水肥耦合对土壤碳氮储量、理化性质及三七产量和皂苷含量的影响

Effects of water-fertilizer coupling on carbon and nitrogen stocks,physicochemical properties in soil and yield and saponin content of Panax notoginseng(Burkill)F.H.Chen ex C.H.Chow

【目的】探究不同水肥耦合条件对土壤碳氮储量、理化性质及三七产量和皂苷含量的影响,为三七水肥调控及土壤碳氮固定潜力研究提供理论依据。【方法】2019—2021年在云南省泸西县三七种植基地进行试验,选取3年生三七为研究对象,设3个灌水水平[W1(5 mm)、W2(10 mm)和W3(15 mm)]和4个按生育期(根增期—苗期—花期—果期)配比的施肥水平[F1(360-360-360-360 kg/ha)、F2(288-360-432-360 kg/ha)、F3(216-432-432-360 kg/ha)和F4(144-576-288-432 kg/ha)],以不进行灌溉施肥为对照(CK)。测定各生育期不同处理的土壤碳氮储量及理化性质,并于2021年11月采集新鲜三七植株测定其产量和皂苷含量,采用主成分降维分析方法探讨土壤碳氮储量与各因子的关系。【结果】相同水肥耦合条件下土壤碳氮储量随土层深度增加而减少,随生育期推进基本呈先增后减的变化规律,其中以花期最高,最大值分别为82.07 t/ha(W1F4处理)和4.41 t/ha(W2F3处理),土壤有机碳储量积累关键期在苗期—花期,全氮储量积累关键期在根增期—苗期。各土壤养分含量以W2F3和W3F4处理较高,降低根增期施肥比例并增加苗期施肥比例能提高土壤养分含量。土壤碳氮储量变化主要依赖于全磷、全钾、速效钾、速效磷、硝态氮及铵态氮含量,碳氮储量增加能提高三七产量及三七皂苷R1含量。主成分降维分析结果表明,全磷、全钾、铵态氮及硝态氮含量对碳氮储量具有显著正向影响(P<0.05)。【结论】土壤碳氮储量与养分含量变化具有趋同性,其中以W2F3和W3F4处理有利于土壤碳氮累积与养分增加,适当增加苗期施肥比例有助于增加土壤碳氮储量并提高三七产量。

【Objective】To investigate the effects of different water-fertilizer coupling conditions on the carbon and ni-trogen stocks,physicochemical properties,and yield and saponin content of Panax notoginseng(Burkill)F.H.Chen ex C.H.Chow in P.notoginseng soil,and to provide theoretical basis for the study of P.notoginseng water-fertilizer regula-tion and soil carbon and nitrogen fixation potential.【Method】The experiment was conducted at the P.notoginseng planting base in Luxi County,Yunnan Province,from 2019 to 2021.Three-year-old P.notoginseng was selected as the re-search object,and three irrigation levels[W1(5 mm),W2(10 mm)and W3(15 mm)]and four fertilizer application rates at different growth periods(rooting period,seedling period,flowering period and fruiting period)were set up[F1(360-360-360-360 kg/ha),F2(288-360-432-360 kg/ha),F3(216-432-432-360 kg/ha)and F4(144-576-288-432 kg/ha)],with no irrigated fertilizer as control(CK).The carbon and nitrogen stocks and physicochemical properties of P.notogin-seng soils from different treatments at each growth period were determined,and fresh P.notoginseng plants were col-lected in November 2021 to determine their yields and saponin contents,and the relationships between soil carbon and ni-trogen stocks and factors were explored using principal component dimensionality reduction analysis.【Result】Soil carbon and nitrogen stocks under the same water-fertilizer coupling conditions decreased with the increase of soil depth,and basi-cally showed the change rule of increasing and then decreasing with the advancement of growth period.Soil carbon and ni-trogen stocks were the highest in the flowering period,with the maximum values of 82.07 t/ha(W1F4 treatment)and 4.41 t/ha(W2F3 treatment),respectively,and the key period for soil organic carbon stocks accumulation was in seedlingflowering period,and the key period for all-nitrogen storage accumulation was in the rooting-seedling periods.The nutrient content of each soil was higher in the W2F3 and W3F4 treatments,and decreasing the proportion of fertiliser applied at the rooting period and increasing the proportion of fertiliser applied at the seedling period improved the soil nutrient content.Soil carbon and nitrogen stocks were mainly dependent on the contents of total phosphorus,total potassium,available potassium,available phosphorus,nitrate nitrogen and ammonium nitrogen,and the increase of carbon and ni-trogen reserves could improve the yield of P.notoginseng and the content of saponin R1.The results of principal compo-nent dimensionality reduction analysis showed that the contents of total phosphorus,total potassium,ammonium nitrogen and nitrate nitrogen had a significant positive effect on carbon and nitrogen stocks(P<0.05).【Conclusion】The changes of soil carbon and nitrogen stocks and nutrient content are convergent,in which W2F3 and W3F4 treatments are more fa-vourable to soil carbon and nitrogen accumulation and nutrient increase,and the proportion of seedling fertilization should be increased appropriately to help increase soil carbon and nitrogen stocks and improve the yield of P.notoginseng.