Abstract:

Nano iron （FeNPs） is a new type of nano metal fertilizer， but its regulation effects on cotton growth and stress resistance are rarely studied. 4 FeNPs treatment levels （0， 1.0， 2.5， 5.0 mg·L^-1） were set to study its effect on root morphology and physiological indexes of hydroponic cotton seedlings under PEG stress. The results showed that total root length， total root surface area， projected area， number of root tips and fresh and dry weight of roots， stems and leaves cultured with 5.0 mg·L^-1 FeNPs were significantly higher than those cultured with 1.0 and 2.5 mg·L^-1 FeNPs. Cotton seedlings were cultured in Hogland nutrient solution with 0 and 5.0 mg·L^-1 FeNPs， and then 10% PEG-6000 was applied at the four-leaf stage. The results showed that the cotton seedlings without FeNPs were more wilting than those treated with 5.0 mg·L^-1 FeNPs， and the fresh weight of root， stem and leaf was significantly lower than that with FeNPs. In addition， FeNPs significantly increased SOD， POD and CAT activities and significantly decreased MDA content in cotton leaves within 6 h of stress. After 9 h， SOD and CAT activities decreased and MDA content increased significantly. In summary， appropriate level of FeNPs would be beneficial to root growth， dry matter accumulation and antioxidant enzyme activity of cotton seedlings， thus enhancing the drought resistance of cotton seedlings.

Key words: cotton, FeNPs, roots, physiological indexes, stress resistance

摘要：

纳米铁（FeNPs）作为一种新型纳米金属肥料，其在棉花生长发育和抗逆调节中的研究很少。设置4个FeNPs处理水平（0、1.0、2.5、5.0 mg·L^-1）研究其对水培棉苗根系生长和干旱胁迫（PEG）下生理指标的影响。结果发现，5.0 mg·L^-1 FeNPs培养的棉苗总根系长度、总根表面积、投影面积、根尖数目及根、茎、叶的鲜重和干重均显著高于对照和1.0、2.5 mg·L^-1 FeNPs。棉花在0和5.0 mg·L^-1 FeNPs的Hogland营养液中培养至四叶期，分别施加10%（质量体积分数）PEG-6000，结果发现，无FeNPs处理较5.0 mg·L^-1 FeNPs处理的植株更萎蔫，其根、茎、叶鲜重显著小于FeNPs处理棉苗；在胁迫6 h内，FeNPs促进棉叶SOD、POD和CAT活性显著升高，MDA含量显著下降；而9 h后，SOD和CAT活性出现大幅下降、MDA含量显著上升。综上所述，适当水平FeNPs有助于棉苗根系生长、干物质积累和抗氧化酶活性增强，进而增强棉苗抗旱性。

关键词: 棉花, FeNPs, 根系, 生理指标, 抗逆性