Effects of Root Cutting on Morphological Characteristics and Endogenous Hormone Levels of Quercus variabilis Seedlings

The objective of this study was to investigate the effects of root cutting stress on the dynamic changes of endogenous hormone content and growth characteristics of Quercus variabilis roots,and to explore the physiological role of endogenous hormones in regulating root-crown interactions in the short term.The morphological characteristics and endogenous hormone contents of normal roots(no root cutting,CK)and cut roots(cut by 1/3 of the length of the main root,RP)were determined by liquid chromatography,which was combined with mass spectrometry at different levels of different developmental stages.The results showed that the root growth indexes and root endogenous hormones in the RP group were superior to those in the CK group.Through comprehensive analysis of endogenous hormones,it was found that the crosstalk of IAA,JA,ABA and SA could activate the root growth defense.After the root cutting treatment,the root growth of Quercus variabilis seedlings could compensate for the inhibition of taproot growth by promoting lateral root growth.The growth and development of compensatory lateral roots contribute to the increase the total root length of plants,thus promoting the absorption of water and nutrients.It is speculated that plant hormones may be the key factors affecting their development,but this is not only related to the content of a single hormone,but more importantly,it is the interaction between various hormones.

Physiological and molecular mechanisms of cytokinin involvement in nitrate-mediated adventitious root formation in apples

Potassium nitrate(KNO_(3))promotes adventitious root(AR)formation in apple stem cuttings.However,evidence for the possible involvement of cytokinin(CK)in KNO_(3)-mediated AR formation in apples is still lacking.In this study,we cultured GL-3 apple microshoots in different treatment combinations.While the T1(KNO_(3)9.4 mmol L^(-1)+6-benzyl adenine(6-BA)2.22μmol L^(-1))and T3(6-BA 2.22μmol L^(-1))treatments completely inhibited AR formation,the control,T2(KNO_(3)9.4 mmol L^(-1)),and T4(KNO_(3)9.4 mmol L^(-1)+lovastatin(Lov)1.24μmol L^(-1))treatments developed ARs.However,T4-treated microshoots developed fewer and shorter ARs,indicating that optimum CK synthesis is needed for normal AR growth.This also suggests that these fewer and shorter ARs developed because of the presence of KNO_(3) in the same medium.The anatomy of the stem basal part indicated that the inhibition of CK biosynthesis delayed AR primordia formation.The endogenous levels of indole-3-acetic acid(IAA)and zeatin riboside(ZR)were higher in T2-treated microshoots,while the abscisic acid(ABA),gibberellic acid 3(GA_(3)),and brassinosteroid(BR)levels were higher in T4-treated microshoots.The expression levels of MdNRT1.1and MdNRT2.1 were higher in T2-treated microshoots at 3 and 8 days,while MdRR2 and MdCKX5 were higher at 8 and 16 days,respectively.Furthermore,higher IAA levels increased MdWOX11 expression,which in turn increased MdLBD16 and MdLBD29 expression in response to T2.The combined expression of these genes stimulated adventitious rooting by upregulating cell cycle-related genes(MdCYCD1;1 and MdCYCD3;1)in response to T2 treatment.This study shows that specific genes and hormonal pathways contribute to KNO_(3)-CK-mediated adventitious rooting in apples.

Response of root morphology, physiology and endogenous hormones in maize(Zea mays L.) to potassium deficiency

Potassium （K） deficiency is one of the major abiotic stresses which has drastically influenced maize growth and yield around the world. However, the physiological mechanism of K deficiency tolerance is not yet fully understood. To identify the differences of root morphology, physiology and endogenous hormones at different growing stages, two maize inbred lines 90-21-3 （tolerance to K deficiency） and D937 （sensitive to K deficiency） were cultivated in the long-term K fertilizer experimental pool under high potassium （＋K） and low potassium （-K） treatments. The results indicated that the root length, volume and surface area of 90-21-3 were significantly higher than those of D937 under -K treatment at different growing stages. It was noteworthy that the lateral roots of 90-21-3 were dramatically higher than those of D937 at tasselling and flowering stage under-K treatment. Meanwhile, the values of superoxide dismutase （SOD） and oxidizing force of 90-21-3 were apparently higher than those of D937, whereas malondialdehyde （MDA） content of D937 was obviously increased. Compared with ＋K treatment, the indole-3-acetic acid （IAA） content of 90-21-3 was largely increased under-K treatment, whereas it was sharply decreased in D937. On the contrary, abscisic acid （ABA） content of 90-21-3 was slightly increased, but that of D937 was significantly increased. The zeatin riboside （ZR） content of 90-21-3 was significantly decreased, while that of D937 was relatively increased. These results indicated that the endogenous hormones were stimulated in 90-21-3 to adjust lateral root development and to maintain the physiology function thereby alleviating K deficiency.

