盐胁迫对海岛棉不同基因型幼苗生长及生理生态特征的影响

Effects of NaCl stress on growth and eco-physiological characteristics of different in sea island cotton genotypes in seedlings

采用水培试验,分析了不同浓度的NaCl(0、50、100、150、200、250 mmol.L-1)处理对两个海岛棉品种新海28号(XH28,耐盐基因型)和新海21号(XH21,盐敏感基因型)植株生长、生物量分配、蛋白质含量、脯氨酸(Pro)含量以及过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)等生理生态指标的影响。研究发现:(1)盐胁迫对海岛棉幼苗鲜重的影响大于干重,对茎叶的影响大于根系;(2)盐处理引起海岛棉幼苗根叶脯氨酸含量的增加;(3)低浓度NaCl处理(≤50 mmol.L-1)显著增加耐盐品种XH28的根长、株高及单株鲜干重;(4)盐胁迫引起海岛棉幼苗根系中可溶性蛋白质含量下降,相反叶片中可溶性蛋白质含量上升;(5)盐胁迫下耐盐品种XH28幼苗中的POD、CAT、APX酶活性明显高于盐敏感品种XH21,但GR活性显著低于XH21。研究表明,低浓度NaCl处理刺激了棉株生长,增加了生物量;盐胁迫下叶内蛋白质、脯氨酸含量明显增加,POD、CAT、APX酶活力升高是海岛棉耐盐品种XH28的基本特征。

Soil salinity is one of the major abiotic stresses having adverse effects on crop productivity and quality.Cotton is the most important cash crop in Xinjiang.Extensive research has been conducted on the effects of salinity on cotton and cotton plant is classified as moderately salt-resistant species in terrestrial plant in most of documents.However,almost all of these researches were focused on upland cotton.Sea island cotton is another cultivation species of cotton,which was distributed only in xinjiang in China and is widely cultivated due to it adopted to weather in Xinjiang and its relatively higher economical values.Few studies documented on effects of salinity stress on the growth and development of sea island cotton as well as its internal adaptive mechanisms.Therefore,this paper try to ascertain mechanism of the eco-physiological sea island cotton adapting to salt stress,supply theoretical foundations and reference index for cultivate management,resistant screening,breeding of sea island cotton.Two cotton cultivars with varied salt-tolerance ability was selected to study sea cotton＇s response when exposed to salt environment.Xinhai 28（XH 28） is a salt-resistance sea island cotton cultivar while Xinhai 21（XH 21） is a salt-sensitive sea island cotton cultivar.The experiment was conducted in a growth chamber,water culture experiments were carried out to study the effects of salinity stress on seed germination and seedling growth.Full nutritional solution was used in at germination stages,NaCl was added to solution at 3 full expand leaves stages at 6 NaCl levels（0,50,100,150,200 and 250 mmol·L-1）.All nutrient solutions were changed once per 3 days and deionized water was added daily to replace the water lost by transpiration.The seedlings were salt-stressed for 30 days,then was sampled and tested for biomass partitioning,soluble protein,Proline（Pro） contents,as well as activities of peroxidase（POD）,catalase（CAT）,ascorbate peroxidase（APX） and glutathione reductase（GR） activities in leaves and roots of the XH 28 and XH 21.The results showed that（1）Fresh weight of sea island cotton was more sensitive to salt stress as compared to dry weight,shoots were more sensitive as compared to roots;（2） Higher proline content was observed both in the roots and leaves when cotton seedling was stressed by salt;（3） Root length,plant height and fresh-dry weight of XH 28 were significantly increased under low NaCl concentration（≤50 mmol·L-1） stress;（4） Salt stress resulted in the decrease of soluble protein in roots of sea island cotton,while soluble protein was enhanced in leaves;（5） Activities of POD,CAT and APX in roots and leaves in NaCl tolerant genotype were significantly higher than that in NaCl sensitive genotype.Whereas activity of GR in roots and leaves was lower in XH 21.In conclusion,low concentration of NaCl can stimulate plant growth and,consequently,result in higher biomass.Protein and proline content increase in roots and leaves and the higher active of activities of POD,CAT and APX can be considered as the physiological characteristics in NaCl tolerant genotypes of sea island cotton.