Effects of environmental factors on bruising sensitivity of button mushrooms (Agaricus bisporus)

White button mushrooms are fragile and discolor soon after mechanical bruising. This hampers the development of mechanical harvesting for button mushrooms and causes loss of postharvest quality. The extent of discoloration can be affected by environmental conditions. A factorial design analysis was conducted to screen the effect of factors influencing the bruising sensitivity of button mushrooms, and to find out a combination of environmental factors generating the largest variation among bruising sensitive and bruising resistant strains. In this way a maximal variation of the trait ‘bruising sensitivity’ can be induced in segregating populations intended to map this trait. Three environmental factors were investigated on four genotypes (strains), i.e., thickness of the casing layer (2.5cm and 5cm), wetness of casing (dry and normal), and relative humidity in the growing room (80% and 87%). Analysis of variance (ANOVA) showed that genotype (strain) was a significant factor influencing bruising sensitivity as well as casing thickness. Significant factor interaction effects were observed. The factor combination generating the largest difference in bruising sensitivity between the four strains was identified, i.e., a thickness of the casing layer of 5cm, normal humidity of the casing, and 87% for relative humidity in the growing room.