Evaluation of Upland Rice Response to Water Stress Using Polyethylene Glycol (PEG -6000) at Germination and Early Seedling Stage

Water stress is one of the most important crop growth limiting factors which leads to low crop productivity and yield instability. Water stress affects crop growth and development, especially during the germination and seedling period. The experiment was conducted in the growth chamber at the seed physiology laboratory of the Department of Seed, Crop and Horticultural Sciences, University of Eldoret to evaluate sixteen upland rice varieties to water stress tolerance at germination and early seedling growth stage. These varieties were tested against four levels of water stress imposed by Polyethylene glycol 6000 (PEG - 6000) at 0%, 5%,10% and 15% concentration. The lay out of the experiment was complete randomized design (CRD) with three replications. Osmotic stress induced by PEG levels significantly (P<.001) reduced plant growth parameters. The result showed that the germination percentage, germination index, Relative seedling height (%), seedling dry weight, Seedling fresh weight, Seedling length, seedling vigor index and mean germination time of all tested rice varieties were found decreasing trends with increasing the levels of PEG from 0 to 15% concentration levels. Among all the sixteen varieties, NERICA rice varieties followed by MWUR, White rice, Kpatawee, and Komboka had an outstanding performed in terms of germination percentage, germination index, seedling height, seedling dry weight, root length and relative dry weight under water induced stress by using PEG concentration levels compared to other varieties. Therefore, these varieties could be useful in breeding programs and can be cultivated in arid and semi-arid environment or where water shortage is a regular constraint.