Tolerance of DAS-444ø6-6 and DAS-444ø6-6 x DAS-81419-2 Soybeans to 2,4-D and Glyphosate in the Cerrado Region of Brazil

ABSTRACT: The DAS-444Ø6-6 soybean expresses AAD-12, 2mEPSPS and PAT enzymes to provide, respectively, tolerance to 2,4-D, glyphosate and ammonium glufosinate. This event is also associated with DAS-81419-2 expressing Cry1Ac and Cry1F proteins to provide protection against a broad spectrum of soybean lepidopteran insect species. Successful adoption by growers of these technologies relies on the traits performing in the diverse environments of Brazil, especially under adverse weather conditions. The objective of this study was to characterize the tolerance of DAS 444Ø6-6 and DAS-444Ø6-6 x DAS-81419-2 soybeans to 2,4-D and glyphosate in the Cerrado region of Brazil. Eight trials across four sites were conducted in the 2015/2016 summer rainy season using a randomized complete block design, with a factorial arrangement of treatments. Factor A was 2,4-D choline salt (456 g a.e. L-1) + glyphosate DMA salt (480 g a.e. L-1) at 975 + 1,025 and 1,950 + 2,050 g a.e. ha-1, respectively and ready-mix of (2,4-D choline salt 195 g a.e. L-1 + glyphosate DMA salt 205 g a.e. L-1) at 2,000 (975 + 1,025) and 4,000 (1,950 + 2,050) g a.e. ha-1. Factor B was application timing at V3, V6 and R2 soybean growth stages. No visible symptoms of leaf chlorosis, epinasty, or growth inhibition were observed. Slight leaf droop was observed at 1 day after treatment (DAT), but it was null at 7 DAT. Less than 6% and 13% of leaf necrosis or injury were observed at 7 DAT, respectively, at 975 + 1,025 and 1,950 + 2,050 g a.e. ha-1 of 2,4-D choline salt + glyphosate DMA salt, regardless of applied as a ready-mix or not, but it was always 2% or less at 28 DAT. Crop grain yield was not influenced by herbicide treatments, application timing and their interaction, regardless of the soybean event and experimental site. DAS-444Ø6-6 and DAS-444Ø6-6 x DAS-81419-2 soybeans showed high tolerance to 2,4-D choline salt and glyphosate DMA in the Cerrado region of Brazil.

摘要：DAS-444Ø6-6转基因大豆表达AAD-12、2mEPSPS和PAT酶，分别赋予其对2,4-滴（2,4-D）、草甘膦（glyphosate）和草铵膦铵盐（ammonium glufosinate）的耐受性。该品系还与表达Cry1Ac和Cry1F蛋白的DAS-81419-2品系聚合，以广谱防控大豆鳞翅目害虫。种植者对这些技术的成功应用，依赖于其在巴西多样环境（尤其逆境天气条件下）的性状表现。本研究旨在表征巴西塞拉多（Cerrado）地区DAS-444Ø6-6以及DAS-444Ø6-6 × DAS-81419-2聚合大豆对2,4-滴与草甘膦的耐受性。

本研究于2015/2016夏季雨季在4个试验点共开展8个试验，采用随机完全区组设计，处理设置为析因组合形式。因子A为2,4-滴胆碱盐（456 g酸当量·L⁻¹）+草甘膦DMA盐（480 g酸当量·L⁻¹），施用量分别为975+1025 g酸当量·公顷⁻¹、1950+2050 g酸当量·公顷⁻¹；以及预混型药剂（2,4-滴胆碱盐195 g酸当量·L⁻¹ + 草甘膦DMA盐205 g酸当量·L⁻¹），施用量分别为2000（975+1025）g酸当量·公顷⁻¹、4000（1950+2050）g酸当量·公顷⁻¹。因子B为施药时期，设置大豆V3、V6、R2三个生育期。

试验未观察到叶片褪绿、偏上生长或生长抑制等可见药害症状。施药后1天（DAT）可见轻微叶片萎蔫，但施药后7天（DAT）该症状完全消失。当施用2,4-滴胆碱盐+草甘膦DMA盐的剂量为975+1025 g酸当量·公顷⁻¹与1950+2050 g酸当量·公顷⁻¹时，无论是否为预混剂型，施药后7天（DAT）的叶片坏死或药害率分别低于6%与13%；而施药后28天（DAT）的该比例始终不超过2%。无论大豆品系与试验地点如何，除草剂处理、施药时期及其交互作用均未对作物籽粒产量产生显著影响。

综上，巴西塞拉多地区的DAS-444Ø6-6以及DAS-444Ø6-6 × DAS-81419-2聚合大豆对2,4-滴胆碱盐与草甘膦DMA盐表现出优异的耐受性。