High frequency plantlet regeneration from nodal segment culture of female <Emphasis Type="Italic">Momordica dioica</Emphasis> (Roxb.)

An in vitro propagation method for female plants of Momordica dioica (Roxb.) has been established. The nodal segments were harvested and the cut ends of the explants were sealed with wax and then surface sterilized and cultured. Bud breaking occurred on Murashige and Skoog’s (MS) agar-gelled medium + 2.0 mg L⁻¹ 6-Benzylaminopurine (BAP) + 0.1 mg L⁻¹ Indole-3 acetic acid (IAA). The cultures were amplified by passages on MS medium supplemented with 1.0 mg L⁻¹ BAP + 0.1 mg L⁻¹ IAA. Further, shoot amplification (29.2 shoots per vessel) was achieved by subculturing of in vitro regenerated shoot clump on MS medium + 0.5 mg L⁻¹ BAP + 0.1 mg L⁻¹ IAA. The micropropagated shoots were subsequently transferred for root formation on half-strength MS medium + 2.0 mg L⁻¹ Indole-3 butyric acid (IBA) with 89% success rate. The in vitro-regenerated shoots were also rooted ex vitro with 34% success. These plantlets were hardened in the greenhouse and transferred to the field. The established protocol is suitable for true to type cloning of mature female plant of M. dioica.     

Alleviation of drought stress in maize by exogenous application of gibberellic acid and cytokinin

The study was conducted to investigate the ameliorative roles of GA₃ and CK on adverse effects of drought in maize. Drought stressed maize plants were applied with GA₃ and CK at 50, 100, and 150 mg L^?l as foliar spray at the vegetative and the reproductive stages. Plant height, internode length, stem diameter, leaf chlorophyll index, and dry matter production were significantly affected by drought. In most cases, GA₃ and CK significantly improved the depressed plant traits, but in varying degrees depending on the growth stage encountering hormones, and their types and concentrations. Both GA₃ and CK were found to be very effective in alleviating drought-imposed adverse effects on maize at the vegetative phase. Such alleviating effects varied depending on the concentration of the hormones. Application of CK at 150 mg L^?l was excellent resulting in a 106% yield advantage compared to drought stress and 79.9% increase relative to well-watered controls. Conversely, GA₃ at 50 mg L^?l performed well showing 78.8% increase in grain yield. However, both GA₃ and CK had very little effect on improving the depressed growth and yield attributes in maize at the reproductive phase. The relative yield advantages for the hormones were mainly attributed to improving the cob and seed-bearing capacity of drought-stressed maize plants.     

培养基、胚龄和激素配比对棉花胚珠离体培养纤维生长发育的影响

 为建立适合棉花胚珠离体培养纤维生长发育的实验体系，以中棉所49为材料，比较研究了培养基类型、激素种类和配比、胚龄等因素对棉花胚珠培养纤维生长发育的影响，以及棉花胚珠离体培养的基因型差异。结果表明：BT基本培养基较适合于棉花胚珠离体培养；液体培养和固体培养均能诱导棉花离体胚珠产生纤维，但液体培养效果优于固体培养；开花前后的胚珠均能诱导离体纤维的生长，但以开花当天的胚珠为外植体的效果最好。外源激素对于棉花胚珠离体培养纤维生长是必不可少的，GA₃、IAA、NAA、Ethylene和BR均促进离体培养胚珠纤维的生长，且GA₃效果最好；2种激素配合使用效果优于单一激素处理，其中5.0 μmol·L^-1 IAA+5.0 μmol·L^-1 GA₃激素配比效果最佳。棉花胚珠离体培养的纤维生长发育存在显著的基因型差异，不同棉花基因型的最适激素种类及配比具有一定的差异。     

Phenotypic correlations and site effects in a Peruvian landrace of peach palm (<Emphasis Type="Italic">Bactris gasipaes</Emphasis> Kunth)

