Studies on Variation in the Number of Sterile Filaments and Its Significance in Classification of Cultivated Peanut Varieties (Arachis hypogaea, L.)

[摘要] This paper dealt with the results investigated on the degree of variation in the number of sterile filaments and its classificatory significance in peanut (Arachis hypogaea, L.), using 121 cultivated varieties or strains originated from various countries of the world and Japan (Table 1). Significance of classification of varieties based on the plant type was investigated by use of discriminant function evaluated by the above character and other 3 characters of varieties (Tables 3 and 4). Results and considerations obtained are as follows: 1) The rate of appearance of "10-", "9-", and "8-anthers-flower" (0, 1, and 2 in the number of sterile filaments, respectively) was characteristic of the varietal groups classified by the plant type, with one exceptional variety. "Eight-anthers-flower" appeared predominantly in all varieties examined. However, significant much higher rate of appearance of "9-anthers-flower+10-anthers-flower" (%) was observed in the erect varieties (Spanish and Valencia types), compared with that in the prostrate and semi-prostrate ones (Virginia Runner and V. Bunch types) (Table 2 and Fig. 1). No significant differences in this values were found between the 2 types in each of the above 2 varietal groups. 2) From these results, the following conclusions were derived: i) The 2 varietal groups of the cultivated peanut, i. e. the erect type and prostrate type (including the semi-prostrate type), are different markedly in the degree of variation in the number of sterile filaments, as one of the floral morphological characteristics of this plant. In other words, the characteristic presence of 2 sterile filaments has almost being stabilized in the latter varietal group than the former one. ii) It is most presumable that the androecium having no sterile filaments is most primitive and fundamental type of the androecium of this plant. And it is of great interest to find out a relationship between varietal groups and the trend of gradual decreasing and stabilization in fertile stamen number in this plant, i. e. "10→9→8" (Table 6), in connection with the assumption on degree of primitiveness or advancement of each varietal group, viewed from the "androecium-morphology". iii) More extensive studies on the "androecium-morphology" in a number of cultivated varieties and the allied species of this plant, and survey of the plant which normally have only "10-anthers-flower" may give a clue to clear up somewhat of the problems on the origin, geographic distribution, varietal differentiation, and classification of this plant. 3) Three discriminant functions, to investigate the classification of varieties based on the plant type, were evaluated by use of 4 characters: rate of appearance of "9-anthers-flower+10-anthers-flower" (%) (x1), width of terminal leaflet (x2), pod volume (x3), and length of calyxtube (x4). High significant difference (p<0.001) in mean discriminant values was recognized only between the erect varieties and the prostrate varieties (including semi-prostrate varieties), and not between prostrate and semi-prostrate, and also between Spanish and Valencia types (Fig. 2). 4) From the above-mentioned results, it appears to be reasonable to take the plant type as the primary basic character in botanical classification of the cultivated peanut varieties.

[学科分类] 农业科学（综合）