| In order to establish standard operation procedure of Radix Hedysari and explore a new way of using less fertilizer to gain high yield in cultivating chinese herbal medicine, the field experiment and laboratory simulation experiment were conducted to determine the effects of palygorskite and fertilizer on the growth and nutrient absorption of Radix Hedysari. The results would be also good for providing theoretical basis of establishing Radix Hedysari GAP base construction. The main results showed that:1. The growth process of plant height and branch height of Radix Hedysari were divided into two stages, the stage from emergence to late July was fast growth phase, and the stage from late July was slow growth stage. The dry matter accumulation center of Radix Hedysari transferred from aerial part to underground part in late July. Single application of palygorskite (1500kg/hm2) and single application of palygorskite (2250kg/hm2) increased plant height, promoted dry matter accumulation in aerial part and root of Radix Hedysari. Combined application of palygorskite (1500kg/hm2) and NPK fertilizer and combined application of palygorskite (2250kg/hm2) and NPK fertilizer improved growth indexes of Radix Hedysari compared with single application of NPK fertilize.2. Single application of palygorskite (2250kg/hm2)and single application of palygorskite (1500kg/hm2) decreased the N content of root per plant by 0.11% and 0.08% at the stage of accumulation of aerial part of Radix Hedysari reached the maxim amount, but improved the whole plant N accumulation amount by 85.82 and 115.73mg/plant at harvest stage. Single application of palygorskite (1500kg/hm2) increased the single plant root N accumulation amount of Radix Hedysari by 78.57 mg/plant at harvest stage. Combined application of palygorskite and NPK fertilizer improved whole plant N content at late growth stage of Radix Hedysari than single application of NPK fertilizer, combined application of palygorskite and NPK fertilizer also improved the N content of corresponding growth center, but decreased the N content of non-corresponding growth center, and combined application of palygorskite and NPK fertilizer improved the whole plant N accumulation amount of Radix Hedysari by 78.80～177.65mg/plant compared with single application of NPK fertilizer at harvest stage. The combined application of palygorskite (2250kg/hm2) and NPK fertilizer prolonged N accumulative time of aerial part of Radix Hedysari and increased N accumulation amount of aerial part and root of single plant at late growth stage. Combined application of palygorskite (1500kg/hm2) and NPK fertilizer increased the amount of root N accumulation of per plant at late Radix Hedysari growth stage.Combined application of palygorskite (2250kg/hm2) and NPK fertilizer increased P accumulation amount of whole plant by 19.32mg/plant compared with single application of NPK, and single application of palygorskite (2250kg/hm2) improved P accumulation in aerial part at late growth stage.Single application of palygorskite (2250kg/hm2)and single application of palygorskite (1500kg/hm2)all increased K accumulation amount of whole plant and root at late growth stage. Combined application of palygorskite (2250kg/hm2) and NPK fertilizer increased K content of root, K accumulation amount of whole plant, aerial part, and root of Radix Hedysari than single application of NPK. Single application of palygorskite (1500kg/hm2) improved K accumulation amount of whole plant and root of Radix Hedysari than single application of NPK during late growth stage.Radix Hedysari showed similar trend in absorption rate of N, P and K at every growth stage. The biggest absorption rate by Radix Hedysari was N, followed by K, and P.3. Single application of palygorskite (2250kg/hm2)and single application of palygorskite (1500kg/hm2) improved soil NO3--N content by 2.64 and 2.53 mg/kg, respectively, compared to the control at late July. Combined application of palygorskite (1500kg/hm2) and NPK fertilizer and combined application of palygorskite (2250kg/hm2) and NPK fertilizer all increased NH4+-N content of 0～20cm soil layer by 2.08 and 1.38 mg/kg, respectively, compared to single application of NPK in late September. Combined application of palygorskite (2250kg/hm2) and NPK fertilizer and combined application of palygorskite (750kg/hm2) and NPK fertilizer all increased available P content in 0～20cm soil layer in Radix Hedysari middle growth stage compared with single application of NPK.4. Compared to treatment applicated urea, treatment applicated palygorskite and urea decreased the amount of ammonia volatilization by 13.55～15.00%, and at the 0.3 and 0.6 g/kg application rate of palygorskite, combined application of palygorskite and urea decreased leaching capacity of NH4+-N and NO3--N, and the leaching amount of N were decreased by 13.71 and 13.56%, respectively, compared to single application of urea, but the leaching amount of N was improved by 6.14% at the 0.9 g/kg application rate of palygorskite compared with single application of urea. Compared to single application of urea, combined application of palygorskite (0.3g/kg)and urea improved NH4+-N content by 0.20mg/kg, but combined application of palygorskite (0.9g/kg)and urea decreased NH4+-N content by 0.42mg/kg. Combined application of palygorskite and urea improved NO3--N content by 1.24～2.52mg/kg compared with single application of urea. Therefore, palygorskite can decrease the amount of ammonia volatilization, the leaching amount of NH4+-N and NO3--N, and ultimately increased NH4+-N and NO3--N content.5. Compared to general urea, urea coated with palygorskite decreased the amount of ammonia volatilization by 10.38%～26.24%, and also decreased the leaching amount of N (NO3--N+NH4+-N) by 5.88%～27.74%. In colume soil, urea coated with palygorskite significantly increased NH4+-N content at the application rate of 20%, and the results also showed that three different amount of urea coated palygorskite significantly increased NO3--N content, decrease the ammonia volatilization, leaching amount of N (NO3--N+NH4+-N), and increase NH4+-N and NO3--N content. In a word, urea coated with palygorskite of 20% could show best and comprehensive ecological effect. |
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