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Hosomi A.,Research Institute of Environment | Miwa Y.,Research Institute of Environment | Mano T.,Hyogo Prefectural Technology Center for Agriculture
Journal of the Japanese Society for Horticultural Science | Year: 2013

Shoot growth and fruit production of 'Masui Dauphine' fig trees (Ficus carica L.) were compared between a novel training method and a control method, with various tree spacing. In the novel training, the shoots were elongated downward from a horizontal limb at 180 cm height, whereas control training had upward growing shoots from a horizontal limb at 40 cm height. Sprouted shoots of the novel training trees leafed a few days earlier than controls. The difference in training did not significantly affect longitudinal growth (the internode length and leaf area) of the shoots but, on the apical portion of the shoots, the shoot diameter and leaf weight per area in novel training were less than in controls. Many lateral shoots sprouted on the shoots of the novel training in autumn. The novel training prevented failure of fruit set, which was observed on the basal portion of control shoots with excess vigour owing to narrow tree spacing. The novel training promoted coloring of fruit on the basal portion of the shoots and depressed it on the apical portion. The size and weight of fruit tended to be reduced on the shoots that underwent novel training. The observed characteristics of novel training may be due to the change of lighting conditions and reduced photosynthetic rate due to downward shoot positioning. © 2013.

Shoji K.,Kobe University | Matsumoto I.,Hyogo Prefectural Technology Center for Agriculture | Kawamura T.,Kobe University
Engineering in Agriculture, Environment and Food | Year: 2011

To enhance the accuracy of an impact-based yield sensor installed inside the grain tank of a combine, we measured the individual impacts of intermittent grain flow accelerated by an auger blade. Non-linear calibration was modeled to relate each impulse received by the sensor to the weight of grain released at a single rotation of the auger blade, taking into account the rotational speed of the auger. The parameters were optimized through pairs of signal recording and grain weight at harvest in situ. The relative error of calibration was less than 2%. The proposed instrumentation and signal processing showed robustness to the flow rate of grain, and the maximum relative error of validation was 3.5%.

Usami T.,Chiba University | Kanto T.,Hyogo Prefectural Technology Center for Agriculture | Inderbitzin P.,University of California at Davis | Itoh M.,Chiba University | And 5 more authors.
Journal of General Plant Pathology | Year: 2011

In January 2002, Verticillium wilt of lettuce (Lactuca sativa L.) caused by Verticillium tricorpus occurred in upland paddy fields in Hyogo Prefecture for the first time in Japan. This fungal species was first isolated from lettuce in California, USA. In the present study, the genetic relationships between the American and Japanese isolates of V. tricorpus from lettuce were analyzed to determine whether the pathogen could have migrated to Japan from the USA, the major lettuce-seed supplier for Japan. Nucleotide sequences of the rDNA internal transcribed spacer regions, as well as the genes coding for translation elongation factor 1-alpha and RNA polymerase II were compared among American and Japanese V. tricorpus isolates from lettuce. The Japanese isolates of V. tricorpus were distinct from the American. Random amplified polymorphic DNA analyses also supported this conclusion. These results demonstrated that Verticillium wilt on lettuce caused by V. tricorpus in Japan was not related to the isolates causing the disease in California. © 2010 The Author(s).

Yamasaki M.,Kyoto University | Ito Y.,Hyogo Prefectural Technology Center for Agriculture | Ando M.,Kyoto University
Canadian Journal of Forest Research | Year: 2014

Bark and ambrosia beetles sometimes kill trees by attacking them en masse; however, their attack is not necessarily successful. Less than half of the fagaceous trees attacked by the ambrosia beetle Platypus quercivorus (Murayama) die, and the factors affecting this mortality are still unknown. To examine this issue, the survival of all stems of fagaceous trees attacked by the ambrosia beetle was investigated in a secondary forest from 2008 to 2010. In an area of 93 ha, 2130 stems (1278 genets) of fagaceous trees were attacked by P. quercivorus during the study period, and 813 of these stems died. A generalized additive mixed model was constructed to predict the probability of mortality of the attacked stems. A best-fit model showed that the probability of mortality was higher in Quercus crispula Blume than in Castanea crenata Sieb. & Zucc. A positive correlation was determined between the density of the attacked trees and the probability of mortality, suggesting that mass attack of P. quercivorus occurs not only on individual trees, but also on groups of trees. Assuming that trees attacked earlier in the season have a higher probability of mortality, the observed negative effects of altitude suggest that P. quercivorus initially seeks hosts at lower elevations.

Yamasaki M.,Kyoto University | Ito Y.,Hyogo Prefectural Technology Center for Agriculture | Ando M.,Kyoto University
Agricultural and Forest Entomology | Year: 2014

The ambrosia beetle Platypus quercivorus uses fagaceous tree species as its hosts, and causes Japanese oak wilt by transporting and introducing the pathogenic fungus Raffaelea quercivora into the host tree. To protect fagaceous trees, it is necessary to understand the host selection process used by the beetle in heterogeneous forests. The occurrence of beetle attack on Quercus crispula and Castanea crenata was monitored from 2008 to 2011 in two 1-ha and one 0.5-ha plots established in a secondary forest. The stem and crown densities of each fagaceous tree species were calculated at 11 different spatial scales for each individual tree. Model application and selection were performed to clarify factors affecting the probability of attack by P. quercivorus. As shown in previous studies, a higher probability of attack was predicted for Q. crispula than for C. crenata, and the predicted probability of attack was lower for trees attacked in the previous year. The effect of stem density on the probability of attack was positive at a small (radius 5m) spatial scale and negative at larger (radius 5-17.5m) scales. We interpreted this to indicate that a dense distribution of fagaceous trees in a small area had a higher probability of attack, and that this probability decreased with an increasing density of fagaceous trees in a surrounding concentric area. A positive effect of crown density was detected, suggesting that P. quercivorus has a means of detecting host trees in areas with high crown densities of fagaceous species. © 2013 The Royal Entomological Society.

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