herbicide: Herbicide efficacy

In smbdata: Data from "Statistical Methods in Biology"

Herbicide efficacy

Description

A factorial experiment was conducted to evaluate the efficacy of three herbicides (Herbicide) across nine different populations of black-grass (Population). Herbicides A and C belong to the same chemical group (Type 1), while herbicide B represents a different group (Type 2). The experiment followed a randomized complete block design with five replicates (Rep), each comprising 27 pots (dummy factor DPot). Six plants were grown per pot, and their combined fresh weight (Fwt, in grams) was measured at the conclusion of the study. The dataset allows investigation of differences in herbicide efficacy both between and within herbicide groups, as well as variation in response among different black-grass populations.

Usage

herbicide

Format

A data frame with 7 variables: ID, Rep, DPot, Population, Type, Herbicide, Fwt.

ID

Factor. Unique identifier for each pot (experimental unit).

Rep

Factor. Block number in the randomized complete block design corresponding to replicate (1–5).

DPot

Factor. Dummy variable indicating the pot number within each block.

Population

Factor. Identifier for the black-grass population (e.g., "P1"–"P9").

Type

Factor. Chemical group of the applied herbicide (1: group for Herbicides A and C, 2: group for Herbicide B).

Herbicide

Factor. Applied herbicide treatment ("A", "B", or "C").

Fwt

Numeric. Total fresh weight (in grams) of six black-grass plants grown in the pot.

Source

Welham, S. J., Gezan, S. A., Clark, S. J., and Mead, A. (2015) Statistical Methods in Biology: Design and analysis of experiments and regression

R. Hull, Rothamsted Research.

Examples

aov(sqrt(Fwt) ~ Herbicide * Population + Error(Rep/DPot), data = herbicide)

smbdata documentation built on Jan. 20, 2026, 5:06 p.m.