Large Number Of Roots Research Articles

Pertumbuhan dan Perkembangan Jaringan Meristem Bawang Merah (Allium ascalonicum L.) Kultivar Katumi Secara In Vitro

This study aimed for knowing and obtaining the best concentration of kinetin and NAA interaction effects in influencing the shoot induction, knowing how the plant growth regulators in induction mediastill affect the shoot additionin the MS0media and also knowing the largest number of roots in rooting media for shallot by in vitro. The experiment was conducted at Laboratory of Tissue Culture Seed Technology, Faculty of Agriculture, Padjadjaran University, during January 2011 until May 2011. This experiment divided in 3 stages, namely shoot induction stage, shoot subculture to MS0 media stage and shoot subculture to rooting media stage. Experimental method used in the shoot induction stage was factorial Completely Randomized Design with three replications. The first factor was the kinetin with four levels,0, 1, 2, and 3 mg L-1. The second factor was the NAA with three levels, as 0, 0.01, and 0.1 mg L-1. Basic media used for each treatment was MS. The experiment result showed there was an interaction between kinetin and NAA on shoot induction stagewith the plantlet height, leaf number, and shoot addition. The best result for leaf number was gained from interaction with 2 mg L-1 kinetin without NAA,while the treatment of 2 mg L-1 kinetin with 0.01 mg L-1 NAA gave a better interaction for theshoot addition variable.

The Effect of In-Field Rain Water Harvesting on Orange-Fleshed Sweet Potato Biomass and Yield

Water scarcity affects both food security and human nutrition. In-field rain water harvesting (IRWH) combines the advantages of rainwater harvesting, no-till, basin tillage and mulching on high drought risk clay soils. In this study, the IRWH system was customized to fit the cropping system of orange-fleshed sweet potato (OFSP). Field trials were conducted over two seasons to compare cultivation of OFSP using IRWH versus conventional tillage (CON). Data collection included plant survival, root initiation, marketable root yield, unmarketable root yield classes and biomass. Planting OFSP using the IRWH system resulted in significantly higher total biomass, higher marketable and total root yield per plant, as well as larger number of roots per plant compared to CON. Despite the relatively higher yield, total production (t/ha) was only significantly higher in season two at 4.6 t/ha vs 2.7 t/ha for CON. Subsistence farmers and households in semi-arid areas may grow small plots of orange-fleshed sweet potato in IRWH opposed to only growing maize and in that way add vitamin A to the diet. This is the first study on the application of IRWH to produce OFSP under rainfed conditions, and more research can be conducted to expand the knowledge on application and benefits of IRWH for OFSP production.

ANALISIS KONDISI HABITAT DAN PERAKARAN TUMBUHAN BAWAH PADA DAERAH TERBUKA DAN DI BAWAH TEGAKAN CEMARA UDANG DI PESISIR LEMBUPURWO, KEBUMEN

Coastal areas with sandy soil structure without trees have high temperature and salinity, strong wind, as well as minimum nutrient content. The limitation of the environment conditions affects the variety of undergrowth. This research aims to figure out the composition, distribution patterns, habitat conditions and rooting from undergrowth species which are found in coastal sandy areas at Lemburpurwo. The research was conducted using line transect method defined by systematic sampling with random start. The observations of undergrowth were carried out on 3 types of treads near from the sea, under and behind Cemara Udang stands. Paths are made perpendicular within approximately 53 m from the shoreline and the distance between lines is 95 m. Each track was divided into segments in the form of 2x2 m2 plots which were laid out diagonally between plots for undergrowth observation. 81 plots were taken, where the size of the area is 72960 m2. Undergrowth plant species were identified, the length and number of roots were measured, environmental conditions and soil quality including pH, DHL, N total content, P and K available were observed. Lembupurwo coastal sandy area consists of 20 species of 13 plant families with 3 types of random distribution pattern and 17 types of clustered distribution pattern. Spinifex littoralis has the longest root as well as the largest number of roots, especially in open areas. The pH values and electrical conductivity below the stands of 6.41; 32,23 µs/cm are lower when compared to locations near the sea. N-total and P available under stands are available 0,03%; 5,05 ppm which is higher than the other two locations.

