Growth traits of pearl mussels and pearl formation percentage and size of non-nucleated pearl after graft operation

In order to screen out the high-quality combination of donor and host mussels, explore the difference and correlation in the growth traits of different pearl mussels after graft operation, compare the difference of the pearl-forming percentage and size in each combination, by using Hyriopsis cumingii (S), H. schlegelii (C) and Cristaria plicata (Z) as donor and host mussels respectively, 9 pearl mussels combinations were obtained. In addition, 3 species pearl mussels without graft operation were taken as control groups. 9 combinations and 3 control groups were compared by measuring the growth traits (body weight, shell length, shell height and shell width) one year after grafting, and at the same time the correlation of growth traits of each combination was analyzed. The number and size of non-nucleated pearl in each combination were measured, the pearl formation percentage and roundness were calculated and the difference among different combinations was analyzed. The results showed that the non-nucleated graft operation affects the growth performance of pearl mussels. The growth traits were better than corresponding values of control group when H. cumingii and H. schlegelii were host mussels. The growth traits of S-S group was biggest when H. cumingii were host mussels. The growth traits of S-C and C-C groups were biggest when H. schlegelii was host mussels. However, the growth of C. plicata groups was ess than the control group; except for the C-C group , the correlation coefficient between shell length and body weight was the highest compared to correlation coefficient of other growth traits in each group. The correlation coefficient between shell width and body weight of C-C group was the largest; the combinations between H. cumingii and H. schlegelii (S-S, C-S, S-C and C-C groups)had higher pearl formation percentage, the same with Z-Z group (91.67%-100%). S-S, S-C and C-C groups were rounder in shape but the pearl size was medium. The results showed that the non-nucleated graft operation affects the growth performance of pearl mussels and the growth performance of various combinations is different. The growth performance and pearl formation percentage of S-S, S-C, C-C groups were better but the pearl size was medium. The results provided an important basis for exploring the differences and correlation between the growth traits of different pearl mussels and the comparison of the pearl-forming rate and size of the non-nucleated pearls produced.