Study Of The Role Of Main Flavonoids In Adapting To Soil Drought In The Leaves Of Ziziphus Spinosa(Bunge)hu

In this paper,With one year Sour jujube seedlings growing under different soil water content (75%, 55%, 35% of the maximum field capacity), controlled by potted planting, effects of different soil water content on the accumulation of flavonoids and its role in adapting to the soil drought was studied. The physiological response and the accumulation of flavonoids were studied under the condition of different soil water content, and determined the net photosynthesis rate (Pn),the activity of main antioxidant enzymes and the content of osmoregulation substance. Preliminary assessed the role of main secondary metabolites (flavonoids) in the course of adapting to soil drought. And it can provide theoretical basis for the study of the role of secondary metabolism in adapting soil drought and the exploitation and application of flavonoidThe study reached conclusions as follows:1.The Physiological Change under different soil water content:the photosynthetic rate (Pn) was a double-peak curve and there was a clear depression at noon, its first peak all occurred at 16:00pm, the second one at 10:00am for 75% and 55% treatment,but for 35% treatment the photosynthetic rate (Pn) increased gradually before 16:00 pm,and decreased then; and with the decrease of the soil water content, the photosynthetic rate (Pn) decreased; with the aggravation of water stress, the content of soluble sugar and the activity of CAT increased, while the proline content, the activity of SOD and POD increased firstly, then decreased. And we came to the preliminary conclusion that, with the decline of the soil water content, the photosynthetic rate was reduced, the Sour Jujube leaves can adapt to the soil drought by synthesizing much osmoregulation substance in short time, the activity of the three main antioxidant enzymes had not the same trend under the same soil water content, after rehydration the activity of antioxidant enzymes was higher than the 75% treatment.2.The content of main secondary metabolites (flavonoids) under different soil water content: With one year Sour jujube seedlings growing under different soil water content (75%, 55%, 35%), controlled by potted planting, the metabolism of flavonoids responding to water stress and its role in the course of adapting to water stress was studied primarily.The results showed that, compared with the CK (75%), PAL activity was increased under medium water stress(55%) and severe water stress(35%) treatment, and the PAL of the 35% treatment was the highest, after severe drought treatment (35%) was recovered to 75% soil water content, PAL activity recovered to the level of the CK; Compared with the CK, the quercetin content had little change under medium water stress(55%), but was decreased by the severe water stress(35%) treatment significantly; Both the total flavonoids and the rutin content increased under 55% water treatment compared with the CK(75%), the malondialdehyd(eMDA) content had no significant change; the total flavonoids and the rutin content were decreased by the 35% treatment compared with the 55% treatment ,the MDA content was increased insignificantly, but the total flavonoids content almost had no significantly change compared with the CK, and the rutin content was much higher than CK; After severe drought treatment (35%) was recovered to 75% soil water content, compared with 35% water content treatment, the total flavonoids and quercetin content increased significantly and recovered to the level of CK, the rutin content was much higher than the CK. The metabolism of flavonoids changed greatly under different soil water content. And it preliminary proved that the metabolism of flavonoids in the leaves of Sour Jujube was an effective way to adapt to the soil drought.3 Zea may L. varieties,'Zhengdan958'was hydroponically cultured to study the role of exogenous rutin on the activity of main antioxidant enzymes in leaves and roots of maize seedlings under different growing condition . The results showed:Compared with the CK (H), SOD, POD, CAT activity and the content of malondialdehyde were increased by 10% PEG treatment in corn leaves and roots, and when add exogenous rutin to the culture solution (H + P +R), SOD, POD, CAT activity and the content of malondialdehyde declined, but exogenous rutin had less impact on SOD, POD, CAT activity and the content of malondialdehyde in the leaves and roots under normal conditions. The results showed that exogenous rutin had more significant effect on corn under water stress.