Peningkatan Konsentrasi CO2 dan Suhu menyebabkan Penurunan Laju Pembukaan Stomata serta Hasil Berat Kering Tanaman Kedelai

Abstract

Global warming phenomenon in the last two decade has paid attention of researchers on how plants response to CO2 elevated and temperature. Increased CO2 in the atmosphere, which is coincided high temperature, it will affect on plants response leading to reduce in yield. Soybean plants were grown at the gradiotron with 2°C higher than ambinet, and two [CO2] regime of ambinet and elevated of 200 ppm higher. Then, plants were transferred into difference [CO2] regime (from ambient to elevated (A-E) or from elevated to ambient (E-A)). Stomatal conductance (gs) at the elevated [CO2] had decreased significantly from 1400 into 700 mmol H2O·m-2·s-1 compared to ambient [CO2] regime at 4 DAT (day after transfer). Moreover, gs at the elevated [CO2] were much lower at 32 DAT or 80 DAS (day after sowing). Dry matter of soybean grown at the elevated [CO2] was 33% higher than ambient at 48 DAS or before transfer, while after transferred into difference CO2 regime at 81 DAS, dry matter difference was 7%. At the early growth in the elevated [CO2] regime, plants cloud use abundant of CO2 for photosynthesis so that dry matter increased significantly, however in the later growth stage i.e. 32 DAT, dry matter did not increase significantly or it was occurring downregulation where elevated [CO2] does not increase photosynthesis even it decreases the photosynthesis. The downregulation was correlated with decreased in gs and it will be getting worst with present of high temperature.