Investigations were carried out to clarify the effects of air and root temperatures on photosynthetic activity and diffusive resistance of leaves in potted‘Muscat of Alexandria’vines.
Throughout the growth stage from setting to veraison root temperature was maintained at 18, 25, and 32°C with ambient temperatures of 20, 25, and 30°C. The rate of photosynthesis was the largest at 20-25°C (air-root temperature), followed by 25-18°C, 20-25°C, and 20-32°C. At 30°C air temperature the photosynthetic rate was low in any root temperature, though higher root temperature resulted in larger rate of photosynthesis. These results were coincident with the results obtained in berry growth. While at both 20 and 25°C of air temperature a diffusive resistance of leaves was the highest at 25°C root temperature, followed by 32, and 18°C.
Using the bearing and non-bearing vines root temperature was maintained at 12, 20, 28, and 36°C with ambient temperature of 25°C. The rate of photosynthesis increased in both bearing and non-bearing vines as root temperature rose, however in the non-bearing vines there were no significant differences among root temperatures. In the bearing vines a diffusive resistance of leaves was significantly low at 20°C, while in the non-bearing ones differences among the plots were not significant.
Root temperature was maintained for one week at 12°C with ambient temperature of 25°C. The rate of photosynthesis was the largest at one day after the start of treatment, after that it decreased as day goes by, and at 7 days it decreased to approximately 25% compared with one day after the treatment. On the other hand, pattern of change in diffusive resistance of leaves was opposite to one of the photosynthetic rate.

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Tree growth and mineral absorption were investigated with 2 year old‘Sanyo Suimitsu’peach trees growing on two kinds of rootstock, Prunus persica and P. tomentosa, in a gravel culture supplied with a constant level of nutrient solution.
1. Shoot growth of the tree on persica was more vigorous than that of the tree on tomentosa during the period from stone hardening to leaf fall. Dry matter accumulation into fruit, stem, trunk and root was also much greater in the tree on persica.
2. The root of tomentosa contained more abundant reserves of N, P, K and Mg than the root of persica in winter, though the dry weights of both roots were nearly the same. The contents of N, P and Mg in the root of tomentosa increased further until blooming, while only the N content increased in the root of persica.
3. Mineral reserves in the root of tomentosa decreased rapidly after blooming and were utilized for the growth of shoot and fruit. Such a distinct decrease was not observed in the root of persica except for N. Mineral absorption by persica rootstock became much more active than tomentosa rootstock after blooming or the beginning of stone hardening.
4. These results show that peach trees on persica absorb a large amount of minerals after blooming until leaf fall if their roots are supplied with abundant nutrients. Mineral absorption of the trees on tomentosa, on the other hand, is less active after blooming, especially during the period from blooming to stone hardening.

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Extension of the period of illumination from photoperiodic to continuous was examined as a way of producing leaf lettuce (Lactuca sativa L. cv. Grand Rapids) economically under artificial light. Plants were grown under photoperiodic (17.5 hr) and continuous illumination at a total daily radiation (moles of photosynthetic photons) of 18.7 mol⋅m^-2⋅day^-1. The continuous illumination increased shoot fresh weight, dry weight of whole plant, stem size and chlorophyll content. Subsequently, plants were grown under continuous illumination at a photosynthetic photon flux (PPF) of 250, 350 and 450 μnol⋅m^-2⋅s^-1. Shoot weight tended to increase when the light intensity was decreased, while root weight had a tendency to decrease under the same conditions. Higher light intensity increased the length of the largest leaf, specific leaf area and dry matter ratio of leaves, and induced the development of tipburn. It was found that continuous illumination under low light intensity promoted the growth of leaf lettuce without causing any abnormality. These results were analysed in relation to the apparent quantum yield in photosynthesis. Since the apparent quantum yield increased with the decrease of the light intensity, growth promotion by continuous illumination under the same total daily radiation is associated with a high quantum yield. The present studies suggest that continuous illumination saves light energy more than photoperiodic illumination under equal total daily radiation, and that continuous illumination with a low light intensity at less than 250 μmol⋅m^-2⋅s^-1 PPF promotes the growth of leaf lettuce without causing abnormalities and contributes to the saving of lamp fixtures.

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The effects of different levels of fertilizer application on peach trees, cv.‘Sanyo Suimitsu, ’on Prunus tomentosa (a dwarf rootstock) were investigated by sand culture method. Trees on P. persica (a vigorous one, generally used) were also tested for comparison purposes.
1. Supplying a high level of fertilizer (N: 160 ppm) from blooming until stone hardening caused vigorous shoot growth and delayed fruit maturation on either rootstock. Fruits harvested were bigger in size but their sugar content was lower than those of control trees supplied with a standard fertilizer solution (N: 40 ppm) throughout the season.
2. Supplying the strengthened fertilizer from one month before blooming inhibited the growth of both shoots and roots, especially in the trees on P. tomentosa. Fruit maturation was also delayed and their quality was unacceptable.
3. Diluting the standard fertilizer to 1/4 normal strength at or after stone hardening accelerated the termination of shoot growth and fruit maturation. Harvested fruits contained a higher level of sugar, though their size was smaller than those of control. These effects were more remarkable in the tree on P. tomentosa than on P. persica.

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1. Greenhouse tomato, cucumber and melon were grown in four temperature treatments (20°C, 24°C, 28°C and control) of nutrient solution in summer. The maximum air temperature in the greenhouse was over 35°C and the root temperature of the control reached 30-35°C in the daytime.
2. The cooling treatments decreased the rotting of root and increased the healthfulness of root.
3. Tomato showed the most notable effect of root cooling treatment. The growth of tomato was promoted and the yield of tomato increased in order of low of cooling temperature.
4. The cooling treatment of 20°C was too low for cucumber to achieve better growth and more yield.The treatment of 28°C was the best temperature for cucumber.
5. The effect of cooling treatment for melon was not recognized definitely on both the growth and the quality.

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Spinach plants (Spinacia oleracea L. cv. Paruku) were grown in deep hydroponic culture while concentrations of oxygen dissolved in the culture medium were varied by either elevating the temperature of the medium or increasing the partial pressure of oxygen. An increase of the solution temperature caused a decrease of oxygen concentration in the medium solution, and reduced respiration rates in roots. Subsequently, photosynthesis was decreased, resulting in reduction of growth. Such growth inhibition was avoided by increasing oxygen concentration in the solution, using an oxygen enricher.

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