title: Physiological responses to low temperature in spring and winter wheat varieties.
abstract: BACKGROUND
  Northward expansion of winter wheat is an efficient means to improve crop yield and quality in many countries. However, inadequate cold hardiness restricts the northward expansion of winter wheat. This study aimed to investigate cold adaption of different wheat varieties and underlying physiological mechanism.
  
  
  RESULTS
  In the field experiment, soluble sugar and proline content, relative electric conductivity (EC) and malondialdehyde (MDA) content were higher in wheat varieties in the overwintering period than those in the pre-wintering period. Superoxide dismutase (SOD) activity was lower in the overwintering period than in the pre-wintering period and spring growth period. Photosynthetic rate was reduced dramatically in the winter variety (Suyin 10), weak winter variety (Lumai 22) and spring (Jinchun 9) variety after low-temperature treatment. Cold treatment inhibited stomatal conductance (Gs) and transpiration rate (Tr). Influences of high-temperature treatment and cold acclimation after vernalization were further analyzed in the greenhouse in wheat variety Jinghe 1. High-temperature treatment after vernalization significantly inhibited SOD and peroxidase activities in the vernalized plants, while cold acclimation after vernalization enhanced peroxidase activity.
  
  
  CONCLUSIONS
  Cold tolerance of wheat varieties may be associated with effective osmoregulation ability, photosynthetic capacity, Gs and Tr , as well as activity of antioxidant enzymes.
authors.affiliation: College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China.|College of Horticulture, Shanxi Agricultural University, Taigu, 030801, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.affiliation: College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Jia
authors.affiliation: College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Gao
authors.affiliation: College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Dong
authors.affiliation: College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China.
authors.forename: Liheng
authors.initials: L
authors.lastname: He
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D009195:Peroxidase / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012621:Seasons; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014908:Triticum / Q000145:classification / Q000235:genetics / Q000502:physiology*
chemical_list: D010940:Plant Proteins; D009195:Peroxidase; D013482:Superoxide Dismutase
keywords: cold acclimation; cold adaptation; photosynthetic capacity; vernalization; wheat