Response of three weed species to sorghum, alfalfa and tobacco plants incorporated into the soil
2016
Mohammadi, G. | Norouzi, Y. | Nosratti, I.
Allelopathic crops are considered as efficient tools for the control of weeds in agroecosystems. An experiment was carried out to evaluate the suppressing effects of sorghum, alfalfa and tobacco plant tissues incorporated into the soil on germination and early growth of three important weed species including barnyard grass (Echinochloa crus-galli (L.) Beauv.)], Johnson grass (Sorghum halepense L.) and redroot pigweed (Amaranthus retroflexus L.). The first factor in the experiment was allelophatic plant species including alfalfa, tabacco and sorghum. The second factor was the quantity of allelophatic plant materials added to 1 kg of soil: 0, 2, 4 and 8 g for alfalfa; 0, 0.5, 1 and 2 g for tobacco and 0, 0.7, 1.4 and 2.8 g for sorghum. Results indicated that the allelopathic plant materials applied at different quantities significantly affected (mostly decreasing effect) the weed species under (no allelophathic crop), while this crop showed the lowest reducing effect on the emergence of E.crusgali-a 75% reduction compared with the control study. All three allelopathic crops drastically reduced the percentage emergence of the weeds under study although they responded differently to the various allelopathic crops, as the lowest emergence, percentage of S. halepense was observed in the soil treated by sorghum plant tissue - a 84.6%, reduction compared with the control. However, for A. retroflexus the lowest values for this trait control. On the average, among the weed species, the higher reductions in the emergence percentage caused by the allelopathic crops were observed on the weed having the smallest seeds (i.e., A. retroflexus).
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