Allelopathic sorghum aqueous extracts reduce biomass of hairy beggarticks

ABSTRACT

Leachates from the landrace sorghum IS9456 were tested on Bidens pilosa emergence and growth at Henderson Research Station in 2018. The trial had six treatments replicated four times. Stover was put in perforated plastic pots suspended on a frame. Watering released leachates, which were received by clay pots under the suspended pots. Atrazine significantly inhibited percentage emergence (P < 0.05) and leaf area (P < 0.001) of B. pilosa compared to leachates from all sorghum plant parts and the negative control. There was no significant effect (P > 0.05) of sorghum plant part as source of aqueous extract, and atrazine on height of B. pilosa. Sorghum stalks, leaves and sorghum stalks combined with leaves significantly (P < 0.05) reduced dry weight of B. pilosa compared to treatments with heads, atrazine and no sorghum herbage. Heads, stalks, leaves and leaves combined with stalks from mature IS9456 have limited allelopathic effect on the emergence of Bidens pilosa compared to atrazine. However, stalks, leaves and leaves combined with stalks can suppress biomass of Bidens pilosa possibly due to high concentrations of water soluble allelopathic compounds. Atrazine can provide early suppression B. pilosa, while allelopathic leachates from sorghum leaves, stalks and leaves combined with stalks can suppress B. pilosa in later growth stages by reducing weed biomass.

Keywords:

• Sorghum allelopathy
• sustainable weed management
• Bidens pilosa

Competing Interests

The authors declares no competing interests.

PUBLIC INTEREST STATEMENT

Sorghum aqueous extracts have the potential to inhibit weed germination, emergence and growth due to water soluble allelopathic compounds. This can reduce farmers’ reliance on herbicides for weed control. This study investigated the potential of sorghum aqueous extracts prepared from different sorghum plant parts to inhibit emergence and growth of B. pilosa, a weed that has developed tolerance to a number of herbicides globally. Aqueous extracts prepared from heads had little allelopathic effect on B. pilosa emergence and growth compared to those prepared from leaves, stalks and a combination of leaves and stalks, suggesting low concentrations of allelochemicals in sorghum heads. Atrazine did not significantly reduce B. pilosa biomass, suggesting that the weed has some tolerance to the herbicide.

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

Handsen Tibugari

Handsen Tibugari is a crop protection lecturer at Gwanda State University in Zimbabwe. He did a PhD on sorghum allelopathy at the University of Fort Hare. Pelagia Marumahoko and Ngonidzaishe Manyeruke are agronomists at Tobacco Industry and Marketing Board. Ronald Mandumbu is a professor of Weed Science at Bindura University of Science Education. Eunice Mangosho is a weed scientist and head of the Weed Research Unit at Henderson Research Station, Mazowe, Zimbabwe. Standreck Tivani and Rachel Magaya are Crop Science masters students at Marondera University of Agricultural Sciences and Technology in Marondera, Zimbabwe. Hardlife Chinwa is a Crop Science masters student at the University of Zimbabwe.