culture of c. indica was obtained from the national mushroom development and extension center ( namdec ) , savar , dhaka , bangladesh .
rice bran , maize powder , and wheat bran of different levels ( 10 , 20 , 30 , 40 , and 50% ) were used as supplements , and 0% was used as unsupplemented control .
the substrates were chopped into 3~4 inch lengths . on a dry - weight basis ,
0.2% caco3 and the five different levels of rice bran , maize powder , and wheat bran supplements were added to the chopped substrates and mixed thoroughly .
substrate ( 500 g ) was added to polypropylene bags ( 7  10 inch ) , and the openings of the bags were plugged with cotton and secured with plastic rings .
the bags were autoclaved at 121 and 15 psi for 1 hr , after which they were inoculated with 2 teaspoons of a c. indica mother culture .
the spawn packet was kept in a dark room and incubated at 30~32 for approximately 30 to 35 days .
v / v ) was used as the casing material and was sterilized at 65 for 4 hr .
after mycelial colonization , the mouth of the spawn packet was covered with casing material and maintained with a 3 cm thickness level .
it was then transferred to the culture room and maintained at a temperature of 30~35 and a relative humidity of 70~80% .
the following data were collected ; the number of days required for the initiation of primordia , the number of effective fruiting bodies , length and diameter of the stalk , the diameter and thickness of the pileus , biological yield , economic yield , and biological efficiency .
biological efficiency was measured using the following formula : biological efficiency ( % ) = total biological yield / total substrate used  100
culture of c. indica was obtained from the national mushroom development and extension center ( namdec ) , savar , dhaka , bangladesh .
rice bran , maize powder , and wheat bran of different levels ( 10 , 20 , 30 , 40 , and 50% ) were used as supplements , and 0% was used as unsupplemented control .
, 0.2% caco3 and the five different levels of rice bran , maize powder , and wheat bran supplements were added to the chopped substrates and mixed thoroughly .
substrate ( 500 g ) was added to polypropylene bags ( 7  10 inch ) , and the openings of the bags were plugged with cotton and secured with plastic rings .
the bags were autoclaved at 121 and 15 psi for 1 hr , after which they were inoculated with 2 teaspoons of a c. indica mother culture .
the spawn packet was kept in a dark room and incubated at 30~32 for approximately 30 to 35 days . cow dung and loamy soil ( 3 : 1 ,
v / v ) was used as the casing material and was sterilized at 65 for 4 hr .
after mycelial colonization , the mouth of the spawn packet was covered with casing material and maintained with a 3 cm thickness level .
it was then transferred to the culture room and maintained at a temperature of 30~35 and a relative humidity of 70~80% .
the following data were collected ; the number of days required for the initiation of primordia , the number of effective fruiting bodies , length and diameter of the stalk , the diameter and thickness of the pileus , biological yield , economic yield , and biological efficiency .
biological efficiency was measured using the following formula : biological efficiency ( % ) = total biological yield / total substrate used  100
primordia formation was observed in all experimental sets . the shortest time ( 13.5 days ) for primordia initiation
was recorded in the 40% rice bran supplement , followed by the 20% ( 14.8 days ) , and 10% ( 15.0 days ) wheat bran supplement . the longest time ( 19.3 days )
was recorded in 0% level of unsupplemented control rice straw substrate ( table 1 ) .
the maximum number of effective fruiting bodies was found in the 30% maize powder supplement ( 16.8 ) treatment , followed by the 40% rice bran supplement ( 16.3 ) , which was statistically similar ( table 1 ) .
the results indicate that 30% maize powder supplementation with rice straw substrate was most effective for fruiting body development in c. indica .
patra and pani   reported that the time required for c. indica primordia initiation on rice straw was 13~16 days .
similar findings were also reported by amin et al .   and jiskani et al . .
substrates containing glucose , fructose , and trehalose produced the greatest number of primordia , whereas abnormal fruiting bodies were produced with glycerol , xylose , sucrose , and fructose .
