Objectives In the quest for an antidote for the problems of drought and growth retardation during the root extension period of flue-cured tobacco in Panzhihua area, the effects of mycelium-straw bowl on the micro-ecological environment and growth of flue-cured tobacco root were studied.
Methods Corn stover were shredded, sterilized and shaped into a centrum first, then inoculated with Fomes lignosus, when the hyphaet wined throughout the centrum, sterilized again and ready as mycelium-straw bowl. The mycelium-straw bowls were placed in nylon bags and buried in soil in situ, the decomposition rate of mycelium-straw bowl was calculated by weight loss method, and the first-order kinetic model was used to fit its decay characteristic parameters. In the field experiment, there was two transplanting methods, namely, 1) mycelium-straw bowl transplanting method (MF), 6-true-leaves tobacco seedlings with substrate were transplanted into mycelium-straw bowl as experimental treatment (MF), and 2) conventional transplanting method, 6-true-leaves tobacco seedlings was transplanted in soil (CF). Soil temperature and humidity, electrical conductivity (EC), root morphology and root biomass were measured during the whole growth period of flue-cured tobacco.
Results Compared with CF, MF reduced soil moisture by 6.2% and 5.7% on the day and 10 days after transplanting, and raised soil moisture by 2.0% and 3.5% on the 20 days and 30 days after transplanting. At the first rainfall, 20 days after transplanting MF decreased soil EC by 251.3 μS/cm compared with 10 days after transplanting. At the second rainfall, 50 days after transplanting MF decreased soil EC by 487.2 μS/cm compared with 40 days after transplanting; at the third rainfall (120 days after transplanting), MF increased EC by 35.0 μS/cm compared with 60 days after planting. The root surface area, volume and root tip number of MF were significantly higher than those of CF, which were increased by 27.5%, 55.7% and 36.4%, respectively. The length of root (diameter >2.0 mm) and the tip number of root (diameter <1.0 mm) in MF treatment were significantly higher than those under CF. The initial and the end day for the rapid accumulation and the initial day for the maximum accumulation rate of root biomass in MF treatment were 3.9 days, 9.9 days and 6.9 days earlier than in CF. The accumulation duration of root biomass in MF was 6 days shorter than CF, and the maximum accumulation rate in MF was 33.3% higher than that of the CF. At the 60, 75, and 90 days of transplanting, root biomass in MF treatment was 6.3 g/plant, 19.3 g/plant and 10.8 g/plant higher than those in CF.
Conclusions The mycelium-straw bowl could improve the rhizospheric physical and chemical environment, thus stimulating an optimum root development by increasing the fine roots and the surface area, and promoting the accumulation of dry matter and absorption of nutrients in tobacco roots.
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