PARENT SESSION
Poster Session 1: Photosynthesis and Water Relations
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Physiological responses of four hazelnut hybrids to water availability in Nebraska.

Awada, Tala^*,1, Josiah, Scott², Eggemeyer, Kathleen ¹, ¹ School of Natural Resources, Lincoln, NE, USA² Nebraska Forest Service, Lincoln, NE, USA

ABSTRACT- Responses of four hazelnut hybrids (88BS, Box1, G17 and Gellatly 502) to water availability (watered, non-watered) were assessed under field conditions in Nebraska. Soil moisture content (SMC), photosynthetic rates at light saturation (Amax), stomatal conductance (gs), water use efficiency (WUE), Photosynthetic nitrogen use efficiency (PNUE), predawn and midday water potentials (pre and mid), carbon isotope discrimination (¹³C), specific leaf area (SLA) and height were measured periodically during the growing season (June - September). Total growing season precipitation was below the long term reported average. Differences in measured parameters among hybrids and water treatments appeared between July and September with the onset of drought. Amax, gs and SLA, differed among hybrids and declined in response to water stress. The decline in gs was greatest in 88BS, followed by G17, Box1 and Gellatly 502. WUE increased in all hybrids, while PNUE was highest and remained relatively stable in Box1 and G17 and increased in 88BS and Gellatly 502 to reach similar values observed in Box1 and G17 in response to water stress. pre followed the same seasonal trend and values were similar in both watered and non-watered plants. mid differed among hybrids and water treatments, midday water potential gradient (mid) was lowest in 88BS and highest in Box1. (¹³C) differed among hybrids and showed little plasticity in response to water stress. 88BS discriminated the least against ¹³C under both water treatments, and was significantly different from others. Height increase did not differ among hybrids and water treatments, except for G17. The later was the only hybrid to display a significant positive response to water. Hybrids displayed genetic variability and significantly different strategies to deal with drought. While 88BS showed the most decline in gs, increase in PNUE, least gradient in mid and discrimination against ¹³C, and low SLA, indicating that this hybrid responded to drought by increasing WUE and conserving water. Box1 maintained both high gs and Amax, displayed the most both gradient in mid and negative ¹³C indicating a greater capacity of this hybrid to absorb soil water and better adaptability to reach limited resources.

Key words: Hazelnut, water relations, Nebraska, drought