A Clustering-based Test for Nonadditivity in an Unreplicated Two-way Layout

Installation of hedgerows around greenhouses to encourage biological pest control: Farmers' perspectives from Southeast Spain

The intensification of agriculture has led to the deterioration of various ecosystem services, including pest control. The installation of hedgerows around greenhouses is presented as a viable option to maintain and favour natural enemies of pests. Despite the economic and environmental advantages of this type of facility, farmers are reluctant to implement it. Therefore, it is necessary to determine the factors that influence the decision to install hedgerows and the most appropriate incentives to promote their establishment. This article analyses intensive agriculture in Southeastern Spain. The application of cluster analysis techniques allowed the detection of four types of farmers in relation to this practice. The factors that drive its installation are an increase in the effectiveness of biological control, a reduction in the use of pesticides and the possible economic and environmental benefits. As a barrier, a lack of knowledge of and confidence in the effectiveness of this practice stand out. Among the measures to encourage their installation, the most valued are training and advice and recurring payments for the ecosystem services generated. The results obtained can be useful for policy makers in regions in which the installation of non-crop vegetation is promoted.

Stability of Hybrid Maize Reaction to Gibberella Ear Rot and Deoxynivalenol Contamination of Grain

Trials were conducted to quantify the stability (or lack of G × E interaction) of 15 maize hybrids to Gibberella ear rot (GER; caused by Fusarium graminearum) and deoxynivalenol (DON) contamination of grain across 30 Ohio environments (3 years × 10 locations). In each environment, one plot of each hybrid was planted and 10 ears per plot were inoculated via the silk channel. GER severity (proportion of ear area diseased) and DON contamination of grain (ppm) were quantified. Multiple rank-based methods, including Kendall's concordance coefficient (W) and Piepho's U, were used to quantify hybrid stability. The results found insufficient evidence to suggest crossover G × E interaction of ranks, with W greater than zero for GER (W = 0.28) and DON (W = 0.26), and U not statistically significant for either variable (P > 0.20). Linear mixed models (LMMs) were also used to quantify hybrid stability, accounting for crossover or noncrossover G × E interaction of transformed observed data. Based on information criteria and likelihood ratio tests for GER and DON response variables, the models with more complex variance-covariance structures-heterogeneous compound symmetry and factor-analytic-provided a better fit than the model with the simpler compound symmetry structure, indicating that one or more hybrids differed in stability. Overall, hybrids were stable based on rank-based methods, which indicated a lack of crossover G × E interaction, but the LMMs identified a few hybrids that were sensitive to environment. Resistant hybrids were generally more stable than susceptible hybrids.