Leaf and anatomical traits in relation to physiological characteristics in mulberry (Morus sp.) cultivars

Abstract

Micromorphological and anatomical traits in relation to physiological characteristics were studied in the leaves of 4 mulberry (Morus sp.) cultivars (V_1, TR_{10}, S_{34}, and Mysore local) by scanning electron microscope. The results revealed that leaf thickness was lowest (124.42 ± 2.21 µm) in the TR_{10} genotype and highest in V_1 (263.77 ± 5.17 µm). Cultivar S_{34} ranked second in respect to leaf thickness (203.57 ± 1.98 µm), followed by Mysore local (127.94 ± 2.19 µm). The thickness of palisade parenchyma was 143.66 ± 2.42 µm in V_1, 64.95 ± 1.60 µm in TR_{10}, 83.92 ± 1.43 µm in S_{34}, and 62.69 ± 1.36 µm in Mysore local. The ratio for the character of palisade parenchyma thickness among the cultivars was 2.30:1.34:1.04:1 for V_1, S_{34}, TR_{10}, and Mysore local, respectively; differences among the 4 mulberry cultivars studied were significant. The thickness of spongy parenchyma differed significantly among the 4 mulberry cultivars studied, and the greatest thickness recorded was 72.61 ± 1.48 µm in S_{34}; it was lowest (34.04 ± 1.03 µm) in TR_{10}. The values of spongy parenchyma thickness were more than double in V_1 and S_{34} when compared to TR_{10}. The experimental data revealed a maximum photosynthetic rate of 27.39 ± 0.65 µmol m^{-2} s^{-1} in V_1 followed by 24.66 ± 1.33, 19.76 ± 0.81, and 17.02 ± 0.71 µmol m^{-2} s^{-1} in TR_{10}, S_{34}, and Mysore local, respectively, and differences among the genotypes were statistically significant. Similarly, leaf pigment content (SCMR values) also exhibited significant intergenotypic differences, ranging from 35.23 (Mysore local) to 42.13 (V_1) and correlating positively with chlorophyllous palisade tissue in the mesophyll and photosynthetic rates. Ultimately, this manifested in leaf yields.