Quality Improvement of Ornamental Flowers

Editor: Kunio Yamada, Masayoshi Nakayama, and Kazuo Ichimura
April 2024

We tried to quantify the relationship between environmental conditions, and yield and quality of cut roses. Three varieties of cut roses with different characteristics were cultured and harvested for three years. Significant negative linear regressions between the interval of flowering flush (growth period) and the mean temperature per growth period were observed. The quality of cut flowers, i.e., stem length, cut flower weight per stem, and specific cut flower weight (the cut flower weight per stem length) was generally negatively correlated with temperature and positively correlated with light intensity. Light intensity also positively affected the total cut flower weight per plant during each growing period. The daily gain in the flower weight of cut flowers per plant (the total cut flower weight divided by the number of days of the growth period) is an indicator of the productivity of the plant; it showed significant positive correlations with the mean daily light integral in three varieties. We believe that such basic analysis is the starting point for the construction of “data-based techniques for crop cultivation”, which has become a hot topic in recent years. (Provided by K. Inamoto: NARO)

Special Issue: Quality Improvement of Ornamental Flowers

Postharvest biology and technology of tropical- and subtropical crops

Editor: Hirokazu Higuchi, Akira Tateishi, and Varit Srilaong
April 2023

Young coconut fruit has become famous recently for its nutritious and refreshing water. To reduce weight for transportation, the husk is often trimmed away and the shell polished, leaving only a cone-shaped husk over the fruit’s stem end. This final product is easy to consume but prone to shell cracking during processing and transport. It is revealed in this research that cracking is due to the strength of the shell, when it is still weak at harvest approximately seven months after anthesis, and where it is thinnest at around midway between the fruit equator and the stylar end, on the largest carpel. In addition, positive internal pressure is another factor responsible for cracking. On the other hand, carbon dioxide accumulating in the water as the coconut grows older was shown to play a limited role in the cracking. It is recommended to delay the harvesting, trimming, and polishing processes to reduce the problem. (Provided by J. Siriphanich: Kasetsart University)

Special Issue: Postharvest biology and technology of tropical- and subtropical crops

Reproductive biology of fruit and nut tree crops

Editor: Chitose Honsho and Tomoya Esumi
April 2022

Seed size and number in blueberry (Vaccinium spp.) fruit is one of the important fruit quality components that influence consumers’ eating preference. Fruit containing no or only aborted seeds (for example, ‘Pearl River’, a pentaploid hybrid) and those containing a large number of mature seeds (for example, ‘Sharpblue’) (fruit photo taken by Mr. Naoki Hiraiwa, Kyoto University) possess different texture characteristics that affect consumers’ texture preference. On the other hand, there is an interesting phenomenon related to seed property in blueberry called “metaxenia”, which is the effect of pollen sources on maternal tissues. In the special issue ‘Reproductive biology of fruit and nut tree crops’, Nagasaka et al. provide further evidence of metaxenia in terms of fruit size in highbush blueberry (V. corymbosum). In addition, they report that the number of mature seeds contributes to metaxenia expression in 14 controlled artificial cross-pollination combinations. To explore the regulation of seed development and the promotional effects of seeds on fruit growth, fruit cell growth in relation to seed development is compared between self- and cross-pollination. In ‘Blue Muffin’ self-pollination, pollen tube reaches ovule (aniline blue-stained pollen tube growth in pistil; photo taken from the master’s thesis of Mr. Shu Ebihara, Kyoto University) but seeds abort probably due to endosperm breakdown during early seed developmental stage (photos taken from Nagasaka et al.). Furthermore, comparative transcriptome analyses suggest that auxin metabolism and signaling activation underpin fruit growth promoted by developing seeds. This study raises the hypothesis that an appropriate pollen source that can activate auxin signaling may contribute to inducing normal seed development and fruit cell enlargement, and provides new insights into the molecular mechanisms underlying metaxenia expression and the potential implications for understanding parthenocarpy expression in blueberry. (Provided by H. Yamane: Kyoto University)

Special Issue: Reproductive biology of fruit and nut tree crops

Plant factory and modern greenhouse

Editor: Eiji Goto and Yasuomi Ibaraki
April 2021

The picture shows the LED module of an LED artificial sunlight source system* that can produce light at wavelengths of 380–940 nm with a spectral irradiance distribution (SID) of the same level as that of ground level sunlight, with arbitrarily modified SIDs and time-varying (dynamic) light with different SIDs, by application of different voltages to 32 different peak-wavelengths (385–910 nm) LEDs. The LED module has 625 circularly arrayed LEDs within a radius of 66 mm on a printed circuit board. The arrangement of LEDs was determined based on calculations of the number proportion of each type of LED required to produce a SID of the same level as that of ground level sunlight. The LED artificial sunlight source system can facilitate the investigation of plant responses in various static and time-varying (dynamic) light environments.
In the picture, some LED light spots are invisible because the wavelengths of the LED light are beyond the visible wavelength range.

*Fujiwara, K., K. Eijima and A. Yano (2013) Second-generation LED-artificial sunlight source system available for light effects research in biological and agricultural sciences. Proc. 7th LuxPacifica, 140–145, Bangkok, Thailand.
(Provided by Kazuhiro Fujiwara, The University of Tokyo)

Special Issue: Plant factory and modern greenhouse

Strawberry

Editor: Masayoshi Shigyo and Takeshi Kurokura
March 2020

Strawberry, one of the most attractive berry crops, has relationship with us in many ways. Selected articles in this issue represents such multi-aspect of this crop, so as the cover image: from laboratory to table. Flowering regulation is a major interest not only for researchers but also for growers, as flowering directly linked to earliness and yield potential of strawberry. This issue covers the history of the development of flowering regulation techniques in Japan, molecular mechanisms of flowering, current status of Fragaria genome research and male sterility to accelerate breeding. New production techniques are also important and articles related how to produce strawberries in sustainable way in field and in plant factories are selected as well. Consumer is another important factor in the strawberry industry so articles of the strawberry allergen and transportation technique to provide good quality fruit to consumers are also included.
(Illustration by Suana Science)

Special Issue: Strawberry

Horticultural production restoration efforts in the aftermath of the Great East Japan Earthquake

Editor: Yuichi Yoshida
January 2019

In 2015, the Journal of the Japanese Society for Horticultural Science (JJSHS) was renamed The Horticulture Journal (Hort. J.) to disseminate cutting-edge information on horticultural science research. The Japanese Society for Horticultural Science, which publishes Hort. J., has organized this special issue to further enhance the attractiveness of this journal. The theme of the first special issue is horticultural production restoration efforts in the aftermath of the Great East Japan Earthquake. Numerous people have died or remain missing and a great many were injured. Agricultural land has also suffered extensive damage from the earthquake, tsunami, radioactive materials, and so on. Technological development to restore agricultural production has been initiated and practical farms have been established to demonstrate ways to combine old and new technologies to promote agricultural production. Unfortunately, many of these research and demonstration efforts are recorded in Japanese, making it difficult for many people to fully understand what has been done. Considering that such farmland reconstruction efforts should be useful in the face of a similar disaster in the future, I planned this first special issue of Hort. J. I expect that various special issues of Hort. J. will follow in the future.
(Provided by Y. Yoshida: Okayama University)

Special Issue:Horticultural production restoration efforts in the aftermath of the Great East Japan Earthquake