Electrical impedance analysis was conducted from February to May in 2005 using current year shoots of four fruit species (grape, apple, kiwifruit and Satsuma mandarin) . When series resistance (Rs) and reactance (X) was plotted on the complex plane, three parameters (Rs measured at extremely low frequency (Z0) and high frequency (Z∞) and an angle of arch (2φ) ) were calculated. Z0 was decreased from the beginning of determination to April in grape and mandarin, and from March to April in kiwifruit, while in apple it was unchanged at the beginning of determination, and then was decreased after bud break. In grape and kiwifruit Z0 turned to be the minimum during bleed of xylem exudates, after that it slightly increased.Z∞ was decreased in apple and mandarin, while it fluctuating within small range in grape and kiwifruit. The value of 2φ was increased in all four species. Correlation coefficient between shoot water content and Z0 was significant in all four species, and of its absolute value was the highest in grape, followed by kiwifruit and mandarin, and the lowest in apple. These data showed that Z0 might be a suitable indicator for the status of sap flow.
Cut rose (Rosa hybrida L.) ‘Sonia’ flowers were placed in vases of which water temperatures were kept at 10, 15 and 23°C under constant air temperature of 23°C. Vase life of cut roses became longer with lowering water temperature; the vase life was 5.2, 6.7 and 7.5 days at 23, 15 and 10°C, respectively. Fresh weight of cut flowers increased over the first 3, 4 and 5 days during the experimental period at 23, 15 and 10°C, respectively and decreased thereafter. Temperature of flower part was very slightly lowered by lowering water temperature. Hydraulic conductance of stem segments decreased on the third day after harvest, and this decrease was suppressed by lowering the temperature of vase water. Bacterial number in vase water increased with time, and this increase was suppressed by lowering the temperature of vase water. These results show that low temperature of vase water might improve the stem water relation and extended the vase life of cut rose flowers.
Earl's Knight Natsukei No. 2 melons (Cucumis melo L.) were grown in a plastic film greenhouse after seeds were sown on June 25 (early sowing) or on July 15 (late sowing), 2002. Melons grown early tended to be higher in weight than those grown late. The average temperature throughout the growth period after the early sowing date was much higher than that after the late sowing date. In both rectangular parallelepipeds (7-mm long samples serially collected beginning at one end of the 10-mm wide strip removed from the 10-mm thick disk at the maximum transverse diameter of the fruit to the opposite end) and fruit, the cell size of melons grown early was greater at every stage of fruit development than that of melons grown late. Sucrose content on 30 and 50 DAA (days after anthesis) was greater after the early sowing than the late sowing. These results show that an increasing number of larger cells during early fruit development after early sowing brings active sucrose accumulation, resulting in high sucrose content in the fruit due to high temperature.
The ultraviolet-B radiation (UV-B: 280 to 320 nm) promotes the accumulation of the anthocyanins in rose plants. Open flowers of Rosa hybrida cultivars ‘Charleston’ and‘Ehigasa’ undergo a striking color change from yellow to red over 10-12 days under natural daylight due to the accumulation of the anthocyanins in the petals. The anthocyanin present in the rose petals was identified as cyanidin 3-glucoside (chrysanthemin) and cyanidin 3, 5-diglucoside (cyanin) by using paper chromatography, partial acid hydrolysis, and HPLC. To determine the role of UV-B in the anthocyanin biosynthesis pathway, rose plants were grown under different light conditions supplemented with or without UV-B. Anthocyanin accumulation was suppressed in the treatment without UV-B and the accumulation started following to exposure to UV-B by a gradual increase of cyanin, followed by a dramatically increase of chrysanthemin. Furthermore, it revealed that the unfolding flower stage 3 to 4 (about 50% anthesis) was critical for anthocyanin biosynthesis in rose.
