Photosynthetic rate, growth, and yield of mustard plants sprayed with 28-homobrassinolide

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10( -10), 10(-8), or 10(-6) M aqueous solution of 28-homobrassinolide (HBR). Th e HER-treated plants were healthier than those treated with water and yield ed more. Maximum increase over control was found in 60-d-old, 10(-8) M-HBR- treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C . 4.2.1.1) activity, and net photosynthetic rate (PN), at harvest in number of pods per plant and seed yield per plant (the respective values were 25, 30, 34, 69, 24, and 29 %). A further increase in the concentration of HER (10(-6) M) did not make any additional impact on the growth and yield. Incr eased CA activity and PN were correlated with growth and seed yield.