Effect of Nitrogen and Trinexapac-Ethyl Rates on the SPAD Index of Wheat Leaves
2009
Espindula, Marcelo Curitiba | Rocha, Valterley Soares | Fontes, Paulo Cezar Rezende | Silva, Raul Carvalho Correa da | Souza, Leandro Torres de
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.
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