Developmental Dynamic Of Segment Membrane And Fruit Mastication Evaluation Of Two Citrus Triploid Hybrids Compared With Their Diploid Female

The edible part of citrus fruit is mainly the capsule,which consists of segment membrane and juice cell.The fruit mastication is closely related to the texture and structure of segment membrane,which is an important indicator of fruit quality.Citrus triploid fruits have high potential for application because of their nucleus-free,high yield,good quality and adaptability,but the field quality data showed that some triploid fruits were not as mastication as their diploid parents,and it is not clear how the texture and structure of triploid vesicles affect the mastication of citrus fruits.Therefore,in this study,two triploid sexual offspring(HJSD-3X and BDZSD-3X)with relatively poor mastication and their diploid parents(local early tangerine and red tangerine)as controls were used to observe and measure the thickness,developmental dynamics,texture and component content of triploid fruit segment membrane to investigate the main reasons affecting the turgidity of triploid fruits.Secondly,the hardness and shear force of the capsule coat of more than 70 triploid sexual offspring of ’Qiuhui × SD’ ploidy crosses were measured to analyze the genetic characteristics of triploid fruit mastication and to screen the superior triploid lines with good mastication,so as to help the selection of parents for citrus triploid breeding and the breeding of new citrus kernelless varieties.The main results of the study are as follows:1.The hardness of capsular coat of triploid progeny at different developmental stages was greater than that of their diploid parents.The hardness of segment membrane of BDZSD-3X,HJSD-3X and their diploid parents was measured by a mass spectrometer from 120 to 230 d after flowering.The results showed that the hardness of capsule coat of both triploid and diploid parents gradually decreased with fruit development,and the hardness of segment membrane at maturity was the least,but the hardness of segment membrane of triploid was significantly higher than that of diploid parents.The shear force of fruit capsule at maturity was measured,and it was found that the capsule shear force of triploid fruit was significantly higher than that of diploid parents.2.The segment membrane thickness during fruit development of triploid progeny was significantly greater than that of their diploid parents.Paraffin sections from 60-210 d after anthesis showed that the segment membrane thickness and number of cell layers of BDZSD-3X and HJSD-3X triploid fruit were significantly greater than those of their diploid parents at all developmental stages;at 90 d after anthesis,the cells between the capsule petals of both triploid and diploid parents began to degrade and the capsule petals began to separate,but the segment membrane thickness and number of cell layers of the triploid were greater than those of their diploid parents at that time.However,the thickness and number of cell layers of the triploid vesicle were greater than those of the diploid parent,and the phenomenon continued until fruit ripening.The cell wall structure of the segment membrane was observed by transmission electron microscopy,and it was found that the cell walls of the two triploid progenis were thicker and denser than their diploid parents at the same developmental period;the cell walls of the triploid fruit segment membrane were rough and opaque,and the cell wall thickness and microfibril distribution density were greater than those of the diploid parents.3.The cellulose,hemicellulose and pectin contents of the triploid progeny were significantly higher than those of their diploid parents at different developmental stages,while the lignin content was lower than that of the diploid parents.The results showed that the cellulose content of BDZSD-3X and its diploid parent showed an increasing and then decreasing trend,while the cellulose content of HJSD-3X and its diploid parent maintained a continuous decreasing trend,but the cellulose content of the triploid was significantly higher than that of its diploid parent at all developmental periods.The hemicellulose content of the two triploid progeny and their diploid parents showed an overall decreasing trend,and the hemicellulose content of the triploid at all developmental stages was significantly higher than that of its diploid parent.the lignin content of the two triploid progeny and their diploid parent showed an overall decreasing and then increasing trend,and the lignin content of the triploid at all developmental stages was lower than that of its diploid parent.the total pectin content of the two triploid progeny and their diploid parent showed an overall decreasing trend.The total pectin content of the two triploid progeny and their diploid parents showed an overall trend of first increasing and then decreasing,and the total pectin content of the triploid was higher than that of its diploid parent at all developmental stages.4.Qualitative analysis of the fruiting residue of ‘Fallglo × SD’ triploid progeny population.Based on the sensory evaluation,the hardness and shear force of segment membrane and capsule flap were measured for two consecutive years in the triploid population of‘Fallglo × SD’,and a total of five triploid lines with good fruit quality and good mastication were selected.The results of the mass spectrometer showed that most of the progeny of the triploid group had thicker capsular coat and 14 lines(about 19 %)had better mastication,and the mastication of the triploid progeny tended to the parent with poorer mastication and was influenced by the parent.Combined with the fruit quality evaluation,five triploid lines with excellent fruit quality and better mastication were initially screened.