Individual and combined effects of ethylenediurea (EDU) and elevated carbon dioxide (ECO₂), on two rice (Oryza sativa L.) cultivars under ambient ozone

Abstract

The present field experiment assesses the individual and combined effects of ethylenediurea (EDU, 200 ppm) and elevated CO2 (ECO₂, 550 ppm), on two rice (Oryza sativa L.) cultivars, Sarjoo-52 and Pusa Basmati-1(PB-1) under FACE (Free Air Concentration Enrichment) facility. During the experiment, the mean ambient ozone (AO3) concentration was 60.3 ppb. EDU treated PB-1 cultivar under elevated CO2 showed less discernible ozone (O3) injury, better photosynthetic rate, photosynthetic pigments, and aggregated more plant biomass in comparison to the Sarjoo-52 cultivar. Non-EDU treated plants showed more O3 induced injury symptoms. PB-1 cultivar was found to be more ozone sensitive than Sarjoo-52 under ambient environment. PB-1 responses to EDU for plant length, grains no plant−1, grain weight plant−1 were better than Sarjoo-52 cultivar under ambient CO2. EDU+CO2 treated PB-1 cultivar showed improved antioxidant capacity than the Sarjoo-52 cultivar. EDU treated PB-1 cultivar under elevated CO2, had more economic yield as compared to the Sarjoo-52 cultivar. Essential human dietary nutrients such as Zn, Ca, and Fe were accumulated more in EDU treated grains of PB-1 as compared to a Sarjoo-52 under elevated CO2 condition. EDU and CO₂ showed significant interactive effects on morphological, physiological, yield, and grain quality attributes of both rice varieties. EDU protected rice plants from ambient O3 pollution, improved rice growth, and yield under both ambient and elevated CO2 conditions.