Impact of elevated CO₂ on nutrient uptake of rice cultivars (Oryza sativa L.)

Rice is grown in over 100 countries and is the primary food for half the people in the world. World population is expected to increase to 8.5 billion by 2025. Invariably, many agricultural solis of the world are deficient in one or more of the essential nutrients. The atmospheric CO₂ could increase from current levels of about 370 ppm to between 540 and 970 ppm by end of the 21 ^st century. The likely effect of global climate change due to predicted doubling of CO₂ was studied in a randomized complete block design. Four popular Indian rice varieties viz Pusa Sugandh-2, Pusa Sugandh-3, Pusa Hybrid-10, and Pusa Basmati-1 were exposed to two CO₂ levels (Ambient 350±20 ppm & Elevated 570±50 ppm) in triplicates in Open Top Chambers (OTC) at IARI-New Delhi in the year 2004. Elevated CO₂ increased the levels of phosphorus, potassium, iron, zinc and manganese in ail the rice varieties. Pusa Hybrld-10 and Pusa Basmati-1 showed increase in phosphorus levels under elevated CO₂ in comparison to Pusa Sugandh-2 and Pusa Sugandh-3. Interestingly, Pusa Basmati-1 also showed increased levels of Fe and Zn in shoot dry matter. On the contrary, a reduction in the nitrogen concentration was observed in ail rice varieties under elevated CO₂ in comparison to those under ambient conditions. In general, differences in growth and nutrient absorption in plants and varieties of a species have been related to differences in absorption, translocation, and shoot demand dry matter production per unit of nutrient absorbed and environmental interactions.