【作者】 王小玲；

【导师】 赵忠；

【作者基本信息】 西北农林科技大学 ， 森林培育， 2011， 博士

【摘要】 四倍体刺槐是由人工诱导二倍体刺槐(2n)体细胞加倍(4n)而育成的优良品种。引种试验证明:四倍体刺槐在我国东经86。～124。、北纬23。～46。的广大地区、甚至西藏高原都可种植,可作为普通刺槐的替代品种。生产上四倍体刺槐主要以嫁接繁殖为主,因繁殖速度慢、繁殖系数低、育苗周期长,难于满足需求,致使苗木价格居高不下;利用组织培养繁殖需要一定的物质和技术条件,在基层单位广泛应用存在一定难度;播种繁殖不能很好的保持母本优良性状,林分生产力低。扦插繁殖作为一种典型的、简单的繁殖方法,已经在许多树种中广泛应用。四倍体刺槐属于扦插难生根树种,国内外虽已有报道解决了扦插成活率低的问题,但由于缺乏对四倍体刺槐插条不定根发生调控机理的研究,其快速育苗技术仍不成熟,成为制约其大范围推广的瓶颈。本研究主要以1 a、3 a和5 a生四倍体刺槐母树上剪取的1 a生硬枝和当年生的半木质化嫩枝为材料,运用阳畦和配有全光照自动间歇喷雾装置的育苗池育苗法,系统开展了四倍体刺槐硬枝和嫩枝扦插繁殖技术研究,通过不定根发生过程中插穗下端形态和解剖学特性变化研究,划分不定根发生的阶段。在此基础上,重点研究了不同扦插技术对插条内生理生化特性的影响,以及不定根不同发育阶段生理生化特性的差异。主要研究结果有:1.四倍体刺槐嫩枝扦插生根率和不定根发生速度大于硬枝扦插。嫩枝扦插生根率最高为87.26%,不定根生成需30 d～40 d;硬枝扦插生根率最高为73.33%,不定根生成60 d左右。2.生长调节物质IBA处理硬枝和嫩枝插穗,可显著促进生根效果。硬枝扦插以IBA1000 mg·L-1,浸泡6 h的处理最佳;嫩枝扦插以IBA1400 mg·L-1,浸泡4 h处理最佳。3.插壤温度对四倍体刺槐硬枝插条不定根发生起着一定的调控作用。不定根发生的最低积温是121.32℃,不定根大量形成的最低积温是276.0℃,当积温提高98.26℃时,生根率可提高13.16%。4.采穗圃母树年龄对四倍体刺槐硬枝和嫩枝插条的生根能力影响很大。随着母树年龄的增加,四倍体刺槐硬枝和嫩枝扦插生根能力下降。嫩枝扦插随着扦插时间的推迟,生根能力也下降。因此,建议四倍体刺槐扦插采用1～3 a生母树,嫩枝扦插以5月中旬～7月中旬为宜。5.四倍体刺槐硬枝和嫩枝扦插生根过程可划分为3个主要时期:a愈伤组织诱导期,b不定根形成期(根原基诱导期),c不定根表达与伸长期。四倍体刺槐硬枝和嫩枝扦插前插穗内无潜伏根原基,扦插后在切口愈伤组织中诱导产生根原基,不定根从愈伤组织伸出。6.扦插过程中,内源IAA是影响四倍体刺槐生根的关键因子,内源IAA含量与生根率呈明显的负相关。硬枝插穗体内IAA含量高于嫩枝插穗,也是硬枝扦插生根率低于嫩枝的主要原因之一。内源ZR可促进插穗生根,其含量与生根率呈正相关。ABA含量的高低不是抑制生根的主要原因,而在生根过程中起协助作用。IAA/ABA比值的高低,可作为衡量其生根的指标之一,比值越低,生根率越高。7. IAAO、POD和PPO是与四倍体刺槐扦插生根有一定关系的3种酶。扦插前,插穗体内IAAO活性对生根率的影响最大,PPO次之,POD影响最小。根原基诱导期,插穗体内PPO活性对生根率的影响最大,IAAO次之,POD影响最小。因此,生根过程中,插穗体内IAAO活性和PPO活性与生根关系密切,POD活性与生根关系不密切。8.四倍体刺槐扦插过程中,可溶性蛋白质含量、可溶性糖含量和C/N比与生根率之间呈正相关。淀粉含量与生根率呈负相关。总氮含量对生根率的影响很小。9.硬枝扦插,基质温度提高后,主要是通过降低插穗体内IAA含量,提高可溶性蛋白质和可溶性糖含量的积累,并促进淀粉水解来影响生根。温度对硬枝插穗体内氧化酶活性的影响较小。更多还原

