Preliminary Study On The Excellent Strains Selection In Pleurotus Ostreatus From Single Spore Cross Breeding

The objectives of this study were to breed new excellent strains of Pleurotus ostreatus by the technique of single spore cross breeding.HP, PG30, JG3 and PG981 were test-strains. Firstly, we cultivated the four strains to fully understand their characteristics.HP was a low temperatural type strain. The color of the cap of its fruit body was purely white during the process of fruit body initiation to maturation, this was a merite. But its yield was low and tastes rough. PG30 was a high temperatural type strain with high yield, but the color of the cap of its fruit body was yellow-white. JG3 tasted good, but the color of its pileus was gray-brown. PG981with very high yield, but its stipe was too long and pileus was gray-black.According to the priciples of selecting crossing-parents and the analysis of characteristics of each tested strain, following crossing combinations had been done: HP×PG30, HP×JG3 and HP×PG981.Useing plate dilution method, we Obtained the total number of colonies of HP, PG30, JG3 and PG981 were 100, 141, 143 and 166. Mycelium were observed under microscope, monokaryons and dikaryons were distinguished by clamp connection. There were no clamp connection in monokaryons, while dikaryons contained. Among these clones, the number of monokaryons of HP, PG30, JG3 and PG981 were100, 94, 73 and 42, respectively.10 monokaryons of each tested strain were randomly selected out for 10×10 hybridization. After the process of crossing, Mycelium of conjunction zone of two monokaryons were observed under microscope, in which the clamp connection were always found in more than one visual fields were primarily determined as hybrids. There were 84, 71 and 79 hybrids from the combinations of HPxPG30, HP×JG3 and HP×PG981 respectively.The mycelium growth rate on complete medium of part of hybridized strains were measured. The results of Duncans comparison showed that there were no differences between hybridized strains so that the growth rate on complete medium was not suitable for taken as an evidence of screening strains.Antagonism test among parts of strains was carried on. Used the parents as controls, the mycelium growth rate in tubes filled with cotton seed shells of all hybrids were measured. On the basis of growth measurement in tubes and antagonism test, about 50, 20 and 20 hybrids from HP×PG30, HP×JG3 and HP×PG981 were selected out for secondly screening by cultivation.Used the four parent strains as controls, 90 hybrization strains together were cultivated. During the process of cultivation, measured the mycelium growth rate in cultivated bags with cotton seed shells, observed color of pileus, recorded agronomic traits such as yield diameter of pileus, stipe length, stipe diameter, lamella length, lamella thickness and so on. After analysed all recorded data, taken yield as a main factor, considered of other agronomic traits, six excellent hybridization strains were selected out, including G32-2, G20-4, G48-3, J30-3, J94-2 and PG68-4, which would further pave way for middle test.