Growth, leaf gas exchange and biochemical changes of oil palm (Elaeis guineensis Jacq.) seedlings as affected by iron oxide nanoparticles

• Main Authors: Ayu Azera Izad, Rosimah Nulit, Che Azurahanim Che Abdullah, A'fifah Abdul Razak, Teh Huey Fang, Mohd Hafiz Ibrahim
• Format: Article
• Language: English
• Published: AIMS Press 2019-01-01
• Series: AIMS Materials Science
• Subjects: biochemical; growth; iron oxide nanoparticles; leaf gas exchange; oil palm seedlings (elaeis guineensis jacq.)
• Online Access: https://www.aimspress.com/article/10.3934/matersci.2019.6.960/fulltext.html

Currently, magnetic iron oxide nanoparticles (Fe₃O₄ NPs) was extensively used in industries and agriculture. However, fewer studies have been conducted on the interaction between these nanomaterials and plants. With that, the work focused on the toxicity evaluation of Fe₃O₄ NPs towards the growth, leaf gas exchange and biochemical of oil palm (<em>Elaeis guineensis</em> Jacq.). Oil palm seedlings were grown in soil and treated with different concentrations of Fe₃O₄ NPs (0, 800, 1600, 2400 mg/L) for 30 days of exposure. The experiment was arranged in a randomized complete block design (RCBD) replicated three times. The study revealed that Fe₃O₄ NPs did not affect the plant growth but significantly (p ≤ 0.05) affected the leaf gas exchange and biochemical responses. Total chlorophyll content and leaf total stomata densities of seedlings were significantly decreased with Fe₃O₄ NPs, in particular with the higher Fe₃O₄ NPs concentration. The results showed that Fe₃O₄ NPs negatively affected the leaf gas exchange characteristics of seedlings as compared to the control. The Fe₃O₄ NPs increased the production of total flavonoids, total phenolics, proline, soluble sugar and malondialdehyde (MDA) in Fe₃O₄ NPs-stressed seedlings leaves extracts. Correlation analysis showed that net photosynthesis rate (A) has a significant positive correlation with leaf gas exchange traits. This showed that the reduction of leaf gas exchange performance of oil palm seedlings under elevated Fe₃O₄ NPs concentration might be due to decreasing of A in oil palm seedlings exposed to high Fe₃O₄ NPs concentration. The concentration of iron (Fe) in leaves was significantly increased with Fe₃O₄ NPs application. In comparison to the control (0 mg/L), the Fe content in the leaves was increased by 52% when the seedlings were treated with the highest Fe₃O₄ NPs concentration (2400 mg/L). Overall, a high application of Fe₃O₄ NPs has induced plant stress, which further affected its growth and development at phenotypic and physiological levels.