The Extent and Its Source of Variation for Characteristics Related to Seed Quality of Adzuki Beans : I. Seed size variation among growers lots in Hokkaido area

Abstract

Seed size and its uniformity of adzuki beans are important indices for estimation of seed quality, in Japan. To obtain information for improving seed quality, mean seed size, seed size variation (expressed as a coefficient of variation on 300 seeds per sample) and some agronomic traits were investigated for 240 samples in 1987 and 203 samples in 1988 on 'Erimo-shozu', a present leading variety, which were collected from the growers at several districts in Hokkaido. A wide range of mean seed size was observed across the districts, with the largest (approx. 150 mg) at Tokachi to 75% of that at Ishikari and Sorachi. Mean seed size were associated with the duration of reproductive period and seemed to be partly due to differences between a usual upland field and converted one from paddy. Mean seed size varied widely also from grower to grower within the same district (e.g. with the range of 109 to 187 mg at Tokachi in 1988). Nitrogen fertilizer level was positively, but not closely, correlated with mean seed size (r=0.300^**). Seed size variation (C.V.) was not markedly influenced by years and by districrs, though ranging 14 to 37% among growers. A significant negative relationship was found between mean seed size and C.V. Results suggest that it should be recommended to introduce or develop a variety more adaptive to the respective districts and to reinvestigate some agronomic practices at least for seed size.