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The addition of nanoparticles has been reported to be an effective strategy for enhancing seed germination, but the underlying mechanisms whereby this occurs are unclear. In the present study, we added silica nanoparticles (SiNPs) to an aqueous growth medium in which tomato seeds were germinated. We examined the effects of SiNPs on growth and possible mechanisms of action. SiNPs had a diameter of 10–17 nm and 110–120 nm. SiNPs shortened the mean germination time from 5.24 ± 0.29 days to 4.64 ± 0.29 days. Seedling vigor, measured by criteria including length and weight, was also improved compared to the control condition. The presence of SiNPs in the seedlings was assessed using an X-ray fluorescence spectrometer. The nanoparticles may have promoted germination by enhancing water imbibition by the seeds or altering the external microenvironment. Scanning electron microscopy revealed changes in the seed coat during germination, many of which were only observed in the presence of nanoparticles. Soil bacteria affect germination; specifically, Bacillus sp. may promote germination. The number of Bacillus sp. changed in the germination medium with SiNPs compared to the control. This suggested that these bacteria could interact with SiNPs to promote germination.

Background and Objectives: Duckweed is a common aquatic angiosperm and is consumed by humans in Southeast Asia. Due in part to their high protein content, duckweeds have been identified as a potential human food source. Here, we conducted a preliminary study to quantify and characterize the protein and lipid content of two species of duckweed, Wolffia arrhiza and Landoltia punctata. Materials and Methods:The plants were grown for 9 days in a controlled cultivation system and proteins were extracted into n-hexane with a Soxhlet extractor. Amino acids were analyzed using high-performance liquid chromatography and all eight essential amino acids were present in both species at concentrations comparable to those in legumes. Lipids from the protein extraction residue were recovered and the fatty acids analyzed by gas chromatography. Results: The protein content was 0.14±0.03 and 0.17±0.01 g protein/g dry biomass and the total lipid content was 0.06±0.01 and 0.09±0.01 g lipid/g dry biomass for L. punctata and W. arrhiza, respectively. Most of the FAs were polyunsaturated, specifically, 58.38% of the total FA Methyl Esters (FAME) for L. punctata and 44.46% of the total FAME for W. arrhiza were polyunsaturated. Among these, most were omega-3 FAs, representing 44.93 and 22.17% of the total FAME in L. punctata and Wolffia arrhiza, respectively. The FAs obtained were mostly long-chain (13-22 C). Conclusion: L. punctata and W. arrhiza have a high content of both proteins and FAs, contain the essential amino acids and a considerable amount of omega-3. We consider that these results support the potential for these duckweed species to serve as a source of proteins and lipids in human food.

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Background and Objective: Bioethanol derived from plants is a renewable energy source and promising alternative to fossil fuels. It can be produced from plant starch by fermentation, but the starch must first be broken down to sugars, a process known as saccharification. Duckweeds are small, fast-growing plants that are easy to cultivate and accumulate high levels of starch and hold promise as a bioethanol source. Here, the growth parameters and starch content of three species of duckweeds were examined and assessed the efficiency of enzymatic saccharification. Materials and Methods: The duckweeds used in this study were Landoltia punctata, Lemna aequinoctialis and Wolffia arrhiza. The saccharification process was performed at 50EC for 24 hrs. Three starch-degrading enzymes were assessed in the saccharification process, specifically, "-amylase, $-amylase and glucoamylase, in equal amounts (1 mL per mg starch) but four different combinations. Results: The measured doubling times were, respectively, 3.57±0.02, 3.77±0.07 and 3.94±0.04 days and the initial starch contents were 0.28±0.02, 0.26±0.01 and 0.24±0.02 g/g. The greatest percentage of starch conversion to sugar was observed when all three enzymes were used in saccharification. The conversion percentages were 82.0±1.3%, 80.8±1.9% and 81.4±1%, for L. punctata, L. aequinoctialis and W. arrhiza, respectively. Conclusion: Results concluded that duckweeds have the potential to serve as a substrate in the fermentation process to produce bioethanol and other products.