Resíduos de atrazine e de tembotrione no solo afetam o crescimento inicial da beterraba

Abstract

-The cultivation of beets is frequently done in a crop rotation system with cereals such as corn. In this case, herbicides with residual effect applied during corn growth can harm the establishment and growth of beets grown in succession. Therefore, three experiments were carried out in a greenhouse to evaluate the residual effect of atrazine and tembotrione, in isolation or in a mixture, on the initial growth of beets. The treatments consisted of six dosages corresponding to 0, 10, 20, 30, 40 and 50% of the recommended dosage. The evaluations were on: plant intoxication, shoot dry matter and SPAD index. Atrazine and tembotrione had a negative effect on the initial growth of beets, presenting reduction in the values of shoot dry matter and SPAD index, as well as increase in the intoxication as the dosage also increased. When the herbicides were applied in a mixture, the effect was enhanced, causing the death of plants in the highest dosages (40 and 50%). Due to these results, the cultivation of beets after the application of atrazine and/or tembotrione in corn crops may become impracticable due to the carryover potential in these situations. efeito residual dos herbicidas atrazine e tembotrione, isolados ou em mistura, sobre o crescimento inicial da beterraba. Os tratamentos consistiram de seis doses correspondentes a 0, 10, 20, 30, 40 e 50% da dose recomendada. As avaliações realizadas foram: intoxicação das plantas, matéria seca da parte aérea e índice SPAD. O atrazine e tembotrione provocaram efeito negativo sobre o crescimento inicial da beterraba, apresentando redução nos valores de matéria seca da parte aérea e do índice SPAD, bem como aumento da intoxicação com o incremento das doses. Quando os herbicidas foram aplicados em mistura o efeito foi potencializado, causando a morte das plantas nas maiores doses (40 e 50%). Em função desses resultados, o cultivo de beterraba após a aplicação de atrazine e, ou tembotrione na cultura do milho pode tornar-se inviável devido ao potencial de carryover nessas situações. Keywords

Residual effect of tembotrione in soil with distinct textures and humidity

“…In the treatments with dried soil, however, there were no aerial sections to collect, due to germination of beet before 28 DAE and occurrence of whitening in leaves, necrosis and death, up to 300 days after tembotrione dosage (Figure 3). These results show that beet is very sensitive to tembotrione, which has a residual content in e soil during the evaluated period, as also reported for França et al (2016).…”

“…On the other hand, this property in laboratory conditions is longer than 342 days (Health Canada Pest Management Regulatory Agency, 2014), being dependent on humidity and soil physical-chemical characteristics. Tembotrione is not persistent in field conditions, except when loamy sands are present (US EPA, 2007), and may be toxic to sensitive crops, as beet (França et al, 2016), and carrot (Bontempo et al, 2016).…”