Flowering period, ethylene production of male flowers and shelf life of fruit were comparatively investigated in four melon cultivars ‘King Nine’, ‘King Melty’, ‘O-3’ and ‘Harukei-3’. ‘King Nine’ and ‘O-3’ have long shelf life characteristics regulated by an ethylene low sensitivity gene, but ‘King Melty’ and ‘Harukei-3’ do not share these characteristics. The flowering periods of ‘King Nine’ and ‘O-3’ were twice as long as ‘ King Melty ’ and ‘Harukei-3’. The amount of ethylene emitted from male flowers of ‘King Nine’ and ‘O-3’ was twice as much as that from those of ‘King Melty’ and ‘Harukei-3’. It is clear that the ethylene low sensitivity gene extended the flowering period of male flowers and incleased the amount of ethylene emitted from those in the subsequent melons.
This study investigated morphological inflorescence characteristics associated with fruit size and concentrated ripening of strawberry fruit for labor-saving during harvesting and preparation of strawberries. Fruit weight was highly correlated with node length and diameter, total pedicle length, node/total pedicle length ratio and node/lower node diameter ratio. Large fruit tended to have long pedicles and wide diameter of the node. Fruit weight during concentrated ripening strawberries was highly correlated with the coefficient of variation in node length and diameter per fruit. ‘Pajaro’ demonstrated desirable characteristics suitable for labor-saving during harvesting and preparation with basal branching clusters and long pedicles and wide node diameter.
Since the seeds of rootstock ‘Torero’ for eggplant have a poor germination rate, the effects of priming processing using some promoting chemicals, such as polyethylene glycol solution, were studied. When the seeds were treated with a combination of GA3 100 mg/liter to PEG 300 g/liter for about 15 days, germination was effectively promoted. Furthermore, the practical effect of treatment persisted for at least 30 days when dried seeds were stored at 5 °C or low humidity. Although the seeds harvested in 1998 did not show exceptionally germination improved by chemical treatment only, the additional treatment of the low temperature procedure for 21 or 31 days before the chemical treatment remarkably improved germination.
Effects of salt application on total soluble solids (TSS) and fruit weight were investigated in tomato plants grown in hydroponics. In plants pinched above the third truss, there was a high negative correlation between TSS content and fruit weight. When electrical conductivity (EC) was reduced after anthesis of the third truss, TSS content was maintained around 9 % without severe reduction of fruit weight. In plants pinched above the 8th truss, TSS content was about 9 % in all 8 trusses and the fruit weight of the upper trusses was not reduced by increasing the nitrogen concentration of the solution and maintaining EC 6 dS·m−1 throughout the cultivation.
Effects of the nutrient level at planting time on growth and quality of cut flower in spray chrysanthemums were investigated. An equal amount of fertilizer measuring approximately N 267 mg/shoot was applied to each plot with different basal fertilizer ratios of 0 %, 25 %, 75 % and 100 %, respectively. The residual nutrients divided into 10 equal dosages were applied every week. For reference, fertilizer was also applied according to the conventional recommended method (N 500 mg/shoot). Initial growth of plants in 25 % and 50 % plots was better than that in the other plots. Necrosis due to excessive fertilization was observed in the leaves of plants in the 75 % and 100 % plots. Regardless of the ratio of basal fertilizer to total application, the quality of cut flowers was good and marketable. The quality of cut flowers from the conventional plot was lower than that from other plots due to excessive growth of leaves and stems. It is desirable to maintain the initial nutrient levels at planting time in a range between 50 and 300 ppm nitrate using a soil solution in spray chrysanthemum production.
Seeds of Lathyrus latifolius L. ‘Pink Pearl’ were sown monthly between 10 January and 10 July and raised in a greenhouse maintained at 15-25 °C. Seedlings were planted on 20 August in a bed in a greenhouse and their old shoots were cut back 2 weeks after planting leaving 2 new shoots to grow. The plants were grown under long day conditions of 16 hours day length and temperature above 5 °C. Those sown before March produced about 3 flower stalks starting in mid-November and continuing to year-end. Flowering was advanced and longer flower stems with more florets per inflorescence were obtained from seeds sown earlier However, there were no differences in the number of nodes to first flower.
This study was investigated to clarify the efficiency of bumble bees (Bombus (Bombus) terrestris) as pollinators, and the cultivar selection of blueberries for forcing culture. The flowering and harvesting dates were accelerated by heating cultivation, and the percentages of berry sets were improved by pollination with bumble bees. However, the difference in the berry set percentage was caused by cultivars and forcing time. The percentage of berry set was increased in ‘Tifblue’ but not in ‘Northland’ by GA treatment. However, this treatment caused retardation of the harvesting period and produced lightweight berries. While forcing culture from late February, very early to medium ripening cultivars of northern highbush or half-high blueberries were usable as they could be harvested during May. It was also indicated that bumble bees were very efficient pollinators of blueberries.
