Tomato seedlings were grown in plug trays at three planting densities (700, 1100, or 1600 m^-2) under two air current speed conditions (0.3 or 0.7 m s^-1) either in closed transplant production system or in a greenhouse without air current speed control. The growth and that uniformity of the tomato plug seedlings decreased with an Increase in the planting density in the closed transplant production system. At the higher air current speed, the growth increased without a decrease in the growth uniformity and excessive stem elongation. The growth and that uniformity of seedlings grown in the closed transplant production system were greater than those of seedlings grown in the greenhouse. These results indicate that the closed transplant production system under the higher air current speed condition enabled transplant production using plug trays with higher planting densities than those in the greenhouse. The environments in the closed system and greenhouse were measured and compared. Based on the results, high integrated light intensity and light sources with a high red to far-red ratio in the closed system appeared to be the reasons for the decrease in excessive stem elongation and increase in growth uniformity when compared with those in the greenhouse.

View full abstract

‘Suioh’ is a sweetpotato (Ipomoea batatas (L.) Lam.) cultivar developed for utilizing the tops as a green vegetable The leaves are rich in lutein and polyphenol, which increases the economic value of the cultivar a functional food. An hydroponic method suitable for tops production from ‘Suioh’ exam ined by comparing a deep flow technique (DFT) system with pumice sand culture (was ) (PSC) system in the phytotron glass room of the Biotron Institute of Kyushu University located in Fukuoka city, Japan. The air temperature and humidity of the were controlled at 25°C and 70% RH, respectively. In early summer, the DFT system showed 2 times higher yield than the PSC system, while the lutein concentration in the leaves in DFT-grown plants was 30% lower than that of those grown in the PSC system In winter, the yield in DFT was 1.2 times higher than that in the PSC system, and both lutein and polyphenol concentrations were almost the same between these two hydroponic systems. Thus, the DFT system is considered appropriate for ‘Suioh’ production, although it requires the development of a cultivation technique to increase the lutein concentration in leaves. The effects of cultural conditions on the concentrations of functional food factors were also investigated. Concentration of the nutrient solution scarcely affected the concentrations of lutein and polyphenol in the leaves, whereas increased light intensity appeared to increase both the lutein and polyphenol concentrations.

View full abstract

We analyzed the relationships between the yearly variation in sprouting, flowering and full bloom time of the 8 main cultivars of Japanese persimmon and air temperature in the Faculty of Agriculture, Kochi University between 1985 and 2004.
The monthly air temperature for March, April and May tended to rise at an annual rate of 0.084, 0.108 and 0.142°C, respectively. Along with this transition, the sprouting, flowering and full bloom time in the main 8 cultivars of persimmon tended to accelerate at rate of 0.45, 0.53 and 0.47 days per year, respectively. On average, between 1985 and 2004, the sprouting time of ‘Hiratanenashi’, Fuyu and the average of 8 persimmon cultivars were 21, 31 and 25 March, respectively, the flowering times were 5, 14 and 9 May, and the full bloom times 10, 18 and 14 May, respectively. There were high positive correlations between the times of flowering and full bloom and the time of sprouting in the 8 main persimmon cultivars. There negative correlations between the temperature during February and March and the sprouting time of 8 persimmon cultivars. There were negative correlations between the mean temperatures in February, March and April and the flowering and full bloom times of 8 persimmon cultivars, respectively. Average correlation coefficient values between the mean temperature of April and the flowering and full bloom time of 8 cultivars of persimmon were -0.88^*** and -0.89^***, respectively.
Based on these findings, it was thought that the early sprouting, flowering and full bloom of persimmon cultivars in the recent 20 years has been due to the rising of temperatures between Feb. and May due to global warming.

View full abstract

We combined a hydroponic-culture-use bed of the water-filling type with a fish-breeding tank, provided a combined production system of vegetable culture and fish-breeding for testing, and considered the possibility of the combined production of fruits, vegetables, and freshwater fish. Experiments were performed using a combined system of tomato and tilapia, and that of water eggplant, carp, and crucian. When a fertilizer for nutriculture was added to the water prepared for breeding and cultivation, the yield of fruits and vegetables was comparable with than that obtained when fish were not fed, and the fish grew steadily even in the culture solution for hydroponic culture. These experimental results showed that the cultivation of fruits and vegetables and farming of freshwater fish may be possible together using a simple nutriculture system configured by just adding a fish-breeding tank to the existing system.

