Allelopathic effects account for the inhibitory effect of field-pea (Pisum sativum L.) shoots on wheat growth in dense clay subsoils
The deep-placement of nutrient-rich organic amendments in poorly-structured subsoils can improve subsoil structure and increase grain yields, but its widespread adoption by farmers is limited by the availability and cost of animal manures, the current choice of amendment. Three glasshouse experiments investigated the effectiveness of dried field pea (Pisum sativum L.) shoots (green chop), as green manure, on wheat growth in three subsoils with contrasting soil chemical and physical properties. The growth of wheat plants was greatly suppressed when the green chop was placed in Sodosol and Chromosol subsoils. In contrast, there was a twofold increase in shoot biomass in response to the addition of green chop to Vertosol. Three allelopathic compounds, pisatin, anhydropisatin, and maackian, were identified at higher concentrations in the extracts of remaining green chop residues in the Sodosol and Chromosol, compared to the Vertosol, directly supporting phytotoxicity as the cause of observed inhibitory effects of green chop in these soils. The persistence of the phytotoxicity in the Sodosol might be attributed to its poor aeration caused by poor structure or compaction. Nevertheless, pre-incubation led to microbial decomposition of the allelochemicals in the Sodosol, though at a much slower rate than in the Vertosol. Further studies are needed to determine the time period required for the disappearance of the phytotoxic effects in soils with different physico-chemical properties.
KeywordsAllelopathic effects Deep placement Green chop LC-MS/MS Organic amendments Dense clay subsoils
This research was supported under Grains Research and Development Corporation Projects funding scheme (project DAV00149).
- Fageria N (2007) Green Manuring in Crop Production. Journal of Plant Nutrition 30 (5):691–719Google Scholar
- Harborne JB (2013) The flavonoids: advances in research since 1980. Springer, BerlinGoogle Scholar
- Harper JL (1977) Population biology of plants. Academic, LondonGoogle Scholar
- Isebell RF (2002) The Australian Soil Classification. CSIRO Publishing, CollingwoodGoogle Scholar
- IUSS Working Group (2015) World Reference Base for Soil Resources 2014, update 2015 international soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports No 106:192Google Scholar
- Kushwah S, Reddy DD, Somasundaram J, Srivastava S, Khamparia R (2016) Crop residue retention and nutrient management practices on stratification of phosphorus and soil organic carbon in the soybean-wheat system in Vertisols of Central India. Commun Soil Sci Plant Anal 47:2387–2395CrossRefGoogle Scholar
- Rice EL (1984) Allelopathy. Acedemic, New YorkGoogle Scholar
- Rugare JT (2018) Allelopathic effects of green manure cover crops on the germination and growth of blackjack (Bidens pilosa L.) and rapoko grass [Eleusine indica (L.) Gaertn]. Stellenbosch University, StellenboschGoogle Scholar
- Sale P, Malcolm B (2015) Amending sodic soils using sub-soil manure: economic analysis of crop trials in the high rainfall zone of Victoria. Aust Farm Bus Manag J 12:22–31Google Scholar
- Yadvinder-Singh, Bijaw-Singh, Khind C (1992) Nutrient transformations in soils amended with green manures. In: Advances in soil science. Springer, Berlin, pp 237–309Google Scholar
- Zuo SP, Wang HM, Ma YQ (2008) Sawtooth effects in wheat stubbles allelopathy. Allelopath J 21:287–298Google Scholar