Biomass allocation and organs growth of cucumber (Cucumis sativus L.) under elevated CO₂ and different N supply

Abstract

This article studied the effects of nitrogen (N) and CO₂ enrichment on biomass and N accumulation and partitioning of cucumber grown in open top chambers. At the seedling stage, elevated CO₂ increased the biomass and N content of the entire plant. The root had the largest increase in biomass and N content among the organs and more biomass allocation. The largest drops of N concentration showed in root at moderate and high N, in leaf at low N, respectively. Elevated CO₂ increased stem biomass allocation at moderate and high N, but decreased leaf biomass allocation at all N levels. At the initial fruit stage, the response to elevated CO₂ of biomass and N content decreased. Elevated CO₂ increased biomass allocation to leaf and resulted in the largest drop of leaf N concentration at low and moderate N supply. High N supply promoted biomass production and N reallocation from the leaf to fruit, but decreased leaf biomass allocation. Thus, biomass allocation is initially affected by root–shoot growth balance to adapt to enriched CO₂, leading to the largest root growth, then biomass allocates to another sink (stem). Long exposure of elevated CO₂ results in photosynthetic acclimation in deficient N supply, which probably attributes to excessive stem and leaf biomass allocation and shortage of fruit storage. But high N shifts biomass allocation from leaf to fruit. Practically, sufficient N supply is needed for an efficient transport of carbohydrates to fruits and increases the yields under elevated CO₂.

Keywords:

• growth
• biomass production
• nitrogen
• roots
• vegetable crops

Additional information

Funding

This research was supported by the National Research Foundation of National Natural Science Foundation of China [No. 41101272], National Science and Technology Support Program of China [No. 2014BAD14B04].