Effects of melatonin-treated Nasturtium officinale on the growth and cadmium accumulation of subsequently grown rice seedlings

ABSTRACT

To study how melatonin (MT) treatment of plants used for stubble affects the heavy metal accumulation of the subsequent crop, the effects of MT-treated Nasturtium officinale on the growth and cadmium (Cd) accumulation of subsequently grown rice seedlings were investigated in a pot experiment. Stubble from N. officinale treated with low concentrations (25 and 50 µmol kg⁻¹) of MT increased the shoot biomass of rice seedlings, whereas other concentrations (100, 150, and 200 µmol kg⁻¹) caused a decrease or had no significant effect. Nasturtium officinale stubble from plants treated with different MT concentrations also affected the rice-seedling contents of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids) and reduced the activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase). Prior treatment of N. officinale with MT (>25 µmol kg⁻¹) decreased the shoot Cd content and translocation factor of subsequently grown rice seedlings. To some extent, the application of a low concentration (25 and 50 µmol kg⁻¹) of MT to N. officinale sown before rice can therefore promote growth and inhibit Cd transport from roots to shoots of rice seedlings, with 25 µmol kg⁻¹ found to be the optimal concentration.

KEYWORDS:

• Nasturtium officinale
• succession cropping
• rice seedlings
• cadmium
• growth

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The research was supported by National Key Research and Development Program [2017YFD0100203]; Rice Breeding Program of Sichuan [2016NYZ0028]; Sichuan Applied Basic Research Project [2018JY0409]; Sichuan Rice Innovation Team of National Modern Agricultural Industry Technology System, Mianyang Experiment Station [CARS-01-92] of National Rice Industry Technology System.