Objective To explore the effect of seed dressing with Mepiquat Chloride (DPC) on seedling traits of cotton under dry sowing and wet emergence cultivation, in order to provide a scientific basis for early and robust growth of cotton seedlings.
Methods For seed dressing, Tahe 2 cotton seeds were treated with DPC at four concentrations: S1 (3.0 g·kg−1), S2 (1.50 g·kg−1), S3 (0.75 g·kg−1), and CK (0 g·kg−1). The cotton fields were managed using the dry sowing and wet emergence technology. Plant height, leaf number, SPAD value, and dry matter of different organs were measured every 10 days after emergence.
Results The results showed that seed dressing with DPC reduced cotton seedling height, while the S2 treatment promoted plant height at the later stage. DPC seed dressing increased the leaf SPAD value at the seedling stage, but the SPAD value in the S1 treatment decreased rapidly at the later growth stage. The number of main-stem leaves at the seedling stage decreased with increasing DPC concentration, and this effect had weakened by early June (when the main stem had 8 leaves). DPC seed dressing promoted dry matter accumulation in cotton, with the S2 treatment being the most effective.
Conclusion Based on these results, seed dressing with DPC at the S2 concentration (1.50 g·kg−1) for Tahe 2 can promote the early and robust growth of cotton seedlings in dry sowing and wet emergence fields. DPC seed dressing effectively reduced cotyledon node height, increased leaf SPAD value at the seedling stage, and promoted root growth and development, thereby enhancing aboveground dry matter accumulation. Although seed dressing significantly impacted the number of main-stem leaves at the seedling stage, its effect weakened by early June. Therefore, to achieve a high-yield plant type in the middle and later stages, reasonable chemical regulation measures should be adopted based on the cotton field's growth conditions.
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