Tissue Of Walnut And Analysis Of Biological Characteristics Of Red Walnut

The walnut industry has great development prospects in our country.Because of its high nutritional value,therapeutic value and medicinal value,it has become a rare woody oil tree species for farmers and the country.At present,in order to develop the walnut industry,variety is the key.The time required to improve walnut varieties through conventional breeding methods is much longer than in vitro culture regeneration systems.Therefore,the walnut regeneration system established by tissue culture technology can not only shorten the breeding time,but also has the advantages of preserving germplasm resources in vitro.In addition,most of the dry matter in walnut fruit is produced by photosynthesis of leaves,and the photosynthetic capacity reflects the adaptability of walnut to the changes of surrounding environment.The leaves,fruits,seed skins and xylem of red pulp walnut are red,which are the special walnut red wood germplasm resources and an important reserve resource for the selection of walnut varieties for both fruit and wood.In this study,walnut stems,leaves and cotyledons were used as explants,and the best medium for inducing callus and walnut stems culture was screened,and the anatomical structure and photosynthetic physiological indexes of red and walnut leaves were determined.Aims to compare the biological characteristics of red walnut and walnut,so as to provide basic information for the development of red walnut resources and the selection of new varieties.The results of the study are as follows:1.Walnut tissue culture(1)The stem section of walnut was cultured in the primary generation.The stem section with axillary bud was connected to the medium with DKW as the basic medium.The different concentration ratio of 6-BA and IBA was set.The best medium for stem section culture was DKW+1.0 mg·L-1 6-BA+0.1 mg·L-1 IBA+500 mg·L-1 Cef+1.5 g·L-1 PVP.The germination rate of the group reached 80%,the sterile seedling grew evenly,the bud grew robust and dark green.(2)Using sterile seedlings and seedling leaves as explants to induce callus,sterile seedling leaves are easier to induce callus than seedling leaves,and the browning rate is lower.Among them,4.0 mg·L-1 6-BA+0.5 mg·L-1 NAA(Treatment 3)had the best induction effect,with a callus incidence of 62%,followed by 3.0 mg·L-1 6-BA+0.5 mg·L-1 NAA(Treatment 4),the incidence of callus was 50%,and the average browning rate was 30.8%.(3)The selection of the best medium for inducing callus of walnut cotyledons.The walnut cotyledons are separated from the fruit and connected to DKW medium.The L9(34)orthogonal design is adopted,and 6-BA,KT,IBA are used as the experimental factors.Without adding hormones as a control.The test results show that the most suitable medium for callus induction from walnut cotyledons is DKW+1.3 mg·L-1 6-BA+2.2 mg·L-1 KT+0.1 mg·L-1 IBA+500 mg·L-1 Cef+1.5 g·L-1 PVP,the callus rate was 63.12%.2.Comparison of leaf anatomical structure and diurnal variation of photosynthesis between red walnut and walnut(1)Comparing the growth indicators of the red walnut tree and the walnut tree,it is found that the trunk ground diameter,the length and thickness of the annual and biennial branches,and the three diameters of the fruit are all larger than the red walnut,and the overall growth of the red walnut tree is stronger than that of green.The walnut tree is weak.The average value of the three diameters of the red walnut fruit is smaller than that of the walnut.(2)The anatomical structure of leaves of red pulp walnut and walnut is similar,and the upper and lower epidermis cells are basically the same,and they are nearly rectangular or oval,and arranged in order.The thickness of leaves,upper and lower epidermis cells,palisade tissue and sponge tissue of red pulp walnut are all smaller than that of walnut.In the determination of pigment content in red walnut and walnut leaves,the content of chlorophyll and carotenoid in the leaves of walnut is higher than that of red walnut,and the content of anthocyanin in the leaves of red core peach leaf is significantly higher than that of walnut.(3)In this experiment,the daily changes of the net photosynthetic rate of red walnut and walnut in 2019 and 2020 were measured respectively.Generally speaking,the net photosynthetic rate of walnut is greater than that of red walnut,that is the photosynthetic capacity of walnut is greater than that of red walnut.