Path analysis and growth curve fitting of morphological traits to body weight of juvenile Lates calcarifer

Objective The study was conducted to explore the influences of morphological traits on body weight of juvenile Lates calcarifer,and provide theoretical evidence for selective breeding of L.calcarifer with sound morphological traits.Method Body weight (Y) and 25 morphological traits (X1-X25) from four-month-old L.calcarifer were measured.The main traits that affecting body weight of juvenile L.calcarifer were searched by correlation analysis and path analysis.The regression equation of morphological traits of four-month-old L.calcarifer to body weight was established by stepwise regression analysis,the optimal fitting curve model was also selected.ResultThe results showed that significant positive correlation between morphological traits and body weight of four-month-old L.calcarifer was found,and all the correlation coefficients reached extremely significant level (P<0.01).The path analysis revealed that distance between proboscis and the end of the second dorsal fin(X12) displayed the largest direct effect(0.589) to body weight,and follow by total length(X4),distance between proboscis and the start of the first dorsal fin(X11) affected body weight indirectly by X4,body height (X5),body width (X6) and X12.The analysis results of determination coefficients showed that the total decision coefficient of six morphological traits to body weight was 0.982,and indicating those morphological traits were the main influencing factors to body weight.The multiple regression equation of four-month-old L.calcarifer morphological traits to body weight was established by multiple regression analysis:Y=-148.455+0.506X4+ 1.382X5+2.268X6-0.064X11+0.342X12, X4,X5, X6,X11 and X12 in the were fitted with body weight respectively,the best fitting model were all power function model:Y=1.18E-05X43.011,Y=0.001X52.851,Y=0.033X62.501,Y=0.001X112.636,Y=0.001X122.799.ConclusionWhen selecting parents with body weight of four-month-old L.calcarifer as the main target,the distance between proboscis to the end of the second dorsal fin(X12) should be considered firstly,and total length(X4),body height(X5),body width(X6) and the distance of the proboscis to the origin of the first dorsal fin should be as assistant traits in the selection.