Abstract

                                As a secondary pollutant, Tropospheric ozone is inadvertently increasingevery year, thereby causing severe loss to agricultural crops. The presentstudy aimed at evaluating the response of tropospheric ozone againstblackgram varieties. Eight ruling blackgram varieties (V.B.N. 1, V.B.N. 2, V.B.N.3, V.B.N. 5, V.B.N. 6, V.B.N. 7, V.B.N. 8 and CO 6) were exposed to elevatedtropospheric ozone concentration (50 ppb) in an open-top chamber. Theexposure was given during 31 days after sowing (D.A.S.) to 40 D.A.S. for sevenhours (10.00 h-17.00 h). The changes in physiological, biochemical, growth,and yield traits were observed by comparing them with control (ambientcondition). Results indicate that physiological, biochemical, growth, and yieldtraits significantly differed under ozone stress. Amongst all varieties, thereduction of all observed traits was higher in V.B.N. 3 and least in V.B.N. 8.The reduction of photosynthetic rate, stomatal conductance, and chlorophyllcontent was higher in V.B.N. 3 (33.57, 29.17 and 35.67 %) and least in V.B.N.8 (26.23, 22.92 and 31.78 %). In the case of biochemical traits, in V.B.N.3, the malondialdehyde and proline content increased twice and ascorbicacid declined by 39.85 %. However, in V.B.N. 8, malondialdehyde and prolinecontent increased by 78.26 and 89.01 %; while ascorbic acid decreased by36.31 % only. Similarly, 100-grain weight reduced in V.B.N. 3 by 8.69 % whileit was only 5.37 % in V.B.N. 8. The current investigation revealed that V.B.N.3 is highly sensitive, while V.B.N. 8 is tolerant to ozone stress.

Key words : Tropospheric ozone; Blackgram; Physiological; Biochemical; Growth; Yield attributes