Field and laboratory experiments were conducted to investigate the weed suppressing effects of cover crops in single and mixed cultivation. Weed densities in the field experiments ranged from 0 to 267 plants/m² with Chenopodium album L., Matricaria chamomilla L., Stellaria media (L.) Vill. as predominant weeds. It was found that mustard (Sinapis alba L.), fodder radish (Raphanus sativus var. niger J. Kern) and spring vetch (Vicia sativa L.) supressed weeds by 60% and cover crop mixtures controlled weeds by 66% during the fallow period at three experimental locations in 2013, 2014 and 2015. The biochemical effect of the same cover crops/mixtures on weed growth was analysed in laboratory experiments. Aqueous cover crop extracts were applied on weeds and analysed using LC/MS/MS. Mean germination time, germination rate and root length of weeds were determined. Extracts prolonged the germination time by 54% compared to the control with only water. In all cases, inhibitory effects on germination rate and root length were measured. Weed density in the field was found to be correlated with the root length in the germination tests. Our work reveals that biochemical effects play a major role in weed suppression of cover crops.
Altieri Miguel A., Lana Marcos A., Bittencourt Henrique V., Kieling André S., Comin Jucinei J., Lovato Paulo E. (2011): Enhancing Crop Productivity via Weed Suppression in Organic No-Till Cropping Systems in Santa Catarina, Brazil. Journal of Sustainable Agriculture, 35, 855-869 https://doi.org/10.1080/10440046.2011.588998
BEZUIDENHOUT S R, REINHARDT C F, WHITWELL M I (2012): Cover crops of oats, stooling rye and three annual ryegrass cultivars influence maize and Cyperus esculentus growth. Weed Research, 52, 153-160 https://doi.org/10.1111/j.1365-3180.2011.00900.x
Bonanomi Giuliano, Sicurezza Maria Grazia, Caporaso Silvia, Esposito Assunta, Mazzoleni Stefano (2006): Phytotoxicity dynamics of decaying plant materials. New Phytologist, 169, 571-578 https://doi.org/10.1111/j.1469-8137.2005.01611.x
Brust Jochen, Claupein Wilhelm, Gerhards Roland (2014): Growth and weed suppression ability of common and new cover crops in Germany. Crop Protection, 63, 1-8 https://doi.org/10.1016/j.cropro.2014.04.022
Brust J., Weber J., Gerhards R. (2014): Do cover crop mixtures have the same ability to suppress weeds as competitive monoculture cover crops? Julius-Kühn-Archiv, 443: 422–430.
De Baets S., Poesen J., Meersmans J., Serlet L. (2011): Cover crops and their erosion-reducing effects during concentrated flow erosion. CATENA, 85, 237-244 https://doi.org/10.1016/j.catena.2011.01.009
Ellis R.H., Roberts E.H. (1980): Towards a Rational Basis for Testing Seed Quality. Butterworths, London, Seed Production.
Farooq Muhammad, Jabran Khawar, Cheema Zahid A, Wahid Abdul, Siddique Kadambot HM (2011): The role of allelopathy in agricultural pest management. Pest Management Science, 67, 493-506 https://doi.org/10.1002/ps.2091
Haramoto Erin R., Gallandt Eric R. (2004): Brassica cover cropping for weed management: A review. Renewable Agriculture and Food Systems, 19, 187-198 https://doi.org/10.1079/RAFS200490
Jabran Khawar, Mahajan Gulshan, Sardana Virender, Chauhan Bhagirath S. (2015): Allelopathy for weed control in agricultural systems. Crop Protection, 72, 57-65 https://doi.org/10.1016/j.cropro.2015.03.004
Lawley Yvonne E., Weil Ray R., Teasdale John R. (2011): Forage Radish Cover Crop Suppresses Winter Annual Weeds in Fall and Before Corn Planting. Agronomy Journal, 103, 137- https://doi.org/10.2134/agronj2010.0187
Liu Quan, Xu Rui, Yan Zhiqiang, Jin Hui, Cui Haiyan, Lu Liqin, Zhang Denghong, Qin Bo (2013): Phytotoxic Allelochemicals from Roots and Root Exudates of Trifolium pratense. Journal of Agricultural and Food Chemistry, 61, 6321-6327 https://doi.org/10.1021/jf401241e
Macías Francisco A, Molinillo José MG, Varela Rosa M, Galindo Juan CG (2007): Allelopathy—a natural alternative for weed control. Pest Management Science, 63, 327-348 https://doi.org/10.1002/ps.1342
Mendes I.C., Bandick A.K., Dick R.P., Bottomley P.J. (1999): Microbial Biomass and Activities in Soil Aggregates Affected by Winter Cover Crops. Soil Science Society of America Journal, 63, 873- https://doi.org/10.2136/sssaj1999.634873x
Pérez Francisco J., Ormeño-Nuñez Juan (1991): Root exudates of wild oats: Allelopathic effect on spring wheat. Phytochemistry, 30, 2199-2202 https://doi.org/10.1016/0031-9422(91)83614-Q
Petersen Jan, Belz Regina, Walker Frank, Hurle Karl (2001): Weed Suppression by Release of Isothiocyanates from Turnip-Rape Mulch. Agronomy Journal, 93, 37- https://doi.org/10.2134/agronj2001.93137x
Radosevich S.R., Holt J.S., Ghersa C.M. (1997): Weed Ecology: Implications for Management. 2nd Ed. New York, John Wiley &
Teasdale John R. (1996): Contribution of Cover Crops to Weed Management in Sustainable Agricultural Systems. jpa, 9, 475- https://doi.org/10.2134/jpa1996.0475
Triplett Jr-G.-B., Dick W.A. (2008): No-tillage crop production: A revolution in agriculture! Agronomy Journal, 100: S153–S165.