rice bran and maize powder are rich in nutrients , which might have promoted the growth and development of c. indica primordia and fruiting bodies .
the maximum diameter of the pileus ( 7.1 cm ) was obtained with the 30% maize powder supplement , followed by 30% wheat bran ( 6.9 cm ) and 50% rice bran supplements ( 6.6 cm ) .
the highest thickness of the pileus ( 2.4 cm ) was found with 10% wheat bran supplement , followed by 30% wheat bran ( 2.2 cm ) and 10% rice bran supplements ( 2.1 cm ) .
the smallest diameter ( 5.1 cm ) and thickness ( 1.4 cm ) of the pileus was observed in the unsupplemented control set ( table 2 ) .
the maximum diameter of the stalk ( 2.8 cm ) was obtained with 30% maize powder and 40% rice bran supplements , while the longest stalk length ( 10.3 cm ) was recorded with 30% rice bran supplement ( table 3 ) .
the results revealed that 30% maize powder and rice bran supplementation to rice straw substrate was significantly effective for contributing to the yield of c. indica .
these findings are comparable with those of previous studies using c. indica [ 18 , 19 ] .
it is likely that rice straw substrate supplemented with maize powder has a high c : n ratio , which resulted in enhanced development of the pileus .
a significant variation was observed in the different levels of rice bran , maize powder , and wheat bran supplementation to rice straw substrate on biological yield , economic yield , and biological efficiency of c. indica . the maximum biological ( 459.3 g ) and economic yield ( 457.0 g )
was obtained with the 30% maize powder supplement . the lowest biological ( 173.8 g ) and economic yield ( 171.3 g )
the biological efficiency results for the different levels of rice bran , maize powder , and wheat bran supplements are presented in figs .
1 results indicate that the maximum biological efficiency ( 77.8% ) was recorded with 40% rice bran .
the highest biological efficiency ( 91.9 and 78.2% ) was with 30% maize powder and wheat bran supplements ( figs . 2 and 3 ) . increasing the amount of supplement resulted in an increase in biological efficiency up to 30% and then the efficiency decreased again .
such a reduction in efficiency may be due to the compactness or poor aeration of the substrates , which results from insufficient utilization of nutrients
. this may also be due to the limitation of spaces or surfaces for developing fruiting bodies .
the cereal bran and maize powder supplementation promoted the secretion of cellulase(s ) , hemicellulase(s ) , and laccases which involved in the degradation of cellulose , hemicellulose and lignin , respectively [ 22 , 23 ] .
the degraded carbohydrates serve as energy sources for constructing the structural components of the fruiting body . in view of the above
, it can be concluded that the yield , yield contributing characteristics , and biological efficiency in the supplemented sets increased as compared to the unsupplemented control set , whereas a reduced yield was noted in the higher levels of supplements .
the 30% maize powder supplement was the best supplement of rice straw substrate for cultivating milky white mushroom .
primordia formation was observed in all experimental sets . the shortest time ( 13.5 days ) for primordia initiation
was recorded in the 40% rice bran supplement , followed by the 20% ( 14.8 days ) , and 10% ( 15.0 days ) wheat bran supplement . the longest time ( 19.3 days )
was recorded in 0% level of unsupplemented control rice straw substrate ( table 1 ) .
the maximum number of effective fruiting bodies was found in the 30% maize powder supplement ( 16.8 ) treatment , followed by the 40% rice bran supplement ( 16.3 ) , which was statistically similar ( table 1 ) .
the results indicate that 30% maize powder supplementation with rice straw substrate was most effective for fruiting body development in c. indica .
patra and pani   reported that the time required for c. indica primordia initiation on rice straw was 13~16 days .
similar findings were also reported by amin et al .   and jiskani et al . .
substrates containing glucose , fructose , and trehalose produced the greatest number of primordia , whereas abnormal fruiting bodies were produced with glycerol , xylose , sucrose , and fructose .
rice bran and maize powder are rich in nutrients , which might have promoted the growth and development of c. indica primordia and fruiting bodies .
