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Herbicide selectivity and weed management in the sugarcane planting with one eye set (OES)


For commercial planting 1 ha of sugarcane are required between 15-18 t ha-1 stolks harvested in nurseries (sugarcane on strict sanitary control). However, if the planting is done with one eye set (OES) will require less than 1 t ha-1 of stolks to form OES enough to plant 1 ha-1 of commercial culture. But the system has intoxication by herbicides as a disadvantage. To propose selective treatments to OES, we have as hypothesis that appropriated management is the herbicides application before planting (PPI) with subsequent complement post-emergence, after establishment the OES. To check the hypothesis, has to study the selectivity of the chemical treatments applied before and after planting (supplement to 40 days) of OES cultivars IACSP95-5000 and IACSP96-2042 of sugarcane, using the isoenzyme profile of catalase and ±-esterase (related to oxidative stress) and phytotechnical characteristics. In the first stage will be developed in pots (40 L), an experiment in sandy soil and clay soil in another, both in Ribeirão Preto and in a completely randomized design in a factorial arrangement with 10 herbicides applied post-emergence of cane sugar (hexazinone, ametryn, metribuzin, isoxaflutole, mesotrione, diuron + hexazinone, 2,4-D, ametryn + clomazone, halosulfuron, trifloxysulfuron-sodium and control) and three tillage systems (OES 7 days after transplantation, 40 with MPB days after transplanting, plants 40 days after planting stalks) +3 witnesses (one for each tillage system) in four replications and to cultivate IACSP95-5000. At 20, 40 and 60 days after application (DAA) will be assessed symptoms of intoxication, due to fluorescence (Fv / Fm), height and number of tillers of plants; at 60 DAA dry mass and isoenzyme profile of catalase and ±-esterase enzymes. In the second phase will be conducted in two field experiments with IACSP95-5000 cultivar to cultivar and two IACSP96-2042. For each experiment will be adopted the randomized block design with 11 treatments in pre-emergence (imazapyr, imazapic, trifluralin + pendimethalin, s-metolachlor + diclosulan, diclosuan + oxyfluorfen, sulfentrazone, amicarbazone, tebuthiuron, metribuzin and witnesses with and without weeding) in four replications. Applications will be performed with tractor before planting (except metribuzin), the incorporation occurring with mild grade; 40 days after planting (DAP) herbicides are applied post-emergence (two best results of the first phase). Will be assessed at 20 days after transplanting (DAT) of BPMs, 40 DAT; 20DAApós (60 DAT), 40DAApós (80 DAT), 60DAApós (100 DAT) and 100DAApós (140 DAT) symptoms of intoxication, due to fluorescence (Fv / Fm), and stand tall. To 60DAApós (100 DAT) and at harvest (260 DAApós / 300 DAT) isoenzyme profile of catalase and ±-esterase enzymes. At the time of harvest production estimate is evaluated. In the end, it is expected that the plants of cane sugar with symptoms of intoxication acceptable and lowest possible loss on the photosynthetic apparatus, development and productivity. It is also expected that the profile of the ±-esterase and catalase enzymes in plants treated with herbicide are similar to those of control plants, since the response of the metabolism of plants recovered from the oxidative stress caused by herbicides. (AU)

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