不同耕作深度对土壤物理性状及烤烟根系 空间分布特征的影响

为探讨不同耕作深度对烤烟产量产值的影响,揭示烟田深耕增产增效机理,以烤烟‘K326’品种为材料,基于田间定位试验,设置对照翻耕20 cm(GS20)、翻耕30 cm(GS30)和翻耕40 cm(GS40)3个处理,研究不同耕作深度对烟叶产量产值、烟田土壤物理性状和烤烟根系空间分布特征的影响。结果表明:深耕措施对改良土体结构、促进土壤蓄水、优化烤烟根系构型和增加烟叶产量产值有较好效果。深耕处理显著降低亚表层20~40 cm土壤容重,同时显著增加该土层土壤总孔隙度和土壤毛管孔隙度。其中,与GS20处理相比,GS30和GS40处理土壤容重分别降低8.4%和9.4%,总孔隙度分别提高15.6%和13.1%,毛管孔隙度分别提高25.8%和24.8%。与对照GS20相比,GS30和GS40处理显著增加团棵期表层0~20 cm土壤含水量,显著增加旺长期、成熟期亚表层20~40 cm土壤含水量。深耕处理不仅显著增加烤烟根系绝对量,还促进根系向深层土壤生长,提高烤烟根系根深指数。其中,GS30和GS40处理根系生物量鲜重分别比GS20高31.2%和89.2%,根深指数分别提高7.6%和4.5%。与对照GS20相比,GS30和GS40处理烟叶产量分别提高7.0%和27.3%,均价分别提高1.8%和6.2%,上等烟比例分别提高10.4%和24.4%,产值分别提高9.0%和35.1%,其中GS40与GS20存在显著性差异。研究发现,深耕措施首先作用于土壤容重、空隙等物理结构,然后影响烟田土壤蓄水储熵,促进烤烟早生快发,优化烤烟根系空间分布构型,进而作用于地上部形态建成,最终影响烟叶产量产值。

Effect of plowing depth on soil physical characteristics and spatial distribution of root system of flue-cured tobacco

AbstractIn order to explore the effects of plowing depth on yield and output of tobacco (Nicotiana tabacum L.) leaf, a field experiment was conducted, and soil physical characteristics and water content, spatial distribution of flue-cured tobacco root system as well as yield of tobacco were investigated. A flue-cured tobacco variety of ‘K326’ was planted with plowing depths of 20 cm (GS20, conventional tillage depth, CK), 30 cm (GS30) and 40 cm (GS40) in 2015 growing season, respectively. Leaf area and soil water content of 0-60 cm were measured after 30 days (rosette stage), 45 days (early vigorous growing stage), 60 days (later vigorous growing stage) and 75 days (early maturing stage) of transplant. Soil bulk density, total porosity, capillary porosity and non-capillary porosity after 54 day of transplant (vigorous growing stage) were investigated. Special distribution of root fresh weight after 65 days of transplant (squaring stage) was investigated too. The results showed that deep plowing had positive effect on soil structure, soil water storage, spatial distribution of flue-cured tobacco root system finally enhanced the yield and output. The deep plowing significantly decreased soil bulk density, increased soil total porosity, and capillary porosity at 20-40 cm subsurface soil layer. Compared to CK (G20), GS30 and GS40 decreased soil bulk density by 8.4% and 9.4%, increased soil total porosity by 15.6% and 13.1%, and increased soil capillary porosity by 25.8% and 24.8%, respectively. The deep plowing with depths of 30 cm and 40 cm significantly increased soil moisture content at 0-20 cm surface soil layer at rosette stage and at 20-40 cm subsurface soil layer at vigorous growing and maturing stages compared to those under GS20. Furthermore, the deep plowing not only significantly increased flue-cured tobacco root weight but also promoted the root content and proportion in deep soil. Root fresh biomass weight under GS30 and GS40 was 31.2% and 89.2% higher than that under GS20, respectively. Root depth index under GS30 and GS40 was 7.6% and 4.5% higher than that under GS20, respectively. In addition, tobacco leaf yield increased by 7.0% and 27.3%, average price increased by 1.8% and 6.2%, the ratio of the first-class tobacco increased by 10.4% and 24.4%, and the output value increased by 9.0% and 35.1% under GS30 and GS40 than those under GS20, respectively. There was significant difference between GS40 and GS20. The results showed that the improved soil physical characteristics, e.g., bulk density, total porosity and capillary porosity under deep plowing could increase soil moisture content at plough layer which benefited tobacco seedling growth, and lead to an optimization of the horizontal and vertical distribution of tobacco root system. A strong root system under deep plowing directly strengthened the growth of over-ground part of tobacco. Finally the yield and output value of tobacco leaf were increased.