the maximum diameter of the pileus ( 7.1 cm ) was obtained with the 30% maize powder supplement , followed by 30% wheat bran ( 6.9 cm ) and 50% rice bran supplements ( 6.6 cm ) .
the highest thickness of the pileus ( 2.4 cm ) was found with 10% wheat bran supplement , followed by 30% wheat bran ( 2.2 cm ) and 10% rice bran supplements ( 2.1 cm ) .
the smallest diameter ( 5.1 cm ) and thickness ( 1.4 cm ) of the pileus was observed in the unsupplemented control set ( table 2 ) .
the maximum diameter of the stalk ( 2.8 cm ) was obtained with 30% maize powder and 40% rice bran supplements , while the longest stalk length ( 10.3 cm ) was recorded with 30% rice bran supplement ( table 3 ) .
the results revealed that 30% maize powder and rice bran supplementation to rice straw substrate was significantly effective for contributing to the yield of c. indica .
these findings are comparable with those of previous studies using c. indica [ 18 , 19 ] .
it is likely that rice straw substrate supplemented with maize powder has a high c : n ratio , which resulted in enhanced development of the pileus .
a significant variation was observed in the different levels of rice bran , maize powder , and wheat bran supplementation to rice straw substrate on biological yield , economic yield , and biological efficiency of c. indica . the maximum biological ( 459.3 g ) and economic yield ( 457.0 g )
was obtained with the 30% maize powder supplement . the lowest biological ( 173.8 g ) and economic yield ( 171.3 g )
the biological efficiency results for the different levels of rice bran , maize powder , and wheat bran supplements are presented in figs .
1 results indicate that the maximum biological efficiency ( 77.8% ) was recorded with 40% rice bran .
the highest biological efficiency ( 91.9 and 78.2% ) was with 30% maize powder and wheat bran supplements ( figs . 2 and 3 ) . increasing the amount of supplement resulted in an increase in biological efficiency up to 30% and then the efficiency decreased again .
such a reduction in efficiency may be due to the compactness or poor aeration of the substrates , which results from insufficient utilization of nutrients .
this may also be due to the limitation of spaces or surfaces for developing fruiting bodies .
the cereal bran and maize powder supplementation promoted the secretion of cellulase(s ) , hemicellulase(s ) , and laccases which involved in the degradation of cellulose , hemicellulose and lignin , respectively [ 22 , 23 ] .
the degraded carbohydrates serve as energy sources for constructing the structural components of the fruiting body . in view of the above
, it can be concluded that the yield , yield contributing characteristics , and biological efficiency in the supplemented sets increased as compared to the unsupplemented control set , whereas a reduced yield was noted in the higher levels of supplements .
the 30% maize powder supplement was the best supplement of rice straw substrate for cultivating milky white mushroom .
 calocybe indica , known as milky white mushroom , grows and cultivated in the sub - tropical and temperate zones of south asia . 
 we investigated the most suitable supplements and their levels for the commercial cultivation of milky white mushroom . 
 rice bran , maize powder , and wheat bran with their different levels ( 10 , 20 , 30 , 40 , and 50% ) were used as supplements to evaluate the yield and yield contributing characteristics of c. indica . 
 primordia initiation was observed between 13.5 and 19.3 days . 
 the results indicated that the 30% maize powder supplement was effective for producing viable fruiting bodies . 
 the maximum diameters of the pileus and stalk were observed with 30% maize powder . 
 the highest biological and economic yield and biological efficiency were also obtained with 30% maize powder as a supplement . 
 the results indicate that increasing the supplement level resulted in less biological efficiency , and that 30% maize powder was the best supplement level for rice straw substrate to cultivate milky white mushrooms . 
Materials and Methods
Mushroom strain and supplements
Preparation of spawn and casing material
Experimental design
Results and Discussion
Effect of supplements on primordia initiation and the number of effective fruiting bodies
Effect of supplements on yield-contributing characteristics
Effect of supplements on biological yield, economic yield, and biological efficiency