The effect of combinational environment control, incorporating supplemental lighting and elevated CO2 concentration (maintained at 1,000 μmol mol−1) and air temperature (TA; maintained between 15 and 27°C in the day), on growth and fruit yield of June-bearing strawberry ‘Benihoppe’ was examined under forcing culture. Supplemental lighting significantly enhanced leaf photosynthesis, and this response was further increased by elevated CO2 and TA treatment. Flower opening on the first and second inflorescences was accelerated by supplemental lighting, and was further accelerated by elevated CO2 and TA, and resulted in a significant increase in fruit yield. Flower number per inflorescence was significantly increased under supplemental lighting and/or elevated CO2 and TA. Increase in flower number and shortening of the fruit maturation period caused by increasing the average air temperature under elevated CO2 and TA resulted in a significant increase in harvested fruit number and yield. By integration of combinational environment control and 1.5-fold increase in planting density (from 8 to 12 plants m−2) with a movable bed system, the fruit yield per unit land area achieved was 10.7 kg m−2 (10.7 t / 10 a), which represented a more than two-fold increase in yield compared with that attained in a conventional stationary bed system.
Fresh-cut melon, ‘Rupia red’ cultivar, was packaged in snap-fit closed packages made from polylactic acid (PLA) and polyethylene terephthalate (PET) and stored at 4 and 10°C for 10 d. Changes in quality of fresh-cut melon, including weight loss, juice leakage, surface color, firmness, soluble solids content (SSC), pH, titratable acidity (TA), vitamin C and sensory quality, were evaluated throughout the storage period. Overall quality of fresh-cut melon declined regardless of the packaging material. Melon cubes in both packages showed increases in weight loss, juice leakage and TA and they showed decreases in surface color (L*, a*, b*), firmness, SSC, pH, vitamin C and sensory evaluation. No significant difference in color, firmness, pH, TA or sensory evaluation was observed either of the packages at 4°C, but significant differences in color (L*, a*, b*, ΔE) between the melon cubes in the two packages were found after 7 d of storage at 10°C. Due to higher water vapor and oxygen permeability, the PLA containers used in this study maintained overall quality of fresh-cut melon better than did the PET containers at 10°C during 10 d of storage. Bio-based PLA is a suitable alternative to petroleum-based PET for storage of fresh-cut melon.
A previous study showed that high air temperature causes poor fruit coloration in strawberries ‘Sachinoka’ (Fragaria ×ananassa Duch). So, to investigate the precise effect of high air temperature on pigment loss, we compared strawberry plants grown in growth chambers under a high air temperature (30/15°C, 14/10 h, day/night) regime and a control (20/15°C, 14/10 h, day/night). The harvested fruits were divided into three sections, skin, flesh, and pith, prior to analysis. First, we measured the anthocyanin concentration in the different fruit sections grown under both temperature regimes. We found that the anthocyanin concentration decreased under the high air temperature regime, especially in the fruit skin and flesh. Then, we analyzed the expression levels of the genes for anthocyanin biosynthesis enzymes and their regulators. In the plants exposed to high air temperature, the expression of flavonoid pathway genes and FaMYB10 in the fruit skin and flesh became lower. In particular, four genes (FaDFR, FaANS, FaUFGT, FaMYB10) showed a significant decrease. Therefore, these results suggest that the poor coloration may be caused by suppressed expression of the pathway genes and FaMYB10.
The purpose of this study was to clarify the effects of light intensity and light/dark period on the concentration of iridoids in the plant Hedyotis diffusa, which finds use in herbal medicine. To investigate the effect of light conditions, plants were grown in a chamber with factorial treatments comprising three light/dark periods (14/10 h, 19/5 h and 24/0 h) and two light intensities (photosynthetic photon flux density of 142 and 40 μmol m−2 s−1). The epigeous dry weight was greatest with the treatments using high light intensity regardless of light period. The concentration of asperuloside (an iridoid) at 24/0 h was noticeably greater than that at 14/10 h or 19/5 h irrespective of light intensity. It was expected that the critical light period for the production of asperuloside would occur between 19 h and 24 h. The content of asperuloside was greatest at 24/0 h under high light intensity. Therefore, high light intensity and a 24/0-h light/dark period can produce high-quality H. diffusa.