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

Abstract

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.