Leaf growth traits and photosynthetic pigments of maize as influenced by water deficit stress

Abstract

Glasshouse study was carried out to evaluate the impacts of water deficit stress (WDS) on leaf growth and photosynthetic pigments of four maize varieties at the Institute of Agricultural Research and Training, Ibadan. Seeds from ‘TZPBSR-W’, ‘ILE1OB’, ‘ART98SW6OB’ and ‘DTESYNSTR’ maize varieties were sown in sixty-four pots in a 4 x 4 factorial CR Design(r=4). The WDS treatments include 100%, 75%, 50% and 25% field capacities (FC). Data were taken weekly on specific leaf weight (SLW), leaf area (LA), leaf weight (LWT) and crop growth rate. At four weeks of WDS, extracts were obtained from 0.2 g cut leaf sample using 96% (v/v) ethanol. Light absorbance of the ethanolic leaf extract (cholorophyll-a (665 nm), chlorophyll-b (649 nm), total chlorophyll and the carotenoids (440 nm)) were read using spectrophotometer. From the results, WDS significantly reduced SLW, LWT, LA and CGR (p<0.001). The SLW ranged from 0.027±0.0 (g cm^-2) (‘ART98SW6OB’) to 0.034±0.0 (g cm^-2) (‘DTESYNSTR’), while the LA ranged from 269.7±25.4 (cm²) (‘ART98SW6OB’) to 220.9±20.9 (cm²) (‘ILE1OB’). Water deficit stress significantly reduced chlorophyll-b (p<0.01), chlorophyll-a and total chlorophyll (p<0.001) and the carotenoid (p<0.05). Chlorophyll-a ranged from 0.038±0.0 mg/g (‘DTESYNSTR’) to 0.050±0.0 mg/g (‘TZPBSR-W’), chlorophyll-b ranged from 0.021 mg/g (‘ART98SW6OB’) to 0.040 mg/g (‘TZPBSR-W’), total chlorophyll ranged from 0.063±0.0 mg/g (‘ART98SW6OB’) to 0.093±0.0 mg/g (‘TZPBSR-W’), while the carotenoid ranged from 0.084±0.08 mg/g (‘ART98SW6OB’) to 0.115±0.09 mg/g (‘TZPBSR-W’). The WDS and Variety interaction on photosynthetic pigments were significant (p<0.05). The Leaf growth traits, photosynthetic pigments and over all crop growth in maize are impaired when subjected to water deficit stress.