نوع مقاله : علمی پژوهشی - کشاورزی پایدار
عنوان مقاله English
نویسندگان English
Introduction
Silicon, primarily absorbed by rice roots in the form of H4SiO4, plays a pivotal role in rice cultivation. It is estimated that approximately 300 kg of silicon is absorbed from the soil per hectare when producing 5 tons of paddy. The critical silicon content in rice during the tillering and ripening stages is 5% of dry weight in the stem and flag leaf. Sufficient silicon levels in the stem help reduce lodging, thus potentially lowering harvesting costs.
Materials and Methods
This research was carried out at the Faculty of Agriculture, University of Guilan, using a completely randomized design with 13 treatments and three replications. The objective was to evaluate the effects of varying silica levels, derived from four different sources, on rice plant height, stem diameter, number of nodes, and silica concentration in the stem. Silica sources included paddy husk, husk ash, husk powder and a siliceous liquid fertilizer. The experiment was performed using 39 pots containing paddy soil. The efficacy of these silica sources was assessed based on changes in plant height, stem diameter, number of nodes, and silica accumulation in both stems and leaves.
Results and Discussion
In the initial measurement, no significant differences in stem height were observed among the 13 treatments, indicating that silicon likely requires a longer period to influence stem elongation in rice. However, with extended exposure to silica amendments, marked effects on morphological traits became evident. For example, in the S3 treatment (silica extracted from paddy husk), stem height increased from 15 cm to 8 cm over the growth period. The average number of nodes in the S3 treatment increased from 3.66 to 7.33 and in the C3 treatment from 3.33 to 6.66, demonstrating a statistically significant difference between the S3 treatment and the others. At the conclusion of vegetative growth, the stem diameters in the control, S3, and C3 treatments were 2.63, 4.98 and 4.97 mm, respectively, with the S3 and C3 treatments significantly outperforming the control.
Silicon uptake and translocation to the stem were highest in the S3 and C3 treatments with statistically significant differences observed among treatments. In July, the silicon content in stems was 7.06% for S3, 6.04% for C3, and only 1.94% for the control (B). By August, significant differences in stem silicon concentration persisted across all treatments, peaking at 10.79% for S3, 8.03% for C3, and 3.69% for the control. In September, the silicon content in stems decreased, with the highest value of 2.1% in S3, which remained statistically significant higher than in C1 and B. The next highest, C3 at 2.06 %, was also significantly higher than C1 and B. Except for C1, all other treatments showed significant differences only when compared to the control. It is noteworthy that the optimal silicon content optimal for rice stems is 8-10%; levels below 5% indicate deficiency. Both S3 and C3 treatments were identified as optimal in terms of plant height, stem diameter, number of internodes and internode length.
Conclusion
The results indicate that as rice plants age and increase in size, silicon concentrations in the stem and leaf decrease, with a more pronounced decline in the leaf. This likely reflects the translocation of silicon from these organs to the husk at the onset of reproductive growth. Among the various treatments, application of 0.24 grams of extracted silicon per 3 kg of soil yielded the greatest improvement in plant growth, followed by commercial siliceous fertilizer. Comparisons between paddy husk ash and rice husk powder treatments revealed that husk ash was more effective for most morphological traits evaluated. Overall, silica addition enhanced rice growth. Therefore, in paddy soils with silicon concentrations less than 100 mg. kg-1, silicon fertilizer application is recommended. Utilizing silica extracted from rice husk milling by-products can fulfill the silicon requirements of rice fields, providing a sustainable and environmentally friendly source of the essential element of paddy soil fertility management.
کلیدواژهها English
