Could rice be the source for a natural herbicide?

Scientists are examining which genetic characteristics of rice best control the growth of a common weed.

The growth of rice (Oryza sativa L.) is of great agricultural importance but it is affected by the common weed, barnyardgrass (Echinochloa crus-galli). Scientists from the Department of Crop Science at Konkuk University examined the use of rice allelopathic potential for weed control.

A laboratory bioassay using water extracts was conducted to determine the alleopathic potential of different parts of rice crop on seed germination and growth of barnyardgrass, and to select high allelopathic potential rice varieties using genetic characters and phenotypes.

The alleopathic potential was evaluated from extracts of leaf, straw and hull of 114 rice varieties, i.e. the first group was of leaf extracts and its inhibition rate was the highest in CUBA 65-v-58, the second group of straw extracts was observed with inhibition rate highest in Dangneunbangju and third group of rice hull extracts was observed with inhibition rate highest in Baekambyeo.

Another part of the study examined comparison of allelopathic rice varieties: using genetic characters and phenological types; from different origins; with different maturity times; with the existence or non-existense of hull color; with the existence or non-existense of an awn or awn color. Scientists have observed about 114 rice varieties with different parts of plant i.e. allelopathic effects of extracts from leaves, straw and hull on barnyardgrass. The study is published in the July-August 2003 issue of Agronomy Journal

Ill-Min Chung, project leader, stated, “These results suggest that rice body parts may be a source of natural herbicides and that it is necessary to develop acceptable selection standard, there may also be genetic variation in rice varieties for their allelopathic potential on barnyardgrass. In the future it might be possible to develop rice varieties with high allelopathic potential.”

Agronomy Journal, http://agron.scijournals.org is a peer-reviewed, international journal of agriculture and natural resource sciences published six times a year by the American Society of Agronomy (ASA). Agronomy Journal contains research papers on all aspects of crop and soil science including agroclimatology and agronomic modeling, military land use and management, environmental quality, international agronomy, agricultural research station management, and integrated agricultural systems.

The American Society of Agronomy (ASA) www.agronomy.org, the Crop Science Society of America (CSSA) www.crops.org and the Soil Science Society of America (SSSA) www.soils.org are educational organizations helping their 10,000+ members advance the disciplines and practices of agronomy, crop and soil sciences by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.