Effects Of Nitrogen Regulation On Beet Yield And Quality And The Spectral Response

Sugar beets (Beta vulgaris L.), besides sugarcane, is an important kind of sugar crop in China, especially in the Northwest China, Northeast China and North China. It is one of the most important economic crops, which plays a significant role in increasing local farmers’ income, improving businesse efficiency and boosting the local economy.In production, farmers often fertilize nitrogen fertilizer excessively to increase the yield of sugar beet roots. However, over-fertilization may lead to low sugar content ratio in beet roots, as well as environment pollution.So, it is a major concern in beet production to guarantee both yield production and qualified sugar ratio on the premise of reasonable application of nitrogen fertilizer.The experiment uses the traditional ways of measuring plants’ nitrogen content, and at the same time, takes advantage of the hyperspectral remote sensing technology in nitrogen montoring in beet samples of different experiment periods, which might set new thinking in nutritional surveillance of suger beets.This experiment sets different nitrogen fertilizer gradients (Okg/hm2,105kg/hm2,120kg/hm2,160kg/hm2, 220kg/hm2), measures nitrogen contents and biomass accumulation of sugar beet samples periodically, and determines spectral reflectivity of canopy as well. By analysing the test data, we find the relationships of the samples’spectral information, biomass and nitrogen assimilation, and draw a conclusion that:1.The nitrogen gradients of 160kg/hm2 promotes beet’s foliage nitrogen assimilation, 105kg/hm2 makes the maximum sugar content, and the nitrogen amount of 120kg/hm2meets the maximum amount of beet tuberous root yield.Balancing the increase of sugar beet yield and sugar ratio, the optimum nitrogen rate of this experiment falls between 105 and 120kg/hm2.2.Hyperspectral remote sensing technology could be used in the monitoring of sugar beet nitrogen content and the other physiological parameters in production. In this experiment, the highest fitting degree among the spectral reflectance and foliage dry matter accumulation amount of beet is 1000nm. The highest fitting degree between the spectral reflectance and dry matter accumulation amount of beet tuberous root is1020nm.Meanwhile, the highest fitting degree among the spectral reflectance and nitrogen uptake level of beet is 1040nm.