Abiotic factors in the effect of herbicides on the physiological quality of rice seeds

ABSTRACTThe aim of this study was to evaluate the physiological quality of rice seeds with the application of herbicides in two sowing seasons, and for the artificial reduction of lighting at different stages of crop development. The field experiment, carried out in the 2012/2013 crop year, consisted of a 2x3x5 factorial, comprising the factors: sowing season (18/10 and 09/11); herbicide [control (weeding), bispyribac-sodium and penoxsulam]; and crop development phase under light reduction (control; seedling stage, vegetative phase, reproductive phase and the entire cycle). The cultivar used was IRGA 424. The following were evaluated in the laboratory: thousand-seed weight, germination, first germination count, cold test, electrical conductivity and the length and weight of seedling shoot and root dry matter. Late sowing results in the production of rice seeds of lower weight and physiological quality. The application of sodium-bispyribac on the rice that was sown later, leads to a reduction in the vigour of the produced seeds. With reductions in artificial lighting during the vegetative phase, rice seeds with greater mass and physiological quality are obtained, whereas when the lighting is a reduced for the entire crop cycle, poor quality seeds are produced.