Shade Avoidance Influences Stress Tolerance in Maize

[ "Postdoctoral research associate, postdoctoral research associate, graduate student, Professor, and Professor, Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road E., Guelph, ON N1G 2W1, Canada. Current address of first author: Agriculture and Agri-food Canada, Greenhouse and Crops Processing Centre, 2585 County Rd. 20, Harrow, ON N0R 1G0, Canada. Corresponding author's E-mail: "]; [ "Turface MVP®, Profile Products LLC Buffalo Grove, IL."]; [ "Dual channel R/FR sensor, SKR 110, 660/730 nm, Skye Instruments Ltd., Llandrindod Wells, Powys, UK."]; [ "LI-COR 3100 Area Meter, LI-COR Biosciences, Lincoln, NE."]; [ "SAS software, SAS Institute, Cary, NC."]
Weed Science (Impact Factor: 1.76). 07/2011; DOI: 10.1614/WS-D-10-00159.1

ABSTRACT Previous studies have suggested that the reduction in the root/shoot ratio that accompanies the shade avoidance response may reduce the tolerance of individuals to subsequent nutrient or moisture limitations. In this work, we examined the impact of the shade avoidance response on maize seedling growth and development and the response of these plants to a subsequent abiotic stress. Seedlings were grown in a field fertigation system under two light quality environments, ambient and a low red to far-red ratio, which were designed to simulate weed-free and weedy conditions, respectively. This system also enabled the controlled restriction of water and nutrients, which reduced the relative growth rate of the crop and created a secondary stress. Results of this study indicate that, while the shade avoidance response did reduce the root/shoot ratio in maize, this effect did not reduce plant tolerance to subsequent abiotic stress. Rather, the apparent additivity or synergism of shade avoidance and the secondary stressor on yield loss depended on whether the net effect of these two stressors was sufficiently large to shift the population toward the point where reproductive allometry was broken. Nomenclature: Maize, Zea mays L.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Crop management decisions such as sowing density, row distance and orientation, choice of cultivar, and weed control define the architecture of the canopy, which in turn affects the light environment experienced by crop plants. Phytochromes, cryptochromes, phototropins, and the UV-B photoreceptor UVR8 are sensory photoreceptors able to perceive specific light signals that provide information about the dynamic status of canopy architecture. These signals include the low irradiance (indicating that not all the effects of irradiance occur via photosynthesis) and low red/far-red ratio typical of dense stands. The simulation of selected signals of canopy shade light and/or the analysis of photoreceptor mutants have revealed that canopy light signals exert significant influence on plant performance. The main effects of the photoreceptors include the control of (a) the number and position of the leaves and their consequent capacity to intercept light, via changes in stem height, leaf orientation, and branching; (b) the photosynthetic capacity of green tissues, via stomatic and nonstomatic actions; (c) the investment of captured resources into harvestable organs; and (d) the plant defences against herbivores and pathogens. Several of the effects of canopy shade-light signals appear to be negative for yield and pose the question of whether breeding and selection have optimised the magnitude of these responses in crops.
    ISRN Agronomy. 03/2013; 2013.


Available from
May 17, 2014

Eric R Page