- Email: [email protected]
Can Edible Mushrooms Promote Sustainability in Beijing?
Mycological Research News for studies of infraspecific variability within the fungus (pp. 808–814). The polygalacturonases secreted by Botrytis cinerea have been analysed, with at least four isozymes being found in the strains studied which varied markedly in their isoelectric points ; the protocols developed are expected to be of value in further studies of these enzymes (pp. 827–831). Molecular methods also have major potential in elucidating aspects of fungal ecology. Here, dark septate endophytes occurring on 81.7 % of root segments in a spruce (Picea abies) stand in Switzerland, were found using ISSR-PCR fingerprinting to represent 21 types – six of which belonged to Phialocephala fortinii (pp. 832–840).
754 Three papers concern newly discovered fungi. A new genus of Harpellales with two new species has been discovered in the hindgut of mayfly nymphs in Spain (pp. 841–846). Two new plant pathogens are reported. First, the causal agent of a leaf-blight of Ipomoea longipedata in Mexico is described as a new species of Phytophthora based on morphological, allozyme, mtDNA, haplotype and rDNA sequence data (pp. 847– 855). Secondly, the cause of a patch disease of buffalo grass, Stenotaphrum secundatum, in Australia, is found to be a new species of Gaeumannomyces which is distinguished from G. graminis by cultural characters, ascospore size, and host range in glasshouse experiments (pp. 856–861).
DOI: 10.1017/S0953756202226647
C A N E D I BL E M U S H R O O M S P R O M O T E S U S T A I N A B I L I T Y I N B EI J I N G ? In mainland China, the annual production of crop straw and tree branches amounts to 0.6 Bn tonnes (Yang 1988) ; Beijing alone produces 3 M tonnes. These agricultural and forestry by-products (75–80 %) are exploited as feed for cattle and sheep, as compost, and as fuel by farmers. The remaining 20–25 % is burnt, constituting a gross wastage of resources and generating environmental pollutants. Smog ensues from the burning of straw in the harvesting seasons, and interferes with the taking off and landing of aeroplanes when visibility is severely affected. Employing crop straw to cultivate edible mushrooms is an efficacious way of salvaging and utilizing branches. Edible mushrooms are much more prolific, and have a heightened biological efficiency in comparison with many plants. The annual yield of protein by the button mushroom Agaricus bisporus is 22 tonnes hax1, and the mushroom can be directly consumed. In contrast, the corresponding yield of protein for most plants is only 1–2 tonnes hax1 yrx1 (Yang 1988, Zhang 2000). Edible mushrooms are not only delicious, but also endowed with a high nutritive value and have important medicinal attributes, including anticancer, immunoenhancing, antidiabetic and hypolipidemic activities (Chang & Buswell 1996). The national production of edible mushrooms in China was 4 M tonnes in 1998, rising quickly to 6.6 M tonnes in 2000. Taking a mean biological efficiency of 30% for various edible mushrooms, the crop straw used for cultivating edible mushrooms in 2000 comprised only 3.68 % of the total quantity of crop straw available. Hence, there is a tremendous potential for development (Chang & Buswell 1996, Chang & Miles 1989, Breene 1990, Wang et al. 1995). During the triennium 1998– 2000, the Science Committee of Wu An City, Hebei Province, in mainland China, and we jointly undertook a collaborative research project ‘Development and utilization of a new culture medium for edible mushrooms ’. Full use was made of the crop straw and tree
branches trimmed off in orchards to develop a new cultivation medium for edible mushrooms. The results were encouraging. The cost of production was lowered by 15–20 %, and the quality and quantity of the edible mushrooms produced were slightly enhanced or comparable to those obtained by conventional cultivation media. After 3 years, the efficiency of the cultivation of edible mushrooms to transform agricultural straw increased from 2.5 % to 10 %. This significantly cut the amount of crop straw that remained. If the amount of edible mushrooms cultivated is taken into account, the rate of transformation can reach 20 %, and this will alleviate the problem of environmental pollution in Wu An City arising from the burning of crop straw and tree branches. In recent years, consequent upon the excessive usage of chemical fertilizers, the content of the carcinogen nitrite (NO2x) in crops greatly exceeded the recommended safety level (First Editorial Office 1998). According to information from the Vegetable Research Institute of Wu An City, the content of nitrite in Chinese cabbage exceeded by 30-fold the safety level in the national regulatory standard. The application of organic fertilizers and the development of green agriculture or organic agriculture are shaping the current trend of development of agriculture. The use of chemical fertilizers and chemicals is strictly prohibited in organic agriculture. Nevertheless, owing to the obvious efficacy and ease of applying chemical fertilizers, farmers are reluctant to produce and use organic fertilizers in agricultural production. Based on an analysis by the China Agricultural University, the content of organic matter (%N, %P2O5, and %K2O) remaining after the production of edible mushrooms is over 10%. Other indices reached or surpassed those of human, pig manure and cow manure (Table 1). Mushroom compost can thus form an organic fertilizer of a desirable calibre (First Editorial Office 1998). The cultivation of edible mushrooms will thus
Mycological Research News
755
Table 1. Analysis of the fertilizer value of compost from the edible mushroom Pleurotus ostreatus (First Editorial Office 1998).
