Abstract
The study was carried out in during period the 1969-70, at the Tanegashima Branch, Kyushu Agricultural Experiment Station. (N 30°40', E 131°), empolying the 46 selected lines the 4th stage bred from 8, 210 initial seedlings, involving 2 varieties of sugarcane, N: Co. 310 and 376, The investigations were conducted with following four sections involved respectively five characters.
(1) Yield components (2) Stalk form
(3) Juice quality (4) Leaf form
From the results of correlation coefficients computed between each others, an ideal varieties with higher sucrose content and yielding ability in sub-tropical districts were considered standing for “stalk number” and “stalk weight” type.
1) Correlation coefficients between the characters are summerized in Table 1. Figure 1 shows the correlation centering around yield of available sugar at above 5% significant level.
2) Correlations for yield of cane are higher with numbers of stalk (r=0.62) than with stalk weight (r=0.56) . It is discussed the reasons why yield of “stalk number” type are predominant over “stalk weight” type as the latitude elevates.
3) It is observed that Brix, sucrose per cent and available sugar ratio of “stalk number” type are higher than that of “stalk weight” type. Considering the relation from a standpoint of leaf habit, “stalk number” type is inclined to have narrow, short and erect leaf blade, which is desirable to perform effective photosynthesis in higher latitudinal districts at low incident angle of sunlight. On the other hand, “stalk weight” type is apt to have wide, long and drooping leaf blade, which gives an unfavourable effects on photosynthesis due to shade the lower leaves and to weaken the light intensity within the community tended to be disadvantageous for maturity.
4) The ideal varieties adapted in higher latitudinal districts are represented by the “stalk number” type exhibited higher yield and sucrose content, whereas the “stalk weight” type shows thick, heavy stalk which may give the illusion of higher yielding potential than the variety possesses.
5) Since sugarcane has the highest light-saturation point, the varieties cultivated under condition of rather lower enersy of sunlight in sub-tropical districts should possess reasonable plant type for efficient light acceptance.
