Abstract
Key messageJuniperus communis males are better adapted than females to changing, seasonal environmental conditions due to their higher photosynthetic capacity and the higher concentration of photosynthetic pigments in their needles. Males cope with ROS more efficiently than females having greater carotenoids concentration in needles.In dioecious woody plants, females often exhibit greater reproductive effort than male plants and as a result, they can be more vulnerable to different stressors. We hypothesized that female plants of J. communis L. could have a lower photochemical capacity and a higher level of antioxidant enzyme activity and that these differences between males and females would be more pronounced under conditions where nutrient availability is limited. We also assume that additional stressors connected with different seasons would increase those differences. Male and female plants of J. communis growing in fertilized or non-fertilized soils were used to test this hypothesis. The effect of fertilization and sex on photochemical parameters derived from chlorophyll a fluorescence light curves, and on the concentrations of photosynthetic pigments in needles, was determined in different seasons within 2 years. To assess the tolerance of male and female plants to the nutrient deficit, antioxidant enzyme activity, and the level of reactive oxygen species (ROS) were determined. Results revealed sex-related differences in photochemical parameters, level of antioxidant enzyme activity, H2O2 levels, the concentration of photosynthetic pigments, and in the leaf mass-to-area ratio. This indicates that J. communis males could be better adapted than females to changing, seasonal environmental conditions due to their higher photosynthetic capacity, as reflected by their higher ETRmax, and a higher concentration of photosynthetic pigments in their needles. The sex-related differences concerning photosynthetic capacity and stress response found in our study are constitutive traits of each sex and are genetically based as they occurred independently of fertilization.
Highlights
Dioecious species of plants form male and female flowers on separate individuals
Curves for ΦPSII and electron transport rate (ETR) vs. PPF were both higher in fertilized individuals than in non-fertilized individuals and the mean values of ΦPSII and ETR were significantly different between the fertilization treatments from the low PPF values (Fig. 1a, b)
The fertilization treatment affected the loss of absorbed energy from needles as heat, expressed as non-photochemical quenching of fluorescence (NPQ), which was significantly higher in non-fertilized plants in the range of 45 μmol m−2 s−1 to 530 μmol m−2 s−1 actinic PPF (Fig. 1c)
Summary
Dioecious species of plants form male and female flowers on separate individuals Due to their different reproductive roles, sexes vary in the structural units they produce and have differences in their morphology, physiology, and in their response to environmental conditions. Female plants have the potential to compensate costs associated with greater reproductive effort through increasing stomatal density, leaf area and gas exchange per unit leaf area as well as different strategies for N storage (Wallace and Rundel 1979; Kohorn 1994; Meagher 1999; Obeso 2002; Iszkuło et al 2009; Montesinos et al 2012; Iszkuło et al 2013; Nowak-Dyjeta et al 2017)
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