The postharvest changes in taste-related compositions (sugar, organic acid and glutamicacid) and antioxidants (ascorbic acid, lycopene and β-carotene) in tomato fruit grown under salinity stress were examined. Salinity stress was applied by adding nutrients (N, P, K, Ca and Mg) of the same ratios as those in the control solution (EC =1.6 dS m-1), until the EC reached by 4.0 dS m-1. Fruits were harvested at a breaker stage (when blossom-end turned red), and then they were stored under the conditions of 20°C, 50-60% of relative humidity in a darkroom. The sugar, organic acid, glutamic acid and ascorbic acid contents on a fresh weight basis of salinity-stressed fruit were higher than those of control fruit throughout the storage. In addition, the results of dry weight basis suggested that the changes in chemical composition during storage in salinity-stressed fruit cannot be induced only by the concentration effect with fruit water loss, but also by the net accumulations. Furthermore, proline content as an indicator of salinity damage was increased in salinity-stressed fruit during storage. These results suggest that postharvest changes in rhemiral composition are influenced by the salinity-effects before harvest.
In this study, an optimal watering scheduling that improves the quality of Satsuma mandarin grown in the field was investigated using an intelligent control technique combined with neural networks and genetic algorithms. The monthly data on fruit responses and climate factors were collected from August to November over 1996-2004. Dynamic changes in the sugar and citric acid contents of Satsuma mandarin, as affected by rainfall and sunshine duration, was first identified using neural networks, and then an optimal watering scheduling (rainfall management) that maximizes the sugar content and that minimizes the citric acid of Satsuma mandarin was determined through simulation of the identified neural-network model using genetic algorithms. The optimal value obtained was a combination of the marked increase in watering during the fruit-developmental stage (August and September) and a significant decrease in watering during the fruit-maturing stage (October and November) . From model simulation, a marked increase in watering during the former stage induced a lower citric acid content, and a significant decrease in watering during the latter stage induced an increase in sugar content. Drip irrigation is commonly used for increasing watering whereas plastic-film mulching is used for reducing it.
Bruising in fruits and its detection is a great concern for food safety to the consumers, and for incurrence of economic losses to industry. This research was aimed at developing techniques for detection of compression bruises in ‘Akihime’ variety strawberries (Fragaria × ananassa Duch.) using near infrared (NIR) hyperspectral imaging. Using 120 fruit samples at 70-80% ripe and full-ripe levels of maturity that had received six levels of bruising force (0 N, 0.5 N, 1.0 N, 1.5 N, 2.0 N and 3.0 N), spectral images were taken from 650 to 1, 000 nm at 5 nm wavelength intervals and from 0 to 4 days after bruising. Using stepwise linear discriminant analysis, optimal wavelengths of 825 nm and 980 nm were identified. The three judgment methods (linear discriminant analysis, normalized difference and artificial neural network) had performed equally well, while the normalized difference method was found to be more useful. Additionally, the extent of bruising damage detected in strawberries by the judgment method had markedly decreased with time, which elucidated temporal changes in bruising pattern while in storage.
An electrolyzed solution is the one generated by electrolyzing a solution containing dissolved electrolytes. Pungency is the most important component contributing to the quality of radish (Raphanus sativus L.) sprouts. The pungency of radish sprouts depends on the 4-methylthio-3-butenyl isothiocyanate (MTB-ITC) . This study was conducted to determine the effects of electrolyzed alkaline solutions on the pungency of radish sprouts with different electrolytes and strengths. The pungency was evaluated by the analysis of MTB-ITC content and the score of sensory evaluation. The MTB-ITC content of plants was observed to be lower in solutions of strength 1/1 and 1/2 than in that of strength 1/5 among KCl electrolyzed alkaline solutions. That of plants was observed to be the lowest in KCl electrolyzed alkaline solution, followed by commercial sea salt one, and the highest in NaCl one among solutions electrolyzed with different electrolytes. The scores of the sensory evaluations were similar to the results of the MTB-ITC contents.