Effect of N Fertilizers on Root Growth and Endogenous Hormones in Strawberry

Endogenous hormones play an important role in the growth and development of roots. The objective of this research was to study the effect of four types of N fertilizers on the root growth of strawberry (Fragaria ananassa Duchesne) and the endogenous enzymes of indole-3-acetic acid (IAA), abscisic acid (ABA), and isopentenyl adenosine (iPA) in its roots and leaves using enzyme-linked immunosorbent assay. Application of all types of N fertilizers significantly depressed (P ≤ 0.05) root growth at 20 d after transplanting. Application of organic-inorganic fertilizer (OIF) as basal fertilizer had a significant negative effect (P ≤ 0.05) on root growth. The application of OIF and urea lowered the lateral root frequency in strawberry plants at 60 d (P ≤ 0.05) compared with the application of two organic fertilizers (OFA and OFB) and the control (CK). With the fertilizer treatments, there were the same concentrations of IAA and ABA in both roots and leaves at the initial growth stage (20 d), lower levels of IAA and ABA at the later stage (60 d), and higher iPA levels at all seedling stages as compared to those of CK. Thus, changes in the concentrations of endogenous phytohormones in strawberry plants could be responsible for the morphological changes of roots due to fertilization.

Effects of IBA on the rooting of branch cuttings of Chinese jujube (Zizyphus jujuba Mill.) and changes to nutrients and endogenous hormones

‘Zhongqiusucui’ jujube secondary shoots were treated with 3-indolebutyric acid(IBA) at three concentrations, 500, 1000 and 1500 mg/L. Results show that IBA could significantly enhance rooting and root characteristics of cuttings and were best with IBA at 1500 mg/L. In the rooting process, the formation of adventitious roots was related to the consumption and accumulation of nutrients(soluble sugars and proteins) and the changes in endogenous hormones in phloem, leaf tips and leaf bases. The rooting of cuttings had a positive correlation with the consumption of soluble sugars during the period of callus formation and with the accumulation of soluble sugars during adventitious root formation and growth. Rooting was positively related to the breakdown of soluble proteins in the phloem when the callus formed, and had a positive correlation with its accumulation during adventitious root formation and growth. Leaf tips and leaf bases showed a reverse trend in changes of soluble protein. However, together with the phloem, leaf tips and leaf bases regulated and controlled the formation and development of adventitious roots. The main activities of soluble proteins exist in the leaf tips as this was the main source of soluble proteins. The relation between rooting and IAA(indole-3-acetic acid) content in phloem was positive and thus a high concentration of IAA could benefit the induction and formation of adventitious roots. However, rooting was negatively related with ABA(abscisic acid) and GA(gibberellic acid) and a high concentration of both could inhibit the induction and formation of adventitious roots. Rooting had a positive correlation with phloem IAA/ABA ratios, and higher ratios could improve rooting. Low concentrations of ZR(zeatin riboside) triggered the induction of adventitious roots, while higher concentrations promoted root growth.Endogenous hormones in leaf tips and bases had an impact on rooting. The activities of endogenous hormones mainly existed in leaf tips because they play a major role in the production and consumption of IAA and its ABA content increased during rooting. The ZR in leaf tips influenced the rooting of cuttings, especially in the callus formation and rooting stage. Leaf tips were the main source of GA.