Pleurotus compost Human manure and urine Pig manure Cow manure
N (%)
P2O5 ( %)
K2O ( %)
1.70 0.60 0.60 0.59
0.61 0.16 0.60 0.28
1.13 0.30 0.50 0.14
concomitantly produce enormous amounts of organic fertilizers. The nitrite level in crops grown with the use of organic fertilizers would be minimized, and at least some consumers would be willing to pay a little more for a safer product. Thus, development of the edible mushroom enterprise is likely to bring wealth, curtail the quantity of residual crop straw, and accelerate the development of organic agriculture. In 2001, the productivity of edible mushrooms in China was 6.6 M tonnes, more than 60% of the world’s production. The amount of straw used was 22 M tonnes (calculated by the method of Yang 1988). The weight of raw material was reduced by about half after harvesting the mushrooms, yielding 11 M tonnes of dried mushroom compost. Except for a minor quantity of mushroom compost to be further processed and utilized, the bulk is used as a high-quality organic fertilizer in agriculture. The nitrogen content of mushroom compost is 1.7 %, amounting to 0.19 M tonnes of nitrogen in 11 M tonnes of compost ; this is equivalent to the nitrogen content of 0.41 M tonnes of urea, sufficient for 1.1 M ha of land in one growing season (Wang 1994, Xin & Chang 1993). Figuratively, edible mushrooms represent a stone to kill three birds : edible mushroom production ; diminution of unused crop straw and minimization of environmental pollution arising from burning ; and production of organic fertilizer and the promotion of organic agriculture. When the size and importance of the ‘birds ’ are compared, there is an increase in size and importance from the first to the third. The production of edible mushrooms in Beijing was only 5 tonnes in 1980. It underwent a dramatic increase to 3500 tonnes in 1990, and further escalated to 8201 tonnes in 1996 ; the mean annual growth rate for edible mushroom production from 1990 to 1996 was 15% (data presented at the Annual Meeting on Edible Fungi, Beijing, 20 March 2001). The production of edible mushrooms in Beijing was respectively 9000, 12 035, 18 577 and 22 000 tonnes in each year of the 1997–2000 period, with annual growth rates of 9.7 %, 33.7 %, 54.4 % and 18.4 % respectively, and a mean of 29 % (data presented at the same meeting). Only 2.4 % of the total amount of crop straw was used for cultivation of edible mushrooms in Beijing in 2000, slightly below the mean national level (Chen 1991). An extensive development of the edible mushroom enterprise and utilization of the market opportunities in Beijing would achieve much more than making farmers richer (Yang 1988, Chang & Miles 1989) :
grocery baskets would be packed with more variety, crop residues would be diminished, and organic agriculture would be promoted. This would go hand in glove with the ongoing ‘blue-sky-and-clean-water ’ project which works towards an unpolluted environment and concurs with the concept of a Green Olympics in Beijing in 2008. If we set a goal that by that date, the use of crop straw for the cultivation of edible mushrooms will involve 20 % of the total quantity of straw, there will be no straw left over and environmental pollution attributed to its burning will be history. To attain this target, the annual growth rate of edible mushroom production will necessarily be 30% [2.4* (1+0.3)8=19.58]. If the growth rate is 25% or 20%, this would involve 14 % and 10 % respectively of the total amount of crop straw by 2008. To realize our objective, the total production of edible mushrooms in 2008 in Beijing will have to reach 0.18 M tonnes (Table 2), an 8-fold increase on production in 2000. Assuming 30 % of the mushrooms are exported and that 70 % are for domestic consumption, and anticipating that the population in Beijing will grow to 15 M by that time, the annual consumption of edible mushrooms by a Beijing resident would need to be 8.35 kg. This figure is by no means high, being the current consumption of edible mushrooms by a resident of Hong Kong (data from the Society on the Study of Edible Fungi, Beijing). In producing 22 000 tonnes of mushrooms in Beijing in 2000, 73 000 