盐分胁迫下控释尿素配施腐植酸对棉花幼苗生长和抗氧化系统的影响

为探究盐分胁迫下,控释尿素配施腐植酸对棉花幼苗生长特性和植株体内抗氧化系统的影响,以滨海盐化潮土(全盐含量4.5 g/kg)为供试土壤,设置普通尿素、控释尿素、普通尿素+腐植酸、控释尿素+腐植酸4个施肥处理,以不施氮肥处理为对照进行棉花盆栽试验,测定棉花植株生物产量、叶片叶绿素含量、叶片及根系抗氧化酶(SOD、POD、CAT)活性和过氧化物质(MDA、O2·-)含量。结果表明:盐分胁迫下,控释尿素+腐植酸配施处理有利于促进棉花幼苗期生物量的累积,较其他处理地上部鲜、干物质量分别提高13.46%~69.46%和12.64%~82.23%,差异显著(P<0.05);控释尿素+腐植酸配施处理植株叶片叶绿素a含量提高11.84%,显著高于控释尿素处理;较普通尿素和控释尿素处理,其配施腐植酸的处理棉花叶片和根系SOD活性提高了3.41%~42.84%,POD活性提高了4.376%~37.87%,CAT活性提高了5.53%~64.61%,其中控释尿素+腐植酸配施处理的SOD、POD以及CAT活性显著高于未施用腐植酸处理。可见,盐分胁迫下,控释尿素与腐植酸配施提高棉花的抗盐能力,其主要通过提高棉花叶片叶绿素含量及叶片和根系的抗氧化酶活性,来提高植株对盐分的耐受能力。

Effects of Combined Application of Controlled-release Urea and Humic Acid on Growth and Antioxidant System of Cotton Seedlings Under Salt Stress

In order to explore the effects of combined application controlled-release urea and humic acid on the growth and the antioxidant system of cotton seedlings under salt stress. A pot experiment was conducted with coastal saline soil (4.5 g/kg of total salt) under five treatments, including no nitrogen fertilizer (CK), common urea (U), controlled-release urea (CRU), common urea + humic acid (U+HA) and controlled-release urea + humic acid treatments (CRU+HA). Cotton biomass, chlorophyll content, antioxidant enzymes (SOD, POD, CAT) activity and peroxide (MDA, SO₂^·-) content in cotton leaves and roots were measured. The results showed that under salt stress, compared with the other treatments, CRU+HA treatment promoted the biomass of cotton seedlings, among of which, the above ground fresh and dry weights increased significantly by 13.46%-69.46% and 12.64%-82.23%, respectively (P<0.05). Chlorophyll a content in cotton leaves increased by 11.84% under CRU+HA treatment, Significantly higher than the CRU treatment. Compared with U and CRU treatments, U+HA and CRU+HA treatments promoted the activities of antioxidant enzymes in cotton leaves and roots, among of which, SOD, POD and CAT activities increased by 3.41%-42.84%, 4.376%-37.87% and 5.53%-64.61%, respectively. The activities of SOD, POD and CAT of CRU+HA treatment were significantly higher than those of the other treatments. In conclusion, under salt stress, CRU+HA improved the salt tolerance of cotton, mainly by increasing the chlorophyll content and antioxidant enzyme activity of leaves and roots.