Peach palm (Bactris gasipaes Kunth) is cultivated by smallholders in Central and northern South America, principally for fruit production. In 1997, the World Agroforestry Centre (ICRAF) and Peru’s National Institute for Agricultural Research (INIA) began a participatory genetic improvement programme of the species. The programme was started by collecting open-pollinated seed from 402 selected trees. We describe relationships between fruit characteristics of these trees, and between these characteristics and environmental variables of the collection sites. Significant relationships included the following: negative correlations between number of fruits raceme⁻¹ and measures of individual fruit size and weight (−0.34 to −0.49); non-independence between exocarp colour and fruit size (fruits with greenish-red exocarps were the largest and heaviest); unstriated fruit tended to be smaller than striated fruit; fruits with white mesocarps had starchy, yellow exocarps and tended to be lighter (but not smaller) than fruits with creamy-orange mesocarps, although total fruit weight raceme⁻¹ was higher for white mesocarps; starchy fruits, which included all yellow fruits, were bigger and heavier than oily fruits, and with higher total fruit weight raceme⁻¹. Total fruit weight raceme⁻¹ and numbers of fruit raceme⁻¹ were affected by site variables, but measures of individual size and weight and categorical fruit variables were largely unaffected. We suggest that categorical fruit variables and measures of individual fruit size and weight are likely to have higher heritabilities than total fruit weight raceme⁻¹ or number of fruits raceme⁻¹, and that phenotypic correlations involving those traits that appear to be little affected by environmental variables are more likely to have stronger genotypic components than correlations involving traits that are susceptible to environmental effects.     

Clonal propagation of triploid <Emphasis Type="Italic">Acorus calamus</Emphasis> Linn. Using dual-phase culture system

Acorus calamus is an important medicinal plant which has been used in Indian traditional medicine since time immemorial. Various bioactive molecules, viz., acorin, α- and β-asarone, asaryldehyde, caryophylene, isoasarone, methylisoeugenol, and safrol have been isolated from this plant. However, the use of this plant for medicinal purpose has been recently banned due to the high toxic property of β-asarone. The triploid Acorus calamus is reported to be low in β-asarone content and thus found to be the ideal raw material for medicinal use. The present investigation represents our finding for successful in vitro clonal propagation of the elite triploid accessions of Acorus calamus for mass propagation. In the dual-phase culture system consisting of agar-solidified Murashige and Skoog medium overlaid by liquid fraction of the same medium, maximum multiple shoot induction was favored by supplementation of α-naphthaleneacetic acid (0.5 mg L⁻¹) and 6-benzylaminopurine (2.0 mg L⁻¹). In vitro rooting of the microshoots was maximum in the medium supplemented with indolebutyric acid at 2.0 mg L⁻¹. The well-rooted microshoots could be successfully hardened and transplanted in the field. This result can be reproduced and is a viable protocol for successful clonal propagation of the seedless triploid Acorus calamus for conservation and sustainable development.     

Production of two mandarin × trifoliate orange hybrid populations via embryo rescue with verification by SSR analysis

Intergeneric sexual hybridizations were conducted between two genera of Rutaceae, with Satsuma mandarin (Citrus unshiu Marc) and Red tangerine (C. reticulata Blanco) as maternal parents, and Poncirus trifoliata (L.) Raf as the paternal parent, in an effort to generate hybrid populations for both molecular mapping and rootstock breeding. Embryo rescue is important for citrus sexual breeding because polyembryony can interfere with hybrid embryo recovery. Immature embryos of 80, 85, 90 days after pollination (DAP) from the Satsuma mandarin (S) × trifoliate orange (P) cross, 80 and 85 DAP from the Red tangerine (R) × trifoliate orange (P) cross, were cultured on MG1.0 medium consisting of MT basal medium supplemented with 1.0 mg l⁻¹ GA₃ and 4% sucrose. The results showed that 80 DAP was the optimal time for embryo rescue of the tested crosses, as evidenced by embryos at this stage exhibiting high germination rates, 37.3% for S × P and 51.3% for R × P. Among the eight tested media, MT medium supplemented with 0.5 mg l⁻¹ GA₃ was the best one for Satsuma mandarin, and MT plus 1.0 mg l⁻¹ GA₃ for Red tangerine. A total of 85 plants were obtained from S × P, and 340 from R × P. Out of them, 44 progenies from S × P and 111 from R × P were sufficiently confirmed to be hybrids by morphological characterization and SSR analysis. In addition, two hybrid callus lines were obtained from S × P and R × P respectively.     

