Gunma Agricultural Technology Center

Maebashi-shi, Japan

Gunma Agricultural Technology Center

Maebashi-shi, Japan
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Yoshida K.,Saga University | Elsayed A.K.,Kagoshima University | Matsuura H.,Yokohama Plant Protection Station | Horigome M.,Gunma Tone Numata General Agricultural Office | And 3 more authors.
Japanese Journal of Applied Entomology and Zoology | Year: 2017

In July 2015, an unidentified gall midge(Diptera: Cecidomyiidae) infesting new leaves of blueberry, Vaccinium spp. was found in Gunma Prefecture, Japan. Morphological examinations of adults and larvae revealed that the gall midge belongs to the genus Dasineura and is very similar to the blueberry gall midge Dasineura oxycoccana(Johnson), which is native to North America and associated with blueberry. In order to confirm whether or not the species of Dasineura on cultivated blueberry is identical to D. oxycoccana, a partial region of the mitochondrial DNA cytochrome oxidase subunit (I COI) (676 bp) gene was sequenced for several individuals collected from Gunma. As a result, the sequence was identical to an individual of D. oxycoccana in the database. Based on the morphological examinations and molecular analysis, we identify the gall midge infesting blueberry in Gunma as D. oxycoccana. This is the first report of D. oxycoccana in Japan.

Koike I.,Toyo University | Taniguchi K.,Toyo University | Taniguchi K.,Gunma Agricultural Technology Center | Shimomura K.,Toyo University | Umehara M.,Toyo University
Journal of Plant Growth Regulation | Year: 2017

For most plant species, auxins and cytokinins are added to the culture medium to induce adventitious shoot formation. In ipecac (Carapichea ipecacuanha (Brot.) L. Andersson), however, shoots form on internodal segments without phytohormone treatment. This creates an opportunity to analyze the dynamics of endogenous phytohormones during adventitious shoot formation. Ipecac is a medicinal plant whose root extract is used as an expectorant and emetic. We explored the relationships among adventitious shoot formation and levels of an auxin (indole-3-acetic acid) and four cytokinins in ipecac. Adventitious shoots that formed in the apical region of internodal segments were derived from epidermal cells. One of the shoots grew vigorously with a vascular bundle connected to that of the segment, and the others were suppressed in the outgrowth. When the biggest shoot was removed, another began to grow. During adventitious shoot formation, endogenous auxin accumulated in the basal region of segments, whereas cytokinins accumulated in the middle region. Thus, the distribution of auxin, not cytokinins, determined where adventitious shoots formed. © 2017 Springer Science+Business Media New York

Kato N.,Japan National Agriculture and Food Research Organization | Kihou N.,Japan National Institute for Agro - Environmental Sciences | Fujimura S.,Fukushima Agricultural Technology Center | Ikeba M.,Agricultural Research Institute | And 4 more authors.
Soil Science and Plant Nutrition | Year: 2015

Huge amounts of radionuclides, particularly radiocesium, were discharged from the Fukushima Daiichi Nuclear Power Plant (FDNPP), and widespread of contamination of the land, including paddy fields, was observed. Because rice is a staple food in Japan, contamination of paddy fields is a serious problem, and practical countermeasures to reduce radiocesium contamination of rice are urgently required. Potassium (K) fertilization was previously shown to be an effective countermeasure in fields contaminated by the Chernobyl accident, but researchers did not study the effects on rice (Oryza sativa L.). In the present study, we performed urgent field experiments to test the use of K fertilization, as well as other soil amendments, to reduce radiocesium contamination of rice. We found that K fertilization was an effective and practical countermeasure to reduce radiocesium uptake by rice from several soil types in Japanese paddy rice culture. Other treatments, including the application of expanded vermiculite or manure, were effective, and the effect appears to be explained by their K content. Based on these results, the recommended level of exchangeable soil potassium to lower the radiocesium content of rice to acceptable levels is about 200 mg K kg–1 soil before the usual fertilization. This K fertilizer application criterion was applied in a wide, low-contaminated area from the 2012 cropping season, and satisfactory results have been obtained generally. © 2014 Japanese Society of Soil Science and Plant Nutrition

