Effects of Combined Application of Biochar-based Organic Fertilizer and Reduced Nitrogen Fertilizer on Soil Enzyme Activity and Yield of Purple Cabbage(Brassica oleracea var.capita rubra)in Yuanmou County

[Objectives]In response to the issue of soil improvement in Yuanmou County,the effects of combined application of biochar-based organic fertilizer and reduced nitrogen fertilizer on soil nutrients,soil enzyme activity,and yield of purple cabbage(Brassica oleracea var.capita rubra)were investigated in the field base of Institute of Thermal Zone Ecological Agriculture,Yunnan Academy of Agricultural Sciences in Yuanmou County.[Methods]A total of 13 treatments were set up by applying biochar-based organic fertilizer at three levels of 15,30 and 45 t/hm^(2)(T_(1),T_(2),T_(3)),combined with top application of nitrogen fertilizer(urea)at four levels:375(N_1),300(N_(2)),225(N_(3))and 0 kg/hm^(2),with non-fertilizing treatment as control check(CK),in order to explore the optimal ratio for the combined application of biochar-based organic fertilizer with nitrogen fertilizer.[Results]The application of biochar-based organic fertilizer could significantly improve soil nutrients,enzyme activity,and purple cabbage yield.The improvement effect of combined application with nitrogen fertilizer was higher than that of single application of biochar-based organic fertilizer,and the improvement effect was enhanced with the application amount of biochar-based organic fertilizer increasing.The contents of organic matter and total nitrogen were the highest in treatment T_(3)N_(3),of which the values increased by 81.39%and 56.09%compared with the CK,respectively.The contents of soil hydrolyzable nitrogen,available phosphorus,and available potassium were all the highest under treatment T_(3)N_(2),with increases of 92.76%,171.01%and 235.50%,respectively.There was a significant positive correlation between the activity of soil catalase,urease,and sucrase and organic matter,total nitrogen,and available nutrients.The overall soil enzyme activity was relatively higher in treatment T_(3)N_(2).The yield of purple cabbage treated with biochar-based organic fertilizer combined with nitrogen fertilizer could reach 85750 kg/hm^(2),which was 94.78%higher than that treated with biochar-based organic fertilizer alone.Based on comprehensive analysis,the optimal combination ratio was 45 t/hm^(2)of biochar-based organic fertilizer and 300 kg/hm^(2)of urea(T_(3)N_(2)).[Conclusions]This study provides data support for the promotion of biochar-based organic fertilizers and reduced fertilizer in agricultural soil in the Dam area of Yuanmou County.

A Visual pH Indicator through Purple Cabbage Dye for Freshness Test of Venison

A visual pH indicator through purple cabbage dye is selected to test the freshness of venison.Chitosan and cassava starch of an equal weight were used to prepare the film-forming matrix of the indicator.The crystallization of natural purple cabbage dyes with a weight ratio of 5%,10%,20%and 40%were added to the matrix,respectively.The pH color test showed that the natural purple cabbage lyophilized powder with a weight ratio of 40%was the best for the pH indicator,which was used to test the freshness of venison stored at 4℃.The total bacterial count,volatile basic nitrogen(TVB-N)and thiobarbituric acid(TBA)of venison were tested through an experiment.When stored at under 4℃,a significant color change of the indicator from pink to blue-green was shown when the total amount of volatile basic nitrogen(TVB-N)(22.78 mg/100 g)exceeded the critical value(20 mg/100 g).The test result showed that the indicator was very sensitive to pH value and it would help customers identify the freshness of venison.

Effects of urea-N and CO_(2) coupling fertilization on the growth,photosynthesis,yield and anthocyanin content of hydroponic purple cabbage Brassica campestris ssp.chinensis

Water and fertilizer coupling is a high-efficiency technology for the development of facility agriculture.However,the interaction effect of nitrogen(N)and air carbon dioxide(CO_(2))on hydroponic purple cabbage,especially on its leaf anthocyanins under hydroponic solution systems,remains unexplored.In this study,six treatments were set as C0N0,C0N2,C0N4,C1N0,C1N2 and C1N4,with N0,N2 and N4 being 0.0 g/L,0.2 g/L and 0.4 g/L exogenous urea-N to hydroponic solution dilution,respectively.C0 and C1 were set as with and without CO_(2)fertilizer(i.e.,800 g CO_(2)agent added one week after transplanting and 600 g CO_(2)agent added when the plant reached 15 cm in height),respectively.Pot experiments were conducted to investigate the interaction effect of N and air CO_(2)(N×CO_(2))on the growth,photosynthesis,yield and anthocyanin content of hydroponic purple cabbage Brassica campestris ssp.chinensis.The results showed N×CO_(2)extremely significantly influenced plant height(H),net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular oxidation concentration(Ci),transpiration rate(Tr),leaf water use efficiency(LWUE)and yield.The C1N0 treatment had the largest yield at 262.5 g/plant,with higher values for root length,root weight,plant height and leaf number than the other treatments.The Pn,Ci and Tr of C1N4 were the highest at 3.05μmol CO_(2)/m2·s,352.8μmol CO_(2)/m2·s and 2.31 mmol H2O/m2·s,respectively.The C1N2 treatment received the largest Gs value of 0.70 mol H2O/m2·s and the largest Tr of 2.31 mmol H2O/m2·s.There was the highest LWUE for C0N2(1.41)and the highest anthocyanin content for C1N2(1.35 mg/kg).There was a significant negative correlation between leaf number and anthocyanin(r=-0.414,p<0.05).The findings demonstrated that adding CO_(2)fertilizer and 0.2 g/L exogenous urea-N to hydroponic solution dilution is a potential N×CO_(2)coupling strategy to increase anthocyanin and the yield of purple cabbage.