Inheritance of beta-carotene-associated flesh color in cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.) fruit

The nutritional value of cucumber (Cucumis sativus L.) can be improved by the introgression of β-carotene (i.e., provitamin A and/or orange flesh) genes from “Xishuangbanna gourd” (XIS; Cucumis sativus var. xishuangbannanesis Qi et Yuan) into US pickling cucumber. However, the genetics of β-carotene content has not been clearly defined in this US market type. Thus, three previous populations derived from a US pickling cucumber (‘Addis’) × XIS mating were evaluated for β-carotene content, from which the high β-carotene inbred line (S₄), ‘EOM 402-10’, was developed. A cross was then made between the US pickling cucumber inbred line ‘Gy7’ [gynoecious, no β-carotene, white flesh; P₁] and ‘EOM 402-10’ [monoecious, possessing β-carotene, orange flesh; P₂] to determine the inheritance of β-carotene in fruit mesocarp and endocarp tissue. Parents and derived cross-progenies (F₁, F₂, BC₁P₁, and BC₁P₂) were evaluated for β-carotene content in a greenhouse in Madison, Wisconsin. While F₁ and BC₁P₁ progeny produced mature fruits possessing white, light-green, and green (0.01–0.02 μg g⁻¹ β-carotene) mesocarp, the F₂ and BC₁P₂ progeny mesocarp segregated in various hues of white, green, yellow (0.01–0.34 μg g⁻¹ β-carotene), and orange (1.90–2.72 μg g⁻¹ β-carotene). Mesocarp and endocarp F₂ segregation adequately fit a 15:1 [low-β-carotene (0.01–0.34 μg g⁻¹): high-β-carotene (1.90–2.72 μg g⁻¹)] and 3:1 (low-β-carotene: high-β-carotene) ratio, respectively. Likewise, segregation of carotene concentration in mesocarp and endocarp tissues in BC₁P₂ progeny adequately fit a 3:1 (low-β-carotene: high-β-carotene) and 1:1 (low-β-carotene: high-β-carotene) ratio, respectively. Progeny segregations indicate that two recessive genes control the β-carotene content in the mesocarp, while one recessive gene controls β-carotene content in the endocarp. Single marker analysis of F₂ progeny using the carotenoid biosynthesis gene Phytoene synthase determined that there was no association between this gene and the observed β-carotene variation in either fruit mesocarp or endocarp.     

IAA、GA3和ABA对稻根负向光性和生长的影响

为探明稻根负向光性与内源植物激素含量的关系,以及外源激素对水稻根系生长的影响,以扬稻6号(籼稻)、日本晴(粳稻)和中花11 (粳稻)的OsPIN1a超表达转基因水稻为材料,观察了根负向光性生长的过程,分析了负向光弯曲部位内源生长素(IAA)、赤霉素(GA₃)和脱落酸(ABA)的含量,以及外源激素对水稻根系形态和解剖结构的影响。结果表明, 扬稻6号和日本晴的根都具有负向光性,扬稻6号侧根和不定根的负向光性大于日本晴;2种材料中,IAA、GA₃和ABA在发生负向光弯曲过程中的含量变化基本一致。光照引起3种激素的含量下降;向光侧的含量低于背光侧。单侧光照和外施IAA共同促进了籼稻根毛的大量发生;与普通水稻相比,OsPIN1a超表达稻株的根负向光性角度增大。外源GA₃和ABA处理与稻根负向光性间无直接关系;外源ABA处理显著抑制了根的生长,单株根系总吸收表面积与根数均减少。10 µmol L^-1 ABA处理的水稻根尖生长异常,分生区和根冠发育不良,细胞伸长受抑,成熟区细胞变形使根局部膨胀,并改变了中央维管组织的发育。     

Corms as a source of explants for the successful clonal propagation of <Emphasis Type="Italic">Crocus cancellatus</Emphasis>

