Yasushi Takano

Evaluation of variation of root shape of Japanese radish (Raphanus sativus L.) based on image analysis using elliptic Fourier descriptors

Variation was of root shape in Japanese radish, due to genotypes, soil types and growth stages, were quantitatively evaluated by principal components scores based on elliptic Fourier descriptors. Photographic images of sampled roots on 35mm color reversal films were converted into digital images. After image processing, the contour of each root was expressed as chain-code and then described by 77 coefficients of elliptic Fourier descriptors. After normalization about size, rotation, and starting point of the contour, two groups of the coefficients, which are related to the symmetrical and asymmetrical variations of shape, were analyzed separately, since artificially determined direction of curvature of the root may influence the results. Principal component analysis of the coefficients showed that the major part of the symmetrical (A) and asymmetrical (B) variations were summarized by at most 5 components. The cumulative contribution was 95.2% and 97.1%, respectively. Analysis of variance of each component indicated that the variety effect was highly significant for the 1st, 2nd and 3rd principal components derived from group A coefficients, which were related to the aspect ratio, bluntness of the distal part of the root, and swelling of the middle part, respectively. This suggests that these traits are heritable and can be effectively selected through quantified measures based on elliptic Fourier descriptors presented in this report. Direction and degree of curvature of root could be analyzed independently of the symmetrical variation.

Estimation of the proportion of offspring having soluble solids content in fruit exceeding a given critical value in Japanese persimmon

In fruit breeding, the selection is often based on individual plant performance, therefore, the expected proportion of offspring having genotypic values exceeding a given critical value (EP) was estimated for soluble solids content (SSC) in Japanese persimmon (Diospyros kaki Thunb.). A simple model was used in the study: the mean value of offspring in a full-sib family is solely determined by the regression of that on midparental value (MP) and all families have an equal within-family variance due to segregation. The population consisted of 39 full-sib families with three offspring each. Between-family variance was much smaller than within-family variance. Genetic variance for MP was much smaller than that for offspring. The EP therefore was not highly affected by the regression. Based on the parental mean performance of 35 fruits on a single tree for three years, the proportion of offspring having SSC higher than 18% was estimated as 32%, 50% and 69% for three groups of MP differing in SSC, i.e. 16.5%, 17.5%, and 18.5%, respectively. The distributions which were predicted using those results for 246 offspring from 46 families, and 86, 44, 43 and 31 offspring from four selected families, respectively, were largely consistent with those observed.

Quantitative evaluation of the three-dimensional fruit shape and size of Citrus species based on spherical harmonic descriptors

A measurement system, which consisted of a CCD laser displacement sensor and two pulse stages, was constructed to obtain three-dimensional (3-D) surface data of Citrus fruit. Fruits of 58 species of three specimens each were measured. By expanding the data measured in a series of spherical harmonic functions, a set of expansion coefficients to characterize the object shape was obtained. The data was normalized to make the coefficients be independent of the x- and y-coordinates of the object. To summarize the information about shape contained in the62 coefficients, a principal component analysis of the standardized spherical harmonic coefficients of each fruit was made. The contribution of each of the first seven principal components was found to exceed that of a single variable. The first three principal components had a cumulative contribution of 0.823.Analysis of variance showed that the variance due to between-species as tested against the variance due to within-species was significant for the 1st,2nd, 3rd, 4th, 7thcomponent score and the volume. A scatter diagram of the 1st and 2nd principal components failed to group the species studied.

Measurements of 220 GHz atmospheric opacity on Mt. Fuji with a radiometer/radome system

We measured atmospheric opacity at 220 GHz at the summit of Mt. Fuji (alt. 3776 m) about one year in order to explore a feasibility of submillimeter-wave astronomical observations. For this purpose, a 220 GHz radiometer system enclosed in a radome (51×51×62 cm3) has been developed. The 220 GHz opacity was lower than 0.06 for a significant fraction (∼ 45 %) of time from November 1994 to March 1995. Diurnal variation of the opacity at the summit of Mt. Fuji is so small that continuous observation at submillimeter-wave is possible through day and night. Yearly variation of the opacity is studied from water vapor pressure data measured at the weather station for the past 3 years. To prevent accumulation of ice and snow on the Gore-Tex membrane in the radome, the outer membrane was supplied with a thermal flux of 0.63 kW m−2 and the adjacent metal radome surfaces were supplied with a flux of ∼0.9 kW m−2. We evaluate from the 220 GHz transmission data that this heat flux is sufficient to keep the membrane on the radome free of ice and snow during 83 % of the time in 5 winter months. The summit of Mt. Fuji appears to be a promising site for submillimeter-wave observations.