Determination of The Optimum Concentration of Polyethylene Glycol 6000 for In-house Maize Seedling Screening System Against Osmotic Stress

บทคัดย่อ

     One of the breeding strategies to shorten a breeding process is selecting on early growth stage with correlated secondary traits. In vitro screening method with Polyethylene glycol 6000 is widely used due to it is more controllable and convenience for inducing osmotic stress to plants. Our In-house screening system was used to find the proper concentration of PEG solution on maize seedling which was the objective of this study. The experiment was conducted in Factorial in RCBD with 2 blocks. The first factor was 7 different concentrations of PEG solution in which caused different osmotic potentials of solution. Whereas the second factor was 4 maize varieties: 2 inbred lines and 2 commercial hybrid varieties. Maize seedlings were treated with the protocol of in-house screening system and were collected for 10 phenotypic traits. The results showed the significant effects of PEG 6000 concentration, maize variety and their interaction on many traits. Moreover, it was found that PEG concentrations that causes statistical changes of treatment means when compared with its control (0% PEG) were different at each trait. For example, the proper concentration was 20% PEG for root to shoot ratio while that of the other traits was different. However, PEG of 25% was recommended for being the effective concentration since this level of stress showed the statistical effect on 8 out of 10 traits. However, in case that a list of phenotypic traits might be changed, the effective PEG concentration for the new list of phenotypic traits should be re-considered. In addition, this study showed that two characteristics, shoot area and primary root length, which were extracted from image processing, shoot area showed strong relationship with leaf greenness (-0.42), shoot weight (0.93), root weight (0.63), total fresh weight (0.89), shoot dry weight (0.66) and root to shoot ratio (-0.50). Therefore, it is another interesting trait that might be used in seedling screening because it was easy to extract from the image processing whereas primary root length contrarily had weak correlation with the other 9 traits of seedlings.