Effects of bulb storage temperature on flower-bud formation and dormancy breaking were investigated in three hybrid lily cultivars, ‘Morino-otome’, ‘Morino-sei’, and ‘Morino-roman’, developed by crossing Lilium × formolongi with L. rubellum. When the bulbs of these cultivars were stored at temperatures of 5~21°C for 8 weeks, flower-buds formed in their bulbs. The optimal temperature for flower-bud formation in these cultivars was about 13°C, which was lower than that of L. rubellum. Dormancy was broken in these cultivars by temperatures of 5~13°C for 8 weeks, which was shorter than that of L. rubellum.

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We investigated the effects of NaCl treatment (NaCl concentration; 0.0%-2.4%, treatment frequency; once or five times, and starting time of treatment; 2.5 or 3.5 leaves stage) to suppress succulent growth and acclimation of cabbage plug seedlings on seedling quality. 1) NaCl density to control shoot length to about 80% of control (0%) plot were 1.6% in a single treatment (ST), and 0.4% in five times treatment (FT). 2) Dry matter ratio increased in FT. 3) Na content of the seedlings increased by higher concentration of NaCl treatment. 4) The growth of seedlings after transplanting was not significant among these NaCl treatments. 5) Plug seedlings were exposed to discontinuous watering to evaluate its drought resistance at the transplanting stage. The survival rate of seedlings was greatly improved by NaCl treatment, and the effect was greater after ST than after FT.
These results show that five times 0.4% NaCl treatments are suitable to decrease the shoot length by 20%. Similar effects to improve seedling quality would be obtained by 1.6% NaCl if a single treatment is required.

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For the purpose of low-cost and labor-saving in the uniform production of cabbage plug seedling on a large scale, an ebb and flow (E & F) irrigation system was developed. Uniform cabbage plug seedlings with high adaptability for mechanical transplantation were raised by E & F irrigation once a day for 10 minutes using 1/10 Enshi standard solution, although they showed slower growth than seedlings irrigated in an ordinary way by hand. Seedlings for more than 40 trays can be raised together by this system. Working time required for seedling production was reduced to 50% by utilizing this system compared with that required by an ordinary manual irrigation system.

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Deep seawater was applied to the satsuma mandarin and tomato for horticultural practice and its effect on fruit quality was investigated. In this experiment, deep seawater was used to irrigate the3 soil directly around each plant. As a result, the size of satsuma mandarin fruits decreased and sugar content in fruit juice was increased by the deep seawater treatment. In tomatoes, the fruit size decreased and both of sugar content and acidity were increased. The inner part of the tomato fruit appeared green following deep seawater treatment. We suggested that the fruit qualities of satsuma mandarin and tomato were affected by salinity of deep seawater. However, the cause for the inner fruit-color of the tomato remains unknown.

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Effects of air temperature and humidity in the greenhouse on the growth of semi-forced cucumber ‘Natsunokaori’. Air temperature of 30°C and 60% relative humidity promoted the development of fruit and suppressed the development of lateral branches. In pinching cultivation, air temperature of 25°C and 40% relative humidity promoted the development of lateral branches by suppressing fruit growth. However, the percentage of marketable fruits and total number of fruits where increased by air temperature of 25°C and 40% relative humidity conditions.
In wire-training cultivation, air temperature of 30°C and 60% relative humidity suppressed unneccessary branches, simplyfying the work of training the plants.

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The possibility of producing cut flowers used exclusively for flower arrangement (i.e., bouquet, home flower display and flower basket) was studied in Gypsophila paniculata L.
1. Effects of planting density on the yield by cul flower size (floret number and shoot length for bouquet were ≧1000 and ≧60 cm, those for home flower display were ≧300 and ≧40 cm and those for flower basket were ≧50 and ≧15 cm, respectively) were investigated. The number of cut flowers for home flower display use doubled at 3-fold density compared with that of standard density (i.e., 4.4 plant/m²). The yield of cut flowers for flower basket use increased to 2.3 times the standard when planted at 4-fold standard density.
2. Five cultivars were tested to determine how inflorescence architecture, that is branching habit, internode length and the number of florets per unit dichasium affected the yield at 4-fold standard density. The yield of cut flowers for bouquet or home flower display in ‘Bristol fairly’ was higher than that of any other cultivars and that for flower basket use in ‘New face’ and ‘Bristol fairy’ was higher than that of any other cultivar.

