JIA-2019-11

2487 Hafiz Ghulam Muhu-Din Ahmed et al. Journal of Integrative Agriculture 2019, 18(11): 2483–2491 sensitive genotypes were G3 followed by G98 under drought stress conditions as displayed in Table 3. Those genotypes having the minimum shoot length and the maximum root length under drought stress considered as drought tolerant genotypes. Conclusively, selection based on seedling length combined with extensive root system, could be resulted in better adaptation to dry land environments. Ahmad et al . (2013) and Faisal et al . (2017) also evaluated the decrease in seedling’s growth, including seedling length and seedling weight with an increase in water deficient stress and their results are in line with the present study. 4.2. Photosynthetic attributes Considering chlorophyll a character, the best tolerant genotypes were G6 followed by G11 and G16, while drought sensitive genotypes were G105 followed by G77 under drought stress conditions as mentioned in Table 3. However, the amount of chlorophyll under drought conditions decreased with the increase in the duration of drought stress probably due to the destruction of chloroplast envelope by drought stress. The reduction in chlorophyll content under drought stress has been taken a distinctive symptom of oxidative stress and may be the result of photo-oxidation of photosynthetic pigments (Anjum et al . 2011). Using chlorophyll b attribute, the best tolerant genotypes were G26 followed by G39 and G21, while drought susceptible genotypes were G98 followed by G91 (Table 3). In plant cells, photosynthesis is a key process which regulates in water culture medium under low concentration. If chlorophyll pigments concentration increases, photosynthesis system will be more efficient. Chlorophyll contents caused more reduction in all wheat genotypes with the increment in levels of water stress because thylakoid membranes disintegrate upon dehydration of cells (Kalaji et al . 2016). Previous studies also highlighted the reduction in chlorophyll under water deficit conditions (Farshadfar and Amiri 2105; Seher et al . 2015) while tolerant genotypes maintained better amount of these pigments under drought stress (Zeng et al . 2016; Pour-Aboughadareh et al . 2017). Considering carotenoid trait, the best tolerant genotypes were G51 followed by G6 and G1, while drought susceptible genotypes were G77 followed by G98 under drought stress conditions as discussed in Table 3. Carotenoids are responsible for scavenging of singlet oxygen and hence their comparative levels in a genotype will determine its relative G1 G3 G5 G7 G9 G11 G13 G15 G17 G19 G21 G23 G25 G27 G29 G31 G33 G35 G37 G39 G41 G43 G45 G47 G49 G51 G53 G55 G57 G59 G61 G63 G65 G67 G69 G71 G73 G75 G77 G79 G81 G83 G85 G87 G89 G91 G93 G95 G97 G99 G101 G103 G105 Chl a -N Chl a -D 1.2 1.3 1.4 1.5 1.6 1.7 Fig. 2 Performance of wheat seedling traits of 105 genotypes under normal and drought conditions. Chl a , chlorophyll a ; N, norma; D, drought; G, genotype.