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Wheat Seed Germination under Low Temperature and Moisture Stress¹

Cultivate differ inherently in their response towards drought. Only those adapted to arid and semiarid conditions become established into uniform and vigorous stands during germination under moisture stress and suboptimal temperature. Seed germination of four wheat cultivars, ‘Najah’ and ‘Mexi-pak’ (Triticum aestivum L.), and ‘Hurani’ and ‘Jori’ (Triticum durum L.), were compared under suboptimal temperatures and various levels of simulated moisture stress. Components of water uptake, germination percentage, speed of germination, root growth, respiration rate, and germination recovery from stress were measured. The rate of water uptake decreased and the time required for germination increased when the seeds were incubated at 6 atm and higher. Seeds of the four cultivars germinated when their moisture content was approximately 50% on a fresh weight basis. Total germination was not affected by moisture stress levels up to 12 atm but was significantly reduced at 15 and 18 atm osmotic tensions. Rate of root growth, speed of germination, and respiration rates were inversely related to moisture stress. Low moisture stress (3 atm) did not inhibit root growth. Significant differences were found among cultivars in the parameters studied. Perforating the pericarps did not eliminate the differences in water uptake and respiration rates between cultivars. Prolonged exposure of ungerminated seed to high osmotic tensions at low temperatures showed high seed germination recovery. These data suggest that any of the germination criteria used can be effective in selecting droughtresistant cultivars.

Key Words: Imbibition • Speed of germination • Root growth • Germination recovery from moisture stress • Drought resistance

² Graduate student and professor of Agronomy (currently visiting agronomist at the Univ. of California, Davis), respectively.

Received for publication August 7, 1975.