Responses of root morphology of peanut varieties differing in drought tolerance to water-deficient stress

Peanut(Arachis hypogaea L.) is an important economic oil crop in China,which is characteristic of drought-and infertile-tolerance.Long-term rainless or seasonal drought is an important environmental factor limiting peanut productivity main factors affecting aflatoxin infection before peanut harvest.As the major interface between the plant various biotic abiotic factors in the soil environment,root tissues could produce root-to-shoot chemical signals to regulate stomatal closure thus reduce transpiration.Root could change morphological,physiological biochemical characteristics to adapt to different soil water environments.The plant root configuration may show significant differences under different soil moisture conditions,and thus affect the ability of plant roots to absorb nutrients water.Researches on the relationship between root morphological development drought tolerance under different soil moisture conditions had a very important role for better understanding peanut water absorption,transporting,utilization,loss mechanisms for cultivating different drought tolerance peanut varieties.To clarify root morphology of peanut varieties differing in drought tolerance its function for drought resistance in peanut,the drought-resistant varieties Huayu 22,Tangke 8,and drought-sensitive variety Huayu 23 planted in the anti-canopy tanks using the soil column under two soil water conditions: well-watered conditions medium drought(corresponding soil water contents are respectively: 80% —85% 45% —50% of field moisture capacity) with three replications.Roots were sampled at 68,99 132 days after sowing(DAS).Root length,root surface area volume were determined by a scanner analyze by WinRhizo Pro Vision 5.0a software.Pod yield was recorded at harvest.The drought coefficient(DC) was calculated as the ratio of the yield under water stress treatment to that under well-watered conditions.The result showed that drought treatment improved the root to shoot ratio of drought-resistant varieties,while the effect on drought-sensitive variety was not obvious.Drought coefficient indicated that the drought resistance ability of the three peanuts in turn was Tangke 8,Huayu 22 and Huayu 23.The root biomass,total root length,total root surface area volume of drought-resistant varieties were significant higher than those of drought-sensitive variety.Correspondingly,the root system of drought-resistant varieties developed much stronger compared to drought-sensitive variety.The total root surface area volume of drought-resistant varieties were enhanced by drought stress,while decreased in drought-sensitive variety.Drought treatment significantly improved the distribution percentage of root length density,root surface area volume of Huayu 22in the soil layer below 20 cm,while these morphological characteristics inTangke 8only increased in the 20—40 cm soil layer.Though not significant in statistics similar phenomenons were also observed in another drought-resistant variety,Huayu 22.The root total length,total surface area root traits in the 0—20 cm soil layer of peanut showed significant or very significant positive correlation with grain yield.In summary,under water-deficient condition,peanut could efficiently utilize water through increased the root length,root surface area,root volume other morphological characteristics in the deeper soil.