The genus Crocus comprises plants with a potential to be developed as a new ornamental crop but to date, there are not many reports on in vitro propagation of many members of this genus. The present study involves in vitro propagation of Crocus cancellatus with ornamental and horticultural value. Two different types of corm explants (apical and basal halves of corms) were cultivated onto Murashige and Skoog’s (MS) medium supplemented with different levels of α-naphthalene acetic acid (NAA) and 6-benzylaminopurine (BAP). One to five cormlets emerged from every responding explant through direct organogenesis. Apical halves of corms were more highly responsive than basal halves and produced a maximum multiplication rate with 3.45 ± 0.06 cormlets per explant in 95.33 ± 2.33% of the explants in MS medium supplemented with 3% sucrose and 2 mg L⁻¹ NAA and 1 mg L⁻¹ BAP. The effect of cold storage temperature on in vitro cormlets sprouting was studied. Cormlets stored at 4°C for 8 weeks had more statistically significant positive effects on cormlets sprouting from the controls. In vitro rooting of cormlets was induced on MS medium without plant hormones.     

Sexual crossing between two genetically female plants and sex genetics of kakrol (Momordica dioica Roxb.)

Summary Application of 200 to 800 mg/l silver nitrate (AgNO₃) to the female kakrol or teasle gourd (Momordica dioica Roxb.) plant was effective for inducing hermaphrodite flowers. Pollen grain viability of the hermaphrodite flowers was as high as that of normal male flowers. Crossing among female genotypes of different fruit morphotypes, taking pollen from the induced hermaphrodite flowers, produced fruits and seeds. Sex of hybrids between female and normal male segregated into male and female in equal proportion, while the hybrids from female homo-sexual crosses produced only female plants. This indicated that sex of kakrol is controlled by a single factor; male being heterozygous and the female is homozygous recessive. The possibility to evaluate both parents for fruit characteristics should facilitate breeding.     

In vitro culture of immature seed for rapid generation advancement in tomato

The importance of fast-trackt generation advancement in developing superior germplasm has been recognized in breeding of many crop species. To address this issue in tomato, immature seeds were excised from fruit at different maturity stages and transferred to culture medium. The best culture medium was modified full strength Moorashige–Skoog (MS) salts supplemented with 0.1 mg l⁻¹ IAA, 0.5 mg l⁻¹ IBA, 0.5 mg l⁻¹ GA₃ and 2% sucrose. If the excised seeds were able to grow, most showed shoot formation after a week. Seeds extracted as early as 10 days after pollination were successfully cultured provided they were transferred aseptically and without injury. No morphological or physiological changes in regenerated plants and their fruit relative to the parent were detected. Germination from immature seeds of tomato is a simpler alternative to in vitro culture of immature embryos or callus, as it can be undertaken in comparatively less stringent laboratory conditions. Using this approach, five generations can be produced in a year in contrast to a maximum of three generations with conventional methods. This offers an opportunity for rapid generation advancement aimed towards population development when coupled with marker assisted selection in tomato breeding for biotic and abiotic stress tolerance.     

<Emphasis Type="Italic">In vitro</Emphasis> plant regeneration,flowering and fruiting from nodal explants of <Emphasis Type="Italic">Andrographis lineata</Emphasis> nees (Acanthaceae)

In the present study, in vitro propagation of tribal endemic medicinal plant, Andrographis lineata has been established using mature nodal explants. High frequency of regeneration (91.4%) was achieved on MS medium containing BA (3.0 mg L^–1) along with IAA (0.2 mg L^–1). Strikingly, irrespective of the season and collection period, we observed axillary flower induction and fruit formation from the above in vitro cultures supplemented with BA and NAA. Transition from the vegetative to the reproductive phase occurred within 2 months of culture, and importantly was influenced by factors such as sucrose and cytokinins. In vitro-regenerated flowers were morphologically identical to in vivo flowers. Furthermore, our scanning electron microscopic studies revealed that pollen external morphology of both in vitro and in vivo flowers were similar. The flowers self-fertilized and produced fruits in vitro. Elongated shoots rooted well on half-strength MS basal medium, and were successfully acclimatized to the garden conditions. Altogether, our established protocol can be utilized in plant breeding for the purpose of ex situ conservation, quick flowering, and fruit set.     

