Morphological and phenological variability of Echinochloa accessions and their herbicide sensitivity

Abstract

Echinochloa species are the most problematic grass weeds in rice fields worldwide. The species of this genus have high intra- and interspecific variability, with many ecotypes. Based on this, the study was conducted to characterize the morphology and phenology of Bangladesh Echinochloa accessions and evaluate their herbicide sensitivity. The results showed a distinct variability of the growth characteristics among Echinochloa ecotypes. The four Echinochloa accessions, designated Echinochloa crus-galli ecotypes A, B, C, and D, were discovered in the various rice-growing regions of Bangladesh. The same ecotypes were treated with pre-and post-emergence herbicides in pot culture and the puddle and dry sowing conditions to determine the herbicide sensitivity. Among the pre-emergence herbicides, all except butachlor in dry sowing conditions and pyrazosulfuron ethyl in both puddle and dry sowing conditions were effective against ecotypes of Echinochloa detected. Bispyribac sodium and metamifop were effective in both the four-leaf and eight-leaf stages of E. crus-galli ecotype D. In contrast, fenoxaprop–p–ethyl was effective at the four-leaf stage. E. crus-galli ecotype B was effectively controlled by quizalofop-p-ethyl when sprayed at the eight-leaf stage and fenoxaprop–p–ethyl at the four-leaf stage. E. crus-galli ecotype C was less susceptible to all the herbicides. However, quizalofop-p-ethyl and fenoxaprop-p-ethyl, although effective at the four-leaf stage in reducing the weed persistence index (WPI). This information helps make weed management decisions and is informative in understanding the speciation and adaptation of weedy Echinochloa species.