The Drought Resistance Of Four Kinds Of Plants Of The Genus Forsythia

Take two years′ Forsythia suspense(Thunb.)Vahl, F.intermelia Zabel, F.mandschurica Uyeki and F. koreana’Suwon Gold’as test materials,which belong to the genus forsythia, using pot with water to gradually reduce soil moisture content until reach the requirements of water stress, analyzing soil moisture content,Relative water contents,Water saturation deficit,Relative electrical conductivity,Content of Chl(a+b),Content of free praline,Content of soluble sugar,Content of soluble sugar,Content of MDA,Activity of SOD,Activity of POD,Activity of CAT,and using principal component analysis method and subordinate function method to evaluate its comprehensive drought resistance ability, the main results were as follows:(1) On the study of leaf under drought stress. Leaf relative water content of four plants of the genus forsythia with the strengthening of drought stress intensity is on the decline, and water saturation deficit changes, by contrast, is on the rise.Later stress, F.intermelia Zabel have the biggest drop in, to 25 d have down to 48.8% by contrast, a drop of 50.3%. F. koreana’Suwon Gold’ has the minimum drop 37.2%, Forsythia suspense(Thunb.)Vahl and F.mandschurica Uyeki decline were 47.9% and 42.8% respectively.After water, four kinds of plants of the genus forsythia leaf relative water content and water saturation deficit basic recovery.Under drought stress, the change trend of water saturation deficit and leaf relative water content instead.(2) The study of chlorophyll under drought stress.Four kinds of plants of the genus forsythia after continuous drought, changes of chlorophyll total not completely the same, but on the whole, are falling.But Forsythia suspense(Thunb.)Vahl in the drought treatment 5 d and 20 d chlorophyll content has a rising trend, F.intermelia Zabel have a rising trend in 10 and 20 d d, F.mandschurica Uyeki chlorophyll content in 20 d has a rising trend, comes to the chlorophyll "enrichment" phenomenon.After water, chlorophyll content of each kind has a recovery, but not up to the level of the early stage of drought stress.Chlorophyll a and chlorophyll b along with the change of prolonged drought trend with the change of total chlorophyll, the decrease of chlorophyll a content is bigger than chlorophyll b.This shows that the drought stress on chlorophyll a, extent of damage is large, but the destruction of the chlorophyll b level is relatively small, so the test of chlorophyll a drop is the main cause of lower chlorophyll content.(3) The study of osmotic regulation substances under drought stress.With the increase of the degree of drought stress, four kinds of plants of the genus forsythia proline content in leaves increased, recovered after water but were higher than in controls.The change of 4 kinds of forsythia soluble sugar can be divided into two.Arabesques of Forsythia suspense(Thunb.)Vahl and F.intermelia Zabel have a trend of greater volatility, and F.mandschurica Uyeki and F. koreana’Suwon Gold’ were first falling and later falling.Lifted after water plants suffer from the condition of drought stress, the soluble sugar content decreased in the body.Four plants of the genus forsythia overall trends is consistent, longer duration of drought, a downward trend, but the decline of the soluble protein content between different kinds of different, forsythia, the largest of north China was 57.14%, the findings and the F.mandschurica Uyeki was 46.67%, the F.intermelia Zabel and F. koreana’Suwon Gold’ minimum, 36.36% and 25%, respectively.After water, soluble protein content were restored.(4)The membrane system and enzyme activity under drought stress.As stop filling and the extension of time, the four kinds of plants of the genus forsythia relative conductivity increased gradually, after water, four kinds of the genus forsythia leaf relative electrical conductivity are dropped substantially, the basic of the early return to soil drought stress level.The change of malondialdehyde in the F.intermelia Zabel, F.mandschurica Uyeki and F. koreana’Suwon Gold’ malondialdehyde content of forsythia showed a trend of rising, and Forsythia suspense(Thunb.)Vahl a slight decline in 10 d, and then increase.After water, MDA content in stress later dropped. Forsythia suspense(Thunb.)Vahl, F.intermelia Zabel and F.mandschurica Uyeki in the process of the whole stress their SOD activity in a slow upward trend, but is a downward trend after water, while F. koreana’Suwon Gold’ SOD activity during stress after water continued to rise after falling.Under drought stress, Forsythia suspense(Thunb.)Vahl and F. koreana’Suwon Gold’POD activity change trend of forsythia are rising before they fell, the more consistent, but the peak time, F.intermelia Zabel down after rising first and rising trend F.mandschurica Uyeki is drop before rising trend Forsythia suspense(Thunb.)Vahl and F. koreana’Suwon Gold’ CAT activity showed a trend of gradual decline, while F.intermelia Zabel and F.mandschurica Uyeki shows the tendency of rise and fall after fall first.(5) The comprehensive evaluation on the drought resistance.For four kinds of plants of the genus forsythia principal component analysis showed that the physiological and biochemical index can reflect the ability of drought resistance index from high to low in turn as soluble sugar, chlorophyll index and water saturation deficit, SOD, leaf relative water content, POD and relative conductivity, MDA, CAT, proline, soluble protein.Using the membership function of fuzzy mathematics method to comprehensive evaluation of four kinds of drought resistance of the plants of the genus forsythia, its drought-resistant ability size order is: Forsythia suspense(Thunb.)Vahl > F. koreana’Suwon Gold’ > F.intermelia Zabel > F.mandschurica Uyeki.