GERMINATION AND VIGOR OF POPCORN SEEDS SUBMITTED TO THERMAL AND WATER STRESS

The objective of this study was to evaluate the germination and vigor of three varieties of popcorn (UFVM2, RUBY IAC and IAC 112) under thermal and water stress, simulated with PEG 6000. In the experiment temperature, seeds of three cultivars were germinated in paper rolls moistened with water, with temperatures during germination of 10, 20, 25, 30 and 35 degrees C. In the treatment at 10 degrees C the scrolls were placed in the refrigerator for five days before going to the incubator at 25 +/- 1 degrees C for seven days. In the experiment of drought stress, seeds of three cultivars were germinated in paper rolls moistened germitest with PEG 6000, with the potentials of 0.0, - 0.2, - 0.4, - 0.6 and - 0.8 MPa, temperature of 25 degrees C. The germination values followed the same trends of characteristics that reflect the vigor, indicating a high correlation between the vigor and germination of popcorn under conditions of sub and supra optimal temperatures and under water stress. A negative effect of water stress and temperatures of 20 and 35 degrees C on germination and seedling growth of popcorn. Cultivar UFVM 2 showed the highest germination and vigor under high water stress conditions.