玉米整株根系水导与其表型抗旱性的关系

Relationship between Maize Root Hydraulic Conductivity and Drought Resistance

以一组遗传背景清楚、表型性状已知的玉米遗传材料杂交种户单 4号 (F1 代 )及其双亲 (♂ ,♀ )为供试材料 ,用PEG 6 0 0 0模拟干旱胁迫 (ψs=- 0 2MPa) ,在室内溶液培养条件下研究了玉米整株根系水导 (Lpwr)与其表型抗旱性间的关系。结果表明 ,玉米整株根系水导与其品种抗旱性间具有显著的正相关 (P <0 0 5 )。在干旱胁迫下 ,玉米叶片净光合速率、蒸腾速率、气孔导度、叶水势均随着整株根系水导的增加而直线增加。品种间相比 ,表型抗旱的杂交种户单 4号(F1 代 )整株根系水导最高 ,不抗旱的父本最小 ,同样抗旱的母本介于二者之间。叶片气体交换参数测定表明 ,水分胁迫下母本的气孔导度 (Cs)和蒸腾速率 (Tr)显著高于F1 代和父本。所以尽管母本的渗透势下降最多 ,可以通过维持较高的吸水和较强的渗透调节能力而抵御干旱 ,但由于其高的气孔导度 (即节流能力差 )而使植株水分状况最差 (低的叶水势 ) ,属于耐旱但低产型 (叶片光合速率显著低于其他两个品种 )。相反 ,F1 代由于高的整株根系水导和低的气孔导度 ,属于抗旱丰产型 ,在水分利用上具“开源节流”优势 ,其光合速率 (Pn)和水分利用效率在正常水分和水分胁迫处理下 ,均高于父母本。

Solution culture method was used to study the relationship between maize whole root hydraulic conductivity(Lp wr.) and drought resistance. The results indicated that for all the three maize genotypes, there was a significant positive correlation between Lp wr. and leaf ψ s, P n, T r and C s, which meant with the increase of Lp wr., the leaf parameters also increased, as a result, the plant water status was improved. Under both normal water supply and water stress by -0.2 MPa PEG, F 1 had a higher Lp wr., so that F 1 could maintain capacity of continually absorbing water from dry soil under water deficiency condition. At the same time, F 1 had a lower C s compared with other two genotypes, and could effectively reduce water transpiration under water deficiency. This capacity of exploring new source and blocking transpiration flow in water use maybe accounted for the F 1's higher drought resistance(respected by it's significant higher P n and WUE). However, under water deficiency, the female parent had a lower ψ s and higher osmotic adjustment ability than the two genotypes, resulting in its drought resistance.