Iranian Journal of Seed Research

Salinity is one of the most important factors limiting agricultural production. Cotton, as an oil-fiber plant, is one of the most important industrial plants and is sensitive to salinity, especially at germination and seedling stages. Therefore, in this study, 14 allotetraploid varieties of commercial and local cotton were selected. The study was carried out as factorial with a completely randomized design and three three replications, using the sandwich method. Germination tests were performed at three salinity levels of 0, 8 and 16 ds.m^-1. Afterwards, root and shoot length, fresh and dry weight of root and shoot, germination percentage, allometric coefficient, seedling water percentage and seed vigor index were measured and stress tolerance indices were calculated based on yield (seedling dry weight) in stress and non-stress conditions. Given these indices, all cultivars were aalyzed at two levels of 8 and 16ds.m^-1, using principal component analysis and biplot diagrams were drawn. Finally, the dendrogram classification of genotypes was plotted based on STI indices (stress tolerance index), SSI (stress susceptibility index), and the performance (dry weight plantlet) in stress and non-stress conditions. The result of variance analysis for genotype, salinity and salinity×genotype demonstrated that dry weight root, dry weight shoot, fresh weight root, stem length, vigor index seedling, allometric coefficient, dry weight seedling, and length seedling were significant in p-value 0.01, and fresh weight shoot, length root were significant in p-value 0.05. Clustering and the biplot of the genotypes based on STI and SSI indices at salinity levels of 8 and 16 ds.m^-1 indicated that the Sepid and Giza genotypes were tolerant and that the Kashmar genotype was sensitive to salt levels at germination stage.

Extended abstract
Introduction: Currently, in most countries around the world, cotton seeds are used in delinted form. The fuzzy cotton seed often lead to slower germination, increased susceptibility of seeds and seedlings to pests and diseases, and disrupts mechanized cotton planting. Delinted cotton seeds have numerous advantages, including the possibility of mechanized planting, reduced seed consumption per unit area, faster germination in the soil, and more rapid field emergence of seedlings. Furthermore, delinted seeds are usually free from pathogenic agents, and the seed quality is improved with the availability of gravity separation and removal of broken, lightweight, and hollow seeds. One of the challenges faced by cotton seed delinting factories in Iran that employ acid-based methods is the reduction in the seed germination of the delinted seeds, which poses a challenge to the continued operation of these factories. This research was conducted to investigate the reasons behind the reduction in the viability cotton seeds in a delinting factory, to examine the physiological and mechanical characteristics of seeds at various stages of delinting in the factory.
Materials and methods: Seed sampling was carried out in a delinting factory in two replications. Traits such as seed vigor, germination percentage, ion leakage, seed density and volume, seed aging, level of abrasion and damage to the seed coat, and seed rupture force were studied. Finally, the data were analyzed using SAS, SPSS, and JMP software.
Results: The test results showed that seed sampling from both replications of the factory before centrifuge had the lowest germination percentage, leaf formation percentage, primary root length, primary stem length, dry weight of primary root, and dry weight of primary stem. These traits indicate that during the centrifugation stage, the seeds sustain significant mechanical damage, leading to a reduction in their vigor. The percentage of breakage, ion leakage, ageing, volume and density of seeds in the first repetition showed that these seeds had a lower quality compared to the seeds related to the second repetition. Therefore, different delinting stages in the factory have decreased the seed vigor. As the percentage of breakage and ion leakage increases, the seed rupture force declines non-linearly. Based on these findings, it can be concluded that acid contact with the cotton seed and the centrifugation process caused more mechanical damage to the seeds, leading to a significant reduction in seed rupture force.
Conclusion: The accuracy of operations at all stages of delinting significantly impacts seed quality. The centrifugation stage, the temperature of the dryer cylinders, and the acid neutralization process require greater attention and monitoring. Therefore, it is necessary to adjust the duration or concentration of the acid used for delinting in the delinting factory to match the seed condition in order to minimize damage to the seeds.

Highlights:

1. Delinting in the factory causes damage to the seeds, but proper management of temperature and acid concentration mitigates this damage.
2. It is necessary to adjust the duration or concentration of the acid used for delinting in the factory to match the seed condition in order to minimize damage to the seeds.
3. Managing the acid spray on the seeds and eliminating the centrifugation section in the delinting factory can prevent severe seed damage in this stage, and seed quality can be improved.
4. Neutralizing the seeds at the end of the delinting process in the delinting factory results in an increase in the storage of delinted cottonseed.

bjective: Cotton seed quality (Gossypium hirsutum L.), as a fundamental input in crop production, is a determining factor in field establishment, final yield, and fiber production. The aim of this study investigates the crucial role of seed morphological characteristics, particularly seed coat thickness and integrity, as a key factor in determining the seed's physiological vigor and its resilience to seed processing.
Method: This study was conducted as a systematic review. To collect information, searches were performed on reputable scientific databases such as ScienceDirect, Scopus, as well as domestic databases such as SID and Magiran, using keywords such as "cottonseed coat," "seed coat thickness," "seed vigor," "cottonseed processing," and their English equivalents. The search was conducted on articles published between the years 2000 and 2024.
Results: The seed coat possesses dual characteristics; its optimal thickness is essential for creating a balance between protection and function. A thicker seed coat provides better protection for the embryo against mechanical damage, safeguards it during the acid delinting process, reduces ion leakage, and plays a fundamental role in greater resistance to pathogens. Furthermore, this type of coat provides a more suitable physical bed for the formation of higher fiber density. Conversely, an excessively thick seed coat can cause physical dormancy and, by creating a mechanical barrier to radicle emergence, lead to delayed and reduced germination rates. On the other hand, seeds with thinner coats, although exhibiting faster water absorption and germination, are highly vulnerable to chemical and mechanical damage, resulting in the production of seeds with low vigor and reduced storability. Harsh seed processing conditions can lead to the formation of micro-cracks in the seed coat, severely compromising its integrity, which directly causes a reduction in germination percentage and seed vigor.
Conclusions: In general, achieving high-quality cotton seeds requires an integrated management approach. This approach includes selecting cultivars with optimal seed coat morphological characteristics, managing environmental stresses during seed filling, and modifying the seed processing procedure to minimize seed damage. Future breeding programs should adopt a dual strategy that simultaneously selects based on beneficial morphological traits and strong physiological performance to develop resilient cultivars that ensure sustainable cotton production.
Highlights

• The cottonseed hull varies among different cultivars.
• The seed hull plays a significant role in achieving seeds with desired vigor.
• In seed processing, the characteristics of the cottonseed hull should be taken into consideration.