High frequency direct plant regeneration,micropropagation and Shikonin induction in <Emphasis Type="Italic">Arnebia hispidissima</Emphasis>

The data presented herein reports a rapid and efficient method for direct plant regeneration at high frequency without intervening callus formation from shoot tip (93%) and nodal segment (60%) cultured on MS media supplemented with 0.5 mg l⁻¹ KIN, 0.25 mg l⁻¹ BAP, 0.1 mg l⁻¹ IAA and 100 mg l⁻¹ CH. Conversely, leaf and internodal explants were poorly responsive. Adventitious shoot buds arose not only from the cut ends but all along the surface of the explants leading to the formation of clusters with multiple shoots. Multiple shoots upon transfer to MS media supplemented with 2.0 mg l⁻¹ IBA induced efficient rooting (80%). In vitro flowering was observed when tissue culture-raised plantlets were maintained for extended period in culture. Shikonin was induced in roots of regenerated plants which often exudates in the culture medium was quantified spectrophotometerically by recording absorbance at 620 nm and estimated to be 0.50 mg g⁻¹ fresh weight of tissue at the end of the 50 days of culture. The regenerated plants were successfully acclimatized, hardened, and transferred to soil in green house for micropropagation. The protocol developed here will be very useful for the supply of Arnebia hispidissima all year as a raw product necessary for obtaining Shikonin for the cosmetic, dyeing, food, and pharmaceutical industries.     

Evaluation of <Emphasis Type="Italic">in vitro</Emphasis> water stress tolerance among EMS — Induced variants of banana (<Emphasis Type="Italic">Musa</Emphasis> spp., AAA), using “morphological,physiological and molecular” traits

Water stress is a serious environmental restriction to banana productivity. Hence, the objective of this study was to employ in vitro mutagenesis in selection and characterization of drought tolerant lines in banana. In vitro culture responses of ethyl methanesulphonate induced variants of banana cultivars, ‘Berangan Intan’ and ‘Berangan’ were assessed concerning morphological, physiological and molecular characteristics involving mutated shoot tips on MS medium supplemented with 30 g L⁻¹ PEG. The results showed that water stress tolerant lines could be obtained from induced variations. Variants L_2–5 and L_1–5 showed the highest number of leaves per shoot (2.37 and 2.06, respectively) and the lowest were recorded in the parental lines L_1-1 and L_2-1 (0.81 and 0.93, respectively). Fresh weight and shoot vigor rate indicated the maximum increase in the water stress tolerant lines compared with susceptible and non-mutated parental lines. L_2–5 exhibited the most increase in the chlorophyll and the most reduction in H₂O₂ and MDA contents when exposed to water stress. Under PEG treatment, proline and relative water content was enhanced in L_1–5, L_2–5, L_2–6, L_1–6, L_2–3, L_2–4, and L_1–4. RAPD analysis revealed polymorphism (18.35 and 21.48%) among variants derived from ‘Berangan Intan’ and ‘Berangan’, respectively. The amplified fragments generated by primers opc01, opc04, opa11, and opa20 observed to be specific for L_2–5 and L_1–5 as more tolerant followed by L_2–3, L_1–4, L_2–6, and L_1–6 as moderately tolerant lines against water stress. This study demonstrates the application of in vitro mutagenesis in selection of water stress tolerant lines of banana as a convenient, cheap, and rapid technique.     

Effects of chromosome 5sh from Gossypium barbadense L. on flower production in G. hirsutum L.

Cotton (Gossypium spp.) yield is directly determined by mature bolls that developed from squares and flowers. The first four to six weeks of flowering accounts for the majority of lint yield in upland cotton (G. hirsutum L.) for most cultivated areas of the southern USA cotton belt. In this study, we evaluated 13 cotton chromosome substitution lines (CS-B) and their chromosome specific-F₂ hybrids, TM-1, 3–79, and six cultivars for the number of flowers produced during the first four weeks of flowering. Results showed that CS-B05sh produced more flowers than TM-1 and 3–79 from 10 July to 5 August. The results suggest that when the short arm of chromosome 5 was substituted from 3–79 (G. barbadense L.) into TM-1 (G. hirsutum) a positive genetic association with flower numbers during this flowering period was exhibited. CS-B05sh had comparable flower numbers with three cultivars, Deltapine 90, Phytogen 355, and Stoneville 474 and more flowers than, Sure Grow 747, Sure Grow 125, and Deltapine 5415. Different patterns for additive and dominance effects on cumulative flowers were observed across weeks of flowering. Dominance effects were more apparent during the early part of the flowering period while additive effects were more apparent towards the end of the flowering period.     

