Tolerance of eucalypt (Eucalyptus spp.) seedlings to imazapyr in nutritive solution

Abstract

-Imazapyr has presented excellent results in controlling coppices in stand reforms of eucalypt forests, despite differences in the efficacy levels. To find out whether these different responses are caused by the genetic variability of the cultivated materials, two experiments were carried out under greenhouse conditions with different imazapyr doses in a hydroponic system in plastic vases containing 2,500 mL solution. The clones IEF-1 (Eucalyptus grandis x Eucalyptus sp. hybrid), GE 463 (E. urophylla x E. grandis), and MN 445 (E. grandis x Eucalyptus sp. hybrid) were used in the first assay, and IEF-1, IEF-2 (E. grandis x E. urophylla) x Eucalyptus sp. hybrid) and the clones 129 and 7182 (E. grandis x Eucalyptus sp. hybrids) in the second assay. Thirty days after transplanting the seedlings to a nutritive solution, imazapyr was applied to the solution at doses of 0.00, 0.05, 0.10, 0.20, 0.40, 0.80, 1.60 and 3.20 µL L -1. Clone GE 463 proved to be more tolerant to imazapyr than clones IEF-1 and MN 445 in the first assay; however, in the second, clone 7182 was the most tolerant. Thus, doses should also be differentiated when controlling coppices, according to the cultivated clone. de 0,00; 0,05; 0,10; 0,20; 0,40; 0,80; 1,60; e 3,20

Exsudato radicular de imazapyr aplicado sobre mudas de diferentes clones de eucalipto

“…Alguns herbicidas são capazes de ser exsudados pelo sistema radicular de plantas daninhas e de culturas agrícolas, como o nicosulfuron (Gubbiga et al, 1996), o 2,4-D (Fites et al, 1964), o glyphosate (Coupland & Caseley, 1979) e o imazapyr (Silva et al, 2004b), podendo vir a causar danos à cultura subseqüente.…”

“…A exsudação radicular do imazapyr por E. grandis e seu efeito em mudas da mesma espécie foram verificadas por Silva et al (2004b). Entretanto, não se sabe se a exsudação é comum para os diferentes clones de eucalipto, tampouco sobre sua distribuição no perfil do solo.…”

Imazapyr root exudation from eucalypt seedlings cultivated in nutritive solution

“…Imazapyr is injected into trees with an insertion of about 2.5 cm at breast height -1.30 m. The dose must be determined according to the species, hybrid or clone used, due to the possibility of different responses to the herbicide (SILVA et al, 2004). Imazapyr controls coppicing efficiently (DANTAS et al, 2001), because it acts on the plant's growing points, inhibiting regrowth (RODRIGUES and ALMEIDA, 1998).…”