Shiitake Mushroom Cultivation: Substrate Logs Rehydration Guide

1. Purpose & Principles of Substrate Logs Rehydration

• Water temperature difference creates thermal stimulation for mycelium
• Rehydration operation provides mechanical stimulation to promote budding
• Short-term low-oxygen environment after water supplementation accelerates primordia formation
• Washes away metabolic waste and residual gas accumulated by mycelium growth
• Replenishes lost moisture to reach the optimal water content for fruiting

2. Optimal Rehydration Timing

• Normally, no rehydration is needed for the first mushroom flush.
• Emergency rehydration is required when substrate moisture content drops below 40% or the log weight decreases by one-third, to avoid poor fruiting and yield loss.

3. Two Common Rehydration Methods & Operation Specifications

3.1 Water Injection Method (Mainstream Method)

• Weather & Temperature: Operate before or after weather changes, ensuring 3-5 consecutive sunny days. Keep temperature within the optimal fruiting range to prevent mycelium death and log rot.
• Water Quality: Use clean water below 16°C, 5°C lower than the log temperature.
• Log Maturity: Only inject water after logs fully mature (firm texture, reddish-brown stem cavities). Premature injection will delay fruiting and cause core rot.
• Weight Standard: Standard 16cm×60cm log weighs 2.5kg originally, 2.1-2.3kg after full mycelium colonization (inject after first flush); inject water in advance if weight drops below 1.9kg.
• Water Volume Control: Rehydrated weight shall not exceed the original weight. First rehydration reaches 85% of original weight; subsequent rehydrations reach 80% of the previous cycle weight (less water is safer than excess).
• Operation Skills: Adopt offset/angled needle insertion; slightly vibrate logs during injection to stimulate budding. Flip logs after injection for even moisture distribution.
• Bag Type Adaptation: Double-layer film bags: high pressure & fast injection, limited water volume (4 needles for first 2 flushes, 8 needles for later flushes); single-layer bags adjust parameters according to water retention.
• Risk Avoidance: Do not repeatedly inject water if no buds grow. Excess water causes hypoxia and rot; drain excess water and punch holes for ventilation if over-injected.
• Cycle Effect: One log can be injected 4-5+ times in the whole growth cycle, with one new flush after each standard injection; buds grow intensively 5-7 days after injection.

3.2 Direct Soaking Method (Traditional Method)

1. Punch 10-15cm deep holes at both ends of logs with No.8 iron wire.
2. Sort logs by moisture loss degree, stack neatly in the rehydration trench.
3. Cover logs with planks and press with heavy stones, then submerge fully in clean water.
4. Check water absorption by cross-cutting logs; white areas indicate incomplete water penetration.