Primordial initiation, yield and yield component traits of two genotypes of oyster mushroom (Pleurotus spp.) as affected by various rates of lime.

Mushrooms are fleshy fungi valued globally for their nutritional and medical benefits. The study was conducted at Ebonyi State University Mushroom Center, Abakaliki, to determine an optimum level of limestone (CaCO) on the genotypes for maximum growth and yield. The experiment was carried out as a split-plot experiment in a completely randomized design (CRD) with the use of Oyster mushroom variety. The two genotypes (GI and GII) were placed in the whole plot while limestone was placed in the sub-plot which consisted of five rates of CaCO(Og,5 g, 10 g, 15 g and 20 g). Sawdust and rice husk substrates were used at the ratio of 60:40 and sterilized for six hours at 121 °C using the steam sterilization cylinder. The media bags were off-loaded after one day and allowed to further cool for another day before inoculation. The cultured spawn was used to inoculate the media upon cooling at room temperature. Data were collected on agro-morphological parameters such as primordial initiation, stalk height, stalk diameter, number of branches, number of fruits, number of productive bags, fresh and dry weights, and subjected to analysis of variance (ANOVA). The result obtained indicated that there was a significant difference (P < 0.05) between the two genotypes studied in all parameters except the dry weight of the mushroom. Also, the various rates of CaCO had a significant difference (P < 0.05) in most agro-morphological traits except stalk diameter, number of fruits and fresh weight. However, the interaction of the whole plot (genotype) and sub-plot (lime rates) showed no significant difference (P > 0.05) in all parameters evaluated except the stalk diameter. Genotype I initiated more primordial compared to primordial initiation in genotype II and they differed significantly (p < 0.05) from each other. More so, the result showed that increasing the rate of CaCO from 0 to 5 g significantly increased the primordial initiation from 17 to 22. However, further increase in lime rates above 5 g significantly reduced the primordial initiation from 22 to 15. It was concluded that the 5 g rate of limestone produced the best primordial initiation. Therefore, genotype I and 5 g of CaCO were recommended. There was also a strong relationship between the primordial initiation and most growth and yield components traits studied. There was a significant positive correlation between primordial initiation and stalk height (r = 0.799*), stalk diameter (r = 0.692*), number of mushroom branches (r = 0.773*), number of productive bags (r = 0.888*), number of fruits (r = 0.810*), fruit weight (r = 0.918*) and dry weight (r = 0.916*). Ideal conditions that would guarantee more primordial initiation for higher yield were recommended.