The Effect of New Nano-Released 1,1-Dimethyl-Piperidinium Chloride (DPC) Drip Application on Cotton Agronomic Traits

The use of 1,1-dimethyl-piperidinium chloride (DPC) in Xinjiang is one of the necessary measures for regulating cotton populations and optimizing canopy structure. However, mechanical spraying involves operation and energy consumption, which can alternatively be achieved via drip application. In the present study, to investigate the effect of drip application, two types of hydrophobic nano-released DPCs were used to regulate plant type at different dosages. DPC dripingation reduced plant height by more than 10 cm and plant width by more than 4 cm, and the effect improved with increasing concentration and times. The main effect of height control was at the 6th–10th nodes of the main stem, and the effect of width control was observed at the 1st and 2nd nodes of the fruit branch. The SPAD value was higher than that in the control group during the initial stages. An irregular downward trend was observed in the subsequent stages. The proline content was higher than that of the control and increased with higher concentrations of DPC. There was no significant difference in the soil DPC content at the different sites. The DPC content decreased by more than 30% at the seventh day after dripping, and the content was 2–4 μg·g⁻¹ in each treatment. At 15 days after application, the soil DPC was lower than 1 μg·g⁻¹ in all treatments. The number of harvested plants was more than 150,000 plants·hm⁻², and the number of bolls per plant increased at least by one, compared with the control. The final yield of seed cotton increased by at least 300 kg·hm⁻², with a maximum increase of 1672.01 kg·hm⁻². Considering the different types of DPCs, nano-released types worked better than the conventional type in terms of plant height, plant width, degradation in soil and boll formation. Nano-released DPC can play an even better role than conventional DPC in chemical regulation with drip irrigation.