Plant Health Program, Doctor of


Document Type

Doctoral Document

Date of this Version

Spring 4-22-2016


Brittain Jr., Gregory Dean 2016 Managing Drought Stress in California Agricultural Systems, Doctoral Document Doctor of Plant Health, University of Nebraska-Lincoln


Doctoral document submitted to the faculty of the University of Nebraska in partial fulfillment of requirements for degree of Doctor of Plant Health. Advisor: Professor Gary L. Hein. Lincoln, Nebraska: April, 2016

Copyright © 2016 Gregory D. Brittain Jr.


California is currently facing a historic drought, and this has led many farmers in the state to severely cut back on irrigation. Optimal use of water for irrigation requires a comprehensive understanding of how plants respond physiologically to water stress (Chapter 1). By monitoring water requirements in crops and managing irrigation to meet those requirements, growers can significantly reduce water use (Chapter 2). This can be done through improving application efficiency of irrigation technology as well as increasing the water use efficiency of the crops themselves. Deficit irrigation practices can be used to manipulate the physiology of water use in plants and increase crop tolerance to drought stress. Imposing minor stress on plants induces chemical signaling within the plant that decreases stomatal aperture, increases root to shoot ratio and manipulates root architecture to optimize water gain and reduce loss. Though these practices have reduced yield compared to conventional irrigation, these reductions are minimal in most cases and can be considered better than severely reduced yields due to poor irrigation planning. Ultimately, deficit irrigation practices increase the yield obtained per unit of water applied. Additional benefits have also been reported with the use of deficit irrigation, such as improved yield quality and reduced shoot vigor.

Monitoring irrigation is an essential first step to optimal irrigation management, and it is an intrinsic part of integrated pest management. Drought stress affects the dynamics of certain plant pathogens and arthropod pests in both positive and negative ways, and this is important to consider when utilizing deficit irrigation practices. Often, avoiding plant stress is crucial, but this is not simply achieved by watering to avoid drought stress. It is important to create the best environment for healthy plant growth, and this may often mean reducing irrigation when necessary to improve a crops tolerance to drought stress and/or pest pressure (Chapter 3).

Advisor Professor Gary L. Hein