Figures (4)  Tables (5)
    • Figure 1. 

      Comparison of shoot growth and leaf anatomy between bermudagrass cultivars Yangjiang and Guanzhong. (a) Yangjiang exhibits more prostrate shoot growth whereas (b) Guanzhong exhibits more upright shoot growth. The leaves of Yangjiang have (c) no trichomes, whereas Guanzhong leaves have (d) many trichomes.

    • Figure 2. 

      Effects of shade on chlorophyll a fluorescence in Guanzhong and Yangjiang. (a) Photochemical quenching coefficient (qP), (b) electron transport rate (ETR), (c) ratio of variable fluorescence to maximal fluorescence (Fv/Fm) of both cultivars were measured under 30.4%, 61.2%, and 90.6% shade. ** indicates significant differences at 0.01 level between the two cultivars. CK, un-shaded control. Vertical bars represent standard errors of the mean (n = 4).

    • Figure 3. 

      Effects of shade on H2O2 production and antioxidant enzyme activity in Guanzhong and Yangjiang. (a) SOD, (b) POD, (c) CAT activities and (d) H2O2 production of both cultivars were measured under 30.4%, 61.2%, and 90.6% shade. * and ** indicate significant differences at 0.05 and 0.01 levels between the two cultivars, respectively. CK, un-shaded control. Vertical bars represent standard errors of the mean (n = 4).

    • Figure 4. 

      Cross-sections of Guanzhong and Yangjiang leaves under different shading treatments. (a)−(d) Images of Guanzhong leaf ribs at 100× magnification highlighting the upper epidermal (UE) and lower epidermal (LE) cell layers of plants treated with (a) no shade, (b) 30.4% shade, (c) 61.2% shade, and (d) 90.6% shade. (e)−(h) Images of Guanzhong leaf ribs at 400× magnification highlighting the vascular bundle (VB) and cells of Kranz anatomy (CKA) of plants treated with (e) no shade, (f) 30.4% shade, (g) 61.2% shade, and (h) 90.6% shade. (i)−(l) Images of Yangjiang leaf ribs at 100× magnification highlighting the UE and LE cell layers of plants treated with (i) no shade, (j) 30.4% shade, (k) 61.2% shade, and (l) 90.6% shade. (m)−(p) Images of Yangjiang leaf ribs at 400× magnification highlighting the VB and CKA of plants treated with (m) no shade, (n) 30.4% shade, (o) 61.2% shade, and (p) 90.6% shade.

    • CultivarsShading level (%)5 d20 d35 d50 d
      TCITQTCITQTCITQTCITQ
      GuanzhongCK7.2bc8.2b7.0c8.5a7.1b8.5a7.1bc8.2b
      30.47.3ab8.3b7.1bc8.0b7.2ab7.9b7.0c7.7c
      61.27.1c8.2b4.5e4.7d4.1d4.3d3.7f3.9f
      90.66.5d7.6c4.3f4.4e3.8e4.1e3.1g3.5g
      YangjiangCK7.3ab8.5a7.3a8.5a7.3a8.5a7.2ab8.3a
      30.47.4a8.5a7.0c8.5a7.3a8.5a7.3a8.0b
      61.27.4a8.5a7.2ab8.5a7.3a8.5a6.2d6.7d
      90.67.2bc8.5a6.8d7.7c6.3c7.0c5.3e5.7e
      Different lower case letters in the same column indicate significant difference at 0.05 probability level. CK, un-shaded control; d, number of days plants were exposed to shade.

      Table 1. 

      Effects of shade on turf quality (TQ) and turf color intensity (TCI) of Guanzhong and Yangjiang.

    • CultivarsShading level (%)TB (g/per plant)AGB (g/per plant)BGB (g/per plant)RAB (g/per plant)
      GuanzhongCK0.56 ± 0.04b0.30 ± 0.04b0.26 ± 0.02b1.15 ± 0.03e
      30.40.51 ± 0.05b0.29 ± 0.0lb0.22 ± 0.01c1.31 ± 0.03cd
      61.20.42 ± 0.04c0.24 ± 0.01c0.18 ± 0.01d1.34 ± 0.04cd
      90.60.33 ± 0.02d0.19 ± 0.01d0.14 ± 0.01e1.36 ± 0.05bc
      YangjiangCK0.68 ± 0.04a0.38 ± 0.01a0.30 ± 0.01a1.27 ± 0.03d
      30.40.65 ± 0.04a0.37 ± 0.01a0.28 ± 0.01ab1.33 ± 0.04cd
      61.20.51 ± 0.02b0.30 ± 0.01b0.21 ± 0.01c1.43 ± 0.07ab
      90.60.42 ± 0.03c0.25 ± 0.01c0.17 ± 0.01d1.47 ± 0.06a
      Data are mean ± SE (Standard Error). Different lower case letters in the same column indicate significant difference at 0.05 probability level. CK, un-shaded control.

