Water availability dynamics have long-term effects on mature stem structure in Vitis vinifera

Area of Science:

• Plant anatomy
• Plant physiology
• Viticulture

Background:

• Vitis vinifera stems have wide and narrow vessels, and high hydraulic conductivity.
• Previous studies focused on drought stress in young stems, with limited data on mature woody stems.
• Mature stem anatomy and hydraulic conductivity responses to drought in V. vinifera are not well-documented.

Purpose of the Study:

• To investigate the anatomical and hydraulic responses of mature Vitis vinifera stems to different irrigation regimes.
• To understand how water availability during specific growth periods affects wood anatomy and conductivity.
• To assess the vulnerability of Merlot vines to drought stress under varying irrigation strategies.

Main Methods:

• Vitis vinifera Merlot vines were subjected to four years of distinct irrigation treatments (low, medium, high, alternating).
• Measurements included trunk diameter, annual ring width and area, vessel diameter, specific hydraulic conductivity, and stem water potential.
• Irrigation regimes simulated early spring or late summer water deficits.

Main Results:

• High early-season water availability led to increased trunk diameter, ring width/area, and wider vessels.
• Specific hydraulic conductivity was significantly higher in vines with ample early-season water (late deficit).
• Vines with high early-season water showed more negative stem water potential later in the season.

Conclusions:

• Early-season water availability in Vitis vinifera positively influences vessel diameter and hydraulic conductivity.
• Increased vessel size and conductivity due to early-season water make vines more vulnerable to late-season drought stress.
• Irrigation management timing significantly impacts mature vine wood anatomy and drought resilience.