| As a essential nutrient elements of plant, nitrogen play important effects not only on growth and development of plant, but also on plants' yield and qualities. In all of essential nutrient elements of plant, nitrogen usually become the first factor which restrict plants' growth and yield. Therefore, it is useful to the development of animal husbandry and improvement of ecological environment in karst area for us to study the characteristics between on absorption and transformation of nitrogen and rhizosphere environment of Legume Herbage in dry cropland of karst area.This study was based on two Legume Herbage Cajanus Cajan (L.) Mjllspaugh and Tephrosia candida DC and their rhizosphere soil, which were planted on two areas of MAOCUN GUILIN (karst area and non-karsr area).The main results as follows:1, effects of drought stress on germination physiology of Cajanus Cajan (L.) Mjllspaugh seed: on normal condition, the index of Cajanus Cajan (L.) Mjllspaugh seed vigour index,seed germination index,Germination rate,biomass in non-karst area were higher than those in karst area. However, on the same drought stress condition, the index of Cajanus Cajan (L.) Mjllspaugh seed vigour index,seed germination index,Germination rate,biomass in karst area were higher than those in non-karst area. the index of SOD activities of Cajanus Cajan (L.) Mjllspaugh seedling in karst area was higher and MDA content was more than those in non-karst area. And the results indicates that Cajanus Cajan (L.) Mjllspaugh seedling in karst area had a stronger drought resistance ability than in non-karst area.2, Dynamic change of Nitrogen Metabolism in Cajanus Cajan (L.) Mjllspaugh and Tephrosia candida DC of karst area: Compared with the plant which growed in red soil of non-karst area, Cajanus Cajan (L.) Mjllspaugh growing in lime soil of karst area had high content in total N, protein N, soluble protein and its GS, NR activities were also high. GS, NR activities of Cajanus Cajan (L.) Mjllspaugh growing in lime soil of karst area appeared a obvious seasonal difference. Nitrogen Metabolism is vigorous during the nutrient growing period (July) and full-bloom stage (october). The change of indexes of nitrogen merabolism of Tephrosia candida DC were similar with Cajanus Cajan (L.) Mjllspaugh, but these had a difference which present that the level of nitrogen metabolism in karst area was higher before august and lower afer august than that in non-karst area.3, Effects of Legume Herbage on soil physical and chemical properties: After planted Cajanus Cajan (L.) Mjllspaugh and Tephrosia candida DC, soil pH decreased 0.4-0.5 unit wether in karst or non-karst area. during the nutrient growing period (june-september), Cajanus Cajan (L.) Mjllspaugh and Tephrosia candida DC rhizosphere soil urease activity was high, then down. Content of Cajanus Cajan (L.) Mjllspaugh and Tephrosia candida DC rhizosphere soil available nitrogen was high during June and October and Content of Cajanus Cajan (L.) Mjllspaugh rhizosphere soil available nitrogen in karst area was lower than non-karst area. Content of Tephrosia candida DC rhizosphere soil available nitrogen and total N in non-karst area was higher than in karst area during June and August(vegetative growth phase)and lower during the early growth period, the vigorous florescence and the seed-filling stage. Content of Cajanus Cajan (L.) Mjllspaugh and Tephrosia candida DC rhizosphere soil available nitrogen reaches its maximum in august and total nitrogen reached its maximum in September.4, Effect of lime application on nitrogen metabolism of Cajanus Cajan (L.) Mjllspaugh in the Acid Soil: In farmland plant experiment, proper dosage lime application significantly increased nitrogen and protein content of Cajanus Cajan. the nitrogen content came to a good state simultaneously when the lime application dose was 100– 150 g/plant. With the lime application dose increasing, the Urease, Protease, NRase activitys in soil showed increase at first and then reduce gradually.5, Effect of soil pH on nitrogen metabolism of Tephrosia candida DC: When soil pH presented a gradient reduce from 7.15 to 5.54, The level of nitrogen metabolism becomes stronger gradually and the ability of adversity-resistant improved gradually. with the decreasing of soil pH, plant height ;biomass;and content of soluble protein and amino acid of Tephrosia candida DC improved gradually, activity of nitrogen metabolism and antioxidant enzyme increased gradually. With the decreasing of soil pH, the content of MDA and soluble sugar reduced gradually. 6, The realationship of Total N and Protein N,Soluble protein and Total N,Protein N,Amino acid and Non-protein N,Protease and GS,Soil pH and Total N,Protein N,Soil urease and Total N are positive correlation in Cajanus Cajan of karst area and non-karst area. In karst area the realationship of Soluble protein and Non-protein N,NR and Soluble protein,Protein N are nagtive correlation;Realationship of these indexes in non-karst area are not significant. The realationship of Total N and Protein N,Soluble protein and Total N,Protein N,Total chlorophyll and Total N,Non-protein N,Soil pH and Total N,Protein N,Soil urease and Total N are positive correlation and The soil pH present a negative correlation to Protease in Tephrosia candida of karst area and non-karst area. In non-karst area Urease activity and Total N,Soil pH and Non-protein,Total chlorophyll show a negative correlation ;GS present a positive correlation to non-protein. Realationship of these indexes in karst area are not significant. |
