Search

Measuring the methane to carbon dioxide ratio (CH4/CO2) from animals could be useful to predict CH4 yield when dry matter intake (DMI) cannot be measured. The objectives were to (1) evaluate the relationship of CH4/CO2 with CH4 yield; (2) compare the CH4/CO2 of 10–60 simulated spot-samples with the CH4/CO2 calculated with data from 48-h of respiration chamber measurements. The DMI and CH4 and CO2 emissions measured every 5–6 min in respiration chambers from a previous experiment with 70 lambs fed ryegrass substituted with 0%, 25%, 50%, 75% and 100% of forage rape were retrieved. Emission data were used to perform simulations of 10, 20, 30, 40, 50 and 60 randomly selected spot-samples per lamb. The CH4/CO2 of 20 or more spot-samples was useful to predict CH4 yield and detect differences between dietary treatments, while the precision of the prediction increased when increasing the number of spot-samples up to 50 samples per lamb. Twenty spot-samples were sufficient to obtain accurate CH4/CO2 estimates; however, variance decreased (precision improved) with an increasing number of spot-samples per lamb up to 50 spot-samples. The CH4/CO2 of 10–60 simulated spot-samples explained 61% to 66% of variation in the 48-h measured CH4 yield. [ABSTRACT FROM AUTHOR]

Light intensity plays a critical regulatory role in determining plant yield and quality, and energy consumption in plant factory with artificial light (PFAL). The effects of different light intensities (200, 300, 400, 500, and 600 µmol·m−2·s−1) of light-emitting diodes (LED) red and blue light with ratio 4:1 on growth, quality, nitrogen and amino acid metabolisms of ryegrass were investigated. The results showed the tiller number and shoot fresh weight in ryegrass were increased, while plant height and stem diameter remained stable with the improvement of light intensity. The highest levels of soluble protein, free amino acid, and DPPH free radical clearance rate in photon flux density (PPFD) at 500 µmol·m−2·s−1, and then significantly decreased with light intensity increased. The highest soluble sugar content was found at PPFD of 600 µmol·m−2·s−1, while malondialdehyde (MDA) content remained stable in all treatments. As the light intensity increased, nitrate content decreased, while nitrate reductase (NR) activity and the ammonium content increased. As light intensity was increased from 200 to 600 µmol·m−2·s−1, nitrite reductase (NiR) activity first decreased and then increased. Moreover, glutamate and cysteine contents increased first and then decreased, while glutamate synthase (GOGAT), glutamine synthase (GS), glutamate dehydrogenase (GDH), and cysteine synthases (CS) activities increased continuously with light intensity. Light intensity was significantly correlated with the parameters of growth, quality, nitrogen and amino acid metabolisms in ryegrass. It was recommended that PPFD at 400–500 µmol·m−2·s−1, photoperiod of 16 h/d was suitable for ryegrass high-efficient production in PFAL with relatively low energy cost. [ABSTRACT FROM AUTHOR]

Based on the growth-promoting effect of plant growth promoting bacteria on plants and the mobilization of Cd by citric acid, an experiment was designed in which the combined treatment of Bacillus megaterium and citric acid promoted ryegrass to repair Cd-contaminated soil. This study aimed to evaluate the effects of different treatments on the antioxidant enzyme activity, photosynthesis intensity, Cd accumulation, and rhizosphere cadmium migration under cadmium contamination conditions. And the soil morphology and structure changes were studied by infrared spectroscopy FourierTransformInfrared(FT-IR) and scanning electron microscope Energy Dispersive Spectrometer(SEM-EDS) before and after different treatments. The results show that the combined treatment of Bacillus megaterium and citric acid significantly improved the oxidative stress defense and plant photosynthesis and increased of rye biomass. rye biomass 1.28 times higher than CK treatment. Joint treatment significantly increased the amount of shoot accumulation of Cd, 2.31 times higher than CK treatment, increased the migration and accumulation of cadmium. FTIR and SEM-EDS also showed that the organic constituents such as O-H, C-O and C-N in soils as a major mechanism for mobilization of the heavy metal Cd. Thus, the combined treatment of Bacillus megaterium and citric acid can promote plant growth, improve the damage to ryegrass caused by single organic acid addition, and improve the plant extraction efficiency, which is a feasible way to repair Cd-contaminated soil through activated extraction system. The novelty of this study is the combined application of bacteria and chelating agents to ryegrass to improve phytoremediation efficiency. Bacillus giganosus has a good role in promoting the growth of ryegrass. As citrate, a small molecule chelate, can activate heavy metal cadmium and detoxify heavy metals, so it was selected. This study revealed in detail the response of ryegrass to the heavy metal Cd after exogenous addition of Bacillus gigansus and citrate, which is important for the application of cadmium removal by phytoremediation. Exogenous Bacillus megaterium has a pro-growth effect on ryegrass. The combined treatment of Bacillus megaterium and citric acid significantly improved oxidative defense mechanisms in ryegrass to alleviate Cd stress in plants. FTIR and SEM-EDS showed that the joint treatment significantly improved the soil nutrient content. Combined application of citric acid and Bacillus megaterium showed the highest removal rate of cadmium. [ABSTRACT FROM AUTHOR]