Double-Regulation Mechanism Of Bio-organic Fertilizer On The Growth Of Flue-cured Tobacco In Loess Plateau Of East Gansu

Continuous mono-cropping and irrational fertilization have been the big problems that restrict the growth, yield and quality of flue-cured tobacco in Loess Plateau of East Gansu Province. With an adjoint nursery trial-pot trial-field trial operated in 2010 based on the results obtained in 2008 and 2009, we systematically studied the double regulation mechanism through rhizosphere and root of bio-organic fertilizer on the growth of flue-cured tobacco.Aiming at revealing mechanism of bio-organic fertilizer on the yield and quality of local flue-cured tobacco. The main results are as follows :Effects of bio-organic fertilizer on nursery growth and metabolism of flue-cured tobacco In order to understand the effects of bio-organic fertilizer on nursery growth and metabolism of flue-cured tobacco, we had measured seedlings biological characteristics, leaf enzyme activity related to carbon/nitrogen metabolism, root activity and microorganism numbers in nursery soil respectively in seedling period and transplanting time.Results showed that:Compared with the control (CK), in seedling period the max leaf area,leaves dry weight and aboveground dry weight of BIO treatment were increased by 28.9%,68.0% and 191.9% respectively; The total root length, root tips, specific root length and root dry weight were increased by 161.5%,290.2%,30.84% and 100%; Invertase of BIO treatment was 65.6% higher than CK; The root total absorbing area,root active absorbing area and dehydrogenase were increased by 69.1%,70.2% and 70.0%; The number of bacteria, fungi and actinomyces in nursery soil were increased by 36.3%,14.3% and 45.8% ; Furthermore the ratio of bacteria/fungi was also increased. All the above illustrated that bio-organic fertilizer had improved soil microbiota, promoted root activity as well as seedlings growth.In transplanting period the dry weight of max leaf and aboveground of BIO treatment were increased by 41.9% and 90.1% compared to CK; The total root length, root tips, specific root length and root dry weight were increased by 151.5%,286.0%,25.8% and 100% respectively; Leaf Invertase,NRase as well as chlorophyll content were increased by 25.0%,14.3% and 34.8%, thereinto SPAD was 46.8% more than seedling period; RAAA and Rdeh were increased by 47.6% and 80.2%; The number of bacteria, fungi and actinomyces were increased by 16.7%,6.5% and 194.7%, and the ratio of bacteria/fungi was also increased. In conclusion, application of bio-organic fertilizer in nursery not only increased soil culturable microorganisms but also improved microbial community structure.Healthy soil microbiota was the reason for developed root, which was helpful for enhance plant resistance and made"Root raised for seedlings"as true.Effects of bio-organic fertilizer on field growth of flue-cured tobaccoThe second application of bio-organic fertilizer in transplanted soil regulated doubly to tobacco growth. In order to understand the mechanism of BIO on field growth and metabolism of flue-cured tobacco, we had measured plant biological characteristics, leaf enzyme activity related to carbon/nitrogen metabolism and to disease resistance, as well as root activity in every period. Results showed that:In root elongation period, the max leaf area of T2(CK+BIO),T3(BIO+CK)and T4(BIO+BIO) were increased by 35.1%,39.7% and 78.0% compared with T1; The root volume of T2,T3 and T4 were increased by 100.6%,111.4% and100.0%, the root tips were increased by117.5%,204.7% and 219.2%; NR,Inv,Dia activity and Rdeh activity of BIO treatments were much higher than T1. Nitrogen metabolism was major in this period.In squaring period, the max leaf area of T2,T3 and T4 were increased by 22.7%,23.7% and 24.8%, the specific leaf weight of T3 and T4 were respectively increased by 104.2% and 92.0%.The total root length of T2,T3 and T4 were increased by 52.0%,14.5% and 72.8%; root volume were increased by 41.8%,43.2% and 80.3%; root dry weight were increased by 101.1%,137.7% and 178.5% respectively;The root structure presented as typical"T"shape, of which more than 80% were distributed in the 0-20cm soil layer, where the ratio of different treatments distribution arrayed as T4>T3>T2>T1. Carbon metabolism was major in this period, leaf Dia activity of BIO treatments were higher than T1, NR activity declined sharply.Besides, bio-organic fertilizer enhanced enzyme activity related to disease resistance. PPO of T2,T3 and T4 in squaring period were increased by 10.6%,49.4% and 54.1% compared to T1, MDA content were increased by 12.3%,51.4% and 68.1% respectively. Catalase activity of T2,T3 and T4 were increased by 73.6%,41.4% and114.6% in mature period, when MDA content of T4 was increased by 40.6% compared to T1. All the above stated that BIO strengthened plant resistant ability, which was the double-regulation result of BIO. It was the signal for"Strong seedlings for disease prevention"and contributed to increase yield and quality of flue-cured tobacco.Meanwhile,application of BIO significantly affectd the microbial diversity in soil planted flue-cured tobacco and reduced the ratio between fungi and bacteria,those could bring about soil being in the state of more health. Namely,enhancement of soil fertility and biological features was the foundation that BIO could prove chemical qualitiy of Flue-cured Tobacco.In conclusion, bio-organic fertilizer regulated doubly in nursery and field period of flue-cured tobacco.On the one hand, it coordinated the correct balance of tobacco nutrition;On the other hand, the functional microbes reproducted and gathered around the new roots and formed microbio wall in the rhizosphere.Soil microflora was rebuilt and regulated that would create good soil environment for plant growth and development, promote plant growth and disease resistance.Finally increased the yield and improved the quality.