| Ligustrum Obtusifolium cv.jinye,as a small colored leaf shrub,belongs to the Oleaceae family Ligustrum genus,It is a variety of Ligustrum Obtusifolium in Northeast China,and a new type of colored leaf plant material.In the process of cultivation,the leaf color of Ligustrum Obtusifolium cv.jinye degenerated and some or all leaves of the plant degenerate to green.Therefore,how to maintain the stability of leaf color variation of Ligustrum Obtusifolium cv.jinye is worthy of further study.In this study,Ligustrum Obtusifolium cv.jinye was introduced from Changsha City of Hunan Province to Jingzhou City of Hubei Province in 2017 and continue to observe its biological habits.The cutting experiment of Ligustrum Obtusifolium cv.jinye was carried out to determine the survival rate of cutting seedlings.And an effective system of tissue culture and propagation of Ligustrum Obtusifolium cv.jinye was established.The 1-year-old cuttings of Ligustrum Obtusifolium cv.jinye were selected to count the number of plants with normal golden leaf color,and the orthogonal experiment of nitrogen,phosphorus and potassium 3 factors and 3 levels of fertilization was carried out.Anatomical methods were used to compare the differences in leaf structure of different leaf color types of Ligustrum Obtusifolium cv.jinye to explain the phenomenon of Ligustrum Obtusifolium cv.jinye less flowers and less seeds.TakingLigustrum Obtusifolium cv.jinye as scion and Ligustrum lucidum Ait.as rootstock,the factors of grafting time,rootstock thickness and scion size were set to discuss the grafting survival rate and determine the shoot biomass of scion(scion length,diameter and shoot number),so as to study the application of LigustrumObtusifolium cv.jinye in landscape greening.The results are as follows:(1)Study on biological habits of Ligustrum Obtusifolium cv.jinyeLigustrum Obtusifolium cv.jinye,as a small colored leaf shrub,belongs to the Oleaceae family Ligustrum genus.Single leaf opposite,leaf blade elliptic or oblanceolate,leaves color golden,but some leaves may turn green.The branches are dense,open and fluffy.Panicle terminal,drooping,flowering in May to July.The fruit is obovate,broadly elliptic or subglobose,and the fruiting period is from August to November,The seed yield of golden plant of Ligustrum Obtusifolium cv.jinye is about25% of that of green plant and Ligustrum lucidum Ait..Ligustrum Obtusifolium cv.jinye can live through the winter naturally,and has the characteristics of resistance to pruning,cold and golden color all year round.(2)Study on the breeding and maintenance of maintaining the stability of leaf color variation of Ligustrum Obtusifolium cv.jinyeThe results showed that: the survival rate of cuttings was 56.54% on peat soil and 45.78% on sand bed.The survival rate of base was 90.13%.The cutting survival rate in February was higher than that in June.The results of tissue culture and propagation showed that: a.Ligustrum Obtusifolium cv.jinye was suitable for inducing callus in spring;b.The best part was stem with buds;c.The best disinfection treatment was 75% ethanol for 2 min +0.1% mercuric chloride for 8 min;d.The best medium formula for inducing callus was 1/2MS + NAA0.2mg/L,the induction rate was 30%;the suitable medium formula for callus subculture was MS+6-BA1.5mg/L+2,4-D0.3mg/L;the suitable medium for callus differentiation was MS+6-BA0.5mg/L + NAA0.5mg/L.Because of the influence of COVID-19,the callus could not be changed and browning,so the test tube plantlets could not be obtained by tissue culture.The results of fertilization and maintenance management showed that:About95% of the cuttings could retain the golden leaf color normally and less than 1% of the cuttings returned to green;In order to ensure the growth of new shoots,the optimal nitrogen concentration was 9.2g/plant,the optimal phosphorus concentration was 3.2g/plant,the optimal potassium concentration was 2.2g/plant.(3)Study on anatomical structure of leaf and flower organs of different leaf color types of Ligustrum Obtusifolium cv.jinyeDue to the instability of leaf color variation of Ligustrum Obtusifolium cv.jinye,there are five types of leaf color: all green(more than 60%),most green(20%-60%),some green(5%-20%),leaves with normal corlor(0%-5%)and leaves with mottled edges(more than 60%).By observing the anatomical structure of leaves,it was found that the thickness of palisade tissue and spongy tissue of leaves with normal leaf color was 1 / 3 thinner than that of leaves with green part.The palisade tissue and spongy tissue of green leaf anatomical structure were stacked regularly,while the palisade tissue and spongy tissue of yellow leaf anatomical structure were scattered preliminary conjecture was made.By observing the anatomical structure of the flower organs of the golden and the green plants of Ligustrum Obtusifolium cv.jinye and Ligustrum lucidum Ait.,it was found that the number of pollen grains in the flower organs of the golden plant was about 25% of the green plants and Ligustrum lucidum Ait.,and the ovules development of the golden plants were not perfect,resulting in less seeds.(4)Study on application of Ligustrum Obtusifolium cv.jinye in landscapingTaking Ligustrum Obtusifolium cv.jinye as scion and Ligustrum lucidum Ait.as rootstock,the factors of grafting time,rootstock thickness and scion size were set to discuss the grafting survival rate and determine the shoot biomass of scion(scion length,diameter and shoot number),the results showed that:the survival rate of afternoon grafting was 58.02%;the survival rate of rootstock with thickness≤30mm was 52.27%;the survival rate of scion with length of 5-7mm was 49.51%.The local tree species Ligustrum lucidum Ait.can be improved by grafting. |
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