不同施氮量对干旱下狗牙根抗氧化酶活性及渗透调节物质含量的影响

Effects of different nitrogen application rates on antioxidant activity and content of substances involved in osmotic adjustment in Cynodon dactylon under drought stress

为探讨干旱下施氮肥是否可以提高狗牙根抗旱性,以新农1号狗牙根为材料,干旱前进行不施氮(0 mmol·L^(-1))、低氮(1.5 mmol·L^(-1))、中氮(7.5 mmol·L^(-1))、高氮(15.0 mmol·L^(-1))4种施氮处理,盆栽试验控制水分缓慢干旱,在干旱0、7、14 d、复水7 d,测定草坪质量、叶片相对含水量、相对电导率、丙二醛含量、抗氧化酶活性[超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)]、过氧化氢以及渗透调节物质可溶性蛋白、脯氨酸、可溶性糖含量,并对干旱7、14 d下狗牙根抗旱性响应指标进行热图聚类及主成分分析。结果表明,不同施氮量对狗牙根草坪质量的影响因干旱程度不同而有所不同。正常灌溉和中度干旱下高氮处理(15 mmol·L^(-1))下狗牙根表现出较好的草坪质量,而中氮处理(7.5 mmol·L^(-1))能显著提高其重度干旱下草坪质量。与干旱对照相比,干旱处理下施中氮可使狗牙根叶片相对含水量、CAT活性、SOD活性、可溶性蛋白、脯氨酸和可溶性糖含量依次显著提高60.98%、154.40%、163.73%、61.75%、144.71%和31.53%,维持较高的草坪质量。且复水后中氮和高氮处理狗牙根草坪质量恢复较快,可能是由于在干旱胁迫时受到损伤较小。综上认为,干旱前施中氮,可以一定程度缓解干旱胁迫对狗牙根幼苗造成的伤害。

This experiment investigated whether application of nitrogen fertilizer could promote the improvement of drought resistance for Cynodon dactylon.Nitrogen fertilizer at various rates including zero nitrogen(0 mmol·L^(-1)),low nitrogen(1.5 mmol·L^(-1)),medium nitrogen(7.5 mmol·L^(-1))and high nitrogen(15.0 mmol·L^(-1))was applied to pot of C.dactylon cv.‘Xinnong No.1’with a slowly developing moisture deficit.The turf quality,relative water content,relative electrolyte leakage,malondialdehyde content,antioxidant enzyme activities[superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)],hydrogen peroxide content,electrical conductivity and levels of substances linked to osmotic adjustment(soluble protein,proline,soluble sugar)were determined at 0,7 and 14 d after water deficit commencement and 7 d after-watering.Heat map cluster and principal component analysis of drought resistance indexes at 7 and 14 days after water deficit commencement were carried out.The results showed that the effect of nitrogen application rates on turf quality differed depending on the degree of water deficit stress.Turf quality of C.dactylon was better under the high nitrogen treatment(15.0 mmol·L^(-1))under normal irrigation and moderate drought stress,and medium nitrogen treatment(7.5 mmol·L^(-1))significantly improved turf quality under severe drought stress.Compared with drought control plants,the relative water content,CAT activity,SOD activity,soluble protein,proline and soluble sugar contents of C.dactylon leaves were increased by 60.98%,154.40%,163.73%,61.75%,144.71%and 31.53%,respectively,with medium nitrogen application under drought stress,and thus maintained higher lawn quality.After re-watering,turf quality of C.dactylon recovered more quickly under medium and high nitrogen treatments,than in low nitrogen treatments.This may be due to reduced damage under drought stress.In conclusion,medium nitrogen application prior to drought stress partially alleviated water deficit damage to C.dactylon seedlings under drought stress.