A proposal for aluminum tolerance selection in white oat under hydroponic conditions

White oat genotypes were subjected to Al stress in hydroponic conditions in order to verify the viability of methods based on minimum nutrient solution (MNS) in comparison to complete nutrient solution (CNS), commonly used in the characterization and selection for Al tolerance in this species. The experimental design was completely randomized blocks with three replicates composed of 10 seedlings each. Six white oat genotypes subjected to different Al levels in minimum (0, 3, 6, and 9 mg L⁻¹) and complete (0, 10, 20, and 30 mg L⁻¹) solutions were evaluated. In this evaluation, the MNS was efficient in identifying aluminum-tolerant, white oat genotypes under hydroponics. The root growth resumption showed to be the most effective trait in the aluminum-tolerant plant selection. At concentrations equal to or higher than 3 mg Al L⁻¹ in minimum and 10 mg Al L⁻¹ in complete solution, severe damage caused by the toxic element on root development was verified. The white oat cultivars UFRGS 14, ALBASUL, and BARBARASUL showed aluminum tolerance in the tested conditions.     

Role of Nitrogen and Gibberellin (GA3) in the Regulation of Enzyme Activities and in Osmoprotectant Accumulation in Brassica juncea L. under Salt Stress

Salt stress alters a wide array of plant metabolic mechanisms. Different strategies of the application of nutrients and phytohormones are required to overcome the adverse effects of salt stress. The main objective of the present study was to determine if added nitrogen (N) and gibberellin (GA₃) in growth medium could alleviate the adverse effects of salt stress on plant metabolism. Two‐week‐old plants were fed with: (i) 0 mm NaCl + 0 mg N kg^?1 sand + 0 m GA₃ (control), (ii) 100 mm NaCl + 0 mg N kg^?1 sand + 0 m GA₃, (iii) 0 mm NaCl + 40 mg N kg^?1 sand + 0 m GA₃, (iv) 0 mm NaCl + 0 mg N kg^?1 sand + 10^?5 m GA₃, (v) 100 mm NaCl + 40 mg N kg^?1 sand + 0 m GA₃, (vi) 100 mm NaCl + 0 mg N kg^?1 sand + 10^?5 m GA₃, (vii) 100 mm NaCl + 40 mg N kg^?1 sand + 10^?5 m GA₃. Growth and physio‐biochemical attributes i.e. shoot length, leaf area, fresh weight, dry weight, net photosynthetic rate, stomatal conductance, malondialdehyde concentration, electrolyte leakage, total chlorophyll concentration, nitrate reductase and carbonic anhydrase activities, proline and glycinebetaine concentration, leaf – N, potassium (K) and sodium (Na) concentration and K/Na ratio were affected by NaCl treatment. But application of N or GA₃ alone as well as in combination proved beneficial in alleviating the adverse effects of salt stress on these growth and physio‐biochemical parameters. However, N applied with GA₃ proved more effective than N and GA₃ applied alone. The results revealed that combined application of N and GA₃ may ameliorate most of the attributes and prove to be a physiological remedy to increase the tolerance against the ill effects of salt stress in Brassica.     

