In vitro seed germination response of corn hybrids to osmotic stress conditions
Walne, Charles Hunt | Gaudin, Annabeth | Henry, W Brien | Reddy, Kambham Raja
Drought is a major environmental stress factor of plants influencing all growth stages. Drought occurring during germination affects both germination percentage and rate. An experiment was conducted to evaluate in vitro seed germination responses of nine corn (Zea mays L.) hybrids to declining osmotic potentials using polyethylene glycol. Time series data for seed germination were generated at different osmotic potentials from 0 to −1.2 MPa at −0.3‐MPa intervals at 25 °C. Maximum seed germination (MSG) and seed germination rate (SGR) were estimated by fitting the data to a three‐parameter sigmoid function. The minimum osmotic potentials at which MSG and SGR rate reached zero (MSGbₐₛₑ and SGRbₐₛₑ) were derived by first fitting linear and quadratic regression models as a function of osmotic potential and then calculating intercepts. Maximum seed germination and SGR decreased as osmotic potential decreased, and differences were identified among hybrids for MSG, SGR, MSGbₐₛₑ, and SGRbₐₛₑ. An osmotic stress response index was developed by summing individual response indices of each parameter for each hybrid and was used to classify the corn hybrids into tolerance groups. AgriGold A6659 and Terral REV 25BHR26 were identified as the most‐ and least‐tolerant corn hybrids during germination, with AgriGold A6659 performing 29% better than REV 25BHR26. Previous studies have used similar methods using polyethylene glycol to create osmotic stress but have not used the parameters used in this study. These parameters establish a new potential screening tool to identify osmotic stress tolerance in corn germplasm.
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