Pepper Rootstock and Scion Physiological Responses Under Drought Stress

Area of Science:

• Plant Physiology
• Agricultural Science
• Horticulture

Background:

• Grafting commercial vegetable varieties onto drought-tolerant rootstocks is a strategy to enhance water stress resilience.
• Previous studies identified the A25 pepper rootstock accession as having good drought tolerance in fruit production.
• Understanding the physiological mechanisms underlying A25's drought tolerance in grafted plants is crucial for agricultural applications.

Purpose of the Study:

• To evaluate the drought tolerance of pepper plants grafted onto the A25 rootstock after short-term water stress.
• To analyze key physiological processes in both roots (rootstock) and leaves (scion) of grafted and non-grafted plants under drought conditions.

Main Methods:

• Pepper plants were grown under severe water stress (-0.55 MPa PEG) or control conditions for 7 days hydroponically.
• Experimental groups included non-grafted (A), self-grafted (A/A), and A/A25 grafted plants.
• Physiological parameters such as root biomass, water absorption, CO2 assimilation, nitrate reductase activity, and oxidative damage markers (ROS, H2O2) were analyzed.

Main Results:

• A/A25 grafted plants exhibited alleviated water stress severity compared to A and A/A plants.
• A/A25 showed increased root biomass, leading to enhanced water absorption, retention, and sustained CO2 assimilation.
• Non-grafted and self-grafted plants experienced reduced photosynthesis, stomatal closure, and increased oxidative damage (ROS, H2O2).

Conclusions:

• The A25 rootstock effectively protects the scion against drought-induced oxidative stress.
• Improved carbon and nitrogen balance in A/A25 plants contributes to biomass maintenance under short-term water stress.
• Grafting with A25 rootstock is a viable strategy to enhance pepper's resilience to drought, potentially increasing field yields.