Response of Blackgram Cultivars to Elevated Tropospheric Ozone

Abstract

As a secondary pollutant, Tropospheric ozone is inadvertently increasing every year, thereby causing severe loss to agricultural crops. The present study aimed at evaluating the response of tropospheric ozone against blackgram 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 elevated tropospheric ozone concentration (50 ppb) in an open-top chamber. The exposure was given during 31 days after sowing (D.A.S.) to 40 D.A.S. for seven hours (10.00 h-17.00 h). The changes in physiological, biochemical, growth, and yield traits were observed by comparing them with control (ambient condition). Results indicate that physiological, biochemical, growth, and yield traits significantly differed under ozone stress. Amongst all varieties, the reduction 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 chlorophyll content 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 ascorbic acid declined by 39.85 %. However, in V.B.N. 8, malondialdehyde and proline content increased by 78.26 and 89.01 %; while ascorbic acid decreased by 36.31 % only. Similarly, 100-grain weight reduced in V.B.N. 3 by 8.69 % while it 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.