Kochia can be a 'killer' on spring wheat
Investigation into allelopathic effects of weeds on the germination and early growth of spring wheat has been investigated in recent years, but one of the first investigations that caught the eye of Jim Bauder, soil and water quality specialist at Montana State University/Bozeman still is quite interesting. It happens that this research into the allelopathic effect was done by two high school students.
Bauder wrote about it as his agronomy note number 255 quoting Jeremy Brimhall and Marshall Overcast’s research, the two students at Northern Toole County Sunburst High School in Montana. He also credited the student’s teacher Lawrence Fauque. The rest of this write-up comes from Bauder’s number 255 report.
The title (abbreviated) of this more than modest investigation was “the allelopathic effects of selected weed exudates on the germination and early growth of spring wheat”. They hypothesized that certain plants, namely kochia, wild oat, and wild buckwheat, produce either root exudates (allelochemicals) or some other mechanism associated with water soluble chemicals that inhibit or adversely affect the germination and growth of spring wheat. They then set out a series of very rigorous and very controlled experiments to find out if their hypotheses were true.
Bottom line - from the abstract: Wild oat and wild buckwheat showed no effect on emergence, rate of growth, average vegetative dry weight or final height and had no effect on germination of spring wheat. In contrast, kochia had a significant negative effect on the emergence and average vegetative dry weight of spring wheat grown in pots.
A little background about this whole allelopathy thing - from the experts. “Allelopathy refers to the exchange of any chemicals known as secondary metabolites of plant, fungal, or microbial origin that influence the growth and development of other plants or microbes. Plants produce many organic compounds that they do not use directly. These compounds are known as secondary metabolites, and can appear in all parts of a plant, including leaves, flowers, fruit, stems, roots, rhizomes, seeds, and pollen. Plants eventually release their secondary metabolites into the soil during germination, growth, or decomposition. The purposes of secondary metabolites are various, and scientists know very little about them. Secondary metabolites such as alkaloids, phenolics, flavonoids, terpenoids, and glucosinolates which do not play a role in primary metabolic processes essential for a plant’s survival, and are produced as offshoots of primary metabolic pathways.”