Allelopathic Effects of Purple Nutsedge Extract on the Physiological Quality of Cabbage and Tomato Seeds

Invasive plants may present allelopathic substances that interfere with the germination and initial development of seedlings of various species. The objective of this study is to evaluate the physiological quality of cabbage and tomato seeds in the presence of different concentrations of purple nutsedge extract. The seeds were left to germinate in different substrates. Individual experiments were performed for both species. Five concentrations (0, 25, 50, 75 and 100%) of aqueous extract obtained from tubers of Cyperus rotundus were used. The seeds of each species were placed to germinate in three types of substrates (sand, commercial, and paper). Germination, normal seedlings, abnormal seedlings, non-germinated seeds, germination speed index, and accelerated aging were evaluated. A completely randomized experiment with a 3 × 5 factorial design (three substrates and five concentrations of purple nutsedge extract) was conducted with four replications. For the substrates, the means were compared by Tukey test at 5% probability. Polynomial regression analyses were carried out for concentrations of purple nutsedge extract. Cyperus rotundus exerts allelopathic effects on the germination of tomato and cabbage seeds. As the concentration of the tuber extract increases, the inhibitory effect increases, thus reducing germination and seed vigor in the different substrates. The commercial substrate for tomato and the paper substrate for cabbage may minimize the allelopathic effects of Cyperus rotundus extract during germination of seeds.