Ikeda K.,Gunma Agricultural Technology Center | Banno S.,Toyo University | Furusawa A.,Gunma Agricultural Technology Center | Shibata S.,Gunma Agricultural Technology Center | And 2 more authors.
Journal of General Plant Pathology | Year: 2014

In this study, we assessed whether crop rotation with broccoli suppressed eggplant Verticillium wilt. In 6 trials of crop rotation in 5 fields from 2009 to 2013, broccoli rotation was coupled with postharvest residue incorporation before planting eggplant. Meta-analysis of the disease incidence data from all the trials revealed that the combined relative disease risk was 0.53 (95 % confidence interval 0.34–0.83). Thus, the disease incidence of eggplant in crop rotation with broccoli decreased to 53 % of that of eggplant without broccoli rotation. Browning of vascular tissue from Verticillium dahliae infection was observed in broccoli, but was limited to the roots and did not reach the aerial plant portion where V. dahliae forms microsclerotia. Estimation of V. dahliae population in soil using quantitative nested real-time polymerase chain reaction indicated that V. dahliae DNA copy number in soil samples tended to decrease owing to broccoli cultivation. These results suggest that broccoli root could act as a “decoy” that traps V. dahliae in soil. Further studies are necessary to elucidate the mechanisms of disease suppression; this is the first report that broccoli cultivation and subsequent incorporation of residue into the soil suppresses Verticillium wilt of eggplant. © 2014, The Phytopathological Society of Japan and Springer Japan.

Kuwabara K.,Gunma Agricultural Technology Center | Yokoi N.,Akita | Ohki T.,Japan National Agricultural Research Center | Tsuda S.,Japan National Agricultural Research Center
Journal of General Plant Pathology | Year: 2010

We improved a one-step multiplex reverse transcription-polymerase chain reaction (multi-PCR) method previously published for the simultaneous identification of five tospovirus species that mainly occur on Solanaceae and Compositae plants. The multi-PCR system is composed of a universal degenerate primer and five virus-species-specific primers that amplify bands unique to Iris yellow spot virus (837 bp), Tomato spotted wilt virus (709 bp), Impatiens necrotic spot virus (589 bp), Chrysanthemum stem necrosis virus (485 bp), and Capsicum chlorosis virus (366 bp). This technique is potentially useful for epidemiological studies of several tospoviruses that have recently been detected in previously uninfected fields of ornamental crops. © 2010 The Phytopathological Society of Japan and Springer.

Kato Y.,University of Tokyo | Osawa M.,Gunma Agricultural Technology Center
European Journal of Agronomy | Year: 2013

Wheat often overproduces kernels when grown in favorable environments, resulting in low kernel weight with high kernel screenings. This indicates that photoassimilation after heading would not be sufficient to support the growth of a large number of kernels. The objective of this study was to examine the effects of crop thinning at heading (experiment 1) and double-row planting (compared with equidistant row spacing; experiment 2) on kernel weight and yield of Japanese wheat cultivars under different levels of soil fertility. In experiment 1, elimination of aboveground competition for radiation by thinning increased yield by up to 32%, mainly due to increased kernel weight. In experiment 2, double-row planting increased kernel weight significantly (by 4-10%) without yield loss by moderately suppressing maximum stem number (by 7-14%) and spike and kernel number (by up to 14%) under high fertility. In both experiments, the effect of crop thinning or row configuration on wheat yield and kernel weight was negligible under low fertility because of little competition for radiation. The results suggested that control of vegetative growth and kernel production would help avoid the shortage of assimilates for kernel growth in fertile environments. For further increasing wheat yield under favorable conditions in Japan, the appropriate crop management options (e.g., planting geometry) should be combined with the suitable varieties having a more communal ideotype (sparse tillering with upright posture) than a competitive phenotype (profuse tillering with lax posture) to enhance photoassimilation after heading. © 2013 Elsevier B.V.