Characteristics of Endogenous Hormone Variations in the Roots of Alfalfa (Medicago sativa L.) Cultivars of Different Fall Dormancies During Spring Regrowth Stage

Regrowth traits of alfalfa （Medicago sativa L.） in spring are closely related to its fall dormancy before winter. In order to determine the relationship between fall dormancy （FD） grade and hormone variation pattern and provide academic references for the variety improvement and production of alfalfa, the variations of gibberellins （GA3）, indole-3-acetic acid （IAA）, and abscisic acid （ABA） in alfalfa roots during regrowth period in spring were examined by high performance liquid chromatography （HPLC）. The study involved seven alfalfa cultivars that belonged to four fall dormant grades, i.e., 2, 4, 6, and 8. The results showed that the differences in spring regrowth among the alfalfa cultivars were partially associated with their root hormone levels. The alfalfa cultivars that belonged to the same dormancy grades presented similar variation trends in endogenous hormone content in their roots during the spring regrowth stage. At the early regrowth stage, cultivars with a higher dormant grade had a higher GA3 concent and a lower ABA content in their roots than the cultivars with a lower dormant grade; and IAA content in roots of non- and semi-fall dormancy cultivars was higher than that of fall dormancy cultivars. During the whole period of spring regrowth, the root ABA content of fall dormancy alfalfa cultivar is significantly higher than those of semi- and non-fall dormancy cultivars. GA3 contents in the roots of all cultivars under study showed a double-peak dynamic curve; root IAA contents of the studied cultivars presented a downward trend. But the trend did not significantly differed among the different fall dormant cultivars. The higher GA3 content and lower ABA content in root of non-fall dormancy alfalfa lead to its earlier regrowth. Regrowth time and rate of alfalfa can be regulated by exogenous GA3 or ABA at the early regrowth stage to meet producing requirement.

Transcriptome analysis reveals the effects of alkali stress on root system architecture and endogenous hormones in apple rootstocks

Soil alkalinity is a major factor that restricts the growth of apple roots.To analyze the response of apple roots to alkali stress, the root structure and endogenous hormones of two apple rootstocks, Malus prunifolia (alkali-tolerant) and Malus hupehensis (alkali-sensitive), were compared. To understand alkali tolerance of M. prunifolia at the molecular level, transcriptome analysis was performed. When plants were cultured in alkaline conditions for 15 d, the root growth of M. hupehensis with weak alkali tolerance decreased significantly. Analysis of endogenous hormone levels showed that the concentrations of indole-3-acetic acid (IAA) and zeatin riboside (ZR) in M. hupehensis under alkali stress were lower than those in the control. However, the trend for IAA and ZR in M. prunifolia was the opposite. The concentration of abscisic acid (ABA) in the roots of the two apple rootstocks under alkali stress increased, but the concentration of ABA in the roots of M. prunifolia was higher than that in M. hupehensis. The expression of IAA-related genes ARF5, GH3.6, SAUR36, and SAUR32 and the Cytokinin (CTK)-related gene IPT5 in M. prunifolia was higher than those in the control, but the expression of these genes in M. hupehensis was lower than those in the control. The expression of ABA-related genes CIPK1 and AHK1 increased in the two apple rootstocks under alkali stress, but the expression of CIPK1 and AHK1 in M. prunifolia was higher than in M. hupehensis. These results demonstrated that under alkali stress, the increase of IAA, ZR, and ABA in roots and the increase of the expression of related genes promoted the growth of roots and improved the alkali tolerance of apple rootstocks.

Effects of in vitro subculture on the physiological characteristics of adventitious root formation in microshoots of Castanea mollissima cv.'yanshanhong'

Microshoots of Castanea mollissima cv.＇yanshanhong＇ in vitro acquired an enhanced rooting capability with increasing numbers of subculture.In this study,we investigated the effect of successive subculture on adventitious root formation in vitro by the determination of the endogenous hormone level and the enzyme activity.The levels of indoleacetic acid（IAA）,abscisic acid（ABA）,cytokinins（CTK） and gibberellic acid（GA3） were determined by high performance liquid chromatography（HPLC）,and the activities of indoleacetic acid oxidase（IAAO）,peroxidase oxidase（POD）,and polyphenol oxidase（PPO） were measured by ultraviolet-spectrophotometer assay after the induction of rooting at 2nd,4th,6th and 8th subculture.The relationships between physiological characteristics and subculture numbers or rooting rate were as follows：The levels of endogenous IAA in microshoots gradually increased,and endogenous levels of ABA,CTK and GA3 in microshoots decreased slightly after serial subcultures.The level of IAA was highly correlated with subculture numbers and rooting rates.The ratios of IAA/ABA and IAA/CTK both acutely raised with increasing rooting rate during successive subcultures and had high correlations with rooting rate.The activity of IAAO and POD are significantly negatively related with subculture numbers,and the activity of PPO increased after subcultures.