      Table 2. 

      Effects of shade on total biomass (TB), above-ground biomass (AGB), below-ground biomass (BGB), and the ratio of above- to below-ground biomass (RAB) for Guanzhong and Yangjiang.

    • CultivarsShading
      level (%)
      1−15 d
      (mm)
      16−30 d
      (mm)
      31−45 d
      (mm)
      GuanzhongCK1.66 ± 0.04a1.63 ± 0.03a1.65 ± 0.04a
      30.41.08 ± 0.02b1.06 ± 0.02c0.67 ± 0.03c
      61.20.93 ± 0.03c0.40 ± 0.01e0.34 ± 0.01e
      90.60.78 ± 0.04d0.24 ± 0.01f0.17 ± 0.01f
      YangjiangCK0.89 ± 0.06c0.87 ± 0.03b0.85 ± 0.04b
      30.40.78 ± 0.04d0.67 ± 0.02d0.45 ± 0.02d
      61.20.61 ± 0.03e0.34 ± 0.01f0.21 ± 0.01f
      90.60.56 ± 0.07e0.23 ± 0.01f0.19 ± 0.01f
      Data are mean ± SE (Standard Error). Different lower case letters in the same column indicate significant difference at 0.05 probability level. CK, un-shaded control.

      Table 3. 

      Effect of shade on the average daily growth rate of Guanzhong and Yangjiang.

    • CultivarsShading level (%)Chla [mg·g−1(FW)]Chlb [mg·g−1(FW)]Total Chl [mg·g−1(FW)]Chla/b
      GuanzhongCK2.26 ± 0.08bc4.33 ± 0.25cd6.59 ± 0.28d0.52 ± 0.02ab
      30.42.11 ± 0.13bcd4.03 ± 0.17d6.14 ± 0.25de0.52 ± 0.01ab
      61.22.03 ± 0.06cd4.06 ± 0.12d6.09 ± 0.17e0.50 ± 0.07ab
      90.61.92 ± 0.02d3.63 ± 0.04e5.54 ± 0.12f0.53 ± 0.05a
      YangjiangCK2.72 ± 0.21a5.48 ± 0.22a8.20 ± 0.28a0.50 ± 0.03ab
      30.42.65 ± 0.08a5.18 ± 0.08a7.83 ± 0.11b0.51 ± 0.02ab
      61.22.31 ± 0.21b4.86 ± 0.16b7.17 ± 0.16c0.48 ± 0.05b
      90.62.04 ± 0.14cd4.52 ± 0.23c6.56 ± 0.21d0.45 ± 0.03b
      Data are mean ± SE (Standard Error). Different lower case letters in the same column indicate significant difference at 0.05 probability level. CK, un-shaded control.

      Table 4. 

      Effects of shade on leaf chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Total Chl) contents, and the ratio of Chla to Chlb (Chla/b) in Guanzhong and Yangjiang.

    • CultivarsShading level (%)Leaf thickness (μm)Thickness of UEC (μm)Thickness of LEC (μm)Vascular diameter (μm)
      GuanzhongCK146.34 ± 6.34a8.34 ± 1.17a7.98 ± 1.23a119.34 ± 6.32a
      30.4134.78 ± 7.25b7.18 ± 1.26ab6.25 ± 1.16abc98.56 ± 5.26bc
      61.2122.91 ± 8.26bc5.19 ± 1.86bc4.98 ± 1.36bcd76.69 ± 7.32ef
      90.693.33 ± 6.31d3.17 ± 1.79c3.12 ± 1.79d65.53 ± 6.29f
      YangjiangCK131.83 ± 5.32b7.51 ± 1.66ab6.97 ± 1.78ab108.76 ± 7.67ab
      30.4122.84 ± 6.69bc6.23 ± 1.47ab5.81 ± 1.32abcd94.32 ± 6.34cd
      61.2118.84 ± 4.86c5.98 ± 1.25ab4.96 ± 1.86bcd84.09 ± 5.21de
      90.6102.71 ± 7.32d4.78 ± 1.38bc3.32 ± 1.79cd72.32 ± 4.29f
      Data are mean ± SE (Standard Error). Different lower case letters in the same column indicate significant difference at 0.05 probability level. CK, un-shaded control. UEC, upper epidermal cells. LEC, lower epidermal cells.

      Table 5. 

      Effects of shade on leaf anatomical structures in Guanzhong and Yangjiang.