Effects of rootstocks on tree growth, yield and fruit qualities in very early ripening satsuma mandarin (C. unshiu Marc.) ‘Yamakawa wase’ were compared between a normal bare ground culture and a sheet-mulching culture from 2000 to 2002. The ground, for the mulching culture, was covered with a moisture permeable sheet from July through October. The order of trunk growth, canopy volume and yield were ‘Shiikuwasha’ > ‘Troyer citrange’ > ‘Rusk citrange’ = ‘Trifoliate orange’ rootstock. Although fruit quality such as Brix was low in ‘Shiikuwasha’, there was no difference among the other rootstocks. Furthermore, there was no difference in titratable acidity among the rootstocks. The ‘Troyer citrange’, vigorous rootstock with minimal fruit quality decrease, was considered to be a suitable rootstock for very early satsuma mandarin ‘Yamakawawase’ under a normal bare ground and mulching culture.
The effects of pollination by honeybees Aphis mellifera on yield and quality of eggplants were examined in forcing cultures at the lowest temperature of 15 °C. Yields of eggplants pollinated by honeybees and by bumblebees Bombus terrestris were equivalent, but the rate of unmarketable fruits pollinated by honeybees was higher than that by bumblebees. When germinative pollen count per one anther was 0.6 mg or more, the rate of unmarketable fruits pollinated by honeybees became equivalent to that by bumblebees. When eggplants were cultivated at the lowest temperature of 18 °C, the germinative pollen count per one anther rose to 0.6 mg or higher.
The influence of rootstock cultivars on the skin and flesh firmness of eggplant fruit was examined. ‘Mizunasu’ was grafted to three kinds of rootstock cultivars, ‘Torero’, ‘Hiranasu’ and ‘AE-RS01’. The samples 19 mm in diameter and 10 mm thickness including skin were prepared for puncture test using the universal testing machine, Instron 5540. A disc shaped plunger 1.5 mm in diameter punctured the samples at a speed of 20 mm per minute. The samples were punctured in both a centripetal direction (through the skin into the flesh) and a centrifugal direction (through the flesh against the skin). In both directions, the skin of the fruit was significantly firmer in ‘Mizunasu’ grafted to ‘Torero’ (M/T) than in ‘Mizunasu’ grafted to ‘Hiranasu’ (M/H) or in ‘Mizunasu’ grafted to ‘AE-RS01’ (M/A). The results of flesh firmness differed according to the puncture directions. The M/T plants showed more vigorous growth than the M/H or M/A plants. It was considered that ‘Mizunasu’ grafted to vigorous rootstock cultivar produced fruit with a firm skin.
We removed 50 % of the leaflets from tomato plants (Lycopersicon esculentum Mill.), which reduced whole plant transpiration and xylem sap, to investigate defoliation effects on the incidence of blossom-end rot (BER). As a result, both ‘NDM0112’ and ‘Summer Kiss’, high and low BER cultivars, respectively, shoed a reduced BER incidence in plants receiving defoliation treatment. Furthermore, the concentration of nutrient solution also effected the incidence of BER: a higher concentration of nutrient solution induced more BER. However, defoliation treatment did not decrease the number of marketable fruit or the fresh weight per fruit. Our results indicated that defoliation treatment of tomato plants could reduce BER incidence without compromising marketable yield.
The relationship between the sugar and vitamin C contents in spinach (Spinacia oleracea L) and komatsuna (Brassica campestris L) and the maximum, minimum and mean air temperatures during the cultivation period was analyzed under conditions of limited solar radiation in winter. The results indicated that the minimum and mean air temperatures 10 days before harvest greatly affect the sugar and vitamin C contents in both crops. The sugar content (less than 1 g·100 g−1FW) and vitamin C content (less than 50 - 70 mg·100 g−1FW) in the two crops were not changed when the minimum air temperature 10 days before harvest was above 5 °C. However, when the minimum air temperature decreased below 5 °C, the two compounds increased linearly with the decreasing temperature. For example, when the minimum air temperature fell from 5 to −5 °C, the sugar content increased linearly from approximately 1 to 5 g·100 g −1FW and the vitamin C content increased from 50 - 70 to 175 mg·100 g−1FW. These date show that the sugar and vitamin C contents of spinach and komatsuna can be increased by controlling the minimum air temperature at 5 °C 10 days before harvesting.
Seedlings and detopped plants of Chinese chive (Allium tuberosum Rottler) were grown in four levels of nutrient solution pH (4.5, 5.5, 6.5 and 7.5 of 1 strength solution) and four concentrations (1/4, 1/2, 1 and 2 units of standard solution of pH 6.0) to study conditions for hydroponic production. The growth of seedlings was less affected by the solution pH, but was reduced at the highest concentration (2 units of standard solution). The re-growth of detopped plants was reduced at pH 4.5 and by the highest concentration. These results show that Chinese chive has the adaptability to wide range of pH and concentration of the nutrient solution in hydroponic cultivation. It is estimated that the optimal pH is 5 to 7, and optimal concentration of nutrient solution is 1/4 to 1 unit of standard solution for hydroponic cultivation of Chinese chive.