剪顶对红松苗木非结构性碳水化合物和内源激素质量分数及不定芽发生的影响

在位于黑龙江省尚志市的东北林业大学帽儿山实验林场老山人工林实验站,以6年生红松(Pinus koraiensis)裸根苗为试验材料,进行不同剪顶时间(高生长速生期、高生长结束后)、不同留干高度(低留干40 cm、高留干70 cm)的剪顶处理,以不剪顶为对照,试验设置5种处理(2剪顶时间×2留干高度+对照),每处理3次重复,每重复40株苗木;每种处理随机选取60株苗木,剪顶后每20 d调查不定芽数量和萌芽株数,测定不定芽长度和基径;选取不定芽发生效果最佳处理(高生长速生期低留干40 cm)的苗木、对照苗木,测定苗木针叶和茎干的可溶性糖质量分数、淀粉质量分数、细胞分裂素质量分数、生长素质量分数、赤霉素质量分数、脱落酸质量分数;以红松苗木不定芽萌发和生长、红松苗木针叶和茎干的非结构性碳水化合物及内源激素质量分数变化为评价指标,以剪顶时间、留干高度为影响因素,采用双因素方差分析法、邓肯(Duncan)多重比较法,从生理角度分析剪顶时间和留干高度及其交互作用对红松苗木不定芽生长指标的影响。结果表明:剪顶时间、留干高度对红松苗木不定芽生长指标的影响显著。高生长速生期剪顶更有利于不定芽发生,低留干苗木的不定芽数量更多,而高留干苗木的不定芽长度更长。剪顶后,红松苗木针叶和茎干非结构性碳水化合物质量分数变化均无显著规律。不定芽萌发前,苗木针叶和茎干内,细胞分裂素质量分数、生长素质量分数显著上升,脱落酸质量分数显著下降;针叶的赤霉素质量分数显著上升,茎干的赤霉素质量分数变化不显著。剪顶促进红松苗木不定芽发生,最优剪顶时间为高生长速生期;低留干促进不定芽萌发数量增加,高留干促进不定芽长度增加。剪顶后,红松苗木不定芽发生与非结构性碳水化合物质量分数变化关系不大,但与内源激素变化有关;针叶和茎干内细胞分裂素、生长素质量分数上升,脱落酸质量分数下降,在红松苗木不定芽发生中起重要作用。

外源脱落酸对干旱胁迫下云南山茶幼苗内源激素代谢的影响

【目的】探究喷施外源脱落酸(abscisic acid,ABA)对干旱胁迫下两年生云南山茶紫袍(Camellia reticulata‘Zipao’)幼苗根和叶内源激素的影响。【方法】采用100 mg·L^(−1)脱落酸对云南山茶幼苗叶面喷施,并用PEG_6000模拟干旱法进行干旱胁迫,研究在干旱胁迫及复水处理下外源ABA对云南山茶根和叶的渗透调节物质和内源激素代谢组的影响。【结果】干旱及复水处理下渗透调节的关键部位是在叶。干旱胁迫下云南山茶幼苗根部促进ABA、赤霉素(gibberellins,GA)、细胞分裂素(cytokinins,CKs)含量,降低生长素(auxin,IAA)含量,而叶部促进ABA、茉莉酸(jasmonates,JA)、水杨酸(salicylic acid,SA)、IAA、CKs含量的积累。复水处理下云南山茶幼苗根部ABA、GA、CKs各激素水平逐渐下降,IAA含量逐渐上升,而叶部通过积累JA、SA、IAA、CKs含量进行调控。差异显著代谢物KEGG富集分析表明,根部代谢物显著富集在二萜生物合成通路中,叶部显著富集在植物激素信号转导途径和玉米素生物合成通路中。渗透调节物质与内源激素的相关性分析表明二者之间存在显著正相关。施用外源ABA在干旱胁迫下可分别提升云南山茶根部可溶性蛋白、可溶性糖、ABA、GA、CKs和叶部游离脯氨酸、ABA、JA的含量,进而提高耐旱力;在复水期可分别降低根部CKs和叶部JA的含量,促进根部和叶部IAA的合成,进而促进植株的恢复。【结论】云南山茶幼苗根和叶对干旱胁迫及复水处理的响应存在差异,施用外源ABA可提高云南山茶的耐旱力。