tonnes of crop straw were used, producing 37 000 tonnes of dried mushroom compost with a nitrogen content of 620 tonnes (equivalent to the nitrogen content in 1360 tonnes of urea). This amount can meet the nitrogen requirement (Wang 1994, Xin & Chang 1997) of 3600 ha of farmland in one growing season. If the production of edible mushrooms reaches 0.18 M tonnes in 2008, the total amount of crop straw utilized will be 0.58 M tonnes. The nitrogen content of 0.3 M tonnes of dried mushroom compost is equivalent to the nitrogen content of 11 000 tonnes of urea, which can meet the nitrogen requirement of 29 500 ha of farmland in one season. In the last few years, the annual growth rate of the production of edible mushroom was 29%. So, while maintaining and slightly augmenting such a growth rate is by no means an easy task, with a concerted effort this can be accomplished. Edible mushrooms are delicacies and at the same time can be used to promote health and provide more sustainable and environmentally acceptable conditions in cities. Mushrooms can be cultivated on a variety of agricultural wastes (Philippoussis, Zervakis & Diamantopoulou 2001) and the practice cannot be too highly recommended for densely populated developing countries in general. It has also resulted in higher levels of employment in India (Behera & Mahapatra 1999). If the targets suggested for Beijing can be realized, this will hold out great hope for people in many other cities and countries.
Mycological Research News
756
Table 2. Production of edible mushrooms in Beijing in recent years and extrapolation for 2008.
1996 1997 1998 1999 2000 a
Production
Growth rate ( %)a
8201 9000 12 035 18 577 22 000
9.74 33.72 54.36 18.43
Predicted production in 2008 (tonnes)
Growth rate required ( %)
Crop branch utilization rate ( %)
9.5 13.1 17.9
20 25 30
10.3 14.3 19.6
Mean growth rate during the 1996–2000 period was 29.06%.
We thank Christine Chung and Fion Yung for expert secretarial assistance.
Behera, U. K. & Mahapatra, I. C. (1999) Income and employment generation for small and marginal farmers through integrated farming systems. Indian Journal of Agronomy 44 : 431–439. Breene, W. M. (1990) Nutritional and medicinal value of speciality mushrooms. Journal of Food Protection 53: 883–894. Chang, S. T. & Buswell, J. A. (1996) Mushroom nutriceuticals. World Journal of Microbiology and Biotechnology 12: 473–476. Chang, S. T. & Miles, P. G. (1989) Introduction to mushroom science. In Edible Mushrooms and their Cultivation (S. T. Chang & P. G. Miles, eds): 3–25. CRC Press, Boca Raton. Chen, W. L. (1991) New changes in production of edible mushrooms in Beijing. Letters of Chinese Edible Fungi 11 : 3–4. First Editorial Office (1998) Review of Chinese Agriculture: Soil Fertilizers. China Standard Press, Beijing. First Editorial Office (1999) Standard Review of Chinese Food Industry: fruits, vegetables and their products. China Standard Press, Beijing. Philippoussis, A., Zervakis, G. & Diamantopoulou, P. (2001) Bioconversion of agricultural lignocellulosic wastes through the cultivation of the edible mushrooms Agrocybe aegerita, Volvarialla volvacea and Pleurotus spp. World Journal of Microbiology and Biotechnology 17: 191–200. Wang, H. X., Liu, W. K., Ng, T., Ooi, V. E. C. & Chang, S. T. (1995) The immunomodulatory and antitumor activities of a
polysaccharide-peptide complex from a mycelial culture of Tricholoma sp., a local edible mushroom. Life Sciences 57: 269–281. Wang, W. M. (1994) Technology of fertilization in arid areas in north China. In Agricultural Technology in Arid Areas in North China (J. Q. He, ed.): 82–94. Chinese Agriculture Press, Beijing. Xin, N. Q. & Chang, X. L. (1993) Experimental area of half-moisture and aridity in Shan Xi Province. In Technology for Integrated Increased Agricultural Production in Different Types of Arid Areas in North China (F. Zhang, ed.) : 121–129. Chinese Agriculture Press, Beijing. Yang, X. M. (1988) Introduction. In Methods for Cultivation of Edible Mushrooms in China (P. G. Zhao, ed.): 1–19. Chinese Agriculture Press, Beijing. Zhang, G. Y. (2000) Production of edible mushrooms in Mainland China in the year 1998. Chinese Edible Fungi 19 : 2.
