| Middle and small lotus'White Bowl','Welcomeing Guests','Colorful Flag'and'Changeable Bueaty'were choosed as experiment materials in this paper. The experiment of accelerating germination and determination of physiological and biochemical indexes were carried on regularly from gradual maturity to overwintering period of lotus rhizome. By the regular determination and analysis of germination index, soluble sugar, starch, soluble protein, polyphenol oxidase, peroxidase, auxin, cytokinin, gibberellin and abscisic acid, the dormancy physiology and dormancy characteristics of middle and small lotus were studied to lay a theoretical foundation for the flowering time regulator of temperate zone lotus, and provide the scientific theory basis for lotus's introduction and so on other related scientific research.1. The lotus mainly experienced the end period of morphogenesis (last growth period), physiological after-ripening period (filling period of new lotus rhizome), true dormancy (endogenous dormancy) period and forced dormancy (ecological dormancy) period from September, 2007 to February, 2008. Because of florescence and size of lotus rhizome are different, the stage division of different variety were slightly different. Research of the lotus dormancy characteristic showed that, two lotuses that were still in growth in September, so they were in the end period of morphogenesis. Lotus still needed physiological after-ripening process after growing stop, to accumulate sufficient nutrition for lotus's germination. During this period, germination index increased gradually, the mature lotus rhizome hadn't obvious dormant period, so long as temperature being suitable, then normally sprouts. Into autumn, lotus experienced true dormancy and forced dormancy successively. The true dormancy is spontaneous endogenous dormancy that regulated by the lotus's autogene. This time even if the suitable growing conditions were provided, also cannot break the dormancy. The forced dormancy is a phenomenon which the growth of plant pauses temporarily, and are caused by the external environment that go against lotus's growth. At the moment if the suitable conditions have been given, the rhizome would sprout again. The medium sized lotus'Changeable Bueaty'entered the true dormancy in November. The dormancy period was about two months, and the dormancy was relatively deep; in small-sized lotus, the florescence of'Colorful Flag'was late, and it enterd the true dormancy in December. The florescence of'White Bowl'was early and the florescence of'Welcomeing Guests'was medium, they both entered the true dormancy in January, 2008. Their dormancy periods were about one month, and the dormancy was weak.2. The carbohydrate and soluble protein are the main nutrients in lotus rhizome. They are the foundation of physiology changes and the center of life activities. From the end period of morphogenesis to physiological after-ripening period, nutrients mainly manifested as the process of increase and accumulation. From the true dormancy to forced dormancy period, the soluble sugar content kept rising.'Colorful Flag'and'Changeable Bueaty'entered the dormancy relatively early. The starch and soluble protein continued to accumulate and increase in true dormancy period, and then decreased in forced dormancy period to resist the low temperature;'White Bowl'and'Welcomeing Guests'entered the dormancy relatively late. The true dormancy and forced dormancy were all in low temperature months, therefore the starch and soluble protein content always decreased.3. Changes of enzyme activity are concrete reflection of plant physiological activity change. The changes of polyphenol oxidase and peroxidase activity have close relations to dormancy of lotus rhizome. The enzyme activity had great differences between different varieties, but had a similar tendency in the same stage. From the end period of morphogenesis to physiological after-ripening period, along with the increase of maturity in newborn rhizome, the rhizome's metabolism increased. The activity of PPO and POD dropped first, and then rised. The enzyme activity had an opposite trend during dormancy. POD activity dropped in true dormancy period, and then increased in forced dormancy period, but the POD activity had an opposite trend.4. The endogenous hormone is a very important influence factor during natural dormancy. They participate in the induction, maintenance and termination of dormancy. The hormone content and IAA/ABA,GA3/ABA,GA3/ABA ratios were larger in physiological after-ripening period, and then decreased along with the gradual maturity of lotus rhizome. ZR and ZR/ABA began to decrease mainly in the early stage of ripening. GA3 and GA3/ABA decreased to the latest. ABA content reached the maximum when rhizomes were completely mature. The increasing ABA content suppressed the effect of growth promoting hormones, and urged the end of ripening in rhizome. We can see that in the end of morphogenesis to the physiological after-ripening period, the growth promoting hormones play a leading role. ZR and IAA mainly promote the growth and preliminary accumulation of nutrition. The influence on lotus's ripening by GA3 can continue to essential maturity. ABA promoted the end of after-ripening, and induced the beginning of doramcy.5. Four hormones continued to decrease during true dormancy period. The decrease amplitude of ABA was relatively small. The hormone ratios are mostly smaller than 1, and the decrease amplitude of GA3/ABA was biggest. The growth promoting hormones with low content, specially the rapid decrease of GA3, reduced the restriction on growth inhibitory hormone ABA, and enabled ABA to play a major role in dormancy of lotus rhizome. During forced dormancy period, the increase of GA3/ABA ratio was helpful to true dormancy release. The change of GA3 and ABA balance played a major role in regulating true dormancy. The lotus's dormancy is not only determined by some hormone content's increase or decrease, but also determined by the hormone balance.
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