Investigation Of Germplasm And The Inheritance Of Fruit Trait In Pear

In order to understand the cultivation adaptability and traits of different pear germplasm in Nanjing,322 germplasm preserved in the Jiangpu Pear Gennplasm Nursery were instigated,observing the phenological period and agronomic traits(including leaves,flowers,fruits,the shoots and other physiological traits).At the same time,hybrids population 'Niitaka'×'Hongxiangsu' was taken as experimental materials,focusing on the inheritances of some fruit traits.The results were as follows:1.The research on the phenological periods of different pear germplasm showed that the period of flower bud sprouting lasted from February 28th to March 23rd.The period of first bloom lasted from March 14th to April 7th.It takes 10-36 days from sprouting to blooming.2.The research on the botanical traits showed that 95.97%of leaf shape is ovate or elliptic.For the shape of leaf base,germplasm were sorted by number of varieties:round>truncated>heart shaped>wide wedge>wedge>narrow wedge.90.07%of the leaves belonged to acute cusp and the other was acuminate type.The leaf margins of 224 germplasms were jagged,and 44 were blunt jagged and only 5 were whole.The leaves of 273 germplasms were not lobed.For the awn,there were 213 awn and 60 non-awning varieties which contained 23 occidental pear ones.The status of leaf extension sorted by number of varieties:embracing>flat>wave>reverse.For the leaf altitude,there were 104 downward germplasms,85 obliquely upwards and 84 horizontally.The number of young leaf color were sorted as follow:light red>red yellow green>brown>light green>green yellow>dark red.The phenotypes of the flower organs of the 191 germplasm resources were abundant,and the majority were light pink flower buds,oval petals and purple anthers,which accounted for 46.60%,41.78%and 31.11%respectively.3.The investigation result of growth and fruiting habits of pear germplasm showed that the shoot biomass of pear germplasm ranged from 12.58 cm to 95.02 cm,with the average value of 53.01 cm.The number of flowers per inflorescence of different cultivars varied from 2 to 11.The fruit setting ratio of these cultivars differed greatly from each other,with the value ranging from 23.53%to 100.00%in 20 days after flowering.4.The single fruit weight of 139 varieties of pear varied greatly,ranging from 34.40 g to 404.60 g.The average mass was 190.10 g,the standard deviation was 81.51 g,and the coefficient of variation was 42.88%.The distribution of fruit shape index was 0.741 to 1.421,with an average of 0.953,a standard deviation of 0.119 and a coefficient of variation of 12.49%.The distribution of fruit stalk length in different pear cultivars was 14.80 mm to 59.80 mm,with an average value of 36.47 mm,a standard deviation of 8.22 mm and a coefficient of variation of 22.54%.The distribution of fruit diameter was 2.01 mm to 7.07 mm,the average value was 3.05 mm,the standard deviation was 0.67mm,and the coefficient of variation was 21.97%.In this experiment,the fruit hardness of 137 germplasm resources was calculated,the distribution ranged from 140.00 to 891.33 g/mm2,the average hardness was 327.37 g/mm2,the standard deviation was 134.53 g/mm2,and the coefficient of variation was 41.09%.The soluble sugar content of different pear varieties ranged from 2.94%to 8.30%,with an average of 5.47%,a standard deviation of 1.28%and a coefficient of variation of 23.40%.The distribution range of soluble solids content of pear fruit was 7.97%to 17.60%,with an average value of 11.20%,standard deviation of 1.41%and coefficient of variation of 12.59%.The range of the content of the cell content of pears in each hectogram was 0.005 g to 2.153 g,which did not conform to the normal distribution,the average value was 0.287 g,the standard deviation was 0.374 g,and the coefficient of variation was 130.31%.5.Through the heredity study of some quality traits(including single fruit weight,longitudinal diameter,transverse diameter,fruit shape index,fruit firmness,soluble solid content and stone cell content)of inter-breeding population 'Niitaka' and 'Hongxiangsu'pear cultivars.The results showed that in the hybrid offspring,the single fruit weight,the fruit longitudinal diameter and the fruit transverse diameter presented a decreasing trend which lower than the low parent,especially the single fruit weight reached 59.26%.The fruit shape index showed a close average value with patents.The highest heritability was the content of soluble solids reached 111.27%,with the individuals that over high parent up to 74.28%showing an obvious additive genetic control.The fruit firmness of hybrid progeny decreased,and the number of stone cells which less than the low parents were in the majority.There was a positive correlation between these two factors.