| The experiments of pot, hydroponics and field cultures using flue-cured tobacco MSK326were conducted to investigate the effects of Mo and N treatments on C and N metabolism, yield and quality of flue-cured tobacco. The main results as follows:1. Pot and field trials were conducted to investigate the effects of Mo and N treatments on dry matter and yield of flue-cured tobacco at different growth stages. The results showed that: nitrogen was detrimental to tobacco growth at early stage, while it was increased dry matter at later period significantly. Mo application also increased tobacco dry matter. Both Mo and N treatment showed synergistic and positive effect on dry matter at rosette and maturity significantly. Nitrogen treatment was significantly increase tobacco yield whether Mo treat or not, while Mo application can increase yield just under superior nitrogen conditions.2. Pot experiment was conducted to investigate the impacts of Mo and N application on Mo concentrations and accumulations of different leaf positions at different stages of flue-cured tobacco. The results suggested that Mo application caused increases of Mo concentration and accumulation of different leaf positions and growth stages. While Mo concentration and accumulation were reduce gradually with the increase of N application. Mo and N have negative effect on Mo concentration and accumulation in leaves. In the certain Mo application,. Mo concentration in lower leaf at topping was the highest, while upper leaf was the highest at maturity. Mo accumulation in the middle and upper leaves was highest at topping and maturity respectively. The peaks of Mo accumulation of all treatments were at the62th day, and then,0.30mg/kg Mo application can significantly increase Mo accumulation rate in three nitrogen treatments,.3. The impacts of Mo and N applications on photosynthesis and soluble sugar of flue-cured tobacco were discussed in our study. The results indicated that contents in tobacco leaves of chlorophyll a, chlorophyll b and the sum of them were increased by Mo application at rosette under higher nitrogen levels. Pn of tobacco leaf at rosette raised first and then significantly descended with increasing of N application. Under N2level, Mo application can significantly increase soluble sugar contents in middle and lower leaf at topping and maturity. Under N3level, Mo application can significantly decrease soluble sugar contents in middle and lower leaf at topping, while increased in lower leaf at maturity.4. Pot and hydroponic experiments were conducted to study the effects of Mo and N applications on N metabolism. The results show that increasing N levels can significantly increase nitrate-N in all leaves at different stages, while Mo application was significantly decrease nitrate-N in all leaves at different stages. Mo and N have synergistic effect to NR, both of them can significantly enhance NR activity. N level was the main factor effects total N, soluble protein and free amid-N contents. Total N and free amid-N were increased with the enhancement of N application. Soluble protein was increased at early growth stage and then decreased at later stage with the increase of N application. The effects of Mo applications on total N, protein and free amid-N contents were restricted by N.5. Pot experiment was conducted to study the effects of Mo and N applications on amino acid compositions. The result showed that both total and free amino acid compositions of high N level were significantly higher than low N level. Asp and total amino acid contents were significant increased by application of Mo under N3. The effects of Mo application on free amino acid compositions are constrained by nitrogen fertilizer:Mo application had no significantly impact on free and total amino acid compositions under Nl level; Mo application was decreased free amino acid compositions content under N2level; while it was promoted free amino acid compositions content under N3level.6. Pot experiment was conducted to study the effects of Mo and N applications on flue-cured tobacco quality. The results showed that nicotine contents in upper and lower leaf were increased by N application significantly, while nicotine content in lower leaf was decrease. Mo application increased nicotine contents in upper and middle leaves under N2level. While Mo decreased nicotine content in upper and lower leaves under N3level. Chlorine content in upper leaf gradually decreased with increasing of N application. All in all, Mo application had no significantly effects on nicotine, chlorine and potassium contents in leaves.7. Pot experiment was conducted to study the effects of Mo and N applications on macro-and micro-elements of mature tobacco. The results showed that N and Mo had varying degrees of effects on concentrations and accumulations of P, Ca, Mg, Fe, Mn, Cu and Zn in flue-cured tobacco of different leaf positions at maturity. |
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