A Study of Morphology and Anatomy of Different Drought Resistance Mung Bean Mutants

The morphology and anatomy of three mung bean mutants 172-3(high resistance),159-1(moderate resistance),145-1(low resistance) and their parent cultivar Zhonglv No.2(drought sensitive) were studied under the water stress and the purpose was to ascertain the mechanism of difference of drought resistance.The results showed that the basic histological structure of root,stem and leaf showed no difference for three mung bean mutants and their parent cultivar.The difference of drought resistance among the experimental materials represented mainly the index of the resistance structure.The high drought-resistance mutant was characterized by more root dry weight(The root dry weight of four materials was successively 172-3159-1145-1Zhonglv No.2),the number of vessel of xylem in the root were more(172-3145-1159-1Zhonglv No.2).The vascular bundle of the high drought-resistance mutant in the stem arranged closely,the number of vessel in the vascular bundle were more,the number of vascular bundle of four materials were respectively 23,25,26 and 18 and the number of vessel were respectively 251,236,207and 127.The cortical cells of high drought-resistance mutant were bigger,the cortex were thicker and the content of ergastic substance tannin was more in the parenchyma cell of pith in the center.The ratio of palisade tissue to spongy tissue of drought-resistance mutant was larger,the value of four materials was 2.23,2.08,2.10 and 1.85 corresponding.The order of main vein of leaf was 172-3159-1145-1Zhonglv No.2 and the radius of vessel of vascular bundle in main vein of leaf was larger for the high drought-resistance mutant.