Implication of nutrition on root development

Grapevine depends on its root system for the uptake of both water and mineral nutrients. Uptake is related to root absorptive surface area, which is influenced by root length and density. In order to reduce inputs the root efficiency is a very important factor for developing sustainable agricultural practices and for assuring optimal quality of grapes. Our study evaluated different nutritional strategies with the aim to verify the effectiveness of new products (by PRP Technologies, France), based on calcium (Ca) and magnesium (Mg), on root development and vine performance. The trial was carried out in north-eastern Italy during the 2011-2014 period on the cultivar 'Pinot gris', in a vineyard in a sandy-loam soil. Three treatments, three times replicated according to a randomized experimental layout, were compared, where test (T) indicates fertilization suggested by advisory services, while S and SF, respectively the fertilization with PRP products via soil or soil plus foliar application. Each year quantitative and qualitative data were collected; nutritional, physiological (SPAD and NDVI measurements), ecophysiological (leaf water potential and quantum efficiency of photosystem II) parameters, and grape mechanical properties (by texture analysis) were recorded. In 2013 and 2014, from each thesis a small quantity of grapes were harvested and vinified in order to obtain wines that were subjected to sensory analysis in the spring of the following year. Density of the roots was evaluated every year in summer-fall by executing the excavation of soil profiles. Both S and SF treatment exhibited a larger number of roots (“medium” and “fine”) in the deeper layers in comparison to T. This behavior significantly reflected in higher yield and better physiological, ecophysiological and berry mechanical status, without modifying nutritional levels, indicating an earlier stage of ripeness of the grapes. PRP strategies seem interesting in stimulating root activity and performance responses of vines.

Effect of mineral contents on the growth of vietnamese ginseng (Panax vietnamensis Ha et Grushv.) cultured in vitro photoautotrophically

Panax vietnamensis Ha et Grushv. is one of valuable ginseng plants in Vietnam for illness treatment and health maintenance in traditional medicine. With the aim of finding proper culture medium to produce in vitro plants of a high quality, in vitro ginseng shoots, each with an unfolded leaf, were used as explants and cultured photoautotrophically by a natural ventilation method. The culture medium was not supplemented with sucrose, vitamins and plant growth substances. Explants were put into Magenta vessels (V = 370 ml with 2 Millipore filter membranes on each vessel lid) contained 70 ml of one among four different culture media, including full-strength MS, modified MS, Enshi-Shoho or Heller medium. On day 90, ginseng plants cultured on the modified MS medium with a half-strength of both KNO3 and NH4NO3 had better photosynthetic ability and growth when compared with those cultured on the full-strength MS, Enshi-Shoho or Heller medium. The plants also had the greatest increase in plant fresh weight (261,3 mg/plant), dry weight (61,0 mg/plant), the greatest dry weight of rhizomes and roots (51,2 mg/plant) and the largest number of roots (7,6 roots/plants). Ginseng plants, cultured in vitro under photoautotrophic condition, of all treatments showed rhizome formation and development during the culture period.

Palaeolinguistics and Ancient Eurasian Pulse Crops

Traditional pulse crops such as pea, lentil, field bean, bitter vetch and chickpea were a part of the human diet in hunter-gatherer communities and are one of the most ancient cultivated crops. It was found that the Proto-Indo-European language had the largest number of roots directly related to pulses, such as *arnk(')- (a leguminous plant), *bhabh- (field bean), *erəgw[h]- (a kernel of leguminous plant; pea), *ghArs- (a leguminous plant), *kek-, *k'ik'- (pea) and *lent- (lentil), confirming their essential place in the nutrition of Proto-Indo-Europeans. Pea was most important among the Proto-Uralic people, while pea and lentil were most significant among the Proto-Altaic people. Pea and field bean were common among Caucasians and Basques, and field bean and lentil among the Afro-Asiatic peoples. Palaeolinguistics may contribute to archaeobotany in understanding the role of traditional Eurasian pulse crops had in the everyday life of ancient Europeans together with plant scientists and archaeobotanists.

