Drought tolerance of some zea maize L. genotypes at the early Growth stage

The effect of different drought stress levels (90%, 70%, 50%, and 30% field capacity) during the early growth stage (greening stage) of maize (Zea maize L.) for 9 genotypes [WataniaI0 (genotype 1), Watania4 (genotype 2), Giza l0 (genotype 3), Giza326 (genotype 4), Bashaier (genotype 5), Nefartiti (genotype 6), Giza314 (genotype 7), Giza 3K1 (genotype 8), Giza123 (genotype 9)] was studied under growth chamber conditions. Root/shoot ratio, leaf area, leaf area ratio (LAR) and dry matter yield were variously affected by drought interaction; this interaction showed that the nine maize genotypes under short duration (25 days old) displayed distinct variation in drought tolerance. The criteria used to classify genotypes with respect to their drought tolerance were based on their root/shoot ratio, leaf area, leaf area ratio (LAR) and dry matter under the severe drought stress levels. According to these data the nine maize genotypes were classified into three categories as follows: Class I contains the most tolerant genotypes at the early growth stage (genotype 5, genotype 3, and genotype 9.), they showed the highest values of growth criteria(root\\shoot ratio, leaf area, leaf area ratio and dry matter production) at the different levels of soil moisture content used. Moreover, these genotypes showed no drastic reduction in these characteristics even at severe drought (30% F.C) compared with the relative control (90% F.C.). Class 11 includes the moderately tolerant genotypes at the early growth stage (genotype 4, genotype 7, and genotype 8), they showed a general moderate reduction of shoot dry matter at the level of 30 % F.C, compared with the relative control. Class III among it the most drought sensitive maize genotypes at the early growth stage is included (genotype 1, genotype 2, and genotype 6), they showed the greatest reduction in growth criteria at the severe soil moisture content. It was conferred that drought stress treatments affected differently the nine maize genotypes during the early growth stage which confirmed the genotypic variation among the studied maize genotypes.