Evaluation of Ageratum conyzoides in field scale constructed wetlands (CWs) for domestic wastewater treatment

Ageratum conyzoides were evaluated in field scale subsurface flow constructed wetlands (CWs) to quantify its nitrogen (N) and phosphorus (P) uptake and compare with wetland plants (Pistia stratiotes, Typha latifolia and Canna indica). The two-field scale subsurface flow CWs, located in the International Crops Research Institute for Semi-Arid Tropics, received wastewater from an urban colony. The CW1 and CW2 had the same dimensions (length:10 m, width:3 m, total depth:1.5 m and sand and gravel:1 m), similar flow rates (3 m³/d), hydraulic loading rates (HLRs-10 cm/d) and hydraulic retention time (HRT-5 days) from July 2014-August 2015. The vegetation in both CWs consisted of Pistia stratiotes, Typha latifolia, Canna indica, and Ageratum conyzoides, respectively. The CW1 (% reduction with respect to concentrations) reduced total suspended solids (TSS) (68%), NH₄-N (26%), NO₃-N (30%), soluble reactive P (SRP) (20%), chemical oxygen demand (COD) (45%) and fecal coliforms (71%), while the CW2 (%-reduction with respect to concentrations) reduced TSS (63%), NH₄-N (32%), NO₃-N (26%), SRP (35%), COD (39%) and fecal coliforms (70%). Ageratum conyzoides can be used in combination with Pistia stratiotes, Typha latifolia and Canna indica to enhance removal of excessive N, P and fecal coliforms from domestic wastewater.

Eco-physiological performance of two invasive weed congeners (Ageratum conyzoides L. and Ageratum houstonianum Mill.) in the Indo-Gangetic plains of India

Morphological (easily measureable) and physiological (hard to measure) traits of two closely related invasive alien congeners-Ageratum conyzoides L. and Ageratum houstonianum Mill. were studied with a perspective that which species will be potentially be more successful as an invader in the Indo-Gangetic plains of India. Leaf construction cost (LCC) is considered as a quantifiable measure of energy demand for biomass production and is related to energy use efficiency as it include component of both morphological and physiological traits. We hypothesised that a low LCC would give the invaders growth advantage by utilizing energy efficiently. Low LCC of A. houstonianum on mass basis (0.54 g glucose g( -1)) and area basis (20.48 g m( -2)) gives insight into the success of this invasive weed over A. conyzoides. The present study gives evidence that how the morphological traits are linked to physiological traits that could directly affect invasive attributes of the invader, which in turn would be crucial to prioritize species for ecosystem management.

Allelopathic potential and chemical constituents of volatiles from Ageratum conyzoides under stress

The allelopathic potential of Ageratum conyzoides was investigated under different environmental stress conditions, including nutrient deficiency. physical damage, 2.4-D treatment, competition with Bidens pilosa, infection with Erysiphe cichoracearum, and feeding by Aphiids gossypii. The inhibitory effects of A. conyzoides volatiles on peanut (Arachis hypogaea), redroot amaranth (Amaranthus retroflexus), cucumber (Cucumis sativus), and ryegrass (Lolium multiforum) increased when plants were grown under nutrient-deficient conditions or in competition with B. pilosa; however, there was no difference with physical damage or 2.4-D treatment. Phytoinhibitory effects decreased under fungal infection and aphid feeding. Volatiles from A. conyzoides plants infected with E. cichoracearum or exposed to A. gossypii feeding inhibited or killed fungi and insects. Precocenes and their derivatives, monoterpenes, and sesquiterpenes were the major volatile components of A. conyzoides.