Drought Response of Winter Wheat Cultivars Grown under Field Stress Conditions1
- D. L. Keim and
- W. E. Kronstad2
Ten winter wheat cultivars (Triticum aestivum L.) were evaluated for grain yield and yield components under moisture stress conditions at three locations. Osmotic potential (Ψn.) was determined from leaf samples taken during the early part of grain filling. Consistent genetic differences were found for Ψn... Significant positive associations of Ψn with yield existed at two locations (r= 0.49 and 0.45). Path-coefficient analysis indicated that Ψn. contributed positively to yield differences primarily by way of kernel weight at Pendleton, the least stressed site. Increased Ψn made contributions to high yield via spikelets/spike, kernels/spikelet, and kernel weight at Pilot Rock, a severely stressed site. High spike numbers had a tendency to be associated with low plant water status (low Ψn). At Heppner, the large direct effect on yield by spikes/m2 negated the small positive indirect effects of Ψn via the later-developed yield components. In a growth analysis study at Pilot Rock, five cultivars were sampled over four time intervals from spike initiation to ripe stage. The mean Ψn decreased over time (- 17.1 to - 31.8 bars). Cultivar Ψn values ranked consistently and differences became larger after the onset of high soil moisture stress (< - 15 bars).
The drought-resistant cultivar ‘Yamhill’ avoided drought stress by maintaining a high plant water status during reproductive development. The high growth rates during heading and anthesis and a high kernel weight indicated that this cultivar was less affected by high external water stress. The drought-resistant cultivar ‘Wanser’ tolerated a high internal stress by maintaining a large number of tillers through development to harvest. Characterization of other cultivars also indicated that both avoidance and tolerance traits contributed to grain yield under drought stress.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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