PJB-2019-807
EFFECT OF NAPHTHYL ACETIC ACID FOLIAR SPRAY ON PHYSIOLOGICAL MECHANISM OF DROUGHT STRESS TOLERANCE IN MAIZE (ZEA MAYS L.)
SAMI ULLAH
Abstract
Present study was aimed to evaluate the effect of Naphthyl acetic acid on physiological mechanism of drought tolerance in the selected varieties of maize (Azam and Iqbal). Pot experiment was conducted in the Department of Botany, Bacha Khan University Charsadda, during maize growing season 2014. The designed experiment of two maize varieties were subjected to different drought levels (5d, 7d, 10d, 12d, and 15d drought) at vegetative stage. The sandy loam rhizospheric soil with pH 6.1-7.5, EC 212-387, % field capacity 8.71-31.52, soil moisture content 0.43-0.5g g−1, organic matter 0.43-0.55 g/kg, N 0.022-0.027 g/kg, P 0.028-0.058 g/kg, K 0.017-0.042 g/kg, root moisture content 0.01-0.17g g−1, stem moisture content 0.222-1.89g g−1 and leaf moisture content 0.05-0.415g g−1 were used in the present experiment. Result indicated that drought sensitive variety, Azam was markedly affected for the activity of antioxidant enzymes including peroxidase, superoxide dismutase and catalase along with osmoprotectant including proline and sugar content even at lowest drought stress level (5d) as compared to drought tolerant variety Iqbal and untreated control. Furthermore marked decrease in the leaf water status, chlorophyll and carotenoid contents were associated with an increase in the accumulation of sugar, proline and antioxidant enzymes (peroxidase, superoxide dismutase and catalase) activities up to significant level (p<0.05) under drought stress along with increase in protein content as a dominant response for both varieties. Analysis of variance between genotype, drought stress and NAA treatment recorded significant at p<0.05 except GRI, TB, CC, SVI-II, SPT and SOD. Variance analysis in terms of interactions between drought and NAA treatment investigated and found significant at p<0.05 for SVI-I, SVI-II, RSR, LAI, LAR, TB, CA, CB, CC, POD and SOD content under high drought stress (15d) irrespective of SVI-I (p<0.001), CB (p<0.001), POD (p<0.001), SOD (p<0.001), RSR (p≤0.01), CB (p≤0.01), SSC (p=0.01) and SPC (p≤0.01) during low drought (5d) condition. Principal component analysis enclosed 70.99% of entire variation among which 57.18 associated with growth regulators, osmoprotectants and antioxidant defense system while 13.81% with growth regulators of plant.
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