不同抗旱性花生品种的根系形态发育及其对干旱胁迫的响应

为明确不同抗旱性花生品种的根系形态发育特征,探讨其根系形态发育特征对不同土壤水分状况的响应机制,在防雨棚旱池内进行土柱栽培试验,研究抗旱型品种"花育22号"、"唐科8号"和干旱敏感型品种"花育23号"3个不同抗旱性花生品种根系形态发育特征及其对干旱胁迫的响应。结果表明:抗旱型品种根系较发达,具有较大的根系生物量、总根长、总根系表面积。干旱胁迫使抗旱型品种根系总表面积和体积增加,而干旱敏感型品种则相反。干旱胁迫显著增加抗旱型品种"花育22号"20 cm以下土层内根长密度分布比例及根系表面积和体积,但"唐科8号" 相应根系性状仅在20-40 cm土层内增加;干旱胁迫使干旱敏感型品种"花育23号"40 cm以下土层内各根系性状升高,但未达显著水平且其深层土壤内各根系性状增加幅度小于"花育22号"。花生根系总长、总表面积及0-20 cm土层内根系性状与产量间呈显著或极显著正相关。土壤水分亏缺条件下,花生主要通过增加深层土壤内根长、根系表面积和体积等形态特性,优化空间分布构型,以调节植株对水分的利用。

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

Peanut (Arachis hypogaea L.) is an important economic and 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 and main factors affecting aflatoxin infection before peanut harvest. As the major interface between the plant and various biotic and abiotic factors in the soil environment, root tissues could produce root-to-shoot chemical signals to regulate stomatal closure and thus reduce transpiration.Root could change morphological, physiological and 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 and water. Researches on the relationship between root morphological development and drought tolerance under different soil moisture conditions had a very important role for better understanding peanut water absorption, transporting, utilization, loss mechanisms and for cultivating different drought tolerance peanut varieties. To clarify root morphology of peanut varieties differing in drought tolerance and its function for drought resistance in peanut, the drought-resistant varieties "Huayu 22", "Tangke 8", and drought-sensitive variety "Huayu 23" were planted in the anti-canopy tanks using the soil column under two soil water conditions: well-watered conditions and medium drought (corresponding soil water contents are respectively: 80%-85% and 45%-50% of field moisture capacity) with three replications. Roots were sampled at 68, 99 and 132 days after sowing (DAS). Root length, root surface area and volume were determined by a scanner and 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 and 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 and 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 and volume of "Huayu 22" in the soil layer below 20 cm, while these morphological characteristics in "Tangke 8" only 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 and 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 and other morphological characteristics in the deeper soil.