Study On Pakchoi Cultivars Screening And Cultivation Techniques

Summer vegetables mainly consist of Pakchoi in Zhejiang Province,so the quality of pakchoi becomes more and more a major concern in local agriculture.In order to select adapatable pakchoi varieties for cultivation during summer in Zhejiang Province,several cultivation techniques are discussed in this dissertation regarding the issue of selecting and optimizing pakchoi varieties.Firstly,seven different pakchoi varieties are proposed for field experiments to screen out pakchoi varieties with best thermal adaptability and quality.Experimental results such as botanical character,yield,content of nutrition and nitrate content of harmful substance are investigated accordingly.Secondly,two pakchoi varieties with different levels of planting density are utilized to determine the reasonable planting density for growth of the pakchoi based on its botanical character in Zhejiang Province.For the third,various kinds of sunshade nets are implemented in field experiments of two pakchoi varieties.Proper kinds of sunshade nets are determined on a basis of variations in quality index of pakchoi varieties,which can be suggested for large-scale cultivation of pakchoi in Zhejiang Province.Analysis results of the field experiments above provide guidance for cultivation of pakchoi varieties in Zhejiang Province.Such analysis results are as follows.1.Analysis results are derived from fuzzy evaluation of seven pakchoi varieties,which demonstrate that ' Ri Ben Hua Guan','Jin Pin 104' and 'Xia Di' grow with better thermal adaptability during summer in Zhejiang Province.Moreover,experimental results of content of nutrition and content of nitrate show that Vitamin C,soluble sugar and content of nitrate of 'Xia Di'is usually higher among the seven pakchoi varieties,and content of nitron in leaf of 'Jin Pin 21' is the highest of all.Besides,results taste tests reveal that 'Ri Ben Hua Guan','Jin Pin 104' and 'Xia Lv' are with good flavor.Above all,relationship between results of taste tests and botanical character,content of nutrition or content of nitrate is investigated.Corresponding results indicate that there is a postive correlation between flavor of certain pakchoi variety and plant weight or leaf width,a negative correlation between flavor of certain pakchoi variety and content of nitrate or content of cellulose,and no significant correlation between flavor of certain pakchoi variety and other botanical character or quality index.2.Analysis results of field experiment indicate that plant hiegiht,leaf length,petiole length,leaf width,leaf number and plant weight decreases significantly with the increase of planting density,in each picking time.Specifically,planting density impacts growth of pakchoi in certain pattern.Meanwhile,when pakchoi is planted with planting density of 100 plants/m2,the yield of pakchoi reaches a peak value,and the yield of pakchoi decreases if pakchoi is planted with a greater planting density.Therefore,pakchoi is suggested to be planted with seeding density of 100 plants/m2.3.Sunshade nets are made of different materials,which have major impacts on growth and botanical character.Experimental results show that the mulching of plastic film,insect-proof,silver gray sunshade nets or black sunshade nets results in attenuation of light,decreases of environmental temperature and soil temperature.As a result,strong light stress is almost removed in field experiment with mulching of sunshade nets and such.Additionally,different options of sunshade nets affect growth of pakchoi in different ways,mainly in increase of plant height,plant expansion and leaf number.In general,according to the analysis results of content of nutrition and content of nitrate,content of Vitamin C and cellulose is lower and content of nitrate is higher in pakchoi with sunshade nets thant that in pakchoi without sunshade nets.