【Abstract】 Tetraploid locust is an excellent cultivar of Robinia pseudoacacia acquired by artificially inducing the doubling of the diplod locust genome. The result of introduction field experiments showed that tetraploid locust can plant grow across large areas in China, between 23°～24°N, and 86°～124°E, including part of Tibet. It could potentially replace the ancestral diplod locust.The tetraploid locust is generally propagated by grafting. The major shortcoming of grafting is its long wait time until maturity. For example, rootstocks need to be prepared 1-2 years before grafting. Then 2～3 more years are needed before the grafted plants can be transplanted. Laboratory-based in vitro propagation is a promising method for producing clonal plants. However, this method is technically demanding and requires good laboratory setup. As a result, it’s difficult to use this method for most plants in most places. Seed propagation is another way to propagate tetraploid locust, but the superior characteristics of the parent plants can’t be guaranteed to pass onto the offspring. As a result, the offspring may not be as productive as the parents. The last method is cutting propagation, a widely used method for clonally reproducing other plants.Cuttings from tetraploid locust are often difficult to root. In some reports, high rooting rate had gotten with proper treatments. However, the rapid reproduction technique is not reality with the absent of rooting mechanism on tetraploid locust. In this study, annual branch (hardwood and softwood cuttings) in the 1-, 3-, 5-year-old cutting orchard of tetraploid locust were token as materials. The reproduction techniques for rooting hardwood and softwood cuttings were systematically studied and the adventitious roots inducing process of tetraploid locust cuttings were divided, which was depended on the studies of morphologic and anatomical characters. Then, the effect of reproduction techniques on physiological and biochemical characters and the physiological and biochemical differences of adventitious roots on rooting processes were studied. The main results are summarized below.1. The rooting percentage and propagation speed of softwood cuttings on tetraploid locust are higher than those using hardwood cuttings. The highest rooting percentage is 87.26% and propagation period is 30 to 40 days in softwood cuttings. In contras, the highest rooting percentage of 73.33% and 60 days are required for hardwood cuttings. 2. Hardwood and softwood cuttings pre-treated with the growth regulator IBA showed significant inprovement in rooting performance of tetraploid locust. We found that hardwood cuttings pre-treated with 1000 mg·L-1 IBA solution for 6 h and softwood cuttings pre-treated with 1400 mg·L-1 IBA solution for 4 h produced the best rooting regeneration.3. The present study showed that increasing ground temperature of significantly improved root generation of hardwood cuttings. The lowest effective accumulated temperature is 121.32℃for root initiation and 276.0℃for large roots formation. Rooting percentage improved by up to 13.16% with increasing effective accumulated temperature 98.26℃.4. Rooting ability of hardwood and softwood cuttings decreased with the age of the parental plant. Rooting ability of softwood cuttings also decreased with the delay of planting time. Our results showed that 1 to 3 year parent stocks produce the highest rooting survival and the optimum time for planting softwood cuttings was between mid-May and mid-July.5. The adventitious root formation of the tetraploid locust goes through three distinct phases, i.e. the callus induction phase, the root primordial formation phase, and the initiation and elongation phase of adventitious roots. There is no root primordial on hardwood and softwood cuttings of tetraploid locust before planting. Root primordial was produced from callus after planting which then initiated the adventitious roots formation.6. During root formation, the high concentration of endogenous IAA is inhibitory. Endogenous IAA concentration is negatively correlated to the rooting percentage. One of the important reasons that the rooting percentage of hardwood cuttings was lower than softwood cuttings is its higher IAA concentration. On the other hand, endogenous ZR can promote rooting of cuttings. ZR concentration is postively correlated to the rooting percentage. Another hormone ABA can assist root formation and is concentration dependent. Overall, the IAA/ABA ratio plays an important role in regulating the rooting of locust cuttings. The higher IAA/ABA ratio, the higher rooting percentage.7. IAAO, POD and PPO are three important enzymes associated with cutting rooting of tetraploid locust. Before planting, IAAO activity had the greatest influence on rooting percentage, the second was PPO activity and POD activity was the smallest. During root primordial formation, PPO activity had the greatest influence on rooting percentage, the second was IAAO activity, and POD activity was again the smallest. Thus, during the rooting process, IAAO and PPO activities in the cuttings were closely related to the development of adventitious roots. However, POD activity of cuttings had relatively little influence on the development of adventitious roots.8. During tetraploid locust rooting, the soluble protein content, soluble sugar content, and C/N ratio are all positively correlated to the rooting percentage. The starch content was negatively correlated to the rooting percentage. The total nitrogen content was not correlated to the rooting percentage.9. The effect of ground substrate temperature on hardwood cutting rooting percentage is mainly trough increasing the content of soluble proteins and soluble sugar, speeding up the degradation of starch. However, ground temperature had little influence on oxidase activity of the cuttings.更多还原