| Pot experiments were carried out in Zhengzhou city henan province from 2006 to 2007. Effects of various level of B and Z on the their distribution and aborstroption as well as content of chlorophyll, content of MDA and related enzyme activity of flue-cured tobacco leaves during the cultivation in farmland were studied, the result showed that:1. Effects on the activity of NR. During the early and middle growing period of flue-cured tobacco, supply of B enhanced the activity of NR significantly, however, the difference of NR activity between the treatments of high and proper B level was not significant. During the later growing period of flue-cured tobacco, the activity of the high B level treatment T3 was higher than the proper level treatment T2 and control T1. During the early and middle growing period of flue-cured tobacco, the supply of Zn could enhance the activity of NR, however, supply of high level Zn couild not enhance the activity of NR significantly. During the later growing period of flue-tobacco, the difference of effect between the treatments which were supplied Zn and the control was not significant.2. Effects on the content of chlorophyll. During the early and middle growing period of flue tobacco, proper supply of B could enhance the content of chlorophyll efficiently, and improved the accumulation of dry weight. During the later growing period of flue-tobacco, supply of B could accelerate the speed of degradation of chlorophyll; as a result, the tobacco quality was improved. However, the effect of excessive supply of B is not significant, it decreased the content of chlorophyll during the early and middle growing period. During the early and middle growing period of flue-tobacco, with the increase in the supply of B, the content of chlorophyll would become less, on the contrary, during the middle and later growing period, the content of chlorophyll would rise.3. Effects on the activity of SOD. During the early and middle growing period, proper supply of B could enhance the activity of Cu·Zn-SOD, however, excessive supply of B inhibited it. During the middle and later growing period of tobacco, with the increase in the supply of B, the activity of Cu·Zn-SOD would decrease. During the early and middle stage of tobacco, the activity of Cu·Zn-SOD would increase along with the increase in the supply of Zn. 4. Effects on the content of MDA. During the early and middle growing period of flue-cured tobacco, supply of B could increase the content of MDA. In 30th and 45th days after transplanted. The MDA content of treatment T3 was the highest, T2 was lower, T1 was the lowest. During the whole growing stage of tobacco, supply of Zn could decrease the content of MDA. The content of MDA of treatment T1 was the highest, T4 was lower, T1 was the lowest.5. Effects on the activity of ATPase in root. During the early growing period of tobacco, with the increase in the supply of B, the activity of root would rise gradually. During the middle and later growing stage of tobacco, the content of MDA of the treatment which was supplied proper B is the highest, however excessive supply of B would decrease the activity of root. Zn could enhance the activity of root during the early growing period of tobacco, however, the effect was not significant during the middle and later growing stage.6. Effects on the accumulation of B and Zn. Proper supply of B could significantly enhance the accumulation Zn in flue-cured tobacco, however, high supply of Zn did not have the same effect. Supply of Zn could increase the accumulation of B in tobacco which was supplied with low level of B at the early stage and middle stage, whereas the effect was not significantly at later stage. The accumulation of B in tobacco rose along with the increase in the level of B supply, and the accumulation of Zn in tobacco rose along with the increase in the level of Zn supply as well. The accumulation of B mostly happened at the medium and later stage but the accumulation of Zn largely happened at the early and later stage.7. Effects on the distribution of B and Zn. Supply of B could decrease the distribution of Zn in leaves as well as street but enhance the distribution in root. Supply of Zn could increase the distribution of B in leaves, whereas decrease it in streets and have complicated relation with the distribution in roots.8. Effects on the B and Zn content of various flue-cured tobacco organs. Both of the B and Zn content in leafs, streets and roots would rise along with the increase in the level of B, Zn supplies. The Zn content was the highest both in leaves and streets in the proper level of B supply, however, in roots, with the increase in the level of the B supply the Zn content rise gradually. Supply of Zn could propel the enhancement of B content in leafs and also increase the B content in streets at early stage, but had a decrease at later growing period. The supply of Zn reduced the B content in root when treatments are in low-B level, but enhanced it in proper level.
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