Suyue Zheng1, Qinghong Liu1, Hexiang Wang1 and T. B. Ng2 1
Department of Microbiology, College of Biological Science, China Agricultural University, Beijing, People’s Republic of China. 2 Department of Biochemistry, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong S. A. R., People’s Republic of China. E-mail: [email protected]
DOI: 10.1017/S0953756202236643
MYCORRHIZAL FUNGI INCREASE AVAILABLE CALCIUM The ecological role of fungi in the breakdown of complex minerals in soil and on rock surfaces has been increasingly recognized. Now, studies at the Hubbard Brook experimental forest in New Hampshire (USA) have shown that mycorrhizal fungi can increase the available calcium in base-poor forest ecosystems. Blum et al. (2002) examined digests of soil minerals from the forests and found apatite, i.e. calcium phosphate, to be particularly abundant. They then studied the sources of calcium in the forest ecosystem using Ca/Sr and 87 Sr/86Sr ratios. Foliage had higher Ca/Sr ratios than those in the soil suggesting some preferential take-up by the trees. The same result did not occur with trees growing on soils lacking apatite. The authors consider
that the most probable source of the calcium is apatite, and that its release is a direct action of mycorrhizal weathering of the mineral. They also estimate that y35% of calcium in stream water comes from apatite breakdown. This suggests that the enhanced apatite breakdown by mycorrhizal fungi is of major ecological importance, especially in forest soils where the available calcium has been depleted by the effects of acid rain. Blum, J. D., Klaue, A., Nezat, C. A., Driscoll, C. T., Johnson, C. E., Siccama, T. G., Eagar, C., Fahey, T. J. & Likens, G. E. (2002) Mycorrhizal weathering of apatite as an important calcium source in base-poor forest ecosystems. Nature 417: 729–731.
754 Three papers concern newly discovered fungi. A new genus of Harpellales with two new species has been discovered in the hindgut of mayfly nymphs in Spain (pp. 841–846). Two new plant pathogens are reported. First, the causal agent of a leaf-blight of Ipomoea longipedata in Mexico is described as a new species of Phytophthora based on morphological, allozyme, mtDNA, haplotype and rDNA sequence data (pp. 847– 855). Secondly, the cause of a patch disease of buffalo grass, Stenotaphrum secundatum, in Australia, is found to be a new species of Gaeumannomyces which is distinguished from G. graminis by cultural characters, ascospore size, and host range in glasshouse experiments (pp. 856–861).
