INFLUENCE OF HIGH TEMPERATURE AND UREA FERTILIZATION WITH N-(N-BUTYL) THIOPHOSPHORIC TRIAMIDE AND DICYANDIAMINDE ON COTTON GROWTH AND PHYSIOLOGY

Abstract

The objective of this growth chamber study was to evaluate the effect of adding N-(n-butyl) thiophosphoric triamide (NBPT) and dicyandiaminde (DCD) to urea fertilizer, on the physiology and growth of cotton (Gossypiumhirsutum L.) under normal and high temperatures. Treatments consisted of two day temperature regimes, 30°C and 38°C, and five nitrogen fertilization applications: unfertilized control, 125 kg ha⁻¹ of urea, 93 kg ha⁻¹ of urea, 93 kg ha⁻¹ urea + NBPT, and 93 kg ha⁻¹ urea + NBPT + DCD. The addition of NBPT to urea fertilizer had positive effects on leaf chlorophyll, leaf area, dry matter, nitrogen (N) uptake, and N use efficiency. The absence of a significant interaction effect indicated that N fertilization was not influenced by temperature. Deficiency of N significantly decreased leaf chlorophyll, increased glutathione reductase, decreased protein and increased leaf nitrate reductase. Physiological changes under high temperature included increased plant N uptake, glutamine synthetase, leaf chlorophyll, protein content, plant height and leaf area were due to high N uptake and utilization.

Keywords:

• Gossypium hirsutum
• nitrogen
• N-(n-butyl) thiophosphoric triamide
• dicyandiaminde
• high temperature
• N use efficiency
• glutathione reductase
• glutamine synthetase
• nitrate reductase

ACKNOWLEDGMENTS

The authors thank Cotton Incorporated for partial funding of this research and M. Quadros for her help in the laboratory. The authors thank Cotton Incorporated and the Fluid Fertilizer Foundation for partial funding of this research.