Uniformity trial with lucerne grown for fodder

Abstract

AbstractData on the yield of lucerne for individual cuts and the total for three cuts from a uniformity trial were analysed. It was observed that CV% values decreased with the increase in plot size, both for each cut and for total yield. The decrease was considerable up to a plot size of 8 to 16 m2. The plot shape did not show any consistent effect. Increasing the size of block resulted in increased CV values, but block shape had no consistent effect. The CV values were highest for the first cut and lowest for the second cut. A relationship between the average CV% and plot size was found. However, this relationship, or its modified form Y= a.X1−b1. X2−b2 taking into account the plot shape and considering the individual CV values, provide a good fit to the data for the cases where blocking was adopted. The coefficient of heterogeneity was less than 0·29, being lowest for first‐cut yields, followed by the total, the third cut and the second cut yields. This showed a high degree of positive correlation between yields of neighbouring plots. Blocking proved useful in increasing the efficiency of the experiment and it is suggested that block size may be kept at 8 or less plots per block. The relationship between average CV% and block size was of the from Y = a Xb. The present study suggests that, for field experiments with luceme, the plot size may be kept to a minimum that does not exceed 8 to 12 m2, in blocks of eight to nine plots with the shapes of plots and blocks being nearly square. Calculating the efficiencies of confounded factorial design and incomplete block design revealed that block size may be kept to a minimum. The recovery of interblock information was found useful and balancing may be attempted, but only, if necessary.