower temperatures became possible by means of using this system as a feedback sensor.

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Humidity controls leaf temperature when other environmental factors are constant. Digital control of leaf temperature by manipulating air humidity, calculated from the on-line data of leaf temperature, was investigated. Leaf temperature of the sunflower (Helianthus annuus cv. Large Russian) was kept stable by manipulating a humidity of less than 10% RH. Dynamic characteristics of leaf temperature involved in the control of humidity are shown to be valid characteristics based on simulation of the plant model as reported in our previous papers. A humidity of more than 20% RH caused a distinct difference in the dynamic characteristics of leaf temperature between the experiment and simulation. Modification of the non-linear, stomatal aperture was reasonable.

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