Н.С. Репкина, И.А. Нилова, Н.М. Казнина.
Сравнительный анализ воздействия избытка цинка на рост побега Sinapis alba L. и Brassica juncea (L.) Czern
Keywords: zinc; Sinapisalba; Brassicajuncea; growth; biomass; tolerance
We studied the effect of zinc excess on shoot growth in white mustard (Sinapis alba L.) and brown mustard (Brassica juncea (L.) Czern.). Nowadays, B. juncea is regarded as a zinc hyperaccumulator – accumulating its high concentrations in aboveground organs. In contrast, S. alba is an “excluder”, mostly accumulating the metal in roots. We know that both species can grow on zinc-contaminated soils, but less is known about their tolerance of the metal. The data about their physiological reactions to excess metal influence are contradictory. We performed a laboratory experiment to study the effect of zinc at concentrations of 5 (control), 25, 50, 100, 150 and 200 mg per kg of substrate on shoot growth parameters in S. alba cv. Raduga and B. juncea cv. Slavyanka. In this study, the effect of zinc on shoot growth mostly depended on the zinc concentration in the substrate as well as on the plant species. Thus, zinc at 25 and 50 mg/kg had a stimulating effect on the growth of S. alba shoots and only higher concentrations (100–200 mg/kg) led to a decrease in the studied parameters. In B. juncea, even the 50 mg/kg concentration caused shoot height and leaf area to decrease. Elevation of zinc concentrations further promoted this negative effect. We suppose that the stronger detrimental effect of zinc at the studied concentrations on shoot growth in B. juncea as a hyperaccumulator compared to S. alba is associated with a higher content of the metal in its aboveground parts. Our results demonstrate the possibility of using the studied varieties of S. alba and B. juncea in the phytoremediation of zinc-contaminated soils.
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