Qualidade fisiolÃgica de sementes de soja convencional e RR associada ao conteÃdo de lignina / Physiological quality of conventional and RR soybean seeds associated with lignin content

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In the latest crops, a strong and growing adherence of Brazilian farmers to RR transgenic soybean was found. Nevertheless, the hypothesis has been raised that these soybean cultivars are presenting differential hypotheses concerning the lignin contents in the plant, when compared with conventional cultivars. Such a variation could be occurring not only in the vegetative part of the plants, but also expressing itself in reproductive parts such as legumes and seeds. Owing to studies in that area being still scarce, it was aimed in the present work to evaluate: agronomic characteristics of the plant, lignin content in the coat and quality of RR and conventional seeds produced in two crops; the increase of weight of intact soybean seeds and legumes at different soaking periods and its relation with lignin contents in the plant, legume and coat of seeds, in RR and conventional soybean seeds collected at three times; the physiological quality of RR transgenic soybean seeds and lignin contents of plants submitted to spraying with herbicide glyphosate. The seed production assays were conducted in the town of Lavras, MG, between the agricultural years 2007/08 and 2008/09, in a randomized block design with four replicates in experimental area of the Federal University of Lavras. Ten soybean cultivars were utilized, comprising the conventional cultivars JataÃ, Celeste, Conquista, BRS 133 and BRS 134 and their respective RR transgenic versions, SilvÃnia RR, Baliza RR, Valiosa RR, BRS 245 RR and BRS 247 RR, essentially derived (coming from EMBRAPA Soja and EMBRAPA Cerrados). For the determination of the soaking percent and hydration speed, both the intact seeds and legumes were submersed into water for periods of 1, 3, 6, 9, 12, 24 and 48 hours for legumes and 1, 2, 3, 4, 5, 6, 7, 9, 12, 24 and 48 hours for seeds. In the assay of harvest times, the seeds were collected at R7, R8 stages and 20 days after R8. For the assay of use of glyphosate, it was sprayed at the dosage of 3l/ha, at the developmental stages V3, V7 and early R5. In general, agronomical traits (plant height, height of insertion of the first legume and number of legumes per plant), lignin content (seed coats, stem, legumes and leaves), soaking percent and hydration velocity index of intact seeds and legumes, sanitary quality and physiological quality of the seeds were evaluated. For the different crops, it follows that lignin content in the seeds of the transgenic cultivar Baliza RR was higher than that of the conventional cultivar Celeste. No important differences as regards the agronomic traits and physiological quality of seeds among the conventional materials and their respective RR were found. Establishing an association between the soaking rate in seeds and legumes and the transgenesis characteristic in the evaluated soybean cultivars was not possible. When evaluated, the seeds submitted to different collection times, behavioral difference among the cultivars as for tolerance to collection delay and significant reduction in germination percentage and vigor of the evaluated seeds with delay of the crop, was found. The sprayings with the herbicide glyphosate altered only the values of electric conductivity of the seeds, its not having altered the other physiological tests and lignin contents in the plant.

ASSUNTO(S)

fitotecnia lignina sementes de soja lignin qualidade fisiolÃgica phisiology quality soybean seeds

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