Application of grey correlation analysis and DTOPSIS method incomprehensive evaluation of introduced apples in Weining,Guizhou

【Objective】In order to establish the comprehensive evaluation model of apple quality and screen out the varieties(lines) with good quality,and provide theoretical basis for the optimization and adjustment of apple variety structure in Weining,Guizhou.【Method】Nine indexes including fruit weight(T1),fruit shape index(T2),peeling hardness(T3),soluble solids(T4),titratable acid(T5),the ratio of solid and acid(T6) as well as fruit color including L*(T7),a*(T8) and b*(T9) of 10 apple varieties(lines) (numbers were Z1-Z10) introduced to Weining,Guizhou were determined.Grey relational degree analysis and DTOPSIS method were used to evaluate apple qualitycomprehensively,and a comprehensive evaluation model was established.【Result】Among the 10 apple varieties(lines),Z9(16-112) had the lowest indexes of fruit weight,peeling hardness and solid acid ratio,while it had the highest value of the titratable acid content which was 0.60%. Z3(2-14),Z1(East 71-31),Z5(Qincui),Z8(8-31),Z5(Qincui) and Z9(16-112) had the highest fruit weight,fruit shape index,flesh hardness,soluble solid content,solid acid ratio and L* value,respectively. The weight values of nine fruit quality indexes were as follows:soluble solid>peeling hardness>solid acid ratio>fruit shape index>fruit weight=a*> titratable acid >L*=b*. The results of grey relational analysis showed that the G_i values were Z5(Qincui) >Z2(South 39-66) >Z1(East 71-31) >Z4(147) >Z7(39-134) >Z8(8-31) >Z10(92) >Z3(2-14) >Z6(Qinmi) >Z9(16-112). The proximity to ideal variety(C_i) values of DTOPSIS analysis were Z5>Z2>Z1>Z10>Z3>Z7>Z4>Z6>Z8>Z9. The ranking trend lines of the two evaluation methods were highly consistent. The two evaluation methods both covered most of the information of fruit quality indicators in the analysis process,which had a reliable statistical basis. The difference of C_i values was greater than that of G_i values. Apple quality evaluation model Y=0.09T1+0.11T2+0.17T3+0.19T4+0.08T5+0.15T6+0.06T7+0.09T8+0.06T9 was established combinedgrey relational degree analysis with DTOPSIS.【Conclusion】The comprehensive evaluation effect of DTOPSIS method is better,and the evaluation model established by the weight coefficient can be used for the comprehensive evaluation of apple quality. The top three evaluation results of grey relational degree analysis combined with DTOPSIS method are Qincui,South 39-66,and East 71-31,which can be used as the key varieties(lines) to optimize the structure of apple varieties in the project area.