Paclobutrazol Effects on Summer Maize

Zhengdan (ZD 958), a summer maize variety was used in the experiment. The experiment comprised of two different application methods (seed-soaking and seed-dressing) with three different concentrations of paclobutrazol, each including a control treatment (CK). The concentrations of paclobutrazol were established in previous experiments. The seeds were first surface sterilized by immersing in a 3% solution of sodium hypochlorite for at least 20 minutes followed by washing several times with distilled water. For seed soaking, the maize seeds were primed at the rate 0, 200, 300 and 400 mg paclobutrazol L⁻¹ water for 12 hrs. For seed dressing the seed were surface dressed with paclobutrazol at 0, 1.5, 2.5 and 3.5 g Kg⁻¹ of seeds. Before sowing, seeds were dried at room temperature until moisture content reached to 10%. The hybrid seeds were manually sown on 14th June 2015 and 16th June 2016, while harvested on 11th October 2015 and 14th October 2016, respectively. Prior to planting, flood Irrigation was applied through a plastic pipe (50 mm diameter) to ensure germination. The experiment was laid out in Randomized complete block (RCB) design with three replications. The plot size was kept as 35 m² (7 × 5 m) with the plant-to-plant and row-to-row distances of 20 cm and 60 cm, respectively. Recommended nitrogen fertilizer at the rate 240 kg N ha⁻¹ was applied and urea (N46%) was used as N fertilizer. Half of the N fertilizer was manually applied prior to sowing. The remaining half was applied before the tasseling stage. A total of 150 kg phosphorus (P₂O₅) ha⁻¹ as calcium superphosphate (P₂O₅ 12%) and 150 kg potassium (K₂O) ha⁻¹ as potassium sulfate (K₂O 45%) was applied at sowing. The crop was solely dependent on soil moisture and natural rainfall in the season.