红花玉兰嫩枝扦插生根的转录组和内源激素变化分析

为探究红花玉兰嫩枝扦插不定根发生的分子机制,利用1000 mg/L的萘乙酸(NAA)处理当年生嫩枝进行扦插,分别对新采回枝条及插穗生根过程中不同阶段进行取样,开展RNA-Seq与内源激素水平分析。结果表明,(1)通过RNA-Seq总共组装了186303个Unigene,其中88161条Unigene得到注释,总注释率达到了47.32%。通过差异表达基因分析可知,相较于新采回插穗的阶段S0,在经NAA处理6 h后的S1、根原基突破表皮的S2和不定根伸长的S3阶段上调表达基因分别有5796、3205和4262个,下调表达基因分别有3795、5248和6305个;KEGG富集分析显示这些基因大多聚集于苯丙素生物合成、植物激素信号转导、淀粉和蔗糖代谢等通路中,其差异表达可能与红花玉兰的扦插生根密切相关。(2)内源激素水平分析表明:与新采回插穗S0相比,S1阶段插穗中IAA、ABA、GA 3和CTKs(IP和Zeatin)浓度均显著上升;在S2阶段IAA和ABA浓度显著降低,但IAA/ABA比值显著升高,GA 3和IP浓度升至最高且与其他阶段相比差异显著,而Zeatin变化不明显;至不定根伸长的S3阶段IAA和ABA浓度显著回升,而GA 3和CTKs浓度则显著下降。综合分析表明,生长素、脱落酸和细胞分裂素等内源激素的动态变化及其比值促进了根原基形成和不定根的伸长生长,植物激素信号转导相关基因的差异表达与内源激素水平的升降相一致,最终诱导红花玉兰嫩枝插条生根。

IAA处理对桑树嫩枝扦插生根形态、内源激素及酶活性的影响

为探讨内源激素和抗氧化酶活性对‘强桑1号’不定根形成的影响及其机制,以4种不同质量浓度(200、500、800、1000 mg/L)吲哚乙酸(IAA)浸泡1a生桑树品种‘强桑1号’插穗30 min,以清水为对照(CK).扦插后每隔10 d收集一次插条样品,共收集5次,每次每个处理取插穗5根,每个处理3次重复.采用酶联免疫法对5种内源激素IAA、ABA、ZR、GA_(3)、JA和3种氧化酶POD、PPO、IAAO进行测定.结果显示,随外源IAA处理浓度增加,内源IAA、ZR与IAA/ABA比值呈先下降后上升的变化趋势,ABA、GA_(3)、JA与IAA/ZR呈先上升后下降的趋势,抗氧化酶(POD、PPO与IAAO)的活性呈先上升后下降的变化趋势.1000 mg/LIAA处理30 min对桑树内源激素和氧化酶影响最大,外源激素IAA的施用增加内源激素IAA、ABA、ZR、JA与氧化酶POD、PPO的合成,同时促进GA_(3)与IAAO的分解代谢.研究结果为‘强桑1号’规模化扦插育苗提供理论技术支撑.

薄壳山核桃嫩枝扦插生根技术与根系发育机理研究

【目的】完善薄壳山核桃嫩枝扦插技术体系,明确影响插穗根系发育的内源性物质。【方法】以卡多、金华、马罕3个薄壳山核桃品种为试验材料,设置激素种类、遮阳率、湿度水平和容器条件四因素四水平正交试验,研究不同因素对薄壳山核桃插穗生根率和根系效果指数的影响,并分析不同根系效果指数下,可溶性糖含量、可溶性蛋白含量、生长素(IAA)含量、脱落酸(ABA)含量、IAA/ABA、过氧化物酶(POD)活性和超氧化物歧化酶(SOD)活性的变化规律。【结果】各因素对薄壳山核桃插穗生根率的影响次序为湿度水平=遮阳率>激素种类>容器条件,在IBA处理、0或60%遮阳率、60%<湿度水平≤90%下可保证薄壳山核桃插穗生根率,以IBA处理、60%遮阳率、60%<湿度水平≤80%下薄壳山核桃插穗根系发育效果较好,处于生根率筛选的优水平区间内。随着根系效果指数的增加,插穗苗干可溶性糖、可溶性蛋白含量降低,IAA含量、IAA/ABA增加、ABA含量降低,SOD、POD活性增加,其中,在根系效果指数≤0.5时,各相邻区间插穗可溶性蛋白含量和POD活性均差异显著(P<0.05);在根系效果指数≥0.3时,各相邻区间插穗IAA含量差异显著(P<0.05),且IAA/ABA提升幅度不断增大。【结论】IBA激素处理、60%遮阳率、60%<湿度水平≤80%为适宜薄壳山核桃扦插生根的优水平,插穗生根效果最优;可溶性蛋白含量、IAA含量、IAA/ABA、POD活性均与插穗根系发育密切相关。

