Silicon In the Growth of Rice Seedlings Pretreated with Dietholate and Subjected to Cold Stress

Silicon (Si) is an enzyme stimulator that can promote signaling for the production of antioxidant compounds, important in cellular detoxification of excess ROS accumulated during stress. The aim of the study was to evaluate the effects of Si on post-germination rice seeds in the mitigation of cold stress combined with stress induced by seed treatment with the dietholate protector. The experimental design was fully randomized with three replicates and a 3x2x2x4x2 factorial arrangement: three temperatures (5, 10 and 20 °C), two cultivars (IRGA 424 RI and Guri INTA CL), two seed pretreatments (with and without dietholate), four rates of Si (0; 4.0; 8.0 and 16 mg.L-1) and two sources of Si (sodium and potassium metasilicate). Seed pretreatment with dietholate reduced shoot and radicle length, especially at the lower temperatures of 5 and 10 °C. Sodium metasilicate as the source of Si was more efficient in boosting shoot and radicle length, both with and without pretreatment, regardless of temperature. Si was found to attenuate low-temperature stress and the impairment of shoot and radicle growth in rice seedlings grown from seeds pretreated with dietholate.

Pretreatment of Seed With Hydrogen Peroxide for Mitigating Salt Stress of Some Hungarian Wheat Landraces at Seedlings Stage

Salt stress is a stringent problem limiting germination and productivity of wheat all over the world, seed pretreatment can effectively induce salt tolerance. The present experiment conducted to investigate the germination, seedling and chemical parameters response of seven Hungarian wheat Landraces (Szentesi, Nyirádi, Kiszombori, Háromfai, Tapiószelei, Nagykállói and Szajlai) to seed soaking at four levels of hydrogen peroxide (H2O2) i.e. control, 0.5,.0 and 1.5% subjected to five levels of salt stress (control, 3.0, 6.0, 9.0 and 2.0 dSm−1). Treatments were arranged in Factorial Experimental based on Completely Randomized Design (CRD) with four replications. Under non-saline and salt stress H2O2 soaking significantly influenced all parameters. Soaking at 1.5% resulted the highest germination ability, seedling parameters, relative water content (RWC%), tolerance index (TI%) and potassium (K+ ppm) as well proline level in parallel with the lowest sodium content. However, wheat landraces responded differently to the treatments. Háromfai landrace came in the first rank followed by Tapiószelei, Kiszombori, Szajlai, Nyirádi, Szentesi and Nagykállói landraces. Háromfai landrace resulted the highest values of germination parameters, RWC, TI, K+ and proline contents. At the same time, the maximum values of Na+ content was detected in reverse order. Increasing salinity stress levels from 3.0 to 12.0 dSm−1’ significantly decreased all studied character except Na+ which was increased as compared with control treatment. Therefore, pretreatment of seeds with 1.5 % of H2O2 increased proline and K+ in contrast to the Na+ content. These results suggest that H2O2 pretreatment helps to increase seedlings growth of Háromfai landrace under high salt stress compared to the other examined wheat landraces.

Effect of Seed Size and Different Pretreatment Methods on Germination of Albizia zygia (DC.) J. F. Macbr

Albizia zygia produces valuable timber which has received some level of prominence in the international market. However, the seeds are dormant, and the tree species remain undomesticated. This study was conducted to evaluate the effect of seed size and presowing on the germination of Albizia zygia in a nursery. Seeds were grouped into four categories in regard to their length, small (≤0.5 cm), medium (> 0.5 < 0.8 cm), large (≥0.8 cm), and mixture of small, medium, and large seeds. The seeds were subjected to five main seed pretreatment methods, namely, soaking in sulphuric acid (H2SO4) for 2 minutes, mechanical scarification, soaking in hot water for 5 minutes, soaking in cold water for 24 hours, and control where seeds were sown without any treatment. The results indicate that combination of mechanical scarification and large seeds produced the highest (100%) germination. Hot water treatment was effective in large seeds producing 69.0% germination. The increased germination for mechanically scarified seeds suggests that seed dormancy in Albizia zygia is mainly due to its hard seed coat. Therefore, it is recommended to farmers to adopt use of mechanical scarification and large seeds, since it is safe and effective.

Asymbiotic germination of Vanilla planifolia in relation to the timing of seed collection and seed pretreatments

Background Vanilla planifolia is an important tropical orchid for production of natural vanilla flavor. Traditionally, V. planifolia is propagated by stem cuttings, which produces identical genotype that are sensitive to virulent pathogens. However, propagation with seed germination of V. planifolia is intricate and unstable because the seed coat is extremely hard with strong hydrophobic nature. A better understanding of seed development, especially the formation of impermeable seed coat would provide insights into seed propagation and conservation of genetic resources of Vanilla. Results We found that soaking mature seeds in 4% sodium hypochlorite solution from 75 to 90 min significantly increased germination. For the culture of immature seeds, the seed collection at 45 days after pollination (DAP) had the highest germination percentage. We then investigated the anatomical features during seed development that associated with the effect of seed pretreatment on raising seed germination percentage. The 45-DAP immature seeds have developed globular embryos and the thickened non-lignified cell wall at the outermost layer of the outer seed coat. Seeds at 60 DAP and subsequent stages germinated poorly. As the seed approached maturity, the cell wall of the outermost layer of the outer seed coat became lignified and finally compressed into a thick envelope at maturity. On toluidine blue O staining, the wall of outer seed coat stained greenish blue, indicating the presence of phenolic compounds. As well, on Nile red staining, a cuticular substance was detected in the surface wall of the embryo proper and the innermost wall of the inner seed coat. Conclusion We report a reliable protocol for seed pretreatment of mature seeds and for immature seeds culture based on a defined time schedule of V. plantifolia seed development. The window for successful germination of culturing immature seed was short. The quick accumulation of lignin, phenolics and/or phytomelanins in the seed coat may seriously inhibit seed germination after 45 DAP. As seeds matured, the thickened and lignified seed coat formed an impermeable envelope surrounding the embryo, which may play an important role in inducing dormancy. Further studies covering different maturity of green capsules are required to understand the optimal seed maturity and germination of seeds.

