In usual method of petty-tomato cultivating in NFT, the young plants were put directly on NFT bed surface, and settled at the planting panel after 10-14 days.
In this paper, a new planting method was reported and compared with the usual method. In the new method, a young plant was planted several centimeters above the surface of nutrient solution, using a piece of cloth which could absorb much nutrient solution and water the plant easily by capillary action. The effectiveness of the new planting method was evaluated early and quantitatively by plant physiological measurements.
It was cleared by plant physiological measurements with laser beam sensors that microscopic dynamics of stem diameter depended on the state of growth. That is, the young plant stem of favorable growth in new method swelled slightly during daytime on a fine day, and on the other hand, the stem of undesirable growth in usual method showed small shrinking. It was considered that these dynamics were caused by quantity of translocation and transpiration. Furthermore, it was observed that the stem diameter changed very accurately re-sponding to the fluctuations of solar radiation intensity.
Through the measuring the stem diameter physiologically and using spectrum analysis method, differences of the state of growth were explained quantitatively by sensitivity to the fluctuations of solar radiation intensity. Namely, the cross-correlation function between stem diameter and solar radiation intensity showed that stem diameter of favorable growth swelled or shrinked exactly responding to the fluctuations of solar radiation intensity with only a few minutes time lag.

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To be of high quality the flesh of watermelon must be red in color, of crisp texture, and sweet. Especially sweetness of fruit, which is outcome of sugar content, is most important. Considering this, investigation was made as to changes of sugar kind and its content in the fruit of watermelon during its development and after harvest with the results as follows: 1) Major sugars detected in the fruit were fructose, glucose and sucrose. 2) Fructose and glucose were found at a very early stage of fruit development and became maximum from 30 to 40 days after pollination, and then decreased. 3) Sucrose came into existence for the first time 30 days after pollination, and thereafter increased in quantity. In each case sugar content was high near the seeds. 4) Fructose and glucose decreased rapidly after harvest, but sucrose, on the contrary, increased after harvest. The reasons for these phenomena are discussed.

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The light compensation point for CO₂ gas exchange is formulated as a function of 2 physiological factors, dark respiration and initial slope of the photosynthetic response curve to light intensity. The response surface curve of light compensation point given by the above model explains how the 2 physiological factors concern the change in light compensation point with temperature or the inter-specific difference. The increase in light compensation point for young growths of T. dolabyata var. hondae with increasing temperature is insignificant until the optimum temperature of photosynthesis. This is due to that initial slope of the photosynthetic response curve increases in parallel with the raise in dark respiration. In the higher temperature region the remarkable increase in light compensation point is seen mainly due to the increase in dark respiration. Light compensation points of young growths of T. dolabyata var. hondae are in the range of 4 to 6 μmol quanta m^-2 sec^-1 at the optimum temperature. Thus they do not have particularly lower compensation points but rather higher values compared with other woody species growing on the same forest floor. Lower light compensation points of the seed-lings of Q, mongolica var. grosseserrata and A. japonica var. borealis is attributed to the low respiration, and those of C. harringtonia var. nana to the effects of the low respiration and steep initial slope of the photosynthetic response curve.

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Measurements of very small weights resulting from the growth of individual plants and optimal control of their growth are discussed. In order to measure plant growth with a reliable high resolution, a balance beam weighing system, which measures only changes of weight after cancelling the initial weight of test plant, was developed. On the basis of examination of the problems such as linearity, noise characteristics and thermal drift of measurement systems, and as the effects of change of water level of the culture tank and change of plant weight when the roots immerged in the water, the possibilities of weighing plant with a resolution better than 1 mg was confirmed.
Using this system, it became clear that the difference in light conditions brought about a difference in the weight change of plants and that a light condition maximizing the weight increase rate could be discovered.
In the next experiments, optimization of weight growth was performed by selecting only light condition as a controlling factor. It seemed that the possibility of obtaining optimal conditions for growth was confirmed by establishing weight increase rate as the performance index.

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Tomato (Lycopersicon esculentum Mill. ev. Ogatazuiko) plants were grown in low concentration (a quarter of the control levels) or control (full strength Yamasaki's tomato solution until 7 weeks, and then 1.5 fold strength) . The EC of the low nutrient solution was adjusted daily to avoid deficiency of nutrient supply. There was significant reduction in leaf dry weight, stem dry weight, crop growth rate (CGR) and leaf area index (LAI) of plants grown in low nutrient solution after 6 weeks. These differences were present for the next 9 weeks. There were no significant differences in root dry weight, total number of fruits and early fruit yield, but the total fruit yield from plants grown in low nutrient solution was 32% less than that from the control plants. The relative amount of assimilate in the fruit and the net assimilation rate (NAR) of plants grown in low nutrient solution was significantly greater than the control plants from week 6 to week 12, however, it was less than the control plants at week 15. The concentration of nutrient solution had no effect on the P, Ca and Mg content in leaves, but the N and K content in leaves was significantly lower in plants grown in low nutrient solution than in control plants at week 15. The experiment showed that it is possible to control excessive vegetative growth without the loss of fruit yield by the use of a low concentration of nutrient solution (EC 0.7-0.9 dS/m) with the frequent supplementing of N and K after topping.

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