Volatile emissions of watercress (Nasturtium officinale) leaves and passion fruit (Passiflora edulis) seeds against Meloidogyne incognita.

Watercress leaf and passion fruit seed macerates produce volatile organic compounds toxic to Meloidogyne incognita and 1-octanol, found in volatile emissions of watercress leaves, shows nematicidal activity against M. incognita.

BACKGROUND: Plants emit volatile organic compounds (VOCs) with several functions, including toxicity to plant-parasitic nematodes (PPNs). However, the toxicity of VOCs from watercress leaves (Nasturtium officinale) and passion fruit seeds (Passiflora edulis) against PPNs has not yet been studied. RESULTS: Biofumigation with watercress leaves and passion fruit seeds reduced the infectivity and reproduction of Meloidogyne incognita in tomato plants. The VOCs emitted by watercress leaves and passion fruit seeds caused immobility of M. incognita second-stage juveniles (J2 ). The reduction in infectivity and reproduction of M. incognita reached 89% and 99%, respectively, when J2 were exposed to watercress VOCs. Additionally, water exposed to VOCs emitted by watercress caused 79% M. incognita J2 mortality. The volatilome of the toxic water contained 12 compounds, mainly alcohols. The emissions from watercress leaves and passion fruit seeds contained 26 and 12 compounds, respectively, according to gas chromatography-mass spectrometry analysis. The 1-octanol occurring in watercress emissions demonstrated in vitro and in vivo nematicidal activity against M. incognita, with a lethal dose necessary to cause 50% mortality (LC50 ) of 382.5 µg mL−1 . CONCLUSIONS: Watercress leaf and passion fruit seed macerates emitted VOCs with nematicidal activity against M. incognita. The compound 1-octanol identified in watercress emissions may be useful for the nematicide-producing industry.

Efficient removal of mercury from aqueous solutions and industrial effluent.

The objective of this study was to examine the ability of a solid waste produced during beneficiation of ornamental rocks to remove mercury (Hg) from an industrial effluent and aqueous solutions under various conditions. Batch studies have been carried out by observing the effects of pH, concentration of the adsorbate, contact time, and so on. Various sorption isotherm models such as Langmuir, Freundlich, and Tóth have been applied for the adsorbent. Film and intraparticle diffusion were both found to be rate-limiting steps. Adsorption was properly described by the Freundlich model (capacity constant of 0.3090 (mg g(-1))(mg L(-1))(-1/n) and adsorption intensity indicator of 2.2939), which indicated a favorable sorption and encouraged subsequent studies for treatment of Hg-containing industrial effluent. Industrial effluent treatment efficiency reached Hg removals greater than 90% by using ornamental rock solid waste (ORSW). Besides, desorption studies indicated that the maximum recovery of mercury was 100 ± 2% for 1 mol L(-1) HNO3 and 74 ± 8% for 0.1 mol L(-1) HNO3. The ORSW could be reused thrice without significant difference on the Hg removal rate from industrial effluent. These findings place ORSW as a promising efficient and low-cost adsorbent for the removal of Hg from aqueous solutions and industrial effluent.