Asymbiotic Germination of Mature Seeds and the Seed Development of Vanilla Planifolia

Background: Vanilla planifolia is an important tropical orchid for production of natural vanilla flavor. Traditionally, V. planifolia is propagated by stem cuttings, which produces identical genotype that are sensitive to virulent pathogens. However, sexual propagation with seed germination of V. planifolia is intricate and unstable because of the extremely hard seed coat. A better understanding of seed development, especially the formation of impermeable seed coat would provide insights into seed propagation and conservation of genetic resources of Vanilla.Results: We found that soaking mature seeds in 4 % sodium hypochlorite solution from 75 to 90 min significantly increased germination and that immature seeds collected at 45 days after pollination (DAP) had the highest germination percentage. We then investigated the anatomical features during seed development that associated with the effect of seed pretreatment on raising seed germination percentage. The 45-DAP immature seeds have developed globular embryos and the thickened non-lignified cell wall at the outermost layer of the outer seed coat. After 60 DAP, the cell wall of the outermost layer of the outer seed coat became lignified and finally compressed into a thick envelope. These features matches the significant decreases of immature seed germination percentage after 60 DAP. Conclusion: We report a reliable protocol for seed pretreatment of mature seeds and for immature seeds culture based on a defined time schedule of V. plantifolia seed development. The thickened and lignified seed coat formed an impermeable envelope surrounding the embryo, and might play an important role in seed dormancy of V. plantifolia.

Effect of Seed Pretreatment and Site Preparation on the Success of Growing Acacia crasicarpa by Direct Seeding

Critical land, which is still very large requires alternative reforestation methods, one of which is direct seeding. This study aims to determine the seed treatment and land preparation in direct seeding of A. crassicarpa seeds. The research was conducted in Parungpanjang, Bogor with a three-factor factorial randomized design, i.e. environmental conditions (A1=under the stand, A2=open area), seed treatment (B1=untreated, B2=soaked in hot water and allowed to cool for 24 hours), and sowing technique (C1=sowing on the soil surface without cleaning, C2=sowing on the soil surface of the cleared and loosened land, C3=sowing with 2-3 cm immerses on the cleared and loosened land). The results showed that seedlings under the stand tended to have better height growth (14.8 cm) compared to seedlings in open area (11.2 cm), as well as for seedlings diameter (under the stand 0.14 cm; in open area 0.11 cm). The application of the direct seeding of A. crassicarpa can be done by treating the seeds soaked in hot water allowed to cool for 24 hours and sowing methods by loosening the soil and immersing the seed 2-3 cm which results in 11% seedling survival, 11.85 cm height, and diameter 0.12 cm at 14 weeks after sowing.

Phoenix dactylifera L. Seed Pretreatment for Oil Extraction and Optimization Studies for Biodiesel Production Using Ce-Zr/Al-MCM-41 Catalyst

This work compared the effect of soaking and roasting Phoenix dactylifera L. seeds pretreatment methods on oil yield. The conversion of the Phoenix dactylifera L. seed oil to fatty acid methyl ester (FAME) was conducted via transesterification reaction using Ce-Zr/Al-MCM-41 monometallic and bimetallic catalysts. The reaction conditions were optimized using response surface methodology based on the central composite design (RSM-CCD). The result shows a quadratic model fitting with an R2 value of ~0.98% from the analysis of variance. In addition, the optimum FAME yield of 93.83% was obtained at a reaction temperature of 60.5 °C, a reaction time of 3.8 h, a catalyst concentration of 4 wt.%, and a methanol to oil molar ratio of 6.2:1 mol/mol. The effect of the regenerated catalyst was significantly maintained for five cycles. The fuel properties of the produced FAME lie within the values reported in studies, ASTM D6751, and EN14214 standards.

Low-temperature plasma applications in chemical fungicide treatment reduction

In order to reduce the environmental burden of chemicals, various new alternatives to seed protection are being sought. Our aim was to find an environmentally acceptable solution leading to the inactivation of seed-borne phytopathogenic fungi Fusarium culmorum on the surface of wheat and barley seeds with a positive effect on their germination. As a low-temperature plasma (LTP) source, a Diffuse Coplanar Surface Barrier Discharge (DCSBD) was used. Plasma generated by DCSBD is non-equilibrium, cold, diffuse, macroscopically homogeneous even in ambient air at atmospheric pressure. Experimental results showed that LTP treatment in the range of 120—300 s significantly inhibits the growth of F. culmorum on the surface of the seeds. The efficiency of LTP treatment was compared with traditional seed protection processes using chemical fungicide and also with combined seed pretreatment by plasma and subsequent application of chemical fungicide. No growth of F. culmorum was observed after the combination of Vitavax 2000 fungicide application in the dose of 10 % and 60 s of LTP treatment even on the 5th day of incubation. Better wettability of seeds with the chemical fungicide was related to the change on seed surface, which becomes hydrophilic after 10 s of LTP application. Short LTP exposure times did not affect germination and improved the growth parameter of cereal seeds. By combining physical (LTP) and chemical (Vitavax 2000) treatments of cereal seeds, it is possible to effectively reduce the required amount of chemical fungicide and to stimulate germination and early growth seed parameters.