Takinami Y.,University of Tokyo | Maejima K.,University of Tokyo | Takahashi A.,Gunma Agricultural Technology Center | Keima T.,University of Tokyo | And 5 more authors.
Journal of General Plant Pathology | Year: 2013

Phytoplasma-induced floral malformations such as virescence, phyllody, and proliferation were observed on hydrangeas in Gunma Prefecture, Japan. Phylogenetic analyses based on 16S rRNA, secY, groEL, and amp gene sequences indicated that the affected hydrangea plants were associated with phytoplasmas belonging to 'Candidatus Phytoplasma asteris', but not to 'Ca. P. japonicum', which occurs in hydrangeas showing phyllody in Japan. This is the first molecular evidence of an association of 'Ca. P. asteris' with hydrangea plants in Japan. © 2013 The Phytopathological Society of Japan and Springer Japan.

Shiraishi T.,Gunma Agricultural Technology Center | Sakai H.,Gunma Prefectural Office | Ikeda K.,Gunma Agricultural Technology Center | Urushibara T.,Gunma Prefectural Office
Journal of General Plant Pathology | Year: 2014

Various methods of inoculating plants with Verticillium dahliae have been described; however, so far, there are no effective preparations of its microsclerotia, a major source of infection under natural field conditions. In this study, we developed a simple and effective method to prepare microsclerotial inoculum of V. dahliae using a cellophane medium that effectively promoted microsclerotia formation. In addition, a sieving process allowed the preparation of inoculum exclusively composed of microsclerotia. Our novel method provides a reproducible and stable inoculum for disease induction by V. dahliae under conditions that approximate natural infections. © 2014, The Phytopathological Society of Japan and Springer Japan.

Banno S.,Toyo University | Saito H.,Toyo University | Sakai H.,Gunma Agricultural Technology Center | Urushibara T.,Gunma Agricultural Technology Center | And 5 more authors.
Journal of General Plant Pathology | Year: 2011

Verticillium longisporum and V. dahliae, causal agents of Verticillium wilt, are spreading through the cabbage fields of Gunma Prefecture. Using the V. longisporum-specific intron within the 18S rDNA and differences between ITS 5.8S rDNA sequences in Japanese isolates of V. longisporum and V. dahliae, we developed three quantitative nested real-time (QNRT) PCR assays. The QNRT-PCR quantification of V. longisporum or V. dahliae in cabbage field soil was consistent with the severity of Verticillium wilt disease in those fields. In field trials of resistant cultivar YR Ranpo grown for three seasons in soil infested with the pathogen, disease severity and pathogen density in the soil were significantly reduced in a field moderately contaminated by V. dahliae, but only slightly reduced in a highly contaminated field. These results suggest that continuous cultivation of a resistant cultivar is an effective way to reduce the pathogen population. QNRT-PCR assays provide a powerful analytical tool to evaluate the soil population dynamics of V. longisporum and V. dahliae for disease management. © 2011 The Phytopathological Society of Japan and Springer.

Pepper (Piper nigrum L.) root rot caused by Fusarium solani f. sp. piperis (FSP; teleomorph: Nectria haematococca f. sp. piperis) includes two symptom types called root rot (RR) type and stem rot (SR) type. In this study, the temporal and spatial associations between perithecial formation of FSP and development of SR were investigated in naturally infested fields to verify the hypothesis that ascospores from the perithecia are the major inoculum source of the SR type on vines in the field. In surveys of all vines in two neighboring pepper fields every month from December 2005 to November 2006, I mapped the locations of all vines with perithecia and all vines the SR type. The frequency of vines with perithecia increased during April and May, the late rainy season. In June, the early dry season, the number of vines with SR type greatly increased. The vertical range of perithecial formation on the vines extended to 200 cm in height, but was restricted to 30 cm in the dry season in both fields. The join-count statistics showed a significant spatial association between vines with perithecia and vines with SR type in one field (P = 0.042), while no significant spatial association was recognized in another field. The results suggested that ascospores from perithecia of FSP on pepper vines are likely to be one of the main inoculum sources of the SR type of the disease on adjacent vines, but they may not be the exclusive source. © 2010 The Phytopathological Society of Japan and Springer.

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