断根对盐胁迫下玉米生长、光合及叶片抗氧化酶的影响

Effects of partial root excision on the growth,photosynthesis,and antioxidant enzyme activities of maize under salt stress

通过盆栽试验,以全根玉米为对照,研究了断根对不同浓度NaCl(无盐0、低盐0.2%、中盐0.4%、高盐0.6%)胁迫下2个玉米杂交种(郑单958、登海9)的生长、灌浆期光合及叶片抗氧化酶活性的影响.结果表明:低盐胁迫下,断根郑单958籽粒产量比全根玉米增加13.1%,登海9籽粒产量比全根玉米增加31.4%.拔节期,玉米生长受断根影响,其根及地上部干质量小于同盐度下的全根玉米,无盐和低盐条件下断根玉米生长恢复迅速.乳熟期,无盐和低盐条件下断根玉米的根及地上部干质量、叶面积、根总长、根总表面积、根系活力、叶绿素含量,以及穗位叶净光合速率、气孔导度、蒸腾速率、POD和CAT活性均显著高于全根玉米,而茎粗和穗位叶MDA含量小于全根玉米;中、高盐度胁迫对断根玉米影响较大,干质量、根系形态及光合指标均小于全根玉米,产量也略低于全根玉米.在整个生育期,断根对盐胁迫下玉米生长的影响与盐浓度有关,无盐和低盐浓度下促进玉米生长,中、高盐度则抑制生长.

A pot experiment was conducted to study the effects of partial root excision on the growth of two maize cultivars （Zhengdan 958 and Denghai 9） throughout their growth period and the photosynthesis and leaf antioxidant enzyme activities at grain-filling stage under salt stress. Four treatments were installed, i. e. , control （no salt）, low salt （0.2% NaC1）, moderate salt （0.4% NaC1）, and high salt （0.6% NaC1）. Under low salt stress, the grain yield of Zhengdan 958 and Denghai 9 with partial root excision was increased by 13.1% and 31.4%, respectively, as com- pared with that of the cuhivars with no root excision. At jointing stage, the growth of the cuhivars with partial root excision was restrained, the rootand shoot dry masses under the same salt stresses being lesser than those of the cultivars with no root excision, but the growth under the conditions of no salt and low salt recovered quickly. At milk-ripe stage and under no salt and low salt conditions, the rootand shoot dry masses, leaf area, total root length, total root surface area, root activity, leaf chlorophyll content, and ear leaf net photosynthetic rate, stomatal conductance, transpiration rate, and CAT and POD activities of the cuhivars with partial root excision were significantly larger than those of the cultivars with no root excision, while the shoot diameter and ear leaf MDA content were in adverse. Moderate and high salt stresses had greater effects on the cuhivars with partial root excision. The root- and shoot dry masses, root morphology, and photosynthesis indices of the cultivars with partial root excision were smaller than those of the cultivars with no root excision, so didthe grain yields. Throughout the growth period of the cultivars, the growth of the cultivars with partial root excision depended on the salt concentration, i. e. , was promoted under no and low salt, and inhibited under moderate and high salt conditions.