Post emergence herbicides influence the leaf yield, chlorophyll fluorescence and phenolic compounds of artichoke (Cynara cardunculus L.)

Abstract

We examined the effects of herbicides on leaf yield, chlorophyll fluorescence and phenolic compounds of artichoke (Cynara cardunculus L.) under field conditions during 2006 and 2007 at the Institute of Agronomy and Plant Breeding I, Giessen, Germany (50°36′N and 8°39′E). Artichoke (cv. Gobbo di Nizza) was cultivated in a randomized complete block replicated four times in 75cm rows. The treatments included five herbicides (haloxyfop, phenmedipham, pyridate, quizalofop-P and prosulfocarb), applied after germination, and a mechanically weeded control. The crop was harvested two times in both experimental years. Pyridate (phenyl-pyridazine) affected the artichoke crop most adversely in both years, and resulted in minimum leaf yield during both growth phases of 2006 and second growth phase of 2007. In general, the second phase of artichoke growth resulted in higher leaf yield than that of the first phase in 2006; whereas, opposite results were obtained in 2007. Chlorophyll fluorescence measurements showed that top two damage causing herbicides were Pyridate and Phenmedipham. Visual toxicity observations showed the same trend as that of photosynthetic data. The toxic effect of the herbicide was recovered during the growth cycle of the crop depending on the prevailing environmental conditions. Phenolic compounds differed during different growth phases and experimental years. Quizalofop-p application increased falvonoids content in artichoke leaves at the first harvest compared to untreated control and other herbicide treatments.