Madan Pal Singh, Indian Agricultural Research Institute, Division of Plant Physiology, New Delhi, India
Atmospheric CO2 levels have changed dramatically since the industrial revolution, increasing by almost 30% to a present day concentration of about 370 µl l-1. Such increase in CO2 may affect the productivity of crop plants through photosynthetic enhancement, particularly in C3 crop species. Very few reports are available about the response of pulse crops to elevated CO2; hence an attempt was made to study the response of chickpea to rising CO2 in the atmosphere. The chickpea plants of cultivar Pusa 1108 were raised in earthen pots inside the open top chambers and exposed to ambient (370±20 µl l-1, CA) and elevated (550±50 µl l-1, CE) CO2 levels from germination till maturity of the crop. The plants exposed to CE showed significant increase in their growth characteristics viz. shoot length, total number of branches, total number of leaves and leaf area per plant. Significant increase in dry weight of above and below ground plant parts was observed under CE. The concentration of non structural carbohydrates such as starch, reducing and non-reducing sugars was more in plants grown under CE, which could be due to higher photosynthetic activity. The increase in sucrose content was accompanied by higher sucrose phosphate synthetase activity (SPS) under CE. Total carbon content increased but the nitrogen content decreased in the leaves, which resulted in higher C/N ratio. The soluble protein content decreased and the magnitude of reduction was almost similar at all the durations of CO2 exposure. There was up to 15 % increase in number of pods and seeds per plant in CE grown plants, which indicates that rising atmosphere may have beneficial impact on yield of chickpea.