Abstract:

【Objective】The aims of the study were to determine the effects of chemical regulator of dimethylpiperidinium choride (DPC) and ethephon on plant ammonia volatilization in cotton of Xinjiang, and to reveal the mechanism on plant nitrogen nutrition.【Method】Ammonia volatilization from the cotton plants, indexes of soluble proteins (SP), activities of enzymes related to nitrogenous metabolism and stomatal characteristics were measured after the cotton plants sprayed with chemical regulators of DPC and ethephon in enclosure growth chamber.【Result】At the flowering and boll setting stages of cotton, average ammonia volatilization of cotton plants was reduced by 28.80% and 35.15% with the spraying of DPC at 1 g?L-1 and 1.5 g?L-1. There was a positive relationship between the ammonia volatilization and either the SP or area of stomata (P＜0.05), and a negative correlation between ammonia volatilization and nitrate reductase (NR) activity, glutamine synthesis (GS) activity (P＜0.05). The average ammonia volatilization of cotton plants with spraying of ethephon at 1.5 mL?L-1 and 2.5 mL?L-1 increased by 47.30% and 37.40% compared with no spraying control. A negative correlation was observed between ammonia volatilization and SP, NR activity, GS activity (P＜0.05), whereas a positive relationship was observed between the ammonia volatilization and area of stomata (P＜0.05). 【Conclusion】 Spraying of DPC reduced ammonia volatilization from cotton plants, which was mainly due to more photosynthetic transfer to reproductive organ from nutritional organs, reduced soluble protein content in leaves, enhanced NR and GS activities, and reduced the area of leaf stomata, which inhibited ammonia volatilization of cotton plants. Spraying of ethephon resulted in accelerating the plant senescence and the protein degradation, inhibiting the NR and GS activities, enlarging the area of leaf stomata, which promoted the ammonia volatilization of cotton plants.

Key words: dimethylpiperidinium choride, ethephon, soluble protein, nitrate reductase activity, glutamine synthesis activity, stomata