Abstract

Sexual dimorphism in secondary traits (differences between the sexes in characteristics others than the sexual organs) is widespread in plants (Geber et al., 1999 ; Barrett and Hough, 2013). Sex differences in ecological, morphological and physiological traits have been commonly attributed to the different costs of reproduction associated with the male and the female function (Reznick, 1985 ; Obeso, 2002) and are usually linked to trade-offs between allocation to reproduction and to other plant functions (e.g., to growth and/or defense). Such trade-offs are likely to be modified under more stressful conditions (Bazzaz and Grace, 1997). In fact, plants are continuously exposed to stressful biotic and abiotic environmental factors during all their life cycle, which usually occur simultaneously (Suzuki et al., 2014). Biotic factors include competitors, symbionts, parasites, pathogens, and herbivores. Abiotic factors include extreme temperatures, water, light and nutrient availability, heavy metals, CO2, or UV radiation. As sessile organisms, plants have developed a wide range of responses to cope with stress, ranging from escape to tolerance and avoidance (Lerner, 1999).