Abstract
ABSTRACT The herbicide lactofen has been used by producers in many conditions, in order to increase the soybean yield. This study aimed to evaluate the influence of lactofen and the phytohormone kinetin on the morpho-agronomic traits, carbohydrate partitioning and yield, in soybean cultivars. Three experiments were carried out in the field, in addition to one experiment in a greenhouse. A randomized block design, with four replications, was used. The treatments were: lactofen [144 g ha-1 of active ingredient (a.i.)], lactofen + kinetin (144 g ha-1 of a.i. + 0.5 g ha-1), kinetin (0.5 g ha-1), manual cutting of apical buds and control. In the subplots, six soybean cultivars (M 6410 IPRO, M 5917 IPRO, NS 7670 RR, NS 6909 IPRO, BMX Lança IPRO and Produza IPRO) were used. In the field, the plant lodging index, plant height, number of nodes and branches, pods and grains per plant, mass of 100 grains and grain yield were evaluated. In the greenhouse, the starch, reducing sugars, sucrose and total sugars in the leaves, stems and roots of three soybean cultivars were quantified. The application of lactofen in the V6 stage influenced the morpho-agronomic traits of the cultivars in the field and increased the soybean yield by 312 kg ha-1, considering all the cultivars. The phytohormone did not influence the morpho-agronomic traits neither the grain yield. The treatments did not induce modification in the partitioning of carbohydrates destined to the roots.
Highlights
Aiming at increasing the soybean yield in Brazil, new crop management techniques have been constantly adopted by producers, despite the lack of scientific support that proves the efficiency of such tools
Among these new crop management proposals, the attempt to break the apical dominance of soybean with the use of growth regulators and some herbicides that play this role indirectly, such as lactofen, is highlighted
This study aimed to evaluate the influence of the use of lactofen and the phytohormone kinetin on morpho-agronomic traits, grain yield and carbohydrate partitioning, in soybean cultivars from different groups of relative maturity
Summary
Aiming at increasing the soybean yield in Brazil, new crop management techniques have been constantly adopted by producers, despite the lack of scientific support that proves the efficiency of such tools. Among these new crop management proposals, the attempt to break the apical dominance of soybean with the use of growth regulators and some herbicides that play this role indirectly, such as lactofen, is highlighted. This contact herbicide, applied to control broadleaf weeds and selective for soybean cropping, has as its mode of action the inhibition of the enzyme PROTOX, related to the production of chlorophyll.
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