This study investigated the cytogenetic characteristics an‎d physiological responses of zinnia genotypes to nanosilica using a completely ran‎domized factorial design. Karyotype analysis revealed that the species possessed 24 chromosomes (12 homologous pairs) with a fundamental arm number of 48, an‎d all chromosomes were classified as metacentric. According to Stebbins’ classification, genotype 5 was placed in group 1A. The greatest karyotypic symmetry occurred in genotypes 1 an‎d 5, whereas genotypes 3 an‎d 4 were more asymmetric. Genotype 2, categorized as class 4A, exhibited the lowest symmetry. These findings indicate overall structural stability alongside considerable variation among genotypes. In the germination experiment, analysis of variance showed significant effects of genotype, nanosilica, an‎d their interaction on seed germination percentage at the 5% probability level. The highest germination was observed in the yellow genotype treated with 0.02 g nanosilica, which exceeded the control by 23%. Across all genotypes, the 0.02 g nanosilica treatment increased germination by 18%. Germination rate was also significantly affected by genotype an‎d nanosilica at the 1% level; the 0.02 g treatment increased germination rate by 46%, while the 0.03 g treatment increased it by 31% compared with the control. Mean comparisons showed that the cream genotype (4) produced the longest radicle, with a 73% increase relative to the control, whereas the shortest radicle was recorded in the yellow genotype (2) under the 0.03 g nanosilica treatment. The 0.02 g nanosilica treatment resulted in an overall 45% increase in radicle length. For plumule length, the same treatment increased growth by 30% in genotype 4 an‎d by 44% overall compared with the control. Biochemical analyses revealed that the orange genotype (5) had the highest total protein content, while the dark-pink genotype (1) showed the lowest. The 0.02 g nanosilica treatment increased total protein by 76% relative to the control. Regarding membrane stability, the 0.02 g treatment reduced ion leakage by 31% in the cream genotype (4). The highest catalase activity was recorded in genotype 4 (98.062 units mg⁻¹ protein), while the highest ascorbate peroxidase activity occurred in genotype 2, representing a 19% increase compared with the control. Overall, nanosilica particularly at 0.02 g enhanced germination, promoted early seedling growth, an‎d improved key physiological an‎d biochemical indices across zinnia genotypes.

علي نيكبخت , مهدي رحيم ملك

محمدرضا سبزعليان دستجردي

مجيد طالبي , محمدحسين اهتمام