不同楸树品种根段及枝干萌条内源激素质量分数及扦插生根率

以3个楸树品种的1年生根段萌条和枝干萌条为材料,对其进行内源激素质量分数测定和扦插生根率统计。结果表明:楸树3个品种根段萌条的生根率皆高于枝干萌条,且不同品种间,根段萌条和枝干萌条的生根率都存在极显著差异,3个品种的生根率从大到小依次为楚楸1号、洛楸1号、金丝楸;除了洛楸1号的茉莉酸和金丝楸的DL-二氢玉米素、赤霉素3的质量分数在根段萌条低于其枝干萌条外,其余激素在不同品种根段萌条中的质量分数皆高于对应枝干萌条;不同部位萌条内源激素质量分数的差异随品种不同而不同,洛楸1号有4种激素在两个不同部位萌条中存在显著差异,楚楸1号有1种存在显著差异,而金丝楸中所有激素都差异不显著;不同品种相同部位萌条中内源激素间差异分析结果表明,除脱落酸外,根段萌条中其他内源激素质量分数间的差异均大于枝干萌条;根段萌条各因素间整体相关性及显著性强于枝干萌条各因素间,反式玉米素、DL-二氢玉米素与生根率存在显著相关性。

吲哚丁酸对桃砧木GF677不定根形成过程中生理生化指标的影响

【目的】明确激素诱导对无性系砧木不定根形成的影响。【方法】以清水为对照组(CK),分别用200、500、800和1100 mg/L吲哚丁酸(3-indole butyric acid,IBA)处理桃无性系砧木GF677的1年生插穗基部,研究其扦插生根过程中生理生化指标的变化。【结果】经200 mg/L IBA(T_(1))诱导的根系效果指数显著大于其他处理(P<0.05),生根率达94.63%。处理组插穗全氮(total nitrogen,TN)、全磷(total phosphorus,TP)和全钾(total potassium,TK)含量均呈下降趋势,降幅均大于CK;插穗多酚氧化酶(polyphenol oxidase,PPO)、过氧化物酶(peroxidase,POD)和吲哚乙酸氧化酶(indoleacetic acid oxidase,IAAO)活性先增强后减弱,吲哚乙酸(indole acetic acid,IAA)含量先升高后降低,上述4个指标均在不定根形成期(21 d)出现峰值,且变幅最大为T_1处理;处理组细胞分裂素(cytokinin,CTK)含量逐渐下降,且以T_(1)处理降幅最大;处理组乙烯(ethylene,ETH)含量缓慢升高,且以T_(1)处理变幅最小。相关性分析显示:生根率与插穗TN、TP、TK和CTK含量极显著负相关(P<0.01),与IAA含量、IAAO活性和PPO活性极显著正相关(P<0.01)。【结论】T_1处理可显著提高插穗酶活性并加速IAA合成,说明200 mg/L IBA能更好地调节氧化酶和内源激素水平,促进不定根形成。