DOI: 10.1017/S0953756202226647
C A N E D I BL E M U S H R O O M S P R O M O T E S U S T A I N A B I L I T Y I N B EI J I N G ? In mainland China, the annual production of crop straw and tree branches amounts to 0.6 Bn tonnes (Yang 1988) ; Beijing alone produces 3 M tonnes. These agricultural and forestry by-products (75–80 %) are exploited as feed for cattle and sheep, as compost, and as fuel by farmers. The remaining 20–25 % is burnt, constituting a gross wastage of resources and generating environmental pollutants. Smog ensues from the burning of straw in the harvesting seasons, and interferes with the taking off and landing of aeroplanes when visibility is severely affected. Employing crop straw to cultivate edible mushrooms is an efficacious way of salvaging and utilizing branches. Edible mushrooms are much more prolific, and have a heightened biological efficiency in comparison with many plants. The annual yield of protein by the button mushroom Agaricus bisporus is 22 tonnes hax1, and the mushroom can be directly consumed. In contrast, the corresponding yield of protein for most plants is only 1–2 tonnes hax1 yrx1 (Yang 1988, Zhang 2000). Edible mushrooms are not only delicious, but also endowed with a high nutritive value and have important medicinal attributes, including anticancer, immunoenhancing, antidiabetic and hypolipidemic activities (Chang & Buswell 1996). The national production of edible mushrooms in China was 4 M tonnes in 1998, rising quickly to 6.6 M tonnes in 2000. Taking a mean biological efficiency of 30% for various edible mushrooms, the crop straw used for cultivating edible mushrooms in 2000 comprised only 3.68 % of the total quantity of crop straw available. Hence, there is a tremendous potential for development (Chang & Buswell 1996, Chang & Miles 1989, Breene 1990, Wang et al. 1995). During the triennium 1998– 2000, the Science Committee of Wu An City, Hebei Province, in mainland China, and we jointly undertook a collaborative research project ‘Development and utilization of a new culture medium for edible mushrooms ’. Full use was made of the crop straw and tree
branches trimmed off in orchards to develop a new cultivation medium for edible mushrooms. The results were encouraging. The cost of production was lowered by 15–20 %, and the quality and quantity of the edible mushrooms produced were slightly enhanced or comparable to those obtained by conventional cultivation media. After 3 years, the efficiency of the cultivation of edible mushrooms to transform agricultural straw increased from 2.5 % to 10 %. This significantly cut the amount of crop straw that remained. If the amount of edible mushrooms cultivated is taken into account, the rate of transformation can reach 20 %, and this will alleviate the problem of environmental pollution in Wu An City arising from the burning of crop straw and tree branches. In recent years, consequent upon the excessive usage of chemical fertilizers, the content of the carcinogen nitrite (NO2x) in crops greatly exceeded the recommended safety level (First Editorial Office 1998). According to information from the Vegetable Research Institute of Wu An City, the content of nitrite in Chinese cabbage exceeded by 30-fold the safety level in the national regulatory standard. The application of organic fertilizers and the development of green agriculture or organic agriculture are shaping the current trend of development of agriculture. The use of chemical fertilizers and chemicals is strictly prohibited in organic agriculture. Nevertheless, owing to the obvious efficacy and ease of applying chemical fertilizers, farmers are reluctant to produce and use organic fertilizers in agricultural production. Based on an analysis by the China Agricultural University, the content of organic matter (%N, %P2O5, and %K2O) remaining after the production of edible mushrooms is over 10%. Other indices reached or surpassed those of human, pig manure and cow manure (Table 1). Mushroom compost can thus form an organic fertilizer of a desirable calibre (First Editorial Office 1998). The cultivation of edible mushrooms will thus
Mycological Research News
755
Table 1. Analysis of the fertilizer value of compost from the edible mushroom Pleurotus ostreatus (First Editorial Office 1998).
Pleurotus compost Human manure and urine Pig manure Cow manure
N (%)
P2O5 ( %)
K2O ( %)
1.70 0.60 0.60 0.59
0.61 0.16 0.60 0.28
1.13 0.30 0.50 0.14
concomitantly produce enormous amounts of organic fertilizers. The nitrite level in crops grown with the use of organic fertilizers would be minimized, and at least some consumers would be willing to pay a little more for a safer product. Thus, development of the edible mushroom enterprise is likely to bring wealth, curtail the quantity of residual crop straw, and accelerate the development of organic agriculture. In 2001, the productivity of edible mushrooms in China was 6.6 M tonnes, more than 60% of the world’s production. The amount of straw used was 22 M tonnes (calculated by the method of Yang 1988). The weight of raw material was reduced by about half after harvesting the mushrooms, yielding 11 M tonnes of dried mushroom compost. Except for a minor quantity of mushroom compost