Uzuki Matsushima

Synchrotron X-ray CT of rose peduncles - evaluation of tissue damage by radiation*

Abstract “Bent-neck” syndrome, an important postharvest problem of cut roses, is probably caused by water supply limitations and/or the structural weakness of vascular bundles of the peduncle tissue. For this reason, advanced knowledge about the microstructures of rose peduncles and their cultivar specific variations may lead to a better understanding of the underlying mechanisms. Synchrotron X-ray computed tomography (SXCT), especially phase-based CT, is a highly suitable technique to nondestructively investigate plants’ micro anatomy. SXCT with monochromatic X-ray beams of 30, 40 and 50 keV photon energy was used to evaluate the three-dimensional inner structures of the peduncles of 3 rose cultivars that differ greatly in their bent-neck susceptibility. Results indicated that this technique achieves sufficiently high spatial resolution to investigate complex tissues. However, further investigations with chlorophyll fluorescence analysis (CFA) and optical microscope imagery reveal different kinds of heavy damage of the irradiated regions induced by synchrotron X-rays; in a cultivar-specific manner, partial destruction of cell walls occurred a few hours after X-ray irradiation. Furthermore, a delayed inhibition of photosynthesis accompanied by the degradation of chlorophyll was obvious from CFA within hours and days after the end of CT measurements. Although SXCT is certainly well suited for three-dimensional anatomical analysis of rose peduncles, the applied technique is not nondestructive.

Structure investigation of soil aggregates treated with different organic matter using X-ray micro tomography*

Abstract Soil aggregation which is favorable for plant growth, can be modified by the presence of organic matter and farmers apply different materials to promote soil aggregation and enhance its stability. However, the relationship between the type of organic matter and the resulting properties of the aggregate structure is unclear. Using micro X-ray tomography, intra-aggregate pore formation in soils from fields in Southwestern Japan fed with different organic fertilizers was compared. Organic matter, especially manure-based matter, increased porosity of the intra-aggregate, which is considered to increase growth conditions. Pores that connected the core of the aggregates with the surface were observed in organic matter-applied fields and sponge-like pores were observed in manure-fed fields.