Growth, fructan yield, and quality of chicory (Cichorium intybus L.) as related to photosynthetic capacity, harvest time, and water regime

Abstract

Fructans are polymers that are widely used in several industrial applications. In the last few years they have received increasing interest because of their positive effects on health. At present, fructans are mostly supplied by chicory, which is only grown and processed in The Netherlands, France, and Belgium. It would therefore be an attractive concept to expand its cultivation to the southern European countries, although water shortage and high temperatures may hinder its growth and yield. So far, few experiments have been carried out on the effects of water, so the present research was focused on the course of growth and fructan quality in rainfed (W₀) and well-watered (W₁) conditions. The positive effects of water restoration mostly concerned the above-ground dry weight (ADW), whereas the root dry weight (RDW) was less influenced. No significant differences on RDW were found in 1999, whereas it was 14% higher (P 1 in 2000. The effect of water was very clear on assimilate allocation: the overall priority at the whole plant scale seemed to be root structures, then storage reserves, and finally ADW. Therefore, the fructan content was higher in W₀, and insignificant differences between W₀ and W₁ were found on fructan yield at the final harvests. The only significant effect of the water regime on fructans was to speed up their storage. The leaf photosynthetic capacity (A) was poorly affected by water availability, whereas it appeared consistently modulated by leaf temperature and leaf nitrogen content. Stomatal conductance appeared to be mostly affected by the soil water content and it was mostly related to A up to about 300 mmol m⁻² s⁻¹. The fructan chain length (DP) was not affected by water regime. Besides, DP classes showed a normal statistical distribution; skewness and kurtosis significantly changed only when the harvest was very late. Equally, a very late harvest time significantly lowered DP.