Effect of mixtures of gibberellic acid and several herbicides on the herbicidal activity against wild oat (Avena fatua L.)

Gibberellic acid와 여러 가지 제초제와의 혼합처리가 메귀리에 대한 제초활성에 미치는 영향

Based on the differential growth response to exogenous gibberellic acid ($GA_{3}$) between semi-dwarf wheat(Triticum aestivum) and wild oat(Avena fatua), we examined the possibility of improving the selective performance of several herbicides by $GA_{3}$ application and the physiological background of $GA_{3}$-induced increase in herbicidal activity. Growth of wild oat was 4 to 5 times higher than that of wheat by $GA_{3}$ treatment. Pretreatment of wild oat seed with 300 ppm $GA_{3}$ increased the herbicidal activities of trifluralin and isoproturon by soil-surface application, but not of alachor and metsulfuron-methyl. $GA_{3}$ applied simultaneously with post-emergence herbicides resulted in a significant or moderate improvement of the efficacy of such herbicides as tralkoxydim, fenoxaprop-ethyl, metsulfuron-methyl, metribuzine and isoproturon, but not in the mixtures of oxyfluorfen or paraquat with $GA_{3}$. In the sequencial treatment of tralkoxydim and $GA_{3}$ at interval of one-day, $GA_{3}$ applied prior to tralkoxydim significantly increased a chlorosis and desiccation of leaf without affecting the growth inhibition by tralkoxydim. Tralkoxydim followed by $GA_{3}$ application had lower herbicidal activity than that of $GA_{3}$ followed by tralkoxydim treatment. Electrolyte leakage response of $GA_{3}$-pretreated or $GA_{3}$-untreated wild oat leaf against several compounds inducing membrane. peroxidation was compared. Differencial responses were observed in oxyfluorfen and isoproturon treatments with an increased electrolyte leakage in $GA_{3}$-pretreated tissue, but not in paraquat and rose bengal treatments. These results suggest that $GA_{3}$-induced increase in herbicidal activity is likely to be dependent on a herbicide type and may be due to activation of a metabolic ability related with herbicidal reponse as well as an increase in the herbicide absorbtion and translocation, rather than due to membrane and cell wall extention induced by $GA_{3}$, which in turn makes the herbicides easily enter.

Gibberellic acid에 대한 밀과 메귀리간에 차등반응을 이용하여 제초제에 gibberellic acid를 첨가함으로써 상대적으로 민감한 반응을 보였던 메귀리를 효과적으로 방제할 수 있는 조합을 찾고, 그 효과증대의 생리적 원인을 조사하고자 실험하였다. 밀은 $GA_{3}$에 대한 낮은 신장반응을 보였으나, 메귀리는 이보다 $4{\sim}5$배 높은 반응을 보였다. $GA_{3}$에 침지된 메귀리 종자를 파종한 후 토양처리했을 때는 isoproturon, trifluralin의 효과가 증진되었다. 경엽처리의 경우 $GA_{3}$는 tralkoxydim fenoxaprop-ethyl, metsulfuron-methyl, metribuzine, isoproturon의 효과를 증진시켰으나, oxyfluofen과 paraquat의 효과에는 거의 영향을 미치지 않았다. 경엽처리조건에서 체계처리를 할 경우 tralkoxydim처리 이전에 $GA_{3}$를 처리하면 tralkoxydim의 효과를 증진시켰으나, tralkoxydim처리 이후에 $GA_{3}$를 처리하면 효과가 낮은 경향이었다. 그러나 $GA_{3}$를 어느 시기에 처리하여도 tralkoxydim의 신장저해효과를 증진 또는 경감시키지는 못하였고, $GA_{3}$가 처리된 잎의 과산화작용 화합물에 대한 반응은 무처리와 비교하여 일정한 경향을 보이지 않았다. 이들 결과로 보아 $GA_{3}$가 일부 제초제의 효과를 증진시킨 것은 조직의 연화(세포신장 촉진)에 의한 높은 제초반응 때문이라기보다는 제초제 흡수, 이행의 변화 또는 제초작용 발현과 관련한 체내대사의 촉진 때문으로 추정된다.