Reducing toxic effect of seed-soaked Cu fertilizer on germination of wheat

A laboratory incubation experiment (20℃) was conducted to find if the detrimental effects of seed-soaked Cu on wheat seedlings can be minimized by reducing time duration of seed in contact with Cu EDTA fertilizer solution. The 24 treatments in a 6 x 4 factorial arrangement included 6 rates/amounts of Cu (0, 15, 30, 60, 120 and 240 g Cu 100 kg-1 seed) and 4 seed-soaking time durations (0, 4, 8 and 16 h). The germination of wheat seed was 100% in the zero-Cu control treatments, irrespective of the duration of seed soaking time. However, seed germination decreased with increasing amount of fertilizer Cu in the seed-soaking solution, and the magnitude of reduction in seed germination due to Cu toxicity increased with increasing duration of seed-soaking time in the Cu fertilizer solution. For the seed-soaked treatments, the detrimental effect of Cu on germination was greatest with 16 h soaking, where only 13% - 18% of the seeds germinated with Cu applied at 15 to 30 g Cu 100 kg-1 seed. For the 4 and 8 h seed soaking treatments, germination of wheat seed ranged from 73% to 83% with 15 g Cu 100 kg-1 seed treatment and 42% to 62% with 30 g Cu 100 kg-1 seed. The findings suggest that the detrimental effect of Cu on germination of wheat seed soaked in Cu EDTA solution can be decreased by reducing duration of soaking time from 16 h to 4 or 8 h, but this needs further investigation using soil under growth chamber and/or field conditions in order to make valid recommendations for use of this new technology on a commercial scale.

Identifying glyphosate-tolerant maize by soaking seeds in glyphosate solution

The identification of glyphosate-tolerant maize genotypes by field spraying with glyphosate is time-consuming, costly and requires treatment of a large area. We report a potentially better technique of seed-soaking to identify glyphosate-tolerant maize genotypes. The effects of soaking maize seeds in glyphosate solution under controlled conditions were studied on seed germination rate, seedling morphological indices, seedling growth and leaf chlorophyll content. These responses were compared among a glyphosate-tolerant transgenic maize cultivar CC-2, glyphosate-susceptible inbred line Zheng 58（the recurrent parent of CC-2） and hybrid cultivar Zhengdan 1002. The results showed that the germination rate, seedling morphological indices and leaf chlorophyll content of glyphosate-tolerant CC-2 seeds did not change significantly among five different concentrations of glyphosate treatment（0 to 2%）. In contrast, germination rates, seedling morphological indices and leaf chlorophyll contents of Zheng 58 and Zhengdan 1002 seeds were significantly negatively affected by exposure to increasing concentrations of glyphosate. The glyphosate-tolerant inbred line CC-2 displayed a strong tolerance to glyphosate after soaking in 0.1 to 2.0% glyphosate solutions, while both the inbred line Zheng 58 and hybrid Zhengdan 1002 were susceptible to glyphosate. The accuracy of the glyphosate-soaking method for screening glyphosate-tolerant maize was confirmed using a field spraying trial.