机收压实对宿根蔗产量及根系生长和内源激素含量的影响

为探明甘蔗机械收获后的土壤压实效应对宿根蔗生长的影响以及根系中内源激素的动态变化规律,以广西蔗区糖料蔗主栽品种桂糖42号作为研究对象,设计了机收时运输车碾压植蔗行和碾压行间2种处理方式,以人工砍收作为对照。结果表明:在宿根蔗苗期阶段,碾压处理后植蔗行和行间土表以下0~50 cm的土壤紧实度均大幅升高,其中0~10 cm区域增幅最大,随着土层加深,土壤紧实度增幅逐渐减小;至伸长期后,植蔗行中土壤0~30 cm纵向区域的紧实度与对照无显著差异,但30~50 cm及行间0~50 cm纵向区域的紧实度仍显著高于对照。在农艺及产量性状方面,碾压植蔗行使宿根蔗发株率显著减少42.0%,12月株高降低19.4%,有效茎数减少26.1%,蔗茎产量减产36.9%,而11月、12月和1月蔗糖分含量分别比对照提高1.40、0.75和0.58个百分点,碾压行间处理的株高、茎径、有效茎数和产量与对照相比均无显著差异。在根系形态及内源激素水平上,机收碾压植蔗行处理的根系干重和根长分别减少9.12%和10.72%,根总表面积和总体积也显著下降,而机收碾压行间的根系形态指标与对照相比无显著差异。压实处理后甘蔗根系中的IAA、GA_(3)、ZR含量均不同程度降低,IAA/ABA、GA_(3)/ABA、ZR/ABA也有同样表现,而ABA含量则显著升高;根系的内源激素含量、比值、根系形态及蔗茎产量之间存在一定相关性,IAA、GA_(3)、IAA/ABA、GA_(3)/ABA与根系干重、根长、株高、有效茎数呈正相关,ZR和ABA则呈负相关。综上,机收碾压可使蔗田土壤紧实度显著增加,使根系内源激素水平发生改变,进而影响甘蔗根系生长和产量,不同处理的减产效应差异显著,即压实植蔗行与压实行间相比,后者可显著降低压实对宿根蔗生长的影响。

桃无性系砧木不定根形成影响因子研究

为明确桃无性系砧木扦插不定根形成影响因子,给桃砧木无性系繁育提供技术指导。以桃无性系砧木GF677一年生绿枝为试材,观测了外源激素、插穗性状等因素对生根率和根系形态的影响。结果表明,外源激素IBA 200 mg/L和组合浓度IBA 120 mg/L+NAA 80 mg/L是最佳扦插浓度,生根率为96.6%和93.3%。插穗长度为15~20 cm,留3~4个半叶,且直径为3.5~5.0 mm的较嫩枝为最佳插穗,生根率保持在92.6%以上。适宜蘸根时间为10 s,基质为纯珍珠岩,或蛭石、珍珠岩、草炭按体积比1∶1∶1配制,生根率是93.5%和89.7%。6月中旬至7月中旬扦插生根率在91.9%以上。综上认为,桃无性系砧木插穗扦插前需对枝条进行连续喷施15%多效唑可湿性粉剂500倍液,或3 g/kg磷酸二氢钾水溶液5次,长15~20 cm、留3~4个半叶、直径为3.5~5.0 mm的嫩枝插穗在IBA 200 mg/L溶液或IBA 120 mg/L+NAA 80 mg/L溶液中浸泡10 s,7月中旬扦插在纯珍珠岩或配方基质中(蛭石、珍珠岩、草炭体积比为1∶1∶1),会获得最高生根率。

‘紫琦’紫薇组织培养及增殖过程中内源激素含量变化

【目的】开展‘紫琦’紫薇组培研究工作,筛选出最适培养条件,建立紫薇新品种‘紫琦’组织培养快速繁殖体系,为‘紫琦’紫薇快速繁殖提供试验参考,并探明组培苗增殖过程中内源激素的调控机理。【方法】以‘紫琦’紫薇幼嫩的带腋芽茎段为外植体,研究HgCl2处理不同时间对外植体萌发的影响;研究不同基本培养基和不同浓度的6-BA与NAA组合对‘紫琦’紫薇增殖的影响;运用酶联免疫吸附测定法测定‘紫琦’紫薇组培苗不同增殖时期4种内源激素(IAA、ABA、ZR、GA3)的含量,研究‘紫琦’紫薇增殖过程中内源激素的含量变化;研究不同IBA浓度及不同遮光天数对‘紫琦’紫薇生根的影响,并对生根组培苗进行炼苗。【结果】用HgCl2对‘紫琦’紫薇茎段进行消毒处理,消毒时间为10 min时,萌发率最高,为81.1%,污染率为19.0%;DKW培养基适合‘紫琦’紫薇继代增殖,增殖系数最高达5.90,且增殖芽多,植株生长健壮。当6-BA浓度为1.0 mg·L^(-1),NAA浓度为0.2 mg·L^(-1)时增殖系数最高;增殖过程中内源GA3含量最高,IAA含量次之,ABA和ZR含量较低,4种内源激素增殖后含量均高于增殖前,GA3/ZR、GA3/ABA和IAA/ZR值波动幅度较大,IAA/ABA和ABA/ZR值波动幅度较小;IBA浓度和遮光天数均对‘紫琦’紫薇生根影响显著,在生根培养基中添加0.6 mg·L^(-1)IBA并遮光5 d,生根率最高为94.0%,且植株生长健壮;炼苗后将组培苗移栽到泥炭土∶珍珠岩为2∶1的基质上,成活率高达94.0%。【结论】HgCl2处理时间为10 min时消毒效果最好,DKW培养基更合适‘紫琦’紫薇继代增殖,最佳增殖培养基为DKW+1.0 mg·L^(-1)6-BA+0.2 mg·L^(-1)NAA,高浓度内源IAA和GA3有利于‘紫琦’紫薇组培苗增殖分化,GA3/ZR、GA3/ABA和IAA/ZR值在增殖过程中起主要调控作用,生根诱导时添加0.6 mg·L^(-1)的IBA并遮光5 d,生根率最高。

