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Temperature and Drought Effects on Blast and Other Characteristics in Developing Oats¹

Increased blast and reduced kernel yield have been observed in oat (Arena sativa L.) when periods of environmental stress occur during the growing season. The objective of this experiment was to determine the differential effects of controlled temperature and drought stress at specific times during panicle development on percent blast (blasted spikelets/total spikelets x 100), total spikdets/panicle, plant height, and several kernel characteristics.

‘Froker,’ a late season cultivar, and ‘Clintland 64’ and ‘Wright,’ midseason cultivars, were grown in pots in a mixture containing equal parts of peat and vermiculite. The pots were irrigated with half-strength Hoagland's solution, and placed in an environmental room programmed for the natural photoperiod and daily normal temperatures and relative humidity for 23 April to 15 August at Madison, Wis. Plants were subjected to heat, cold, and drought treatments at four times during panicle development: 26, 40, 53 and 63 days after planting, stages 1 to 4 respetively.

Typical environmental stresses that occur during the growing season of oats were found to increase blast and decrease yield and kernels/panicle. Blasting in Froker was increased by temperature and/or drought at all stages, in Wright by drought at stage 1 and temperature at stages 2 and 3, but in Clintland 64 only by drought at stage 4. Total spikelets/panicle were reduced by drought and heat at stages 2 and 3 (mean of all cultivats). These effects resulted in fewer kernels/panicle and reduced yield. The most severe yield reductions occurred as a result of drought at stage 2 and 4, and heat at stage 3. Compensation for increased blasting by formation of heavier kernels did not occur. Drought at stage 4 reduced kernels/fertile spikelet to near 1.0. In general, plant height was reduced by the same treatments causing yield reductions. Kernel protein concentration was mostly unaffected, except for an increase in kernels from plants that were drought stressed at stage 4.

These results emphasize the value of early planting to avoid the potential damage of heat and drought. Cold treatments had the least effect on yield. The data suggest cultivar variability in stress tolerance. Stress-tolerant cultivars could possibly be developed by selection and breeding, if suitable screening procedures could be established.

Key Words: Avena sativa L. • Stress • Heat • Cold • Yield • Sterility

² Research assistant, Dep. of Agronomy, Univ. of Wisconsin-Madison (now Biologist, Diamond Shamrock Corp., P.O. Box 348, Painesville, OH 44077); plant physiologist, SEA, USDA, and Associate Professor, Dep. of Agronomy, Univ. of Wisconsin, Madison, WI 53706.