著者

Hisashi Yamada Shun Ito Daisuke Toshinari Keiko Kataoka Tsuyoshi Habu

出版者

一般社団法人 園芸学会

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.OKD-097, (Released:2017-06-21)

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To apply the beneficial results obtained for potted citrus trees to field-grown ones, the effects of seawater application on soil electrical conductivity (EC), water relations, and fruit quality in field-grown satsuma mandarin (Citrus unshiu Marcow.) trees were determined. In 2010, periodical applications of smaller amounts of half-strength-diluted (1/2X) or undiluted seawater (1X) delayed the reduction of leaf water potential to the objective level at 0.3 to 0.5 MPa lower than that in the control, resulting in an insignificant increase in soluble solids content (SSC). Thus, half of the total amount of 1X per area applied in 2010 was irrigated once or twice in September in 2012 and 2013. Soil EC in 1X markedly increased after just the first application at above 1.8 dS·m−1 and was kept at a significantly higher level than in the control until harvest, although it gradually decreased by leaching due to rainfall. Leaf water potential at predawn was reduced by 1X and the objective value was achieved from early-October and mid-September to harvest in 2012 and 2013, respectively. SSC was higher in 1X than the control throughout the experimental period and the difference between 1X and the control at harvest was 1.4 and 1.2°Brix in 2012 and 2013, respectively. Other fruit quality parameters including titratable acidity (TA) were not significantly affected by seawater irrigation in either year, except for fruit size which was slightly inhibited in 1X. No difference was observed in the leaf chlorophyll index and abscission between 1X and the control, although the Na content in the leaves was increased in 1X. These results suggest that application of relatively higher amounts of undiluted seawater in the early stage of maturation could induce moderate salt or water stress through the inhibition of water absorption by roots and improve fruit quality by increasing SSC without any visible leaf injury in field-grown satsuma mandarin trees.

著者

Xi Li Akira Kitajima Tsuyoshi Habu Keiko Kataoka Rihito Takisawa Tetsuya Nakazaki

出版者

一般社団法人 園芸学会

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.MI-145, (Released:2016-06-15)

被引用文献数

1

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A new method of inducing fruit abscission by incubating detached ovaries and fruits in agar medium was developed in citrus. Ovary and fruit abscission in the satsuma mandarin, ‘Kiyomi’, hyuganatsu, and ponkan during early physiological fruit drop was characterized using this method. For primary physiological fruit drop, the abscission of detached ovaries could be divided into three patterns, including an early type in hyuganatsu, a medium type in ‘Kiyomi’, and a late type in satsuma mandarin and ponkan. The cumulative abscission ratio of four species and cultivars was over 80% at 96 h after treatment. However, for secondary physiological fruit drop, the initiation of fruit abscission was earliest in hyuganatsu, and latest in satsuma mandarin. The cumulative abscission ratio was highest in ponkan at 84% and lowest in hyuganatsu at 6%. The pattern of abscission was different for primary and secondary physiological fruit drop in the four species and cultivars. High temperature promoted the abscission of detached ovaries and fruits in satsuma mandarin and ponkan. Leaf attachment suppressed fruit abscission in ‘Kiyomi’, hyuganatsu, and ponkan at 7 weeks after anthesis in 2012 and ponkan at 5 weeks after anthesis in 2013. Ovary and fruit abscission in four species and cultivars during early physiological fruit drop was characterized by incubating detached ovaries and fruits in agar medium.

著者

Tsuyoshi Habu Hisayo Yamane Ippei Naito Soichiro Nishiyama Ayumi Nonaka Takashi Kawai Hisashi Yamada Ryutaro Tao

出版者

一般社団法人 園芸学会

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.MI-119, (Released:2016-02-09)

被引用文献数

8

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Japanese persimmon ‘Totsutanenashi’ (TTN) is a spontaneous small fruit mutant derived from ‘Hiratanenashi’ (HTN). To characterize the small fruit phenotype of TTN, we carried out a histological analysis, plant growth regulator treatments, and a transcriptome analysis using Illumina sequencing. The parenchymal cell number in TTN fruit was significantly less than in HTN fruit, and the parenchymal cell size in TTN fruit was also significantly smaller than that in HTN fruit at the later growing stage. However, the fruit size of TTN recovered by cytokinin treatments [50 or 200 ppm N-(2-chloro-4-pyridyl)-N′-phenylurea]. Thus, diminished cytokinin activity in TTN fruits may lead to less cell division in the early growing stage and less cell enlargement in the later growing stage. A large-scale transcriptome analysis was conducted using Illumina sequencing to determine the differences in gene expressions between TTN and HTN fruits. Illumina sequences were processed, resulting in 21,662,190 read pairs from HTN and 23,195,203 read pairs from TTN. After assembly of all sequences from HTN and TTN, 118,985 contigs (referred to as unigenes hereafter) ranging from 201 to 11,954 bases, with an average length of 915 bases, were obtained. Digital expression analyses revealed that the expression levels of 164 unigenes were significantly higher in HTN than in TTN, while the expression levels of 265 unigenes were significantly higher in TTN. A parametric analysis of gene set enrichment using the expression levels of unigenes showed that the biological process Gene Ontology categories of “cell cycle” and “regulation of cell cycle” were significantly down-regulated in TTN. The cell cycle-related differentially expressed genes included D3-type cyclin and Mitogen-Activated Protein Kinase Kinase Kinase. Based on the obtained results, the possible involvement of cell cycle-related genes in regulating the small fruit phenotype in TTN is discussed.