Effects of water level and soil type on the survival and growth of Persicaria thunbergii during early growth stages

•We studied survival and growth of P. thunbergii seedling under different conditions.•Water level was the most critical factor for seedling survival.•They died under water level over 6 cm above the ground or over twice their heights.•Seedling growth was affected by soil texture and available nutrients.•P. thunbergii seedlings in wetland can be removed using water level regulation.

We investigate the effects of water level and soil type on the survival and growth of Persicaria thunbergii during the recruitment phase. Plants in four early growth stages (uprooted seed, seedling with cotyledon, seedlings with two and four foliage leaves) were planted under combined conditions of six water levels (dry, wet, flooding) and two soil types (loamy sand, sand). Six weeks later, the survival rates, plant heights and biomass were measured. The uprooted seeds survived under water levels lower than 6 cm. The seedlings in other growth stages could not overcome water levels twice their height. Under dry conditions, the plant height and biomass were higher in sand than in loamy sand, yet under saturated conditions, the opposite result was obtained. The water level relative to seedling height was the most critical factor for early survival, and seedling growth was also affected by soil type. Thus, P. thunbergii in constructed wetlands can be removed during the seedling recruitment phase using water level regulation.