Desempenho fisiológico e produtivo de cultivares de trigo em resposta ao elevado CO2

Abstract

The wheat (Triticum aestivum L.) is one of the most ancient grains of the world, its origins goes back more than 10.000 years, in ancient Mesopotamia. This grain is widely distributed and consumed around the world, specially, due to its great diversity of derivative products, such as pastas, bread and biscuits, which develop an important energetic and nutritional function on human feeding. However, studies regarding climate changes, mainly on elevated concentration of CO2 (e[CO2]), have been reporting changes on the nutritional and industrial quality of the grains, mostly on C3 species, such as wheat. Alongside with the e[CO2], it is noted an accelerated populational growth, that, up until 2050, it is estimated to reach more than 11,3 billions of people, demanding an improvement on grain production over 70%. Therefore, it is important to understand the plants' behaviour concerning climate changes scenario. Thus, this study aimed to characterize the high concentration of CO2 effect on physiological and biochemical parameters and also, the productivity of the FPS Certero, FPS amplitude and ORS vintecinco wheat cultivars. The wheat cultivars were cultivated on Open Top Chambers (OTC’s) under two CO2 concentrations, 400 ppm (Ambient) and 700 ppm (Elevated). Chlorophyll evaluations were accomplished during the culture reproductive stadiums (74, 81, 88, 95 DAS) and the gas exchange were evaluated on 88 DAS (Anthesis). As for the gas exchange, it was observed a similar behaviour between cultivars, which presented an increase on net carbon assimilation, internal concentration of CO2 and water use efficiency, besides the stomatal conductance and transpiration under e[CO2] reduction. The liquid photosynthesis improvement on e[CO2] was accompanied by increases of total soluble sugar, starch and sucrose proportion on the cultivars' wheat leaves. The a and b chlorophyll indexes presented a reduction under e[CO2] on 88 and 95 DAS. The e[CO2] provided gains on the spikes per plant, grains per spikes and production per plant, nevertheless presented less Thousand Grain Weight (TGW), possibly due to smaller grain size regarding control (400 ppm). On the wheat grains, it could be observed that e[CO2] increased the total starch proportion, though a reduction on the crude grain protein percentage was perceived, pointing out a higher relation C/N on wheat grains under e[CO2].