Efficient plant regeneration from shoot apex explants of maize (Zea mays) and analysis of genetic fidelity of regenerated plants by ISSR markers

An efficacious regeneration system was developed from shoot apex explants of Zea mays using a two-step culture procedure. Seventeen Indian genotypes were assessed for their regeneration potential. The maximum response of shoot induction was obtained from explants cultured on Murashige and Skoog medium supplemented with 4.5 µM thidiazuron and 26.7 µM glycine. Maximum mean number of shoots (17.2) was observed in genotype COH (m)-5 while NPK was the least responsive (6.7). Shoot clumps transferred from shoot induction medium to multiplication (second) medium amended with 1.1 µM thidiazuron and 0.88 µM N 6 -benzylaminopurine showed increased number of shoots in COH (m)-5 (36.1 shoots); NPK was the least responsive with an average of 9.5 shoots. The best response in root induction, with a larger number of roots (10.5) and longer roots (6.6 cm), was observed in Murashige and Skoog medium supplemented with 7.3 µM indole-3-butyric acid and 7.9 µM phloroglucinol. Analysis of variance indicated that plant regeneration response varied greatly among the genotypes. In vitro raised plants were successfully transferred to the field after hardening, with a 99 % survival rate. Inter simple sequence repeats analysis revealed that the similarity matrix pair-wise value was 1, the Mantel test value was p 1.0; Analysis of molecular variance genetic variances were 93 % within the population and 7 % between populations; Principal component jolliffe cut off was 0.15, Principal component and Principle coordinate analysis % variance was 13.19. These values were congruent for both the mother and the in vitro-raised plants, confirming genetic integrity.

Regeneration in Tetrapleura tetraptera via Indirect Somatic Embryogenesis from Isolated Axillary Meristems

To facilitate the use of biotechnological techniques for conservation, germplasm exchange and improvement of Tetrapleura tetraptera, the study investigated in vitro plant regeneration via somatic embryogenesis from isolated axillary meristem of the plant. Indirect primary somatic embryos were induced on MS basal medium supplemented with nine different concentrations of 2,4-D. Pre-embryogenic calli were made to mature on MS basal medium containing BAP alone or with four concentrations of NAA. Secondary somatic embryos were induced on MS basal medium supplemented with nine different concentrations of 2,4-D. Maturation of the secondary pre-embryogenic calli took place on MS medium fortified with eight concentrations of BAP. Medium fortified with 6.0 mg/l 2, 4-D had the highest frequency of primary embryogenic callus (16.4%) and average number of primary immature embryo per callus (2.3). Culture media supplemented with 0.6 mg/l BAP and 0.1 mg/l NAA recorded the highest primary embryogenesis (24.5%) and average number of matured primary embryo per explant (2.8 embryos/explants). Medium fortified with 1.2 mg/l BAP gave the highest secondary embryogenesis (72.4%) and average number of matured embryo per callus (3.1 embryos per callus). Explants in medium receiving 1.0 mg/l BAP and 0.7 mg/l IBA recorded largest number of shoot-bud (27.6%) and average number of shoot-bud per explant (2.4/explant) with vigorous and green appearance. Shoot elongation was greatest in medium fortified with 1.0 mg/l BAP and 15.0 mg/l IBA with vigorous appearance. The largest number of roots (4.3/plantlet) were formed by plantlets grown in medium supplemented with 1.0 mg/l BAP and 15.0 mg/l IBA with normal appearance. The study concluded that indirect somatic embryos obtained from isolated axillary meristem with 2,4- D, BAP, NAA were capable of regeneration into normal vigorous plants.

Regeneration of multiple shoots from petiole callus of Viola serpens Wall

Experiments were conducted to develop methodology for in vitro propagation and rapid multiplication of Viola serpens Wall. using petiole explant. The MS medium supplemented with 2, 4-D (6.78 μm) was found most suitable for callus induction in petiole explant. The best growth response and higher rate of shoot regeneration from petiole callus was observed on MS medium containing BAP (11.10 μm) as the average number of shoots could be increased to 36.4 on fourth successive subculturing. Higher rooting response with larger number of roots were observed in shoots inoculated on the half-strength MS medium supplemented with IBA (19.68 μm).

