水保所知识产出(1956---)知识库

研究种植行距对植物根系分布及形态特征的影响，对田间水肥管理具有重要意义。
柳枝稷(Panicum virgatum L.)为禾本科多年生丛生草本，适应性强，产量高，即可作为能
源植物和优质牧草，又可用于水土保持。本文以在黄土丘陵区梯田栽培的第 6-7 年柳枝
稷草地为研究对象，采用根钻法，分别于 2016 年 4 和 10 月份对柳枝稷种植行上与行间
0-150 cm 深度的根系进行取样，比较研究了三种种植行距下（20 cm，40 cm 和 60 cm）
柳枝稷根系生物量与形态特征分布规律，主要结果如下：
1. 柳枝稷根系主要由细根(d≤1 mm)组成，其所占总根量的比例平均以 40 cm 行距下
最高：在 4 月份，20 cm、40 cm 和 60 cm 行距下细根生物量分别占总根量的 90%、88%
和 83%，10 月份分别为 77%、83%和 79%。
2. 柳枝稷根系集中分布于 0-40 cm 土层，平均占总根量的 70%以上，其中在 40 cm
行距下根系生物量在不同土层的分布均较高：表现为在较窄行距 20 cm 和 40 cm 栽培下
浅层 0-20 cm 土层中细根生物量均显著高于 60 cm 行距(p<0.05)，在 20-150 cm 土层中，
40 cm 和 60 cm 行距下细根生物量均高于窄行距 20 cm，这说明在垂直方向上，20 cm 行
距有利于根系生物量向浅层分配，限制了细根向下延伸；水平方向上，行上与行间细根
生物量均随种植行距增大而增加，表明宽行距有利于单株植物根系生长。种植行距影响
粗根分布深度，随行距增加粗根分布越深，只有 60 cm 行距下粗根分布至 150 cm 深度。
3. 柳枝稷 70%以上的根长是由 d≤0.5 mm 的根系组成，其中在 40 cm 行距下，d≤0.5
mm 的根系平均根长密度最高，根系平均直径较小，根长密度、根表面积、比根长以及
比根面积均较高：在 0-20 cm 土层中，40 cm 行距下平均根长密度和根表面积最高，而
比根长和比根面积随种植行距增大而增大；20 cm 以下土层中，平均根长密度，根表面
积，比根长和比根面积在 20 cm 行距下较低，且细根平均直径在显著高于 40 cm 和 60 cm
行距(p<0.05)。
4. 生育期影响根系形态特征，10 月份平均根长密度，比根长和比根面积均高于 4
月份，而根系总生物量在 20 cm 行距下稳定，40 cm 和 60 cm 行距下均显著低于 4 月份，
具体变化表现为：不同种植行距下直径 0.1~0.3 mm 根长密度显著升高，0.8-1.0 mm 的显
著降低(p<0.05)，而粗根在 20 cm 和 40 cm 行距下增加。
5. 20cm 行距下有利于提高地上生物量累积和土壤水分利用效率。综上所述，在黄土丘陵区梯田条件下，宽行距有利于单株根系生长与根系的向下延
伸，行距过大不利于表层地下根系生物量累积以及对土壤资源的充分利用。本试验结果
表明，40cm 行距下在不同土层中根系生物量分布均较高，细根根长密度和根表面积最
大，平均直径小，平均比根长和比根面积较高，更有利于柳枝稷地下根系生物量累积、
根系生长发育和形态建成，而 20cm 行距下显著提高了地上生物量累积与水分利用效率。
关键词:柳枝稷；种植行距；根系分布；根系形态特征；水分利用效率

Better knowledge of root distribution and characteristics of plants would be important in
field water and nutrient management. Switchgrass (Panicum virgatum L.) is a perennial
tussock grass with high production and great ecological adaptation, often used as biofule crop,
high-quality forage as well as for water and soil conservation. Root biomass and
characteristics above and between rows were investigated for switchgrass after 6-7 years
plantation, which was grown on a terrace under three different row spacings of 20 cm, 40 cm
and 60 cm in loess hilly-gully region of China. Results showed that:
1. Fine roots (d≤1 mm) were the dominant component in the root system of switchgrass
and the fraction of fine root biomass in row spacing of 40 cm exhibited the highest value
among these three row spacings: in April, the proportion of fine root biomass in 20 cm, 40cm
and 60cm was 90%,88% and 83%, respectively; while in October there were 77%，83% and
79%, respectively.
2. More than 70% of root biomass distributed in the upper 0-40 cm soil layer in all three
row spacings, of which row spacing of 40 cm exhibited higher root biomass in the upper as
well as deeper soil depth: Fine root biomass in 0-40 cm soil layer in narrower row spacing of
20 cm and 40 cm were significantly higher than that in 60 cm, but it was lower in spacing of
20 cm than that in 40 cm and 60 cm in the deeper soil profile, which suggested that spacing of
20 cm limited the root growth in the deeper soil; horizontally, fine root biomass at and
between rows increased with increasing row spacing, suggesting that wider row spacing was
of benefit to root extension. The thick root depth increased with the increasing row spacing,
which provided fine roots in wider row spacing with easy access to soil resources in deeper
soil.
3. More than 70% of the fine root length was attributed to roots ≤0.5mm in diameter and
this fraction was the highest in row spacing of 40 cm which produced roots with smaller root
average diameter, higher fine root biomass, root length density, root surface area, specific root
length and specific root area in both shallower and deeper soil depths: In 0-20 cm soil layer,
averaged root length density and surface area were the highest in row spacing of 40 cm, and
specific root length as well as specific surface area increased with increasing row spacing. In  the soil depth down below 20 cm, mean root length density, root surface area, specific root
length and specific root area were lower in spacing of 20 cm. The root average root diameter
throughout the whole soil profile was significantly the highest in spacing of 20 cm.
4. In October, average root length density, specific root length and specific surface area
were higher in all row spacings than April, while root biomass was lower in spacing of 40 cm
and 60 cm: Root length density of 0.1-0.3 mm in diameter increased and 0.8-1.0 mm
decreased significantly in October (p<0.05), resulting in the reduction in the FRB. And thick
root biomass increased in row spacing of 20 cm and 40 cm.
5. Row spacing of 20 cm improved above-ground biomass accumulation and soil water
use efficiency significantly.
In summary, wider row spacing were beneficial for root growth of individual and
downward extension, but root biomass accumulation and utilization of soil resource in the
upper soil would decline if row spacing was too large. We concluded that row spacing of 40
cm produced higher fine root biomass, root length density, surface area, specific root length,
specific root area and more roots with smaller root diameters, which is more beneficial for the
water and nutrient acquisition, but spacing of 20 cm improved above-ground biomass
accumulation and water use efficiency significantly.
Keywords: Switchgrass, Row spacing, Root distribution, Root characteristics, Water use
efficiency