紧实胁迫对不同类型土壤玉米根系时空分布及活力的影响

摘要

[目的]明确不同土壤类型玉米根系时空分布、根系活力,玉米产量及其对土壤紧实胁迫的响应.[方法]采用微区桶栽,设计土壤类型和紧实度两因素试验,研究紧实胁迫下玉米根分布、活力及产量变化特征.[结果]紧实胁迫下玉米根形态指标(根干重,根长度,根体积和根条数)及产量均呈下降趋势,3类土壤上根形态指标大小和产量高低均表现为:潮土>砂姜黑土>黄褐土;根吸收活力(根总吸收面积、活跃吸收面积和根脱氢酶活性)及根系还原强度与根形态指标变化趋势一致,但比吸收表面、比活跃吸收表面随紧实度增加而增大.降低紧实度促进了单株根系干重、长度、吸收活力和产量的增加,尤其促进了20-40 cm土层根长密度和根干重密度的增加,但单根的吸收能力呈下降趋势;3类土壤上玉米根系生长、根活力和产量对紧实胁迫的响应以砂姜黑土和黄褐土较为敏感.[结论]紧实胁迫严重限制了根系生长、分布和吸收功能以及产量形成,但根系并不是被动地忍受逆境的胁迫,而是积极主动地调节其生理代谢过程,以减缓紧实胁迫伤害,但缓解能力有限,且不同类型土壤上根系的响应程度与土壤本身理化性质密切相关.%[Objective]The objective of this study was to identify the spatial and temporal responses of root distribution, root activities and yield in maize to soil compaction in different soils.[Method]A two-year, 2007-2008, barrel-culture experiment was conducted with three soil types and two levels of soil compaction on the Experimental Farm of Henan Agricultural University.The characteristics of spatial and temporal distribution of roots, root activities and yield in maize were studied.[Result]The results showed that root morphological indexes and yield were restricted in the three selected soils under soil compaction stress.The maximum length, dry weight, volume, and activities of roots and yield were found in the fluvo-aquic soil while the minmum were observed in the yellow cinnamon soil.The total and active absorbing areas of root per plant and dehydroganase activity of root were significantly different among the three selected soils with highest in the fluvo-aquic soil, followed by the lime concretion black soil and yellow cinnamon soil.Ratio of absorbing area and ratio of active absorbing area to dry root weight were increased under soil compaction stress.With the relief of soil compaction, root morphological and physiological parameters increased significantly in all selected soils, resulting in the increase of yield.The density of root length and dry root weight were increased significantly in the 20-40 cm soil layers compared with that in 0-20 cm soil layer in the three selected soils, but the ratio of absorbing area and the ratio of active absorbing area to dry root weight were decreased with decreases of soil compaction in three soils.The changes of root parameters and yield in lime concretion black soil and yellow cinnamon soil were more sensitive than in the fluvo-aquic soil.[Conclusion]Root growth and distribution were restricted under high soil compaction.This clearly showed that plants were not passively tolerant to soil compaction stress, but actively regulated their physiological metabolic processes to reduce injury by the environment.Response of maize root soil to soil compaction stress in the three selectedl soils was closely related to soil physical properties.