Optimal plot size in lettuce seed germination experiments

Abstract

Lettuce in works under controlled conditions is widely used in experiments with a direct focus on the species itself, or as an indicator species used in allelopathy works. But despite its frequent use, there is no support in the literature for using a single plot size and, therefore, there are works from the use of 5 to 100 seeds per experimental plot. It is understood that the works have been developed using different experimental precisions. The low experimental precision caused by a smaller-than-optimal plot size can lead to a high residual value in the analysis of variance and consequent difficulties in detecting statistical difference between treatments. On the other hand, the use of a high number of seeds per plot can lead to unnecessary expenditure and does not contribute to improving experimental precision. The objective of this work was to determine the optimal plot size in seed germination experiments under controlled conditions. The modified maximum curvature method according to Meier and Lessman was used. After the subsequent analysis, the high variations between different sizes and the factors that can be interfered because of this were observed, and the optimal plot size was defined as six seeds for the biogerminative test of lettuce by petri dishes of 10 cm in diameter.