Greater Yields with Diverse Crops

healing the earth, the body, the mind and spirit --- a non-profit web site		Agri News

weeds

invitation

Genetic Diversity Boosts Yields Dramatically

An 89% increase in yield, and a 96% reduction of plant diseases - just by growing genetically diverse crops - has been documented in China, in a very large area, comprising all the farms in a total of 15 townships. The trials were so successful that the use of fungicides was terminated.

This is stunning news. What this means to farmers - an 89% increase in yield, a 96% reduction of plant diseases, plus the massive savings in fungicide costs, and in application equipment and labour - is nothing less than phenomenal.

Moreover, and not mentioned is the fact that genetically diverse crops also have a far greater chance of survival in adverse conditions. And there is no better proof than Life itself. It is only through diversity that Life has survived for 4 billion years on this Earth - and through such massive planetary upheavals as dozens of ice ages, several planetary extinction events, and the constant drifting of the continents. Something has always survived to carry on, and only because of diversity.

All this is nothing more than plain old common sense. Any mono-genetic crop offers an open field - and absolutely ideal conditions - for any plant disease, whereas genetically diverse crops provide barriers at every turn. This, of course, goes completely against what the seed manufacturers and pesticide producers want to sell you.

The second study comes to the same conclusions - and in support of several other studies - although it was focused upon representative natural ecosystems on global and regional scales, and is far greater in scale than the above agricultural study in China.

Original Abstracts:

Genetic Diversity and Disease Control in Rice

Crop heterogeneity (diversity) is a possible solution to the vulnerability of monocultured crops to disease. Both theory and observation indicate that genetic heterogeneity provides greater disease suppression when used over large areas, though experimental data are lacking.

Here we report a unique cooperation among farmers, researchers and extension personnel in Yunnan Province, China—genetically diversified rice crops were planted in all the rice fields in five townships in 1998 and ten townships in 1999. Control plots of monocultured crops allowed us to calculate the effect of diversity on the severity of rice blast, the major disease of rice. Disease-susceptible rice varieties planted in mixtures with resistant varieties had 89% greater yield and blast was 94% less severe than when they were grown in monoculture. The experiment was so successful that fungicidal sprays were no longer applied by the end of the two-year programme. Our results support the view that intraspecific crop diversification provides an ecological approach to disease control that can be highly effective over a large area and contribute to the sustainability of crop production.
YOUYONG ZHU, HAIRU CHEN, JINGHUA FAN, YUNYUE WANG, YAN LI, JIANBING CHEN, JINXIANG FAN, SHISHENG YANG, LINGPING HU, HEI LEUNG, TOM W. MEW, PAUL S. TENG, ZONGHUA WANG & CHRISTOPHER C. MUNDT [ Nature 406, 718 - 722 (2000) © Macmillan Publishers Ltd.]

Consistent Patterns and the Idiosyncratic Effects of Biodiversity in Marine Ecosystems

Revealing the consequences of species extinctions for ecosystem function has been a chief research goal and has been accompanied by enthusiastic debate. Studies carried out predominantly in terrestrial grassland and soil ecosystems have demonstrated that as the number of species in assembled communities increases, so too do certain ecosystem processes, such as productivity, whereas others such as decomposition can remain unaffected. Diversity can influence aspects of ecosystem function, but questions remain as to how generic the patterns observed are, and whether they are the product of diversity, as such, or of the functional roles and traits that characterize species in ecological systems.

Here we demonstrate variable diversity effects for species representative of marine coastal systems at both global and regional scales. We provide evidence for an increase in complementary resource use as diversity increases and show strong evidence for diversity effects in naturally assembled communities at a regional scale. The variability among individual species responses is consistent with a positive pattern of ecosystem function with increased diversity.
MARK C. EMMERSON, MARTIN SOLAN, CHAS EMES, DAVID M. PATERSON & DAVE RAFFAELL [ Nature 411, 73 - 77 (2001) © Macmillan Publishers Ltd. 03 May 2001]

| BACK | INDEX | NEXT |

NEWS INDEX