Abstract
The relationships between grain yield and cross-sectional area of stalks (CSA) were studied using the data from a hybrid, Tomorokoshi Koh No. 7,planted at various populations on the soils of different fertility levels (Table). The logarithms for yield per CSA decreased linearly as the CSA per land area was increased and there was a high correlation coefficient betwen them. Using the linear relationship, a yield-CSA curve was determined. The formulae for the relationship are expressed by equations as follows : log y=log K+bS or y=K·10bS Y=yS=SK·10bS Where y is the yield per CSA, K is the constant, b is the regression coefficient, S is CSA per land area and Y is the yield per 10a. If the latter equation is differentiated with respect to S and the result equated to zero and solve for S, the result is : Sopt=-1/2.303b Where Sopt is the CSA that will give the maximum yield. The method above mentioned is assumed to be very useful and convenient for predicting yield since stalk-diameter attains at earier stage before silking and only two yield-CSA values are needed regardless plant populations.
