Effects of high ammonium level on biomass accumulation of common duckweed Lemna minor L.

Abstract

Growing common duckweed Lemna minor L. in diluted livestock wastewater is an alternative option for pollutants removal and consequently the accumulated duckweed biomass can be used for bioenergy production. However, the biomass accumulation can be inhibited by high level of ammonium (NH4 (+)) in non-diluted livestock wastewater and the mechanism of ammonium inhibition is not fully understood. In this study, the effect of high concentration of NH4 (+) on L. minor biomass accumulation was investigated using NH4 (+) as sole source of nitrogen (N). NH4 (+)-induced toxicity symptoms were observed when L. minor was exposed to high concentrations of ammonium nitrogen (NH4 (+)-N) after a 7-day cultivation. L. minor exposed to the NH4 (+)-N concentration of 840 mg l(-1) exhibited reduced relative growth rate, contents of carbon (C) and photosynthetic pigments, and C/N ratio. Ammonium irons were inhibitory to the synthesis of photosynthetic pigments and caused C/N imbalance in L. minor. These symptoms could further cause premature senescence of the fronds, and restrain their reproduction, growth and biomass accumulation. L. minor could grow at NH4 (+)-N concentrations of 7-84 mg l(-1) and the optimal NH4 (+)-N concentration was 28 mg l(-1).

Carbon and energy fixation of great duckweed Spirodela polyrhiza growing in swine wastewater

“…On the other hand, samples in higher (28, 49, and 70 mg L −1 ) or lower (1.4 mg L −1 ) ranges of TAN concentrations resulted in a significant decrease in chlorophyll content. This is different from our previous results where the highest chlorophyll content was attained at a much higher TAN concentration in improved Hoagland solution (pH 5.5) and with NH 4 + as the sole nitrogen source (Wang et al 2014). Aside from TAN and other pollutants in OSW and ADE, the pH of the culture solution could also inhibit the synthesis of photosynthetic pigments.…”

“…To guarantee genetic uniformity, all of the plant materials used were from a single colony that was cultivated in an improved Hoagland solution (Wang et al 2014).…”

“…However, high nutrient levels in the wastewater could also cause nutrient stress and inhibit the growth of duckweed, subsequently affecting biomass accumulation and the wastewater purification capacity (Xu and Shen 2011). For example, high levels of total ammonia nitrogen (TAN) have been identified as one of the key factors that inhibit the growth of duckweeds (Caicedo et al 2000;Wang et al 2014). Hence, dilution of the swine wastewater is necessary before it could be used for duckweed cultivation (Xu et al 2012).…”

Improving the Rice Performance by Fermented Chitin Waste

“…The FCW supplementation of soil led to an excess available N level, which may account for the prolonged vegetative (Hodges, 2010) of the rice compared to those plants in the other treatments. In addition, an increased available N supply can increase the level of photosynthetic pigments, as previously reported in algae (Pancha et al, 2014;Zubia et al, 2014) and plants (Wang et al, 2014), since N is required for chlorophyll synthesis. The increased available N supply, therefore, can lead to increased chlorophyll a, chlorophyll b and carotenoid contents until it reached the optimal concentration in the medium (Wang et al, 2014).…”

“…In addition, an increased available N supply can increase the level of photosynthetic pigments, as previously reported in algae (Pancha et al, 2014;Zubia et al, 2014) and plants (Wang et al, 2014), since N is required for chlorophyll synthesis. The increased available N supply, therefore, can lead to increased chlorophyll a, chlorophyll b and carotenoid contents until it reached the optimal concentration in the medium (Wang et al, 2014). In this study, the application of 0.5% (w/w) FCW to the soil of rice plants was optimal for enhancing the leaf photosynthetic pigment contents (Table 3), yet the highest net photosynthesis rate at the reproductive stage was found in the plants grown in 1.0% (w/w) FCW supplemented soil and no significant difference in the net photosynthesis rate was found among the different FCW application levels.…”