Study On The Growth Promoting Substance Of The Fermentation Liquid Of Trichoderma Harzianum On Black Straw Crop

The soil samples were collected from the rhizosphere of plant speciesin different districts in Hunan. As a result of isolation and purification,228 Trichoderma strains were obtained of which the antagonistic activitywas tested against fungus pathogens in tomato, rice, cucumber, chilliandrape, and T. harzinum strain T_2-16 was found antagonistis is strongest. Thefermented production of T. harzinum strain T_2-16, obtained from certainfermentation medium and fermentation conditions, was used during theprocess of cowpea growth. The result showed that the germination rate andvigor index of cowpea seed pretreated increased notably, and the freshweight and quality of pod raised compared to the control, too. The studypaper about the phenomenon and mechanism of enhanced growth of cowpea ofT. harzianum fermented production on cowpea have no been reported.Firstly, The paper studied on the effect of fermented production ofstrain T_2-16 on cowpea seed vigor, disease resistance of cowpea, yield andquality. The results as the follows.1. The seeds germinating energy of cowpea were significant improved bypresoaking the seeds with T_2-16 fermented production. The results showed thatgermination rate and vigor index of cowpea seed pretreated increased notably,and the conductivity rate decreased compared to the control.2. The seedling growth of cowpea were significant enhanced . Seedsof yeard long cowpea (Vigna sesquipedalis) were soaked in strain T_2-16fermented production for 6 hours before sowing. The treatments increased,to different extents, epicotyl length, hypocotyls length, epicotyl:hypocotyls ratio, seedling height, chlorophyll content and protein contentof the seedlings. On the other hand, strain T_2-16 fermented production increased the taproot length of the seedlings, the fresh and dry weightof the roots, the root: top radio, the root volume and the vitality of theroot system, the number and weight of root nodules. The strain T_2-16 fermentedproduction T_2-16, therefore, may help seedlings to grow and metabolize.3. The fermented production of stain T_2-16 was applied in cowpea by seedsoaking. In field tests, the treated cowpea seedlings at 6-7 leaf stage wasinoculated with Fusarium oxysporum and Rhizoctonia solani. The defensiveenzyme activities of peroxidase (POD), polyphenol oxidase (PPO) andphenylalanine ammonia-lyase (PAL) in cowpoa seedling leaf pretreated withthe T_2-16 strain were increased by various level after inoculation with thepathogen. The activities of PPO in T_2-16 treated cowpea seeds was significantlyhigher than that in untreated one at 7d after inoculation, and the activitiesof POD, PAL in T_2-16 treated cowpea seeds was significantly higher than thatin untreated one at 12d after inoculation with F. oxysporum and R. solani.The results also showed T_2-16 treated cowpea seeds reduced the rates ofdiseased and disease index. The efficiency of resistance to the pathogenwas 72.19ï¼…and 75.66ï¼…. The fermentation production of strain T_2-16 could induceresistance of cowpea seedlings to F. oxysporum and R. solani.4. The effect of application the strain T_2-16 fermented production to theroot surface in transplanting seedling on the root system, photosyntheticproperties of leaf and onpod yield, quality were investigated under fieldcondition. The results indicated that strain T_2-16 fermented production couldimprove the activity of root system obviously, increase the chlorophyllcontent of leaves and keep more photosynthetic rate in the leaves duringlate growth stage when it was used T_2-16 fermented production treatment. Podyield treated by T_2-16 fermented production had significant increased thanother treatments, and pod quality was best among all treatments, too.Then, the paper studies on the isolation ,purification and effectmechanism of growth promoting substance in the fermented production ofTrichoderma harzianum T_2-16.Various multiple column layers were adopted in the isolation and the purification of the growth promoting substance with thin layerchromatography (TLC)and color reaction as chemical examination, and thecowpea germination test. The substance was further purified byhigh-performance liquid chromatography(HLPC). The test result suggested thegrowth promoting substance was a kind of peptide.The Effect mechanism of the growth promoting substance was studied, too.The result as follows.1. The effects of the substance on the seeds vigor were studied. Theseeds vigor of cowpea were significant improved by the substance. Theconductivity rate decreased compared to the control. During germinatingperiod, the specific activities of protective enzymes, superoxidedismutase(SOD) and catalase (CAT) all increaSed, than those of the control.This indicated that increasing of vigor index through pretreatment withT. harzium have interned relations with the increasing of activity oxygenmetabolism The strain T_2-16 the growth promoting substance made the cellmembrane permeability, the contents of protein, dissoluble sugar andproline in cell exudates of cowpea seedlings decrease compared withtreatment by water. The results also shoved that The substance increasedall the number of lateral roots, root primordial, and the length of thesegment where initiated lateral roots and root primordial.2. The effects of the substance on nodule development andnitrogen-fixing functions of cowpea were studied. The major finding weresummarized as follows: The substance had great effects on number of noduleinitials, excisable nodule, nodule dry weight and nitrogenase activity.The results showed that the substance had important effects on noduledevelopment first, and then had great effects on nitrogen-fixation functionsof cowpea nodule.3. The effects of the substance on microstructure and nitrogen-fixingfunction of cowpea nodule were studied in pot experiment. The results shovedthat remarkably increased leghaemoglobin content of cowpea nodule. At thesame time, nodule microstructure and bacterioid ultrastructure were changed, the following results were obtained: (1) Cells in the developing and maturenodules of cowpea treated by the strain T_2-16 fermented production had muchsmaller vacuoles than those in treated by water; (2) The number of bacteroidper cell of cowpea treated by the strain T_2-16 fermented production wasdistinctly increased; they contain a large quantity of mature infected cellswhich possess abundant cytoplasm and many bacteroids, larger vacuoles havedisappeared. The results showed that cowpea treated by the strain T_2-16substance had higher production of leghaemeglobin and differentmicrostructure and bacteroid ultrastructure of cowpea nodule which led toa higher nitrogenase activity of cowpea nodule.4. Rhizobium strains were isolated and purified from the nodules of 2cultivars of cowpea collected from different treatments between the strainT_2-16 fermented production and water. These strains of Rhizobium werecomparatively studied by determining their biological characteristicsincluding growth rate, acid-alkali endurance, salt stress, resistance ofintrinsic antibiotics, utilization of carbon sources. Rhizobium, collectedfrom the nodule treatment with growth promoting substance, growth promotingsubstance was a fast-growing type of Rhizobium It could form colony within48-72h, while Rhizobium collected from the nodule treatment with waterwithin 72-96h. Comparisons of esterase isoenzymes of Rhizobium spp weremade. The result showed that difference among various treatment.