Condicionamento de sementes de arroz com extrato de cenoura

Abstract

Rice is one of the world's most important agricultural crops, but its productivity is highly affected by different type of abiotic stress during crop stages of development. When these occur during the seedling period of the crop, it can compromise the plant standard, as it directly affects the vigor and seeds viability. In this regard, the conditioning of seeds in vegetal extract appears as an alternative to improve the expression of seed vigor, improving the tolerance of abiotic stress. Thus, the present work had the objective of evaluate the effect of the rice seeds conditioning on carrot extract as a possible attenuator of abiotic stress in rice crop. Thus, four studies were conducted: evaluation of the cytogenetic activity of root rice meristems in response to conditioning in carrot extract and salinity; Bioprotectant potential of carrot extract on seed viability and antioxidant responses of rice seedlings under saline stress; Carrot extract: effect on growth and antioxidant activity of rice plants cultivated in rhizotrons; Application of index to evaluate the cold tolerance in the viability of rice seeds conditioned in carrot extract. The cytogenetic analysis in the root meristems showed that there was an increase in the mitotic index in response to the carrot extract in cultivar BRS 358 even under saline stress conditions, characterizing the positive effect of the extract. Regarding the viability tests, the use of carrot extract kept the germination close to the control treatment even under salinity conditions for the cultivar BRS Querência. For both of the cultivars, there was an increase in seedling growth in both laboratory and greenhouse conditions. The extract also decreased the oxidative stress caused by salt, justified by the reduction in the accumulation of hydrogen peroxide and lipid peroxidation, besides the increase in the chlorophyll and nitrogen index and the smaller senescent area of the rice leaves submitted to saline stress. Thus, the use of carrot extract in seed conditioning is a promising technique for the attenuation of abiotic stresses.