to be further processed and utilized, the bulk is used as a high-quality organic fertilizer in agriculture. The nitrogen content of mushroom compost is 1.7 %, amounting to 0.19 M tonnes of nitrogen in 11 M tonnes of compost ; this is equivalent to the nitrogen content of 0.41 M tonnes of urea, sufficient for 1.1 M ha of land in one growing season (Wang 1994, Xin & Chang 1993). Figuratively, edible mushrooms represent a stone to kill three birds : edible mushroom production ; diminution of unused crop straw and minimization of environmental pollution arising from burning ; and production of organic fertilizer and the promotion of organic agriculture. When the size and importance of the ‘birds ’ are compared, there is an increase in size and importance from the first to the third. The production of edible mushrooms in Beijing was only 5 tonnes in 1980. It underwent a dramatic increase to 3500 tonnes in 1990, and further escalated to 8201 tonnes in 1996 ; the mean annual growth rate for edible mushroom production from 1990 to 1996 was 15% (data presented at the Annual Meeting on Edible Fungi, Beijing, 20 March 2001). The production of edible mushrooms in Beijing was respectively 9000, 12 035, 18 577 and 22 000 tonnes in each year of the 1997–2000 period, with annual growth rates of 9.7 %, 33.7 %, 54.4 % and 18.4 % respectively, and a mean of 29 % (data presented at the same meeting). Only 2.4 % of the total amount of crop straw was used for cultivation of edible mushrooms in Beijing in 2000, slightly below the mean national level (Chen 1991). An extensive development of the edible mushroom enterprise and utilization of the market opportunities in Beijing would achieve much more than making farmers richer (Yang 1988, Chang & Miles 1989) :
grocery baskets would be packed with more variety, crop residues would be diminished, and organic agriculture would be promoted. This would go hand in glove with the ongoing ‘blue-sky-and-clean-water ’ project which works towards an unpolluted environment and concurs with the concept of a Green Olympics in Beijing in 2008. If we set a goal that by that date, the use of crop straw for the cultivation of edible mushrooms will involve 20 % of the total quantity of straw, there will be no straw left over and environmental pollution attributed to its burning will be history. To attain this target, the annual growth rate of edible mushroom production will necessarily be 30% [2.4* (1+0.3)8=19.58]. If the growth rate is 25% or 20%, this would involve 14 % and 10 % respectively of the total amount of crop straw by 2008. To realize our objective, the total production of edible mushrooms in 2008 in Beijing will have to reach 0.18 M tonnes (Table 2), an 8-fold increase on production in 2000. Assuming 30 % of the mushrooms are exported and that 70 % are for domestic consumption, and anticipating that the population in Beijing will grow to 15 M by that time, the annual consumption of edible mushrooms by a Beijing resident would need to be 8.35 kg. This figure is by no means high, being the current consumption of edible mushrooms by a resident of Hong Kong (data from the Society on the Study of Edible Fungi, Beijing). In producing 22 000 tonnes of mushrooms in Beijing in 2000, 73 000 tonnes of crop straw were used, producing 37 000 tonnes of dried mushroom compost with a nitrogen content of 620 tonnes (equivalent to the nitrogen content in 1360 tonnes of urea). This amount can meet the nitrogen requirement (Wang 1994, Xin & Chang 1997) of 3600 ha of farmland in one growing season. If the production of edible mushrooms reaches 0.18 M tonnes in 2008, the total amount of crop straw utilized will be 0.58 M tonnes. The nitrogen content of 0.3 M tonnes of dried mushroom compost is equivalent to the nitrogen content of 11 000 tonnes of urea, which can meet the nitrogen requirement of 29 500 ha of farmland in one season. In the last few years, the annual growth rate of the production of edible mushroom was 29%. So, while maintaining and slightly augmenting such a growth rate is by no means an easy task, with a concerted effort this can be accomplished. Edible mushrooms are delicacies and at the same time can be used to promote health and provide more sustainable and environmentally acceptable conditions in cities. Mushrooms can be cultivated on a variety of agricultural wastes (Philippoussis, Zervakis & Diamantopoulou 2001) and the practice cannot be too highly recommended for densely populated developing countries in general. It has also resulted in higher levels of employment in India (Behera & Mahapatra 1999). If the targets suggested for Beijing can be realized, this will hold out great hope for people in many other cities and countries.
Mycological Research News
756
Table 2. Production of edible mushrooms in Beijing in recent years and extrapolation for 2008.
1996 1997 1998 1999 2000 a
Production
Growth rate ( %)a
8201 9000 12 035 18 577 22 000
9.74 33.72 54.36 18.43
Predicted production in 2008 (tonnes)
Growth rate required ( %)
Crop branch utilization rate ( %)
9.5 13.1 17.9
20 25 30
10.3 14.3 19.6
Mean growth rate during the 1996–2000 period was 29.06%.
We thank Christine Chung and Fion Yung for expert secretarial assistance.
