Abstract:

Non-structural carbohydrates （NSC） played a fundamental role in plant growth， reproduction， defense and survival. To explore the effects of N and P addition on NSC of Lycium ruthenicum，a field manipulation experiment combined three nutrient supply levels （Low， Medium， High） and three N：P supply ratios （5∶1， 15∶1， 45∶1） was conducted on three-year-old L. ruthenicum. The results indicated that： （1） Soluble sugar was the major contributor to the total NSC in different organs， starch accounts for about 37.3%. On average， the concentrations of NSC in different organs followed the order of： coarse roots & fine roots>leaves>current-year>one-year& two-year branches. The concentrations of soluble sugar， starch and the ratio of soluble sugar to starch followed the order of coarse roots & fine roots>leaves>current-year branches>one-year branches>two-year branches； fine roots>coarse roots>two-year branches>one-year branches>leaves & current-year branches； leaves>current-year branches>coarse>one-year branches>two-year branches>fine roots respectively. （2） Changes in soluble sugar，starch and NSC concentrations in different organs of L. ruthenicum. reflected significant interactions between N∶P supply ratios and supply levels. When the N∶P supply ratios was 5∶1， the NSC concentrations of leaves and branches was higher under high supply level， when the N∶P was 15∶1， the NSC and its components concentrations of leaves，current-year and one-year branches in the low supply level is significantly higher than the high supply level， when the N∶P was 45∶1， the NSC concentrations of leaves，one-year and two-year branches in high level of supply is significantly higher than low supply level. N∶P supply ratios and supply level had no significant effect on root soluble sugar concentrations. （3） The NSC concentrations of one-year branches reached the maximum value （5.05% DW） before germination and dropped to the lowest value （3.79% DW） during the shoot growth period； NSC concentrations of two-year branches decreased before germination （4.23% DW） and reached the maximum value in the foliage period （4.33% DW）. （4） The NSC concentrations of coarse roots was negatively correlated with NSC concentrations of leaves、one and two-year branches； NSC concentrations of current-year branches was positively correlated with NSC concentrations of leaves and starch content of two-year branches； soluble sugar concentrations of one-year branches was negatively correlated with that of two-year branches； starch concentrations of two-year branches was negatively correlated with starch and NSC concentrations of coarse roots.When compared the impact of N and P addition on NSC concentrations of vegetative organs of L. ruthenicum， the results showed obvious organ difference adapted to N and P supply condition by adjusting accumulate and distribute NSC in different organs. Choosing to store more NSC in root system can enhance carbon balance and survivability in a nutrient-restricted environment， and also provide greater flexibility for the interaction with the non-biological environment.

Key words: nitrogen and phosphorus addition, N∶P, non-structural carbohydrate, Lycium ruthenicum