两个不同彩色棉纤维品质性状形成特点及生长调节剂调节作用

选择天然棕色棉品种湘彩棉2号和绿色棉品种皖棉39,研究其纤维品质性状形成特点及激素调节作用。结果表明与常规白色陆地棉苏棉9号(对照)相比,2个彩色棉品种的纤维长度均较低,尤其皖棉39显著低于对照,主要是花后10~30 d伸长速率明显下降。两个不同彩色棉品种的纤维比强度、马克隆值和成熟度值均显著低于对照,且主要与各个品质指标形成关键期的增长率较慢有关。两个彩色棉品种10 DPA (days post anthesis)和20 DPA纤维中IAA含量,30 DPA和40 DPA ABA含量均显著低于各自对照。应用20 mg L^-1 GA₃处理棉铃后,湘彩棉2号、皖棉39 20 DPA纤维中IAA含量分别比各自对照提高51.07%、64.33%;吐絮时纤维长度分别比各自对照增加8.13%、13.96%;应用20 mg L^-1 ABA处理棉铃,40 DPA纤维中ABA含量分别比各自对照提高38.96%、24.40%,纤维比强度、马克隆值和成熟度也显著增加,其中又以皖棉39增加幅度较大。说明天然彩色棉纤维内源激素IAA和ABA含量不足影响纤维品质性状的形成,而通过植物生长调节剂应用可调节内源激素含量,改善纤维品质,且调节效应因植物生长调节剂和品种不同而异。     

Carbamate-induced flowering in asparagus (Asparagus officinalis L.) seedlings: optimization of treatment and cultivar variation in flowering response and pollen germination

Optimal carbamate treatment conditions were studied for flower induction in seedlings of an asparagus cultivar ‘Mary Washington 500 W’. Flower induction was most accelerated by soaking seeds in 50 mg l⁻¹ carbamate solution for 12 days at 25 ^°C under the fluorescent light. Longer exposure to carbamate over a 12 day period induced a higher percentage of seedlings to flower. A higher percentage of flowering seedlings were male. Flower induction frequency among seven cultivars through carbamate treatment widely ranged from 13 to 67%. ‘Geynlim’, ‘Mary Washington 500 W’ and ‘Welcome’ exhibited a high percentage of flowering seedlings, while ‘Larac’ and ‘Vulkan’ showed low values. Only male flowers were induced in all-male cultivars. Variation in pollen germination was found within all cultivars. ‘Geynlim’, ‘Cito’ and ‘Mary Washington 500 W’ showed high values of average pollen germination. Application of carbamate compound to induce flower production can rapidly produce homogenic cultivars which include both sexes. This is necessary for genetic studies and breeding purposes. This revised version was published online in August 2006 with corrections to the Cover Date.     

外源ABA和6-BA对不同持绿型小麦籽粒灌浆进程及蛋白质含量影响

本文旨在揭示持绿型小麦品种的灌浆特性和籽粒蛋白质含量对外源激素的响应,认识植物激素调控籽粒灌浆和蛋白质合成的作用机制。自盛花期开始,连续4 d喷施10 mg L^-1脱落酸(ABA)和6-苄基腺嘌呤(6-BA),持绿型品种汶农6号的灌浆期(t₃)、活跃生长期(D)、平均灌浆速率(G_mean)、最大灌浆速率(G_max)、千粒重(TGW)和产量(GY)均大于非持绿型济麦20,且强势粒的各项灌浆参数均大于弱势粒。喷施两种外源激素显著提高两品种的G_mean、G_max、TGW和GY,对t₃和D的影响存在粒位及品种效应。喷施ABA和6-BA均显著提高花后35 d的籽粒蛋白质含量,显著提高汶农6号强、弱势粒的麦谷蛋白含量,但济麦20强、弱势粒的麦谷蛋白含量显著降低。喷施ABA后,汶农6号强势粒花后7~21 d的玉米素核苷(ZR)含量显著升高;喷施6-BA后,济麦20弱势粒花后14~35 d的ZR含量显著升高,而汶农6号强势粒7~21 d的赤霉素(GA₃)含量显著降低,弱势粒花后7~28 d的GA₃含量显著提高。喷施外源ABA和6-BA显著提高两品种强势粒花后7~21 d的生长素(IAA)和ABA含量。ABA和6-BA处理显著提高花后7~21 d谷氨酰胺合成酶(GS)活性。可见,喷施外源ABA和6-BA使小麦内源激素水平变化,促进籽粒灌浆,增加粒重和产量,提高籽粒GS活性和蛋白质含量,改变蛋白质组分。