Screening of maize (Zea mays L.) genotypes for drought tolerance using photosynthetic pigments and anti-oxidative enzymes as selection criteria
Ambreen Khadija Alvi, Muhammad Sajid Aqeel Ahmad, Tanzila Rafique, Mehwish Naseer, Fozia Farhat, Habiba Tasleem and Arfa Nasim
The present study was conducted to screen the drought tolerance in some promising maize genotypes viz. FH-1285, FH-949, FH-1292, FH-985, FH-1046, FH-1257, FH-922, FH-988, FH-1137 obtained from Ayub Agricultural Research Institute (AARI), and, Yousafwala hybrid, 3025w/6129, SWL-539516, YSC-15, P1543/2567600 developed by Maize Research Institute, Yousafwala, Sahiwal, Pakistan. The experiment was laid out in a Completely Randomized Design (CRD) with three replicates. Drought was applied at three leaf stage by maintaining three levels of irrigation i.e.100% field capacity (full watering), 70% field capacity (mild drought stress) and 40% field capacity (severe drought stress). After 50 days of maintaining drought, plant sample was collected to record the growth and physio-biochemical parameters i.e. concentration of photosynthetic pigments, (Chl. a, Chl. b, total chl. and carotenoid content), anti-oxidative enzymes (SOD, POD, and CAT) and total soluble proteins. Drought stress severely hampered growth attributes that was clearly linked to a concurrent decrease in concentration of photosynthetic pigments at both mild and in particular at severe drought stress. Genotypes Yousafwala hybrid, P3164w/2403481 and FH-1137 showed less decrease in all growth parameters at both mild and severe drought levels indicating their resistant nature, whereas, genotypes FH-922, FH-985, FH-949 and FH-1257 were drought sensitive as they showed more than 50% growth reduction under severe drought stress. Genotypes P1543/2567600, YSC-15, FH-949 and FH-949 were considered moderately tolerant as they showed less decrease in growth parameters under mild drought conditions (70% field capacity), but under severe drought conditions (40% field capacity) a greater decrease in growth was recorded in the same genotypes. Antioxidant enzymes i.e. SOD, POD and CAT activity increased at both drought levels (70% and 40% field capacity) as compared to control plants (100% field capacity) accompanied by a concurrent increase in total soluble proteins in the genotypes Yousafwala hybrid, FH-1257, 3025w/6129, SWL-539516 and P3164w/2403481. Cluster analysis grouped the genotypes in distinct clusters indicating similarities among the various genotypes regarding their resistance to drought stress. The drought tolerant genotypes Yousafwala hybrid, P3164w/2403481 and FH-1137 are recommended for cultivation and improved crop yield in water deficit areas.
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