| As the agricultural products with unique advantages in Yunnan province, Coffee arabica mainly distributes in dry-hot valley and humid tropics, and its planting area and yield account for90%of the whole country. According with the problems of drought and water shortage, serious contradictory of water and heat, extensive management of water and fertilizer, drought and under nutrition restricting production of coffee arabica, and yield and quality can not be guaranteed, the project mainly studies the effects of limited irrigation and nitrogen on growth dynamics, physiological characteristics, transformation and utilization of water and nitrogen in root zone. The project seeks for efficient mechanism of water and nitrogen on coffee arabica under limited irrigation, quantitatively optimizes decision of irrigation and nitrogen, and perfects theory of efficiency use of water and nitrogen on coffee arabica.This study took coffee arabica as an example, adopted pot experiment, set four water treatment:Sufficient water Ws (75%～85%)oF, High water WH (65%～75%)θF, Medium water WM (55%～65%)θF, Low water WL (45%～55%)θF and four nitrogen treatment:High nitrogen NH (0.60g N/kg dry soil),Medium nitrogen NM (0.40g N/kg dry soil),Low nitrogen NL (0.20g N/kg dry soil),Non-nitrogen NN (0g N/kg dry soil).The experiment conducted in the greenhouse of intelligent control in Faculty of modern Agricultural Engineering, Kunming University of Science and Technology from April to December,2012. The primary research of this paper concentrate on the effect of nitrogen application and watering on growth characteristics, physiological property, water and nitrogen utilization and dry mass accumulation and distribution of coffee arabica under limited irrigation. The main results of this study as follows:(1) Under the same nitrogen treatment, increasing irrigation could promote the growth of coffee arabica significantly, and improve the morphological index (plant height, stem diameter, leaf area and shoot length), while in high nitrogen treatment, low water treatment is not conducive to the development of various morphological index. Sufficient water treatment with high nitrogen was beneficial to leaf area and shoot length growth of coffee arabica, and sufficient water treatment with low nitrogen beneficial to growth of coffee arabica seedling that plant height, stem diameter were better than the high, medium nitrogen treatment significantly.(2) Chlorophyll and carotenoid content with nitrogen treatments was higher than that in non nitrogen treatment significantly, and high nitrogen and water supply is inadequate or low nitrogen and sufficient water supply are not beneficial to synthesis of chlorophyll and carotenoids under the interaction of water and nitrogen. Physiological indexes of leaf (MDA, proline, soluble sugar) with nitrogen treatments were higher than those in no nitrogen treatment, values of physiological indexes of coffee arabica under the low water are higher than the other three water treatments. At the same nitrogen treatment, increasing irrigation could improve the root activity of coffee arabica significantly, the maximum of root activity was sufficient water treatment with high nitrogen.(3) Nitrate accumulation and mobile in soil profile mainly affected by nitrogen and soil water content, and positively correlated with nitrogen, negatively correlated with soil moisture content. Nitrate content in soil with high, medium nitrogen treatment was higher than low, no nitrogen treatment significantly. At the same nitrogen treatment, irrigation of low water has a positive effect on nitrogen accumulation.(4) Compared with the low water treatment, increase irrigation could increase dry mass accumulation, water consumption and water use efficiency by68.01%-141.90%,28.93%-73.35%and22.48%-40.89%respectively. Compared with the non-nitrogen treatment, nitrogen application could increase dry mass accumulation, water consumption and water use efficiency by22.48%-40.89%and24.73%-3.01%respectively. Daily evapotranspiration of coffee arabica seedling decreased with the increase of nitrogen slightly, while increased with the increase of irrigation significantly. Peak value of each part organs of total nitrogen content related to nitrogen content and negatively correlated with irrigation obtained in the NHWL treatment. The average Nitrogen utilization rate was11.95%,12.70%and31.69%respectively under the NH, NM and NL treatment. In the same volume of irrigation, nitrogen fertilizer utilization decreased with the increase of nitrogen significantly.Comprehensive consideration of growth and physiological characteristics, dry mass accumulation, water use efficiency and other factors, optimal water and nitrogen supply mode of coffee arabica:Sufficient irrigation Ws (75%-85%) of with low nitrogen NL (0.20g pure N/kg dry soil). |
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