ORIGINAL PAPER Effect of elevated ultraviolet-B on four tropical soybean cultivars: quantitative and qualitative aspects with special emphasis on gas exchange, chlorophyll fluorescence, biomass and yield Krishna Kumar Choudhary • S. B. Agrawal Received: 17 June 2014 / Revised: 8 January 2015 / Accepted: 9 January 2015 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2015 Abstract Four Indian soybean cultivars (Glycine max L. cv. JS-335, JS 97-52, PK-416 and PS-1042) were grown under field conditions in suburban area of Varanasi to evaluate the varietal differences against ambient and ele- vated ultraviolet-B (ambient ? 7.2 kJ m -2 day -1 ) for two consecutive years. Elevated UV-B caused negative impact on the assessed parameters with varied magnitude amongst the test cultivars. Reductions in rate of photosynthesis and stomatal conductance were observed maximum in JS-335 and minimum in PS-1042. Elevated UV-B also affected the plant abilities to utilize sunlight and increase the photoin- hibitory response, which was displayed by reduced F v /F m in tested cultivars. Similar results were also observed for the biomass, yield and seed quality with maximum reduction in JS-335 followed by PK-416, JS 97-52 and PS- 1042. Decline in the rate of photosynthesis, extra allocation of photosynthates for repairing and change in translocation pattern of solute and nutrients are mainly responsible for the deterioration in seed quality. Cumulative stress response index (CSRI) and quality response index (QRI) also revealed the sensitivity of soybean cultivars against elevated UV-B. Indexing of cultivars suggests that JS-335 was most sensitive whereas PS-1042 was resistant amongst cultivars. Keywords UV-B  Glycine max L.  Photosynthesis  Yield  Seed quality  Cumulative stress response index Abbreviations C i Internal CO 2 DAG Days after germination F 0 Initial fluorescence in dark adapted leaves F m Maximum fluorescence in dark adapted leaves F v Variable fluorescence in dark adapted leaves F v /F m Photosynthetic efficiency gs Stomatal conductance HI Harvest index LB Leaf biomass NSPP Number of seeds plant -1 NSPPo Number of seeds pod -1 Pn Photosynthetic rate PoB Pod biomass RB Root biomass SB Shoot biomass SC Starch content SP Soluble protein TB Total biomass TFAA Total free amino acids TSS Total soluble sugar TW Test weight WSPP Weight of seeds plant -1 WSPPo Weight of seeds pod -1 WUE Water use efficiency Introduction Anthropogenic emission of hydrochlorofluorocarbons, chlo- rofluorocarbons, methyl chloroforms and halons has been identified as a major cause for depletion of the stratospheric Communicated by O. Ferrarese-Filho. K. K. Choudhary  S. B. Agrawal (&) Laboratory of Air Pollution and Global Climate Change, Department of Botany, Banaras Hindu University, Varanasi 221005, India e-mail: sbagrawal56@gmail.com K. K. Choudhary e-mail: choudhary.krishna2@gmail.com 123 Acta Physiol Plant (2015) 37:31 DOI 10.1007/s11738-015-1780-4