Selectivity of pre-emergence herbicides in potato cv. Innovator

ABSTRACT Herbicide tolerance differs among potato cultivars. Thus, pre-emergence herbicides in potatoes need to be studied. We evaluated weed control, selectivity and potato yield of cv. Innovator with the herbicides clomazone, metribuzin and linuron. The experimental design was randomized blocks with four replications. One experiment was installed in 2014 (experiment 1, 5 treatments) and another in 2015 (experiment 2, 7 treatments), irrigated by central pivot in Perdizes-MG, Brazil. In experiment 1 treatments consisted of a control (T1), a hoed control (T2), clomazone (360 g ha-1) (T3), metribuzin (480 g ha-1) (T4), and linuron (990 g ha-1) (T5). The treatments in experiment 2 repeated those in experiment 1 (T1 to T5) and added clomazone + metribuzin (360 + 480 g ha-1)) (T6), and clomazone + linuron (360 + 990 g ha-1) (T7). We determined the number of stems per meter, length of longest stems, phytotoxicity, weed control, soluble solids content (%), yield and classification of tubers. The herbicides, either by themselves or in combination with another herbicide, provided 100% control of Eleusine indica and Digitaria horizontalis. Clomazone by itself or in combination with metribuzin or linuron provided the best control of Commelina benghalensis. Plots treated with clomazone presented phytotoxicity symptoms at 10 days after emergence (DAE); however, the plants recovered from these symptoms at 30 DAE. Metribuzin reduced soluble solids content, which affects industrial yield. The herbicides significantly influenced potato yield. In, 2014, the greatest “total” yields were observed in treatments with linuron (34.48 g ha-1) while the greatest “special” potato yields were achieved with clomazone (20.21 g ha-1) and linuron (21.13 g ha-1). In 2015, the greatest “total” yields were observed in treatments with clomazone [“special” (20.98 t ha-1) and “total” (35.11 t ha-1)] and metribuzin [“special” (20.85 t ha-1) and “total” (35.45 g ha-1)] followed by clomazone+linuron (30.95 g ha-1). Therefore, while metribuzin and linuron controlled Eleusine indica and Digitaria horizontalis, they may also reduce potato quality. Clomazone may be an option for controlling Eleusine indica, Digitaria horizontalis and Commelina benghalensis without affecting potato yield and soluble solids content.

摘要：不同马铃薯品种对除草剂的耐性存在差异，因此有必要针对马铃薯田芽前除草剂开展相关研究。本试验以品种Innovator为供试材料，评估了氯草酮（clomazone）、嗪草酮（metribuzin）与利谷隆（linuron）对杂草的防除效果、药剂选择性以及马铃薯块茎产量。试验采用随机区组设计，设置4次重复，分别于2014年（试验1，含5个处理）和2015年（试验2，含7个处理）在巴西米纳斯吉拉斯州佩尔迪泽斯市布置，采用中心支轴喷灌系统供水。

试验1的处理包括空白对照（T1）、人工中耕对照（T2）、氯草酮（360 g·ha⁻¹，T3）、嗪草酮（480 g·ha⁻¹，T4）以及利谷隆（990 g·ha⁻¹，T5）。试验2的处理在试验1的5个处理（T1至T5）基础上，新增了氯草酮+嗪草酮（360+480 g·ha⁻¹，T6）与氯草酮+利谷隆（360+990 g·ha⁻¹，T7）两个处理。本试验测定的指标包括每米茎秆数、最长茎秆长度、药害症状、杂草防效、可溶性固形物含量（%）、块茎产量与块茎分级。

供试除草剂无论单剂施用还是复配施用，均可100%防除牛筋草（Eleusine indica）与横果马唐（Digitaria horizontalis）；氯草酮单剂或与嗪草酮、利谷隆复配施用，对孟加拉鸭跖草（Commelina benghalensis）的防除效果最佳。喷施氯草酮的处理组在出苗后10天（DAE）出现药害症状，但在出苗后30天（DAE）植株即可恢复正常。嗪草酮会降低块茎的可溶性固形物含量，进而影响工业加工产量。各类除草剂对马铃薯块茎产量均有显著影响：2014年，利谷隆处理组的总块茎产量最高（34.48 t·ha⁻¹），氯草酮（20.21 t·ha⁻¹）与利谷隆处理组（21.13 t·ha⁻¹）的特级块茎产量最高；2015年，氯草酮处理组[特级块茎产量20.98 t·ha⁻¹，总块茎产量35.11 t·ha⁻¹]与嗪草酮处理组[特级块茎产量20.85 t·ha⁻¹，总块茎产量35.45 t·ha⁻¹]的总块茎产量最高，其次为氯草酮+利谷隆处理组（30.95 t·ha⁻¹）。

综上，嗪草酮与利谷隆虽可有效防除牛筋草和横果马唐，但会降低马铃薯品质；氯草酮可在不影响马铃薯产量与可溶性固形物含量的前提下，同时防除牛筋草、横果马唐与孟加拉鸭跖草，是较为理想的除草剂施用方案。