BROCCOLI GROWTH, ANTIOXIDANT ACTIVITY AND HEALTH TISSUES RESPONSES TO ASCORBIC ACID UNDER DEFICIT IRRIGATION

Abstract

Two field experiments were conducted during 2013/2014 and2014/2015 in a private Farm, Ibshway district, Fayoum, Egypt to study deficitirrigation (60, 80 and 100% ETc) and ascorbic acid foliar application (0, 200and 400 mg l-1) on growth, relative water content (RWC), membrane stabilityindex (MSI), electrolyte leakage (EL), leaf photosynthetic pigments (LPS),osmoprotectants (OS) and DPPH radical-scavenging activity of broccoliplants. The obtained results clarified that, irrigation amount at 80% or 100%ETc, significantly, resulted in higher mean values of stem length anddiameter, number of leaves plant-1, leaf MSI, RWC, carotenoids, DPPHradical-scavenging and total free amino acids content than irrigation amountat 60% ETc. On other side, irrigation amounts, irrespective the level used, didnot reflect any noticeable impact on number of branches plant-1 and headcontents of ascorbic acid. Increasing irrigation water from 60% up to 100%ETc decreased the contents of leaf EL, chlorophyll A, B, A + B, anthocyanin,free proline and TSS. Exogenous application of ascorbic acid atconcentrations of 200 and 400 mg l-1, significantly improved most studiedgrowth parameters, RWC, MSI, anthocyanin, DPPH, total free amino acidsand endogenous ascorbic acid however, leaf EL decreased gradually.Moreover, the impact of ascorbic acid, irrespective of the concentration used,on leaf photosynthetic pigment, free proline and total soluble sugars contentswas at par.