不同培养条件及其组合对杉木无性系T-c22组培苗不定根诱导的影响

【目的】不定根诱导是杉木优良无性系繁殖的重要手段,杉木组织培养中不定根诱导受到多种因素影响,但起主导作用的关键因素尚不清楚。本研究通过比较不同培养条件对杉木不定根诱导的影响,以期研究出最适宜杉木生根的培养因素,为后续试验和研究奠定基础。【方法】以杉木T-c22无性系为试验材料,通过改变营养物质条件、植物生长调节剂种类及浓度、去除针叶情况、有无活性炭、光照条件以及不同光质等不同培养因素,统计杉木生根的各种指标,研究不同培养因素以及不同因素与光照之间的交互作用对杉木生根的影响。【结果】(1)光照比黑暗显著提高杉木组培苗的株高、生根率、平均根数以及平均根长,显著抑制杉木的根鲜质量。(2)白光和红光均能提高杉木的生根率,生根率达100%;白光能够显著提高杉木的生根数量;红光和蓝光均会显著降低杉木的根长,但能够显著提高杉木无菌苗的株高。(3)添加IBA、NAA等单一植物生长调节剂显著提高杉木的株高、平均生根数量、平均根长、根鲜质量以及根干质量;光照和单一生长调节剂的交互作用显著提高平均根数以及平均根长。(4)培养基中含有适量营养成分会显著提高杉木的生根率、生根数量、平均根长、平均根鲜质量以及平均根干质量;光照和有无营养的交互作用显著提高杉木的株高和平均根长。(5)去针叶显著提高杉木无菌苗株高、根的平均长度及平均干质量;光照和有无去针叶的交互作用对杉木不定根的诱导没有显著的影响。(6)活性炭显著降低杉木无菌苗的生根率、生根数量、根鲜质量以及根干质量;活性炭和光照的交互作用显著降低杉木的生根率以及平均根长。【结论】本研究中影响杉木T-c22无性系生根的因素重要性排序为:营养物质>植物生长调节剂的种类和浓度>不同光质>光照时间以及光照与其他因素的交互作用>有无去针叶和活性炭。最适宜杉木T-c22无性系生根的培养基配方为1/2MS+NAA 0.5 mg/L+IBA 0.5 mg/L;最适宜杉木生根的培养条件为添加适宜的营养物质、适宜浓度的植物生长调节剂(NAA 0.5 mg/L)、去除部分针叶以及红光(16 h/d)处理。

长梗柳带叶插穗不定根形成中内源激素含量变化

为了解长梗柳(Salix dunnii)带叶插穗在红光条件培养后的内源激素和不定根发育的响应,采用连续组织切片技术观察不定根发生过程,并利用酶联免疫法(ELISA)检测4种内源激素的含量。结果表明:长梗柳不定根起源于皮层,属于诱生根原基。在不定根形成过程中,随着皮层出现膨大圆点,皮部IAA含量显著上升;随着不定根的形成,插穗皮部IAA含量显著下降;插穗皮部ABA含量最高,BR含量较低,GA含量最低;而低浓度BR能诱导侧根的形成,少量GA有利于插穗基部的不定根诱导分化。通过对长梗柳bHLH基因表达量进行分析,进一步了解内源激素BR对长梗柳扦插生根的作用机理。因此,长梗柳带叶插穗的生根是由不同内源激素调控的复杂发育过程。