| Hulunber grassland is currently one of the best preserved grasslands in China, which ecosystem has a unique geographical features and typical characteristics. In recent years, with the varying degrees of natural grassland degradation, the situation of forage supply appeared grim, which has posed a severe test to the vigorously develop animal husbandry in Hailar City’s economic development, in order to ensure healthy development of animal husbandry, to ensure an adequate supply of forage, artificial grassland played an important role, in addition, grassland ecological compensation mechanism for the implementation of the seed subsidy has been impled, which provided an opportunity for the development of artificial grassland in Hulunber region. Alfalfa varieties were to study production performance, photosynthesis, soil respiration characteristics and the characteristics of CO2emissions flux, and to analyze the economic benefits and outlook of growing alfalfa.1. By using a Li-6400portable photosynthesis system, the diurnal dynamic of photosynthetic characteristics and its yield factors of five alfalfa varieties which including Medicago falcata, M. sativa L. cv. Original seed variegated alfalfa, M. sativa cv. Variegated alfalfa, M. sativa cv. Zhaodongand, M sativa cv. Longmu801were studied in field. The results showed that different alfalfa varieties showed different diurnal variation curves in Pn, T(?), WUE, Ci and Gs,and also not all presented double-peak. Correlation analysis showed that a significant positive correlation between Pn, Tr and Gs, chlorophyll, and had negative correlation between Pn, Tr and WUE, RH and Temperature. There was a significant positive correction between yield and leaf dry weight, dry weight per plant, width and stem dry weight, and there was a low correction between yield and photosynthetic factors and environmental factors. Principal Component Analysis showed that height, PAR, yield, width, dry weight per plant, stem dry weight, leaf dry weight and fresh/dry could reflect and predict alfalfa yield better.2. The soil respiration rate was measured by Li-6400, at the same time, soil temperature, air temperature and soil water content were measured in different alfalfa rangeland. The results showed that the soil respiration rate change of five alfalfa varieties appeared "double-peak" curve, the maximum of soil respiration rate was at6:00of Medicago falcata, M. sativa cv. Longmu801and M. sativa cv. Zhaodong, and the lowest at14:00,8:00and12:00, respectively, the maximum soil respiration rate of M. sativa L. cv. Original seed variegated alfalfa, M. sativa cv. Variegated alfalfa, both appeared8:00, and the lowest appeared14:00and12:00; the changes trend of five alfalfa rangeland was M. sativa cv. Variegated alfalfa> M. sativa cv. Zhaodong> Medicago falcata, M. sativa L. cv. Original seed variegated alfalfa> M. sativa cv. Longmu801; soil respiration rate had a significant positive correlation with the soil temperature, and there was a one-place quadratic correlation between soil respiration rate and air temperature, and had negative correlation between soil respiration rate.3. Box method based automatic observation techniques was used to continuously observe CO2emissions throughout the growing period of the alfalfa and bromegrass. The article discussed the seasonal and diurnal variation CO2emissions of alfalfa and bromegrass, and analyzed the influence of temperature, soil moisture, rainfall to the CO2emissions flux. Results showed that the seasonal and diurnal variation of greenhouse gas emissions of alfalfa and bromegrass in general was "multi-peak "variation. Throughout the growing season, CO2emissions were more than other months between July and August; daily change, CO2emissions flux between10:30-16:30more significant. DNDC model was used to simulate the CO2emission flux of alfalfa and bromegrass, compared with the measured observation, which could reflect CO2emission flux in different ultilization. However, there was difference between the measured and simulated due to the use type, which would continue to explore in further.5. Analyzed the alfalfa industry economic benefit, the results showed that planting alfalfa could get considerable income in theroy. However, From the current status of industrial development point of view, the outlook is not very optimistic, mainly due to food subsidies, alfalfa. harvest, storage, standardized production, technology and promote grass, alfalfa price volatility and other factors, how to solve these factors would influnce the industrial development of alfalfa. Although there was a certain national investment for forage production, compared with other crops, less funding, alfalfa industrial development was still long way to go. |
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