耕作方式对山地烟田土壤物理性状及烤烟根系空间分布的影响

Effects of tillage methods on soil physical properties and spatial distribution of flue-cured tobacco (Nicotiana tabacum) roots in mountainous tobacco fields

为探讨不同耕作方式对山地烟田烤烟产量产值的影响,揭示山地烟田深耕深松增产增效机理,以烤烟‘K326’为研究材料,采用大田试验,设置旋耕20 cm(RT20,对照)、深耕30 cm(DT30)、深松30 cm(ST30)和深松40 cm(ST40)4个处理,研究不同耕作方式对烤烟生长发育、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:与对照RT20相比,深耕、深松措施显著提高烤烟产量、产值,其中DT30、ST30、ST40产量分别提高12.2%、12.3%和16.0%,产值分别提高10.5%、13.8%和21.8%。深耕、深松措施明显改善土壤亚表层(20~40 cm)物理结构,其中DT30、ST30、ST40土壤容重分别比对照低6.1%、5.3%和8.0%,毛管孔隙度分别比对照高11.3%、13.1%和21.6%;团棵期DT30、ST30和ST40土壤含水量分别比对照高4.9%、2.3%和5.7%,现蕾期分别比对照高4.5%、3.8%和5.6%。深耕、深松措施增加烤烟根系鲜重绝对量,促进烤烟根系纵向下扎生长,缓解上层根系的拥挤度。DT30、ST30和ST40处理根深指数分别比对照高5.32%、8.26%和16.20%。土壤亚表层(20~40cm)不同处理间烤烟根系鲜重差异最显著,其中深耕、深松措施20~30cm烤烟根系鲜重比对照高162.2%~469.0%, 30~40 cm比对照高56.5%~292.9%。研究发现:深耕、深松措施改善山地烟田土壤容重、孔隙度、土壤水分等土壤物理性状,优化植烟土壤环境,促进烤烟根系生长发育,优化根系空间分布构型,对增加烤烟干物质、提高烟叶产量产值有较好的现实生产意义。

To explore the effects of different tillage methods on the yield and output value of flue-cured tobacco(Nicotiana tabacum) in mountainous tobacco fields and to reveal how deep tillage and subsoiling in mountainous tobacco fields increases yield and efficiency, a field experiment was conducted, and soil physical characteristics, soil water content, spatial distribution of the tobacco root system, and the growth of tobacco plants were investigated. A flue-cured tobacco variety,‘K326’, was planted and subjected to tillage methods of 20 cm of rotary tillage(control, RT20), 30 cm of deep tillage(DT30), and 30 cm(ST30) and 40 cm(ST40) of subsoiling tillage. The results showed that DT30, ST30, and ST40 significantly increased the yield and output of the flue-cured tobacco when compared with RT20. The yield was increased by 12.2%, 12.3% and 16.0%, meanwhile the output was increased by 10.5%, 13.8%, and 21.8% under DT30, ST30, and ST40 treatments, respectively. Moreover, deep tillage and subsoiling tillage significantly improved the physical structure of soil subsurface layer in the range of 20–40 cm. The soil bulk density was decreased by DT30, ST30, and ST40 treatments;the soil bulk density values under DT30, ST30, and ST40 treatments were 6.1%, 5.3%, and 8.0% lower than that of RT20 treatment, respectively. However, the treatments increased the capillary porosity of the soil;capillary porosity values under those three treatments were 11.3%, 13.1%, and 21.6% higher than that under RT20 treatment, respectively. Additionally, the soil water content of the 20?40-cm soil layer was also increased by 4.9%, 2.3%, and 5.7% under DT30, ST30, and ST40 treatments compared with RT20 treatment, respectively, when measured at the rosette stage. At the budding stage, it was still increased by 4.5%, 3.8%, and 5.6% under DT30, ST30, and ST40 treatments over RT20 treatment, respectively. Deep tillage and subsoiling tillage treatments increased the absolute fresh weight and promoted vertical growth of tobacco roots as well as alleviated the crowding of the upper roots. The DT30, ST30, and ST40 treatments increased the root depth index by 5.32%, 8.26%, and 16.20% compared with RT20 treatment, respectively. The difference in the fresh weight of the tobacco roots was the most significant among different treatments of soil subsurface(depth of 20–40 cm). Among them, the fresh weight of tobacco roots in the 20–30-cm soil layer with deep ploughing and deep loosening measures was 162.2%–469.0% higher than that with the control, and in the 30–40-cm soil layer it was 56.5%–292.9% higher. It also turned out that subsoiling and deep tillage improved soil physical properties such as soil bulk density, porosity, and moisture in mountainous tobacco fields, which enhanced the soil environment for tobacco planting and benefited tobacco root growth. These treatments also allowed for optimization of the horizontal and vertical distribution of the tobacco root system. Furthermore, these tillage treatments significantly increased the dry matter of flue-cured tobacco, which resulted in increased yield and output value of tobacco.