Study on optimum plot size and optimum plot shape of soybean crop

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Date
2010
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UAS, Dharwad
Abstract
The total area used to conduct uniformity trial was 1898 sq m. Rows are along E-W direction columns are N-S direction. Observation on plot yields were recorded plot wise at the time of threshing. The basic unit being of size 1.2 sq.m (4 column plants at 30 cm *10 cm spacing). The total area divided into 1470 units each unit have size of (1.2 *1.0) sq m. The coefficient of variation decreased as the plot size increase but not proportionally in case of both characteristics, viz., yield per unit plot and number of pods per unit plots. The sum of squares worked out for rows and columns separately showed relatively higher fertility gradient along the columns. The presence of rough fertility along the rows also can be seen in the contour map. The observed relation between plot size and variance was in conformity with the Fairfield Smith variance law. At the larger plot sizes, the regression line showed a tendency to curve down although Fairfield Smith method and maximum curvature showed some difference in case of both the characters, viz., yield per unit plot and number of pods per unit plot taken separately. And trend in decrease of coefficient of variation is found almost similar for both the characters. From all these above considerations, a plot size of 3.6 Sq. m (3.6 m *1.0 m) is found advisable for conducting field experiments in soybean. The optimum plot size based on number of pods did not differ significantly from that determined by yield. Although number of pods is economically best in determining the optimum plot size and shape, yield factor is considered to be the best for the purpose of identifying fertility contours and optimum plot size and shape.
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Agricultural Statistics
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