How Zinc Affects Plant Health and Sugar Production in Stressed Rice Seedlings

Jim Crocker
28th May, 2024

Image Source: Natural Science News, 2024

Key Findings

The study was conducted by researchers at Jilin Agricultural University to investigate the effects of zinc on rice plants under saline-sodic stress
Zinc application increased chloroplast pigment content and improved photosynthesis in rice leaves under saline-sodic conditions
Zinc supplementation reduced soluble sugars and starch in rice leaves while increasing starch content in the roots, enhancing carbohydrate metabolism

Saline-sodic stress poses a significant challenge to rice cultivation by limiting the absorption of essential nutrients, particularly zinc (Zn), which is crucial for normal photosynthesis and carbohydrate metabolism. A recent study conducted by researchers at Jilin Agricultural University investigated the effects of exogenous zinc application on rice plants grown under saline-sodic conditions. This study aimed to determine whether zinc supplementation could mitigate the adverse effects of saline-sodic stress on rice photosynthesis and carbohydrate metabolism^[1]. The experiment involved two rice varieties, 'Changbai 9' and 'Tonghe 899', which were subjected to different treatments: a control (CT), zinc treatment alone (Z), saline-sodic treatment alone (S), and a combination of zinc and saline-sodic treatment (Z+S). The researchers used the JIP-test to analyze variations in excitation fluorescence and MR820 signal in rice leaves, as well as the impact of zinc supplementation on carbohydrate metabolism in both rice leaves and roots under saline-sodic stress. The findings revealed that zinc application under saline-sodic conditions increased chloroplast pigment content, specific energy flow, quantum yield, and the performance of active PSII reaction centers (PIABS). Additionally, zinc enhanced the oxidation (VOX) and reduction rate (Vred) of PSI in rice leaves. These improvements in the photosynthetic apparatus were accompanied by a decrease in relative variable fluorescence (WK and VJ) and quantum energy dissipation yield (φDO) in the rice plants. Moreover, zinc application reduced the content of soluble sugars and starch in rice leaves while increasing the starch content in the roots. These changes suggest that zinc promotes electron and energy transfer in the rice photosystem under saline-sodic stress, thereby enhancing carbohydrate metabolism and improving the rice plants' ability to withstand such stress. This study builds on previous research that has explored the role of zinc in plant growth and stress tolerance. For instance, earlier studies have shown that rice grown in zinc-sufficient conditions preferentially takes up lighter zinc isotopes, indicating a complex mechanism of zinc uptake and transport in plants^[2]. Additionally, research has demonstrated the importance of zinc-containing enzymes, such as carbonic anhydrases, in photosynthesis and crop yield. These enzymes facilitate the interconversion of carbon dioxide and bicarbonate ions, influencing CO2 diffusion and availability in chloroplasts, which is crucial for photosynthesis^[3]. The current study's findings align with the notion that zinc plays a vital role in maintaining photosynthetic efficiency and carbohydrate metabolism, especially under stress conditions. By increasing the chloroplast pigment content and enhancing the performance of photosystem II (PSII) and photosystem I (PSI), zinc supplementation helps rice plants better manage the energy demands of photosynthesis under saline-sodic stress. This is particularly important given that saline-sodic stress can disrupt the ion balance and limit the absorption of essential nutrients, as observed in other crop studies such as cotton^[4]. In summary, the research conducted by Jilin Agricultural University demonstrates that exogenous zinc application can significantly improve the photosynthetic performance and carbohydrate metabolism of rice plants under saline-sodic stress. By enhancing the efficiency of the photosynthetic apparatus and promoting better energy transfer, zinc supplementation helps rice plants better tolerate adverse conditions, ultimately supporting their growth and development. This study underscores the importance of zinc in plant physiology and offers valuable insights for improving rice cultivation in saline-sodic soils.

Agriculture Biochem Plant Science

References

Main Study

1) Zinc regulation of chlorophyll fluorescence and carbohydrate metabolism in saline-sodic stressed rice seedlings

Published 27th May, 2024

https://doi.org/10.1186/s12870-024-05170-w

Related Studies

2) Evidence for the mechanisms of zinc uptake by rice using isotope fractionation.

https://doi.org/10.1111/j.1365-3040.2009.02085.x

3) OsαCA1 Affects Photosynthesis, Yield Potential, and Water Use Efficiency in Rice.

https://doi.org/10.3390/ijms24065560

4) Growth, ionic homeostasis, and physiological responses of cotton under different salt and alkali stresses.

https://doi.org/10.1038/s41598-020-79045-z