Leaf Traits and Water-Use Characteristics of Impatiens hainanensis, a Limestone-Endemic Plant under Different Altitudes in Dry and Foggy Seasons

Abstract

The southwestern mountains of Hainan Island are distributed in the southernmost tropical karst landscape of China, and the unique hydrological structure and frequent solifluction droughts lead to double water stress for local plants. Highly heterogeneous water environments affect the water–use characteristics of plants. Plants develop local adaptative mechanisms in response to changes in the external environment. In this paper, hydrogen–oxygen and carbon stable isotope technology, and physiological index measurements were applied to determine the leaf traits, water–use efficiency, and photosynthetic characteristics of Impatiens hainanensis leaves in dry and foggy seasons, hoping to expound the adaptation mechanism of I. hainanensis leaves to the water dynamics in dry and foggy seasons. In dry and foggy seasons (November 2018 to April 2019), the leaves of I. hainanensis at low and medium altitudes have the following combination of traits: larger leaf dry weights, leaf areas, and specific leaf areas; smaller leaf thicknesses and leaf dry matter contents; and higher chlorophyll contents. In comparison, the leaves of I. hainanensis at high altitudes have the following combination of traits: smaller leaf dry weights, leaf areas, and specific leaf areas; larger leaf thicknesses and leaf dry matter contents; and lower chlorophyll contents. The leaves of I. hainanensis can absorb fog water through their leaves. When the leaves are sprayed with distilled water, the water potential is low, the water potential value gradually increases, and the leaves have a higher rate of water absorption. The leaves of I. hainanensis at low and medium altitudes have the following water–use characteristics: high photosynthesis, high transpiration, and low water–use efficiency. At high altitudes, the Pn of I. hainanensis decreases by 8.43% relative to at low altitudes and by 7.84% relative to at middle altitudes; the Tr decreased by 4.21% relative to at low altitudes and by 3.38% relative to at middle altitude; the WUE increased by 16.61% relative to at low altitudes and increased by 40.79% relative to at middle altitudes. The leaves of I. hainanensis at high altitudes have the following water–use characteristics: low photosynthesis, low transpiration, and high water–use efficiency. I. hainanensis develop different physiological mechanisms of water adaptation by weighing the traits of the leaves and their use of light and water to obtain resources during dry and foggy seasons.

Phenotypic Diversity Analysis in Elaeagnus angustifolia Populations in Gansu Province, China

“…At the same time, with a decrease in altitude, longitude, and precipitation, the size of E. angustifolia leaves showed an increasing trend. Previous studies have also found that the leaf area of many plants decreases with increasing altitude, while the leaf thickness increases with increasing altitude [66,67]. This is consistent with our findings.…”

Karst fissures mitigate the negative effects of drought on plant growth and photosynthetic physiology

“…When the water was evidently limiting (at W30%), SF group still could keep the same Pn as the S group, but increased its WUE, along with greater biomass accumulation. These ndings rea rm that soil-lled karst ssures have a positive impact on alleviating drought stress in plants (Huang et al 2022;Du et al 2023). The F group increased Pn but at the cost of a decrease in WUE and also possibly elevated respiration, resulting in a lower biomass accumulation in response to karst drought.…”

Cocopeat Perlite Mixture as an Alternative for Rooted Cuttings Growth Medium of Impatiens hawkeri x platypetala in Indonesia

“…The following morphological observations were made: 1) the number of primary root branches, 2) the root length, which referred to the distance between the base of the stem and the tip of the longest root, 3) the stem diameter, measured beneath the node from which the last petiole grew, 4) the plant height, considered as the distance between the apical shoot tip to the base of the stem, 5) the leaves thickness, measured using micrometers three leaves from the top (Huang et al, 2022), 6) survival rate, calculated as the number of growth plant divided by the total number of plant x 100% (Wang et al, 2018). The morphological characteristics were assessed at 14, 21 and 28 days after planting (DAP).…”