Effect of soil mechanical impedance on root growth of two rice varieties under field drought stress
Effect of soil mechanical impedance on root growth of two rice varieties under field drought stress
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DOI：
10.1007/s11104-005-0134-1
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发表时间：
2004-12-01
期刊：
影响因子：
4.9
通讯作者：
Mullins, CE
中科院分区：
文献类型：
--
作者：
Cairns, JE;Audebert, A;Mullins, CE
两个旱稻品种。在西非水稻发展协会（WARDA）试验农场的两个大田对Azucena和Bala进行了干旱和灌溉处理下的根系生长筛选。科特迪瓦，1999/2000年旱季。选择这些样地是为了代表高地样地土壤剖面渗透阻力（PR）特征的对比，尽管两者都是相对阻碍的。在播种后35、56、77和98 d以10 cm深度间隔计算单位面积通过水平样条的节根轴数（根密度）。Azucena的根密度始终高于Bala，并且Azucena的根生长到30 cm深度的比例更高（22.7%比8.4%）。水分状况对根系分布的影响很小，但有证据表明，在高PR位点，深度低于20 cm的根数较低。土壤深度和品种的相互作用表明，杜鹃花根系受非常高的PR的影响比巴拉更强烈。随着土壤的干燥，0 ~ 30 cm深度的PR随土壤含水量的减少而显著增加。这种增加很可能阻止或极大地损害了这一层内结根的进一步生长。在40 cm深度，PR较高（3 ~ 4 MPa），但干旱期间PR没有增加。在这个深度，尽管有水分，根系的生长速度可能会大大降低。这些结果表明，在实验室中表征的根系形态的品种差异也可以在阻碍的田间土壤中检测到根系密度的差异。干旱条件下根系生长相对较差，可能是由于植物在干旱季节的高机械阻抗和/或生理应激所致。我们的研究结果表明，在干旱期间，高机械阻抗是比土壤水分有效性更基本的限制足部生长的因素。因此。根系渗透能力的品种差异可能对这类土壤的干旱规避非常重要。
Two upland rice varieties. Azucena and Bala, were screened for root growth under droughted and irrigated treatments in two field sites at the West Africa Rice Development Association (WARDA) experimental farm. Cote d'Ivoire, during the dry season of 1999/2000. The sites were chosen to represent contrasting soil profile penetration resistance (PR) characteristics on upland sites, although both were relatively impeding. The number of nodal root axes per unit area passing through horizontal transects (root density) was counted at 35, 56, 77 and 98 days after sowing (DAS) at 10 cm depth intervals. Azucena consistently maintained a greater root density than Bala and a greater proportion of Azucena roots grew to 30 cm depth (22.7% vs. 8.4% at 77 DAS). There was little, detectable effect of water regime on root distribution but evidence of lower root numbers at depths below 20 cm in the higher PR site was revealed. A site by variety by soil depth interaction suggests that Azucena roots are more strongly affected by very high PR than those of Bala. PR between 0-30 cm depth increased greatly with decreasing soil water content during the drought as the soil dried. This increase is likely to have prevented or greatly impaired further nodal root growth within this layer. At 40 cm depth, PR was high (3-4, MPa) but did not increase during the drought. At this depth root growth rate was likely to be greatly reduced despite the availability of water. These results demonstrate that varietal differences in root morphology characterised in the laboratory can be also detected in impeding field soils as differences in the density of roots at depth. Relatively poor root growth in these fields in the absence of drought was probably due to the high mechanical impedance and/or the physiological stress of the plants in the dry season. Our results indicate that high mechanical impedance was a more fundamental constraint on foot growth than soil water availability during the drought. Thus. varietal differences in root penetration ability might be very important for drought avoidance in soils of this type.