View full abstract

To examine the most suitable concentration of nitrogen in recirculating nutrient solution, the growth and total nitrogen uptake of potted miniature rose was compared under nutrient solution with 60, 75 or 90 mg dm^-3 of total nitrogen. The ratio of nitrate- to ammonium-N in recirculating solution was 2:1. Under cultivation using a nutrient solution with 60 mg dm^-3 of total nitrogen, low nitrogen content per dry weight of plants was caused by the nitrogen supply deficiency, and plant growth retarded. Under cultivation using a nutrient solution with 90 mg dm^-3 of total nitrogen, the high concentration of nitrogen in the recirculating solution disrupted the balance of evapotranspiration and nitrogen uptake, increased the nitrate nitrogen in soil solution and inhibited water uptake due to the high osmotic potential. These results may lead to both low efficiency and low amounts of nitrogen uptake per dry weight of plant. However, under cultivation using a nutrient solution with 75 mg dm^-3 of total nitrogen, plant growth normal, and both the efficiency of nitrogen uptake and amount of nitrogen content per plant were high. Furthermore, there was no excess cumulation of nitrogen in the soil solution as there was when nutrient solution with 90 mg dm^-3 of total nitrogen was used. These results indicated that the amount of nitrogen supplied by fertigation should be balanced to the amount of nitrogen uptake by plants. The composition of each ion in recirculating nutrient solution was not markedly changed using a nutrient solution with 75 mg dm^-3 of total nitrogen. Therefore, 75 mg dm^-3 is considered the most suitable concentration of nitrogen for cultivation of potted miniature rose using a recirculating nutrient solution.

View full abstract

Lower concentrations of synthetic jasmonic acid derivatives enhanced shoot formation from rhizome segments of terrestrial Cymbidium species in vitro. Number of shoots developed from rhizome cultures of C. kanran was increased by the addition of jasmonic acid derivatives at concentrations less than 0.1μM. Shoot formation in C. ensifolium was promoted by the addition of jasmonic acid derivatives. Methyl jasmonate (Me-JA), methyl dihydro jasmonate (MDJ) and n-propyl dihydrojasmonate (PDJ) were more effective in increasing the shoot number developing from rhizome culture of C. kanran. PDJ was effective for increasing the shoot number in rhizome cultures of C. ensifolium. In C. kanran cultures, higher rates (> 70%) of shoot formation obtained by treatments of PDJ (0.01-0.1μM) and MDJ (0.001-0.01μM). Higher rates (85%) of shoot formation of C. ensifolium cultures were obtained by treatment with jasmonic acid derivatives. Some shoots developed roots following treatment with jasmonic acid derivatives. Rate of rooting in C. kanran rhizomes was highest (15%) at 0.001 and 0.01μM MDJ. The rooting rate in C. ensifolium rhizomes was highest (20%) at 0.1 and 1μM CSJ.

View full abstract

The effect of short-time far-red (FR) irradiation at the end of light period on stem elongation in Chrysanthemum morifolium Ramat. cv. ‘Jimba’ was investigated. Cuttings were inserted into a 128-cell plug tray filled with propagating medium, and grown in a greenhouse where the minimum temperature was set at 18°C. Night interruptions of 4 hours (from 22:00 to 02:00) were performed using incandescent lights. After 3 weeks, seedlings were transplanted to plastic pots filled with the same medium and grown in the greenhouse for 10 days.
The plants were set into two growth chambers with different FR condition. One chamber was set to irradiate FR of 10 Wm^-2 on the canopy for 15 minutes at the end of the light period using a LED panel. The other chamber had no FR irradiation. Both growth chambers were maintained at 20°C during the day and the night and a photosynthetic photon flux (PPF) of 100 μmol s ^-1m ^-2 was provided at the canopy level during the 9 hours light period (09:00 to 18:00).
An image processing system was employed to monitor stem elongation in five to six C. morifolium Ramat. cv. ‘Jimba’ plants every 15 minutes for five days. Stem elongation after five days with a 15-minute FR irradiation at the end of light period was 17.5 mm. On the other hand, stem elongation without FR irradiation was 6.7 mm during the same period. The difference in growth was statistically significant with a p-value<0.01. We concluded that 15 minutes FR irradiation had a remarkable positive effect on stem elongation in C. morifolium Ramat. cv. ‘Jimba’.

View full abstract