| Tobacco(Nicotiana tabacum L.)is an economic crop that harvests leaves and is also a fertilizer crop.Reasonable fertilization can not only improve the yield and quality of tobacco leaves,but also improve soil fertility and protect the ecological environment.In order to screen the best ratio of nitrogen,phosphorus and potassium in local flue-cured tobacco production and the most suitable organic fertilizer source,Jiyan 9 flue-cured tobacco varieties were used as materials.Firstly,based on the nitrogen application rate screened in the previous work of the research group,five different phosphorus and potassium ratio treatments were set under equal nitrogen conditions to screen the best ratio of nitrogen,phosphorus and potassium.Secondly,under the optimum ratio of nitrogen,phosphorus and potassium,three different organic fertilizer sources were set up to select the most suitable organic fertilizer.The effects of different fertilizer combinations on yield and quality of flue-cured tobacco were studied by measuring agronomic traits,economic traits,photosynthetic physiological indexes,activities of some related enzymes,physical properties,chemical components and neutral aroma substances content of flue-cured tobacco.At the same time,the comprehensive evaluation of different treatments was carried out based on principal component analysis.It aims to provide theoretical basis and technical support for flue-cured tobacco production.The main research results are as follows:(1)The results of N-P-K ratio test showed that the yield,superior tobacco ratio,photosynthetic rate,NR and INV enzyme activities,nicotine content,potassium/chlorine,tensile strength and total content of neutral aroma substances of 15 indexes in each treatment were increased rapidly at first and then tended to be gentle with the increase of phosphorus and potassium content under the condition of equal nitrogen(75 kg/hm~2).When the ratio of nitrogen,phosphorus and potassium reached 1:1.5:2.5(C treatment),they reached or approached the peak.The reducing sugar content,total nitrogen content,Schmuck value,filling value and other eight indicators,under the condition of equal nitrogen with the increase of phosphorus and potassium content,showed a rapid decline first and then tend to flatten trend,when the ratio of nitrogen,phosphorus and potassium reached 1:1.5:2.5(C treatment),were reached or close to the valley value.At the same time,it was found that there was no significant difference between the three nitrogen,phosphorus and potassium ratio treatments near the peak or valley value.(2)The results of principal component analysis based on the measured values of 16indicators showed that the comprehensive evaluation order of 5 NPK ratios was 1:1.5:2.5(C),1:2:2.5(D),1:2.0:3.0(E),1:1:1.5(B)and 1:0.5:1(A).(3)The results of the combined application of chemical fertilizer and organic fertilizer showed that the combined application of chemical fertilizer and organic fertilizer(T2 and T3)was significantly better than that of the single application of chemical fertilizer(T1)in agronomic traits,economic traits,photosynthetic physiological indexes,antioxidant enzyme activity,physical characteristics,chemical composition and neutral aroma substance content.The soybean cake fertilizer(105 kg/hm~2)as the source of organic fertilizer(T3)was better than that of the tobacco-specific organic fertilizer(225 kg/hm~2)(T2).In summary,in the local flue-cured tobacco production,the treatment combination with soybean cake fertilizer(105 kg/hm~2)as organic fertilizer source and nitrogen,phosphorus and potassium ratio of 1:1.5:2.5 showed the best comprehensive performance under nitrogen application of 75 kg/hm~2.That is not only to ensure the suitable yield of tobacco leaves,but also to increase the proportion of superior tobacco leaves and aroma quantity,at the same time,the chemical composition of tobacco leaves tends to be coordinated and the industrial usability tends to be better,which can provide technical support for the production of high quality filler tobacco. |
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