Chin J Plant Ecol ›› 2014, Vol. 38 ›› Issue (7): 776-784.DOI: 10.3724/SP.J.1258.2014.00073

• Research Articles • Previous Articles     Next Articles

Effects of atmospheric CO2 enrichment on phloem sap composition and root nitrogen accumulation in oilseed rape

YANG Chun1, TAN Tai-Long2,*(), YU Jia-Ling1, LIAO Qiong1, ZHANG Xiao-Long1, ZHANG Zhen-Hua1, SONG Hai-Xing1,*(), GUAN Chun-Yun2   

  1. 1College of Resources and Environmental Sciences, Hunan Agricultural University, National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer, Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Provincial Key Laboratory of Plant Nutrition in Common University, Changsha 410128, China
    2National Center of Oilseed Crops Improvement, Hunan Branch, Changsha 410128, China
  • Received:2014-01-06 Accepted:2014-03-20 Online:2014-01-06 Published:2014-07-10
  • Contact: TAN Tai-Long,SONG Hai-Xing

Abstract:

Aims The rising global atmospheric CO2 concentration has become an indisputable fact. It will like to impose significant impacts crops. Our objective was to study the effects of elevated CO2 concentration on soluble sugars and free amino acids in the phloem sap and nitrogen (N) accumulation in roots.
Methods Two oilseed rape (Brassica napus) varieties, ‘814’ and ‘Xiangyou 15’, were chosen in this study, and the soluble sugars and free amino acids in the phloem sap and nitrogen accumulation in roots were measured under two CO2 concentrations (normal: 400 μmol·mol-1, elevated: (800 ± 20) μmol·mol -1) and two N application levels (without N application, normal N application).
Important findings The result shows that: 1) Soluble sugars in the phloem of oilseed rape were increased in the elevated CO2 treatment. With N application, the soluble sugar content reached 0.29% in ‘814’ at the bolting stage, and reached 0.25% in ‘Xiangyou 15’ at the flowering stage; both genotypes had greater soluble sugar content under elevated CO2 concentration and under the normal CO2 treatment. 2) Free amino acids in the phloem of oilseed rape were reduced by elevated CO2 treatment with or without N application in ‘814’. In the treatment without N application, the free amino acids in the phloem of ‘Xiangyou 15’ were increased by 1.87%, 40.43%, 11.01%, and 224.90% under elevated CO2 at seedling stage, bolting stage, flowering stage, and silique stage, respectively; Whilst with normal N application, the percentage of increases was as high as 7.17%, 29.73%, 15.13%, and 5.38%, respectively. 3) Dry weight and N accumulation of roots were increased by elevated CO2 treatment. It is demonstrated that the soluble sugars and free amino acids in phloem are positively related to the dry weight and N accumulation of roots.

Key words: atmospheric CO2 enrichment, Brassica napus, dry biomass, free amino acid, nitrogen (N) accumulation, soluble sugar