Table 1.
Experimental setup of the four experiments described in M&M.
Fig 1.
Schematic diagram of a cultivation bed for button mushrooms.
The upper layer (grey) consists of casing soil that covers a layer of substrate (brown). At three different heights, iron grids were placed, one between the casing soil and the substrate and the two others at two different depths in the substrate dividing the substrate into three equal layers. On top a schematic visualization of the different crop phases and the upright arrows indicate the time points in the crop phase at which the substrate was sampled for analysis.
Fig 2.
A: Trays used for a short daily interruption of the connection of the casing layer with all of the substrate or part of the substrate from venting up to the formations of pins (5 days, treatments 2, 4 and 6) or from venting up to the harvest of the first flush (10 days, treatments 3, 5 and 7). B: Trays with a sidewise extension of the substrate. The cultivation area (casing soil) is a fixed area and identical to those in A whereas the height of the substrate and length of the sidewise extension varies as indicated.
Fig 3.
The changes in fresh weight (A), moisture content (B) and dry weight (C) of top, middle and lower layer of the substrate during the crop cycle of two flushes. Error bare represent ±1 SD.
Fig 4.
The effect of depth of substrate on the production of mushrooms in two flushes expressed as kg/m2 (A), kg per tonne of substrate (B) and the effect of substrate depth on the quality of mushrooms (C). The quality is expressed as the percentage of the yield of Class I fine + Class I middle of the total yield (all classes). Data are means ± standard deviation. Significance at alpha = 0.05.
Fig 5.
The production profile (left, kg/m2) and the yield per flush and the in-between-flush (right) of the treatments where the connection of the casing soil with all of the substrate (A) or part of the substrate (B) where daily shortly interrupted. Compared to the control with no interruption (Treatment 1), a clear delay of the first picking day is seen when the connection of the casing soil with all of the substrate in interrupted (treatments 2 and 3). No delay in production of flush one is seen when interruptions were done with only part of the substrate (5B). All treatments show a more or less shift from the yield in flush 1 towards flush 2 compared to the control (treatment 1). Error bars represent ± 1 SD.
Fig 6.
A: The short disruption of contact between the casing soil and all or part of the substrate causes shifts in yield from flush one to flush two. This leads to a strong negative correlation between yield in flush one and flush two (Pearson’s Correlation r = -0.847. B&C: The effect of the interruption of the connection between the casing soil with all or part of the substrate on the yield is mainly caused by the change in the number of mushrooms formed in flush one and flush two. A strong correlation is seen between the number of mushrooms and the yield in flush one (Pearson’s Correlation r = 0.881) and in flush two (Pearson’s Correlation r = 0.852).
Fig 7.
The mushroom yield (flush one + two) in the experiments with a sidewise extension of the substrate.
The X-axes represent the amount of substrate underneath the casing soil. A: There is an increase of the yield in two flushes with an increase of the amount of substrate underneath the casing soil. B: There is also a tendency of increasing yield per tonne of substrate with a decreasing of the amount of substrate offered underneath the casing soil. C: As seen before, there is a tendency of a decrease in quality with a decrease in substrate depth (significant differences in fraction quality Class 1 between the two highest and lowest substrate depths (p≤0.01). Error bars represent ± 1 SD.
Fig 8.
Relative laccase activity in the sidewise substrate extensions measured at the peak of flush 1.
The high activities at a distance >20 cm away from the casing soil indicate that beyond this distance the substrate mycelium is not under the influence of fruiting and not involved in feeding mushrooms (the mean difference significant at 0.001 level). Error bars represent ± 1 SD.
Table 2.
Substrate depth, substrate underneath the casing soil (kg/tray) and the total amount of substrate/tray) for all treatments.
Fig 9.
The ergosterol content of the substrate during the crop cycle of two flushes (samples taken from Experiment 1).
Especially the steeper increase during the development of flush one indicates a mycelial growth (probably branching) during the development of this flush which levels of after flush one and remains approximate the same at least until after flush two (the mean difference significant at 0.05 level). Error bars represent ± 1 SD.
Fig 10.
The expression of the major CAZyme genes (A) and their protein concentrations (B) during the crop cycle of two flushes after Pathyshakuliyeva et al. [11]. Expression of genes is expressed in RPKM (Fragments Per Kilobase Million). A clear peak is seen in the gene expressions during flush one which resumes only after flush two. This coincides with the formation of new mycelial biomass in the substrate. The protein concentrations, however, remain fairly high indicating that the enzymes, after secretion, remain active.