Physiological and Biochemical Traits of Needles Imply That Understory Light Conditions in the Growing Season May Be Favorable to Pinus koraiensis Trees

Light is often considered the primary factor leading to regeneration failure of Korean pines (Pinus koraiensis) under forest canopy. However, studies on effect light mainly focus use an artificial sunshade net control shade; field canopy are extremely scarce, and current experimental results contradictory. For a deeper understanding relationship between conditions understory pine trees, low, middle, high full (control) were tested at 18 years age. The photosynthetic pigments, chlorophyll fluorescence, non-structural carbohydrate metabolism, antioxidant enzyme activity, nutrient concentrations current-year needles from trees measured. From June September, intensity quality decreased light, but following leaf fall, improved slightly. As improved, pigments in decreased, Car/Chl highest light. All had positive correlation with glucose Rubisco activity. Full-light APX DPPH scavenging capacity, proline concentration, as well higher NPQ lower Fv/Fm readings. This indicated that full-light stressed inhibited photosynthesis some extent, while environment may alleviate stress. conservative strategy storing more starch using less be one reasons for observed differences growth rates among varying conditions. Overall, this study implies during growing season not always unfavorable 18-year-old trees; means still have shade tolerance extent capable living deciduous trees.