Mudanças fisiológicas e moleculares na cultura do arroz e em plantas daninhas C3 e C4 submetidas a estresses abióticos

Abstract

Due to predictions of climate change many studies have been realized to predict the effect of abiotic stresses on plants. Rice, weedy rice and barnyardgrass have their morphology, physiology and gene expression modified by abiotic stress, and these plants respond differently to environmental stress. The objective of the research was to compare morphological, physiological, biochemical and molecular changes in rice plants and wweed of this crop with photosynthetic pathway C3 and C4 when the plants are submitted to stress due water deficit, supra-optimal temperature and different quality of light; and to evaluate the effect of CO2 levels on E. colona biotypes with multiple herbicide resistance. Four studies were realized to meet the objectives, and the results allow to infer that: rice and weedy rice have similar physiological and molecular responses when exposed to water deficit and supra optimal temperatures, elevation demage to biomolecules and incresed in gene expression linked to protection of abiotic stresses, in both plants. As for light quality, rice has physiological and grow variables positively affectd by blue light whereas red light only incresed growth variables, and weedy rice has increase in groth variables where exposed to blue light. In a climate change scenario, the C4 plant, barnyardgrass, is even more competitive with rice, because unlike the C3 plants, it practilly does not present physiological and molecular change when exposed to water deficit, supra-optimal temperature, and different light qualities. Furthemore, barnyardgrass increases growth and productivity in atmospheres with high [CO2], however, biotypes of herbicides-resistant barnyardgrass have fitness cost in high envirinments [CO2] compared to susceptible biotype.