放置外源营养袋时期对六妹羊肚菌菌核诱导、原基分化及产量的影响

Abstract

[Objective] Exogenous nutrient bag (ENB) application is the core technique for stable and high yield in field cultivation of morels, and its placement timing directly affects nutrient uptake, transformation and storage by soil mycelia. To determine the optimal placement timing of ENB for Morchella sextelata cultivated in winter in South China, [Method] a single-factor experiment was conducted with five placement timings (5, 10, 15, 20 and 25 d after sowing), taking no ENB placement as the control (CK). Mycelial growth, ENB colonization and contamination, sclerotium formation, primordium differentiation and yield traits were systematically measured. [Result] The occurrence time of conidial "frost" did not differ significantly among treatments. ENBs placed 10 d after sowing (T2) showed the shortest full-colonization time (9.3 d), the lowest contamination rate (2.7%) and the highest substrate weight loss (58.6%); sclerotial density and fresh weight reached 93.7 sclerotia/m² and 21.3 g/m², significantly higher than those of other treatments (P<0.05). Primordium density (428/m²), primordium survival rate (42.5%) and effective primordium number (181.9/m²) of T2 all ranked first; the yield of T2 reached 305.2 kg/667 m², which was 269.5% higher than CK and 104.6% higher than the latest placement (T5). Sclerotial density was extremely significantly and positively correlated with primordium density and yield (r=0.995 and 0.993, P<0.01). Placing ENBs too early (5 d) resulted in a contamination rate as high as 12.3%, whereas placing too late (20-25 d) sharply reduced sclerotium formation; both led to significant yield loss. [Conclusion] For winter cultivation of M. sextelata in South China, ENBs should be placed about 10 d after sowing, at the peak stage of conidial frost formation; in practice, mycelial vigor on the bed surface rather than the calendar date should be taken as the primary criterion, so as to avoid aggravated contamination or insufficient sclerotium formation caused by premature or delayed placement.