Tomato (Lycopersicon esculentum Mill. cv Momotaro) were cultured with a limited supply of nitrate and phosphate in DFT culture system. Experiments were carried out during the spring to summer season and autumn to winter season in a greenhouse. During the spring to summer season almost all of the nitrate and phosphate supplied at a rate of 50 me·plant−1·week−1 and 20 me·plant−1·week−1, respectively was absorbed. Fruit weight was 3.5 kg·plant−1. Occurrences of blossom end rot, malformed and puffy were limited. During the autumn to winter season, nitrate was absorbed at a rate of 35 me·plant−1·week−1 regardless of the nitrate amount supplied, and phosphate was absorbed at a rate of 16 me·plant−1·week−1. Fruit weight was 2.5 kg·plant−1. About 25 % of fruit were puffy. From this experiment, it was shown that tomatoes can be cultured with a limited supply of nitrate and phosphate.
Growth and tuber formation of Chinese water chestnut (Eleocharis tuberosa Roem) cultured in flooded conditions until the end of cultivation were obserbed. The tuber was planted on May 24 th. Daughter hills and stems increased rapidly from July. The number of daughter hills was about 110 in October. Maximum stem height was about 2 m in November. Stolons and tubers increased rapidly after September and October, respectively. Most of the tubers were formed within 15 cm from the ground surface regardless of planting depth. Many large tubers were formed when the tuber was planted at a depth of 7~8 cm from ground surface.
The effects of planting density on the growth of Welsh onion in NFT (Nutrient Film Technique), were investigated to obtain basic knowledge to promote stable production and improve its quality. Welsh onion was grown for 14 weeks on a panel (99 × 31 × 2 cm) with different numbers of planting holes (36, 68, 84 or 116 holes per panel). Three plants were planted per hole. The leaf sheath became significantly thinner at higher planting densities. The thinnest diameter of leaf sheath 5.9 mm was attained, when a panel with 116 holes was used. The shoot and root weight per plant tended to decrease at higher planting densities. However, the yield per one square meter tended to increase at higher planting densities and the yield amounted to 4.3 kg on panel with 116 holes. It was considered from a suitable diameter of leaf sheath and yield that Welsh onion grown as a condiment is suitable for growing hydroponically on a panel with 116 holes (380 holes per square meter; 1134 plants per square meter).
To clarify the mechanism regulating anthocyanin biosynthesis in ‘Kokuo’ grapes grown under high night temperatures, we examined flavonoid accumulation and the activities of related enzymes in the grapes. When grapes were grown at 25 °C day temperature and high night temperatures (25 °C), anthocyanin content in the skin was higher than that of grapes grown under low night temperatures (15 °C). On the contrary, at 30 °C day temperature conditions, anthocyanin content in the skin of grapes grown under high night temperatures (30 °C) was markedly lower than that of grapes grown under low night temperatures (15 °C). Flavonol and proanthocyanin contents in the skin of grapes grown under high temperatures were higher than that of grapes grown under low night temperatures. Although there was little effect of night temperatures on phenylalanine ammonia lyase (PAL) activity in the skin, UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGT) activity in the skin of grapes grown under high night temperatures was lower than that of grapes grown under low night temperature. These results suggest that anthocyanin accumulation in the skin of grapes grown at continuous high night temperatures is decreased due to decreased UFGT activities.
The influence of 2-3 months storage at 5 ± 1 °C and 85 ± 4 % or > 98 % relative humidity conditions with or without prestorage conditioning treatment was investigated in recent cultivars of medium and late ripening citrus. The concentration of soluble solids increased slightly during storage. Acidity decreased rapidly in ‘Imamura’ Satsuma mandarin, ‘Harumi’, ‘Setoka’ and ‘Hareyaka’, while ‘Kiyomi’ and ‘Shiranuhi’ showed small changes in acidity. Prestorage conditioning treatment decelerated the rate of decrease in soluble solids and acid in ‘Shiranuhi’ and ‘Hareyaka’. Prestorage conditioning treatment promoted the occurrence of rind disorder in all cultivars except ‘Harumi’. Severe rind disorder occurred in ‘Kiyomi’ and ‘Hareyaka’. Though the storage relative humidity did not influence the appearance or internal quality of the fruit, higher humidity decreased fresh weight loss contributing to maintaining the freshness of stored fruit. ‘Kiyomi’ fruit were stored at 5 ± 1 °C for three months then transferred to ambient conditions (approximately 25 °C) to investigate responses to shipping after storage. Rind disorder occurred promptly within one week. However, wiping the moisture off the fruit surfaces when transferring could prevent or delay the ocurrence.
Vitamin U (VU) concentration in cabbages harvested in Hokkaido ranged from 7.0 - 66.2 mg kg−1, and the mean was 28.9 mg kg−1 (1996-1998, n=92). Among cropping seasons, the mean VU concentration in cabbages was highest in July (40.6 mg kg−1), then declined gradually until October (13.2 mg kg−1). VU concentration in cabbages increased with increases in applied nitrogen (N) fertilizer, or growth in fields with higher N fertility, and in summer cropping rather than autumn cropping. In the case of cabbbage production using organic matter to reduce usage of chemical fertilizer, the VU concentration in cabbage grown with fish meal (fast-N-release) was higher than that growth with rice bran (slow-N-release). These results indicate that changes in VU concentration in cabbages depend on N nutritional condition.