Silicon Application Promotes Productivity, Silicon Accumulation and Upregulates Silicon Transporter Gene Expression in Rice

Application of Silicon Influencing Grain Yield and Some Grain Quality Features in Thai Fragrant Rice

Silicon (Si) is a beneficial nutrient that has been shown to increase rice productivity and grain quality. Fragrant rice occupies the high end of the rice market with prices at twice to more than three times those of non-fragrant rice. Thus, this study evaluated the effects of increasing Si on the yield and quality of fragrant rice. Also measured were the content of proline and the expression of the genes associated with 2AP synthesis and Si transport. The fragrant rice varieties were found to differ markedly in the effect of Si on their quality, as measured by the grain 2AP concentration, while there were only slight differences in their yield response to Si. The varieties with low 2AP when the Si supply is limited are represented by either PTT1 or BNM4 with only slight increases in 2AP when Si was increased. Si affects the gene expression levels of the genes associated with 2AP synthesis, and the accumulation of 2AP in fragrant rice mainly occurred through the upregulation of Badh2, DAO, OAT, ProDH, and P5CS genes. The findings suggest that Si is a potential micronutrient that can be utilized for improving 2AP and grain yield in further aromatic rice breeding programs.

Silicon mitigates K deficiency in maize by modifying C, N, and P stoichiometry and nutritional efficiency

Potassium (K) deficiency in maize plants damages the nutritional functions of K. However, few studies have investigated the influence of K on C:N:P stoichiometry, the nutritional efficiency of these nutrients, and whether the mitigating effect of Si in plants under stress could act on these nutritional mechanisms involved with C, N, and P to mitigate K deficiency. Therefore, this study aimed to evaluate the impact of K deficiency in the absence and presence of Si on N and P uptake, C:N:P stoichiometric homeostasis, nutritional efficiency, photosynthetic rate, and dry matter production of maize plants. The experiment was conducted under controlled conditions using a 2 × 2 factorial scheme comprising two K concentrations: potassium deficiency (7.82 mg L-1) and potassium sufficiency (234.59 mg L-1). These concentrations were combined with the absence (0.0 mg L-1) and presence of Si (56.17 mg L-1), arranged in randomized blocks with five replicates. Potassium deficiency decreased stoichiometric ratios (C:N and C:P) and the plant's C, N, and P accumulation. Furthermore, it decreased the use efficiency of these nutrients, net photosynthesis, and biomass of maize plants. The results showed that Si supply stood out in K-deficient maize plants by increasing the C, N, and P accumulation. Moreover, it decreased stoichiometric ratios (C:N, C:P, N:P, C:Si, N:Si, and P:Si) and increased the efficiencies of uptake, translocation, and use of nutrients, net photosynthesis, and dry matter production of maize plants. Therefore, the low nutritional efficiency of C, N, and P caused by K deficiency in maize plants can be alleviated with the supply of 56.17 mg L-1 of Si in the nutrient solution. It changes C:N:P stoichiometry and favors the use efficiency of these nutrients, which enhances the photosynthesis and sustainability of maize.

Silicon inhibits the upward transport of Cd in the first internode of different rice varieties in a Cd stressed farm land

Silicon spraying on leaves can reduce the accumulation of cadmium (Cd) in rice grain. However, it has been found that not all rice varieties decrease in Cd content after silicon (Si) application. A field study was conducted to check the performance of Si on the accumulation and transport of Cd in four rice varieties. TY390 and YXY2, having 51.5%- 60.6% Cd content of grain was inhibited by foliar Si, were classified as CRS varieties; BXY9978 and YXYLS, having Cd content of grain is nonresponsive with Si, were classified as CNS varieties. The Cd contents were mainly accumulated in stem, especially in the first stem node. While foliar Si reported no changes in the Cd content of first node in four different rice varieties. Comparing the correlation between Si and Cd contents in the above part of the first internode of CRS and CNS, as well as the relative expression of Cd transport genes in the first internode suggested that first internode was the key site to effect Cd transport through Si application, and OsZIP7 is a key Cd transporter protein responsive to Si, leading to different response of Cd transport and accmulation between the CRS and the CNS varieties of rice.