Effect of Nitrogen and Trinexapac-Ethyl Rates on the SPAD Index of Wheat Leaves

ABSTRACT

The objective of this study was to evaluate the effect of nitrogen (N) and trinexapac-ethyl (TE) rates on the SPAD index in wheat flag leaf. The treatments were five N rates (30, 60, 90, 120, 150 kg ha⁻¹) combined with four TE rates (0, 63, 125, 188 g ha⁻¹). The experiment was carried out in a randomized block design with four repetitions. SPAD index, leaf N content and grain yield showed quadratic response to the increase in N rates, whereas area, wet and dry weight of flag leaf presented linear increase. TE caused linear increase in SPAD index, linear decrease in leaf area, reduction in grain yield with smaller N rates and increase with larger N rates. The N content, and the wet and dry weight of flag leaf were not affected by TE. SPAD calibration to estimate N status in wheat should be specific for each TE rate.

Keywords:

• Triticum aestivum
• diagnosis
• chlorophyll
• green

ACKNOWLEDGMENTS

The authors would like to thanks the National Council for Scientific and Technological Development (CNPq) and the Research Foundation of the State of Minas Gerais (FAPEMIG) for the grants and financial support.

Notes

¹The flag leaf characteristics were determined from 8:00 a.m. to 11:00 a.m., under sunlight (day without clouds); grain yield was determined at the maturity.

¹The flag leaf characteristics were determined from 8:00 a.m. to 11:00 a.m., under sunlight (day without clouds); grain yield was determined at maturity.