Study On The Flowering And Fruiting Characteristics Of Four New Varieties Of Camellia Gauchowensis Chang

Camellia gauchowensis Chang is a woody edible oil tree species planted in southern China.It has the advantages of tall tree shape,large fruit size,and high yield per plant.However,in the past,Camellia gauchowensis Chang was mostly planted with seedlings that were actually bred,resulting in severe differentiation,resulting in uneven growth and low yield in the Camellia oleifera forest.In the early stage,our research group selected four new varieties,namely ’Meilin 1’,’Meilin 2’,’Meilin 3’,and ’Meilin 4’,from more than 20000 actual oil tea plantations in Gaozhou,Guangdong.In 2022,we were granted new plant variety rights.This article takes these four new varieties of Camellia gauchowensis Chang as test materials and conducts a systematic study on their main characteristics such as flowering characteristics,insect pollination characteristics,fruit growth and development characteristics,and the impact of variety configuration on fruit setting.The aim is to explore the flowering and fruiting characteristics of these four new varieties,in order to provide scientific basis for high-yield and high-quality cultivation in production.The main results are as follows:(1)There are differences in flowering characteristics among the four varieties of Camellia gauchowensis Chang.The flowering period of four new varieties in Qingyuan,Guangdong is from mid to late November to mid January of the following year.The initial flowering period of different varieties is different,and the flowering time is from morning to evening,followed by Meilin 4,Meilin 1,Meilin 3,and Meilin 2.The flowering period of the four varieties is about 30 days.The flowering period of a single tree is generally 45 days,and the flowering time of a single flower is 6-9 days.Before flowering,the stigma has strong receptivity.On the first day after flowering,the stigma has strong receptivity,and the receptivity period after flowering is 4 days.There are significant differences in the number and germination rate of single flower pollen among four different varieties,ranging from 590000 to 850000 pollen grains.Among them,Meilin 2 has 850000 pollen grains and Meilin 3 has only 590000 pollen grains;The pollen germination rate ranges from 49.62%to 59.78%,with Meilin 3 being the highest and Meilin 4 the lowest.Different varieties have different pollen sizes and shapes,with pollen grains with polar axes ranging from 49.13 to 55.10 μm among them,Meilin 1,Meilin 3,and Meilin 4 are large grain pollen,and Meilin 2 is medium grain pollen;The equatorial view of all four varieties is oblong,while the polar view is triple lobed and nearly circular.The pollen outer walls of Meilin 1,Meilin 2,and Meilin 3 have wrinkled patterns,while Meilin 4 has hole shaped patterns.The field pollination and P/O values of Camellia gauchowensis Chang indicate that its breeding system is a specialized outcrossing type.The OCI value of the hybridization index indicates that it is an outcrossing type and requires cross pollination to complete fertilization.(2)The study on the pollination characteristics of four varieties of Camellia gauchowensis Chang shows that it is an insect borne flower,and the visiting insects mainly include 17 species in 11 families,4 orders.During the blooming period,the number of visiting insects ranked from high to low in order is Apis cerana,Vespa bicolor,Phytomia zonata,Chrysomyia megacephala,and other insects.The main pollinating insects are Apis cerana,Vespa bicolor,and Phytomia zonata.The main time and frequency of flower visits vary among different insects during the day.The peak period of flower visits by Apis ceranas is from 11:00 to 13:30 every day,while the peak period of flower visits by Vespa bicolors is from 10:00 to 11:30 and from 14:00 to 15:00 every day.The peak period of flower visits by Phytomia zonata is from 10:00 to 11:30 every day;The Apis cerana has the highest frequency of visiting flowers,reaching 4.16(flowers/min),followed by the Vespa bicolor at 3.6(flowers/min),and the frequency of the Phytomia zonata is the lowest at 2.5(flowers/min).(3)Fruit growth and development characteristics of four varieties of Camellia gauchowensis Chang.There are a large number of hairs on the epidermis of four varieties during the young fruit stage,and the hairs gradually disappear as the fruit grows;At maturity,the color of the seed coat changes to milky white,beige,reddish brown,or black.The vertical and horizontal diameters of the fruits of the four varieties all showed an "S" shaped growth curve,which continued to increase from late April to late September.Among them,Meilin 1 and Meilin 2 had a rapid growth period in vertical and horizontal diameters from late July to late September.However,Meilin 3 and Meilin 4 had a stable growth in vertical and horizontal diameters and had no significant rapid growth.The fresh fruit weight and fresh seed weight of Meilin 1,Meilin 3,and Meilin 4 all exhibit an "S" shaped growth curve,growing rapidly from July to October.The fresh fruit weight and fresh seed weight of Meilin 2 exhibit a double "S" shaped growth curve.The fresh fruit weight rapidly increases from early July to early September,from late September to early November,and from late July to late September,and from late October to late November.The water content of fresh seeds during the development period of four varieties increased rapidly from April to August,and gradually decreased as the fruits matured.The oil formation of four varieties began in mid August,and the period from late August to early November was a period of rapid oil formation.The oil formation of Meilin 1 and Meilin 2 was slightly later than that of Meilin 3 and Meilin 4.The oil content of dry kernels and fresh fruits during the mature stage of the four varieties was 44.02%-45.20%and 4.79%-7.56%,respectively.In the process of oil formation,the contents of stearic acid and oleic acid in dry kernels of the four varieties gradually increased,while the contents of palmitic acid,linoleic acid and linolenic acid in dry kernels gradually decreased.At maturity,the contents of unsaturated fat acid in dry kernels of the four varieties were 86.05%-88.62%,of which the contents of palmitic acid,stearic acid,oleic acid,linoleic acid and linolenic acid were 8.39%-10.86%,1.98%-2.47%,78.32%-83.93%,4.69%-7.73%and 0.196%-0.276%,respectively.(4)The study on the influence of four varieties of Camellia gauchowensis Chang on fruit setting showed that there were significant differences in fruit setting rate and economic traits among different pollination combinations,with a fruit setting rate of 40%-74.19%,among which Meilin 3 × Meilin 1,Meilin 3 × Meilin 2,Meilin 3×Meilin 4,the fruit setting rates of combination were 70.27%,74.19%,and 65.63%,respectively.Meilin 3 as the main pollination variety,had higher fruit setting rates than other combinations;All varieties have obvious pollen xenia.Taking Meilin 3 as the main cultivar,Meilin 1,Meilin 2 and Meilin 4 are pollinated respectively,with fruit sizes of 117.54g,107.42g and 98.81g,kernel oil content of 40.85%,39.33%and 43.24%,and unsaturated fat acid content of 86.93%,87.73%and 88.17%,respectively.Principal component analysis was conducted on the economic characteristics and fruit setting rate of different combinations of fruits,and the best combination of new varieties of Camellia gauchowensis Chang selected through comprehensive evaluation is:Meilin 1 × Meilin 2,Meilin 2 × Meilin 4,Meilin 3 ×Meilin 4,Meilin 4 × Meilin 3.