Abstract

Rapid and uniform seedling growth is a pre-requisite for better establishment of oil palm plantations. Chemical pretreatments can be used to increase the rate and uniformity of seed germination. Thiamethoxam and imidacloprid are insecticides classified in the broad-spectrum systemic neonicotinoid group and their use in seed treatment has been claimed to increase seed germination and vigor in some crops. Thiamethoxam at the rate of 0, 0.1, 0.3, 0.6 and 0.9 g ai. L^-1 of water and imidacloprid at the rate of 0, 0.2, 0.5, 0.9 and 1.4 g ai. L^-1 of water were evaluated using dry-heated seed (seed with 18% moisture content heated at 40°C for 60 days) to observe the differences in germination response and seedling vigor. The results revealed that imidacloprid at the rate of 0.5 g ai. L^-1 of water significantly increased shoot length while thiamethoxam did not. Both neonicotinoids did not affect the germinated seed percentage, the time taken to reach 50% germination (T₅₀) and root length. It can be concluded that imidacloprid could increase seedling vigor by stimulating the shoot growth of dry-heated oil palm seed. No phytotoxicity of thiamethoxam and imidacloprid following dry-heated seed germination was observed.

Key words: Thiamethoxam, imidacloprid, germination, seedling vigor, tenera oil palm seed.