RESUMO
Aims: To determine the impact of Pb on seed germination and early seedling development in A. auriculiformis species. Place and Duration of Study: The study was carried out in Department of Biology, University Putra Malaysia, between April 2016 and February 2017. Methodology: The concentrations of lead from 0 to 4 g/L (interval of 0.5 g/L) were used. Seeds were germinated in vitro condition. Different parameters were measured including germination percentage, seedling vigour index, tolerance index, germination index, mean germination time and relative injury rate. Results: The noticeable finding of this study reveals that A. auriculiformis seeds have the ability to germination and resist Pb toxicity up to 1.5 g/L. Increasing Pb concentration from 1.5 to 3.5 g/L decreased the germination percentage from 57% to 4% respectively. Conclusion: Acacia auriculiformis seeds germination in a high level of Pb (up to 1.5 g/L) indicated species resistance which probably can be used as Pb hyperaccumulator agent in areas or sites contaminated with this metal.
RESUMO
This study evaluates the growth, body composition, and resistance to Aeromonas hydrophila challenge in juvenile African catfish (Clarias gariepinus) fed diets supplemented with spirulina (Arthrospira platensis). Five experimental diets containing different percentages of locally grown dried spirulina (0, 1, 3, 5 and 7%) were fed daily to catfish juveniles at 5% of their body weight. The growth and body composition of the catfish were determined up to 90 days of the study period. At day 91, the catfish were intraperitoneally injected with 107 CFU/ml of virulent A. hydrophila. Generally, the growth and body composition of the catfish in spirulina inclusion groups showed no significant difference with the control group. The survival rate following A. hydrophila challenge was significantly low in the control group compared to all of the other treatment groups. After the challenge trial, only the white blood cell count value was significantly higher in all of the groups supplemented with spirulina compared to the control group. We concluded that the locally grown spirulina do not improve growth and body composition, but it increased the catfish resistance towards A. hydrophila infection.
RESUMO
Even though Arthrospira is a well-known superfood, it is not extensively commercialized in developing countries like Malaysia due to the high production cost with low biomass yield. Based on literature, the algal production cost can be discounted by reducing the cost of medium utilizing cheaper and readily available chemicals. Therefore, the present study was conducted to experiment the prospect of Arthrospira platensis cultivation in newly designed medium with commercial or industrial grade fertilizers under real environment. Consequently, growth and yield of A. platensis was investigated under outdoor condition using modified Kosaric medium (MKM) which was designed by substituting the major laboratory chemicals in standard Kosaric medium (SKM) with commercial grade baking soda, sea salt, urea, phosphoric acid, potassium hydroxide and Epsom salt. Urea as an alternative nitrogen resource to sodium nitrate was pulse-fed throughout the cultivation period. The algal growth was measured through optical density, biomass dry weight and chlorophyll a content. The algal yield was determined by calculating its productivity and specific growth rate. The growth and yield of A. platensis was significantly higher (p < 0.05) in MKM in terms of optical density with 2.541 ABS, biomass dry weight with 1.30 g L-1, chlorophyll a content with 12.96 mg L-1, productivity with 0.141 g L-1 d-1 and specific growth rate with 0.253 µ d-1 compared to SKM in eight days of cultivation period. The present finding showed the potential of MKM in lowering the medium cost up to 97% compared to SKM without compromising the algal yield under natural condition with proper cultivation techniques such as preadaptation and fed-batch addition of urea in the late evening.