Effects of different herbicides and application times on the apical development and grain yield of wheat (Triticum aestivum L.)

The influence of different herbicide treatments and application timings on the apical development of wheat (Triticum aestivum L.) was evaluated in field trials conducted during two subsequent growing seasons in Aydin province of Turkey. Three common herbicides (tribenuron-methyl, 2,4-D amine and cladinafop-propargyl) were applied. The timing of herbicide application was adjusted to the apical development of wheat, which was continuously monitored by microscopy using wheat samples collected from field plots. Herbicide treatments were done before (early treatment) and after double ridge stage of wheat (late treatment). Results showed that early 2,4-D amine treatments prolonged the spikelet development period (SDP), because the double ridge stage was reached earlier with this treatment. Tribenuron-methyl shortened the SDP and prolonged the floret development period. Grain yield values showed that the herbicide applications and the herbicide x variety interaction had a significant influence on grain yield. Early cladinafop-propargyl treatments gave the highest yield and corresponded with the untreated control. In general, the yield of untreated or early treated plots was significantly higher than the yield of plots treated after double ridge stage. Therefore, in order to ensure high yields and prevent crop injury it is recommended that the herbicides tested should be applied before double ridge stage.