The structure of temperate deciduous forests dominated by Fraxinus spaethiana and Pterocarya rhoifolia in V-shaped valleys in the Chichibu Mountains, central Japan was studied to clarify their dynamics, with special reference to disturbance. Forest structure and annual ring analysis revealed that the forests have been subjected to mass movement (mud flow) in the past. The size and age structure, and diameter growth curves, indicated that F. spaethiana is relatively shade tolerant, long living and slow-growing, while P. rhoifolia is less shade tolerant, short living, but fast growing. Pterocarya rhoifolia appears to depend on large-scale but rare disturbances. Fraxinus spaethiana establishes its seedlings on relatively unstable substrate in V-shaped valleys, but once established, they survive a long time with high shade tolerance, The dominance and coexistence of the two species may primariIy depend on the intensity and frequency of geomorphological processes.

This research was conducted to investigate the changes in moisture retention capacities of expanded rice-hull (ERH)-based root media and their influences on the growth of mother and daughter plants in vegetative propagation of 'Seolhyang' strawberry. The proportion of water at the container capacity of ERH medium was in the range of 20 to 23%. This range was lower than the 60 to 66% of strawberry-specialized medium, the 30 to 34% of soil mother material (SMM) and the 30 to 35% of loamy sand. The moisture content of ERH was reduced to 10 to 12% at 8 hours after irrigation, and there were large variations among replications of ERH medium. Among four kinds of root media formulated to contain ERH, the medium of ERH + coir dust (CD) (55 + 45%, v/v) had 26.5 and 32.5% water contents at 20 and 40 days after irrigation to daughter plants, respectively. The media of ERH + sandy loam (SL) and ERH + SMM showed similar trends in moisture retention. The pH and EC in the all root media tested were in the range of 6.7 to 7.1 and 0.03 to 0.08 dS･m -1 , respectively. The pHs and ECs measured at 20 and 40 days after irrigation were not significantly different in each root medium. Among the root media formulated to contain ERH, the growth of daughter plants was the highest in the treatment of ERH + SL (55 + 45%, v/v). As the blending rate of coir dust was elevated in the ERH + CD media, moisture retention capacity increased gradually, but the growth of daughter plants became worse even though the medium showed higher moisture retention capacity than other root media tested. The growth of roots and aboveground tissues of daughter plants deteriorated in the root media formulated by blending ERH + perlite (PE) at various ratios. The results of this research suggest the optimum formulations of root media and management of moisture content in raising of strawberry daughter plants when ERH is a component of root media.

The aim of this study was to confirm that effects of supplemental LED illumination on a strawberry yield and fruit quality when strawberry grown on a bottom bed to be deficient ambient light due to shading of a upper bed during cultivation by a two-bed bench system. A strawberry was cultivated as a drip irrigation system in the two-bed bench system filled with a strawberry exclusive media from October 2015 to January 2016. The upper and the bottom bed without LED illumination for growth of a strawberry were using as a control. For LED light treatments, from 10 am to 4 pm, we illuminated LEDs as 100 µmol•m -2 •s -1 of light intensity by using blue, red, and mixing LED (blue plus red) on the strawberry plants of the bottom bed. In the yield of strawberry fruit, the strawberry grown on the bottom bed treated with the blue LED significantly increased compared with that of the bottom bed part control, and increased to by near 90% of the strawberry output of the upper bed part control. The soluble sugar content of strawberry fruit grown on the upper bed part control and on the bottom bed illuminated with blue or mixed LED was higher than that of red LED and the control of the bottom bed. The content of anthocyanin was the highest increased in the strawberry grown on the upper bed part control that received a lot of ambient light, however when comparing only the bottom bed, strawberry fruits grown on all LED treatments were higher than that of the control. Therefore, we considered that using of the blue LED light on the bottom bed of two-bed bench system during strawberry cultivation is advantageous for the increase of yield and improvement of fruit quality.

No abstract