Management And Evaluation Modeling Of Low-nitrate In Pakchoi Production

With the decrease of cultivated land, shortage of labor resources,development of science and technology, leafy green factory becomes atrend. Nitrogen fertilizer management is important in the productionofleafy green vegetables. Cultivation and management of vegetables withlow nitrate is of great significance to vegetables safety and environmentalprotection.The research is based on industrialized breeding. In order to achieveclean, efficient and safe production of leafy green, some important partsof technologies about factory production system are explored. The test isdivided into three parts. Firstly, we explored the appropriate rooting-zonevolume of pakchoi in trays. Trays with128,200,288apertures werechosen and1,2,3grains was sowed per aperture respectively.9rooting-zone volumes were constructed and we analysed growth potential,photosynthetic capacity, economic yield and nitrate content of pakchoiwith the change of volume. Secondly, after fixing the proper rooting-zone volume, varieties comparison was conducted under the optimalrooting-zone volume. We chose8pakchoi varieties: Huawang,Aikangqing, Xiawang, Dongxiu, Jinshenreqing and Kangre605, withorganic fertilizer Fudefeng at the volume ratio15%to matrix to explorethe differences of organic nitrogen uptaking among eight varieties.Finally, we choose the best variety Huawang to find out thecharacteristics of different fertilizer types used in pakchoi. Pakchoi weretreated with urea, Fudefeng, urea: Fudefeng (3:7) and urea: Fudefeng (7:3)and yield and quality was analysed. The test results were as follows:Different rooting-zone volumes showed different optical property,yield and nitrate nitrogen content. Planting density of6.5ml was2.8times of18.0ml while the production was4.8times of18.0ml. Itillustrated that thoughthe single plant weight was small, the smallrooting-zone volume had not yet have a negative impact on yield,indicating that6.5ml is the best choice for the pursuit of the economicoutput of the entire tray. Nitrate content, plant height, dry weight,economic yield were separated through principal component analysis.Further cluster analysis of9kinds of rooting-zone volume showed6.5mlbelonged to the category of volume which the pakchoi were high yieldand low nitrate.6.5ml was the best volume of cultivation with trays.Growth test of eight varieties of the same volume showed that theorganic fertilizer Fudefeng had different contribution to different varieties. The cluster analysis showed Huawang had a strong ability to use thenitrogen source and it could also gained high yield and moderate contentof nitrate and nutritional quality while605had failed to play the biggestrole of the nitrogen source taking under the same conditions with weakgrowth potential. Correlation analysis helped to determine thedependence relationship between economic output or nitrate nitrogen andother indexes, and establish a regression model between nitrate nitrogenand plant height, dietary fiber and a regression model between economicproduction and plant height, dry weight, VC.Results of nitrogen fertilizer analysis showed that free amino acids,kjeldahl nitrogen and soluble protein content were higher using the pureurea.7:3was able to obtain a higher economic yield and dietary fibercontent. Mixed fertilizer3:7accumulated more nitrate nitrogen whilenitrate nitrogen was not significantly different in other fertilizertreatments. Pure organic fertilizer is more conducive to synthesis ofsoluble sugar. Correlation analysis showed that plant height, fresh weight,dependencies between chlorophyll, net photosynthetic rate, free aminoacids had an obvious impact on economic yield of one tray. Stepwiseregression model predicted economic output using plant height andchlorophyll content when pakchoi were treated with fertilizer.Fuzzy model was applied to evaluate rooting-zone volumes,genotypes and fertilizer treatments respectively. Nitrate nitrogen, economic output, fresh weight per plant, dry weight per plant andcotyledon height were main indexes. According to the comprehensivejudgment results, rooting-zone volume of4.3ml,6ml,13ml,9ml and6.5ml, Huawang and Aikangqing and treatment7:3were placed at thefront of choosing queue. It showed high consistency compared to resultsof cluster and analysis of independent indexes.