Pentoxazone

Pentoxazone is a protoporphyrinogen IX oxidase (PPO) inhibiting herbicide. It hinders the synthesis of chlorophyll and heme, leading to the accumulation and oxidation of protoporphyrinogen IX. This process also generates singlet oxygen, which oxidizes cell membranes and causes cellular damage. Pentoxazone effectively reduces the fresh weight growth of various weeds while showing lower activity against weedy rice. It is applicable in research for controlling weeds in direct-seeded rice fields.

Pentoxazone exhibits broad-spectrum herbicidal activity against weeds in direct-seeded rice fields at dosages of 225-450 g/hm² (measured 21 days post-treatment). When applied at 225 g/hm², it achieves over 90% fresh weight inhibition on five weed species, and at 450 g/hm², it shows over 90% inhibition on seven species, but it exhibits lower activity against Oryza sativa f. spontanea. At dosages ranging from 60-600 g/hm², pentoxazone effectively controls Echinochloa crus-galli, Digitaria sanguinalis, Eclipta prostrata, and Cyperus iria, with GR₅₀ values between 82.15 to 189.17 g/hm² and GR₉₀ values from 158.60 to 513.01 g/hm². Pentoxazone at 450-1800 g/hm² (applied four times) is safe for eight tested major rice varieties up to 1800 g/hm², where plant height inhibition ranges from 1.89% to 5.16% and fresh weight inhibition from 1.47% to 4.14%. The compound demonstrates good selectivity between four tested rice varieties and four weed species in direct-seeded fields at 0-2700 g/hm², with a selectivity index of 3.27 to 28.24, showing superior selectivity for rice over Eclipta prostrata and Cyperus iria compared to the control herbicide.