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Description
Although hydroxyapatite nanoparticle was reported to have potential for enhancing plant growth, its effect on rice had never been investigated. The objective of the present study was to investigate the effects of hydroxyapatite nanoparticles (HAp-NPs) at concentrations of 0, 10, 25, 50, 100, 500, 1,000 and 2,000 µg/ml on seed germination and seedlings of rice (Oryza sativa L.). Assessments of root and shoot growth, cell death, and electrolyte leakage at early seedling stage were made. The results showed that HAp-NPs had no apparent positive or negative effect on seed germination, although there may be some negative effect at high concentrations of 1,000 and 2,000 µg/ml. NPs distribution in seed was observed by using transmission electron microscope. Micrographs showed nanoparticles to be primarily trapped in the cell wall. The synchrotron radiation based micro-X-ray fluorescence (micro-XRF) was used to track the presence and chemical speciation of calcium within the rice seed. It was found that seeds treated with high concentration of HAp-NPs (2,000 µg/ml) had higher amount of calcium than the control. In addition, rice in seedling stage (20-30 days) showed better growth and more chlorophyll content with increasing concentrations of hydroxyapatite nanoparticles. In summary, HAp-NPs has no effect upon exposure on short term basis, but positively affects the seedling stage on long term basis at concentrations of 500 to 2,000 µg/ml.
Keywords: Nanoparticles, Hydroxyapatite (HAp), Rice (Oryza sativa L.)
