Visualization of 3-D network of gas-filled intercellular spaces in cucumber fruit after harvest

Gas-filled intercellular spaces are the predominant pathways for gas diffusion through plant organs and as such, are greatly related to the characteristics of gas exchange. However, their detailed structure is still unclear. In this study, X-ray computer microtomography (X-ray muCT) was applied to the investigation of a three-dimensional (3-D) network of gas-filled intercellular spaces in the sarcocarp of cucumber fruit stored at 20degreesC. The attained spatial resolution was 2.48 mum. Results showed that X-ray muCT enabled the observation of gas-filled intercellular spaces without artificial influence, and it was proved experimentally that the gas-filled intercellular spaces, with a volume of 1000 mum(3) and higher, form a complex network inside the tissue. However, 3-D imaging of gas-filled intercellular spaces revealed that these spaces were not completely interconnected and were disrupted in some parts. Moreover, the size distribution of gas-filled intercellular spaces demonstrated that the subdivision of intercellular spaces advanced with storage period. These observations and analyses suggested that the gas-filled intercellular spaces got blocked with water during senescence. This change in the network of gas-filled intercellular spaces with time after harvest will affect the gas diffusivity. (C) 2004 Elsevier B.V. All rights reserved.