Behera, U. K. & Mahapatra, I. C. (1999) Income and employment generation for small and marginal farmers through integrated farming systems. Indian Journal of Agronomy 44 : 431–439. Breene, W. M. (1990) Nutritional and medicinal value of speciality mushrooms. Journal of Food Protection 53: 883–894. Chang, S. T. & Buswell, J. A. (1996) Mushroom nutriceuticals. World Journal of Microbiology and Biotechnology 12: 473–476. Chang, S. T. & Miles, P. G. (1989) Introduction to mushroom science. In Edible Mushrooms and their Cultivation (S. T. Chang & P. G. Miles, eds): 3–25. CRC Press, Boca Raton. Chen, W. L. (1991) New changes in production of edible mushrooms in Beijing. Letters of Chinese Edible Fungi 11 : 3–4. First Editorial Office (1998) Review of Chinese Agriculture: Soil Fertilizers. China Standard Press, Beijing. First Editorial Office (1999) Standard Review of Chinese Food Industry: fruits, vegetables and their products. China Standard Press, Beijing. Philippoussis, A., Zervakis, G. & Diamantopoulou, P. (2001) Bioconversion of agricultural lignocellulosic wastes through the cultivation of the edible mushrooms Agrocybe aegerita, Volvarialla volvacea and Pleurotus spp. World Journal of Microbiology and Biotechnology 17: 191–200. Wang, H. X., Liu, W. K., Ng, T., Ooi, V. E. C. & Chang, S. T. (1995) The immunomodulatory and antitumor activities of a
polysaccharide-peptide complex from a mycelial culture of Tricholoma sp., a local edible mushroom. Life Sciences 57: 269–281. Wang, W. M. (1994) Technology of fertilization in arid areas in north China. In Agricultural Technology in Arid Areas in North China (J. Q. He, ed.): 82–94. Chinese Agriculture Press, Beijing. Xin, N. Q. & Chang, X. L. (1993) Experimental area of half-moisture and aridity in Shan Xi Province. In Technology for Integrated Increased Agricultural Production in Different Types of Arid Areas in North China (F. Zhang, ed.) : 121–129. Chinese Agriculture Press, Beijing. Yang, X. M. (1988) Introduction. In Methods for Cultivation of Edible Mushrooms in China (P. G. Zhao, ed.): 1–19. Chinese Agriculture Press, Beijing. Zhang, G. Y. (2000) Production of edible mushrooms in Mainland China in the year 1998. Chinese Edible Fungi 19 : 2.
Suyue Zheng1, Qinghong Liu1, Hexiang Wang1 and T. B. Ng2 1
Department of Microbiology, College of Biological Science, China Agricultural University, Beijing, People’s Republic of China. 2 Department of Biochemistry, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong S. A. R., People’s Republic of China. E-mail: [email protected]
DOI: 10.1017/S0953756202236643
MYCORRHIZAL FUNGI INCREASE AVAILABLE CALCIUM The ecological role of fungi in the breakdown of complex minerals in soil and on rock surfaces has been increasingly recognized. Now, studies at the Hubbard Brook experimental forest in New Hampshire (USA) have shown that mycorrhizal fungi can increase the available calcium in base-poor forest ecosystems. Blum et al. (2002) examined digests of soil minerals from the forests and found apatite, i.e. calcium phosphate, to be particularly abundant. They then studied the sources of calcium in the forest ecosystem using Ca/Sr and 87 Sr/86Sr ratios. Foliage had higher Ca/Sr ratios than those in the soil suggesting some preferential take-up by the trees. The same result did not occur with trees growing on soils lacking apatite. The authors consider
that the most probable source of the calcium is apatite, and that its release is a direct action of mycorrhizal weathering of the mineral. They also estimate that y35% of calcium in stream water comes from apatite breakdown. This suggests that the enhanced apatite breakdown by mycorrhizal fungi is of major ecological importance, especially in forest soils where the available calcium has been depleted by the effects of acid rain. Blum, J. D., Klaue, A., Nezat, C. A., Driscoll, C. T., Johnson, C. E., Siccama, T. G., Eagar, C., Fahey, T. J. & Likens, G. E. (2002) Mycorrhizal weathering of apatite as an important calcium source in base-poor forest ecosystems. Nature 417: 729–731.