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The effect of ultraviolet cut-off film on the coloration of fruits was investigated to clarify the role of ultraviolet rays on red coloration in ‘Irwin’ mango. One group of the fruits was bagged with transparent ultraviolet cut-off film and another group of fruits was exposed to natural light on the trees grown in a plastic house.
The film cut off 310~400 mm rays and greatly reduced the dose of 220~300 mm and 360~480 nm rays. When fruits were exposed to high light intensity, bagging did not affect the coloration of fruits. High light intensity, more than 10,000 lx, increased the degree of red coloration compared with that under low light intensity in both bagged and control fruits. Definite occurrence of red coloration made the fruit skin more vivid. Bagging decreased the total soluble solids in the juice of ripened fruit.
The results indicate that ultraviolet ray is not necessary for red coloration of ‘Irwin’ mango ftuit, and the coloration of fruit may be improved with high light intensity.

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We studied the effect of the diffence between periodic renewal of whole nutrient solution at intervals of twenty days versus non-renewal while adding water and fertilizer based on electric conductivity (EC) level in NFT on the composition of solution, tomato growth and yield in each cropping type. In non-renewal treatment, slow increase of Ca and Mg, decrease of P over cultivation, and decrease of K during the fruit development stage were observed in both cropping types. Fruit yield was increased with non-renewal treatment compared to that with renewal treatment in semi-forcing culture. While in retarding culture, since the EC value rose to 3.0 dS/m with non-renewal treatment, there were no significant differences in fruit yield between treatments.
Provided that the concentration of each element was within the range found in this experiment, fruit yield was not decrease with non-renewal of the solution. Renewal of the whole solution was not necessary.

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Growth, yield and uptake of nutrients were compared in strawberry (Fragaria × ananassa Duch. cv. Nyoho) grown with peat-based substrate (3 peat-moss: 1 RW granules) under CO₂-enriched conditions (700-900 ppm, 16 November to 8 April), and supplied with three nutrient solutions. As the ratio of the absorbed amount of P and K to that of N increased with CO₂ enrichment, 1 mM of KH₂PO₄ was added to the standard solution (N: 8.85, P: 0.85, K: 3.90, Ca: 2.05, Mg: 0.93 mM) containing micro elements. Absorption of P and K, and concentration of P in leaves increased in the plants supplied the solution containing additional KH₂PO₄, but the concentration of K in leaves was similar to that in those grown with the standard solution. When plants were supplied with a soluble fertilizer containing Ca, Mg and micro elements (N: 8.83, P: 0.94, K: 3.04, Ca: 0.89, Mg: 0.44 mM), absorbed amount of Ca and Mg decreased to ca. 50% of that in those grown with the standard solution. However, no symptom of Ca or Mg deficiency was observed and the concentration in the leaves did not decrease. Plant growth and fruit yield were similar among plants supplied with the three different solutions. It was suggested that a commercial soluble fertilizer, not a balanced solution formulated by nutrient absorption of strawberry, can be applied for strawberry production with peat based-substrate.

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A study was carried out to evaluate the effect of cultivar, extent of cumulative chilling exposure, age of rootstock and sex on growth of the spear in asparagus (Asparagus officinalis L.) forcing culture. The following results were obtained:
As the extent of cumulative chilling exposure increased, crooked spear occurrence decreased. There was no browning due to Fusarium wilt observed in the vessel of crooked spears. These results suggest that crooked spear occurrence in forcing culture was caused by dormancy. Regardless of cultivar, as the extent of cumulative chilling exposure increased, the number of spears and marketable spear weight increased. Even if the cumulative chilling exposure was not extensive, crooked spear occurrence of ‘Baitoru’ and ‘Welcome’ decreased, and the number of spears and marketable spear weight of these cultivars were sufficient, suggesting that the dormancy of these cultivars was less than that of ‘Green tower’ and ‘Super welcome’. Planting of one-year-old male, female and two-year-old male asparagus rootstock of ‘Green tower’ in a hotbed can be done 2 weeks earlier than that of two-year-old female rootstock.

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Effect of root zone temperature on bolting of Japanese bunching onion (Allium fistulosum L.) was investigated using a root zone temperature controlling apparatus. High root zone temperature promoted the growth of three cultivars ‘Kincho’, ‘Asagi-kujo’ and ‘Cho-etsu’ irrespective the air temperature conditions. High root zone temperature 5-20°C under low air temperature inhibited the bolting of three cultivars. In contrast, low root zone temperature 5-15°C under high air temperature promoted the bolting of ‘Kincho’ and ‘Asagi-kujo’. The importance of root zone temperature in flower initiation of Japanese bunching onion was presented.

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[in Japanese]

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