ENRAIZAMENTO EX VITRO E ACLIMATIZAÇÃO DE PLANTAS MICROPROPAGADAS DE Tectona grandis

O enraizamento de espécies arbóreas é bastante complexo devido à maturidade dos tecidos. O objetivo deste trabalho foi avaliar o efeito de AIB no enraizamento ex vitro de brotos micropropagados a partir de plantas jovens de Tectona grandis L. em dois substratos, bem como da porção do broto para enraizamento. Foram utilizados brotos multiplicados in vitro inteiros, ou excisados ao meio (porção apical e basal), submetidos a imersão por 10 segundos em soluções contendo diferentes concentrações de AIB (0, 100, 1000, 2000, 4000 mg.L-1) e plantados em bandejas plásticas contendo vermiculita ou Plantmax® como substratos. O enraizamento ex vitro ocorreu em todos os tratamentos, inclusive na ausência de AIB. O maior número de raízes e o maior crescimento relativo do caule foram observados para os tratamentos com o uso de AIB, em ambos os substratos. O enraizamento ocorreu em 100% dos explantes de origem apical e basal, em ambos os substratos. O enraizamento ex vitro de brotos micropropagados de T. grandis é viável a partir de plantas jovens, e a taxa de multiplicação é duplicada com o seccionamento dos brotos em porções apical e basal.Palavras-chave: Teca; produção de mudas; micropropagação; condição ex vitro; porção do broto. AbstractEx vitro rooting and acclimatization of micropropagated plantlets of Tectona grandis. The rooting of tree species is very complex due to the maturation of tissues. The objective of this study was to evaluate the effect of IBA on ex vitro rooting of micropropagated shoots from juvenile plants of Tectona grandis L. into two substrates, as well as the portion of the shoot to root. Shoots multiplied in vitro were used with whole or excised shoots (apical and basal) submitted to immersion for 10 seconds in solutions of IBA (0, 100, 1000, 2000, 4000 mg.L-1) and planted in plastic trays containing vermiculite or Plantmax ® as substrates. The ex vitro rooting occurred in all treatments, even in the absence of IBA. The largest number of roots and higher relative growth of the stem were observed in all treatments with IBA in both substrates. The survival of acclimatized plantlets occurred in all treatments. Rooting occurred in 100% of explants from apical and basal origin in both substrates. The ex vitro rooting of micropropagated shoots of T. grandis is feasible from juvenile plants and the multiplication rate is duplicated when shoots are cutin apical and basal portions.Keywords: Teak; seedlings; micropropagation; ex vitro condition; portion of the shoot.

Microtuberização in vitro de cultivares de mandioca: aspectos morfológicos e anatômicos

Objetivou-se induzir o processo de microtuberização in vitro de cultivares de mandioca (Manihot esculenta Crantz.), em dois tipos de meio, sob a ação de diferentes reguladores de crescimento e concentrações de sacarose, e verificar as alterações estruturais decorrentes do processo de tuberização. Foram analisadas a influência do tipo de meio, a ação do BAP e ANA e doses de sacarose (3%, 6% e 8% p/v) através das características comprimento da parte aérea, o número médio de raízes, o padrão morfológico das raízes tuberiformes, bem como características anatômicas. Verifica-se que as cultivares de mandioca respondem diferentemente à microtuberização in vitro. A cultivar Parazinha responde melhor à indução de raízes tuberiformes, tendo o tratamento constituído de 0,4 µM BAP, 1,6 µM ANA e 8% sacarose como indutor na formação da raiz tuberosa, tanto em meio semisólido quanto em meio líquido. Para o comprimento da parte aérea, da raiz mais longa e o número de raízes destaca-se a Mantiqueira, porém, em meio de indução à raiz tuberiforme, foi considerada recalcitrante. Anatomicamente, a microtuberização in vitro caracteriza-se pela presença de grãos de amido.

Effect of cutting positions and growth regulators on rooting ability of Gonystylus bancanus

The effect of cutting positions and growth regulators on rooting ability ofGonystylus bancanus were studied. This study, aims to determine the effects of cutting positions (top, middle, and bottom) and hormonal treatments (control, Seradix 3, Planton 3000, IBA 100 mg and IBA 150 mg) on the rooting ability of G. bancanus. The top position recorded the highest survival percentage of 90.7% followed by the middle and bottom with values of 86.0 and 74.7%, respectively. Hormonal treatments also showed significant differences (p ≤ 0.05) in which the untreated cuttings survived the highest (93.3%) followed by Planton 3000 (88.9%) and Seradix (83.3%). Top cutting showed the highest rooting percentage of 78.0 followed by middle and bottom positions with percentages of 76.7 and 65.3, respectively. There was no significant difference observed in the rooting ability in terms of hormonal application. However, results in terms of root development based on the number of roots and vigour showed otherwise (significant at p ≤ 0.05), whereby, cuttings from bottom positions treated with IBA 150 mg produced large number of roots which were thicker and healthier. Key words: Gonystylus bancanus, cuttings positions, growth regulators, rooting ability.

Effects of plant growth regulators on the rapid proliferation of shoots and root induction in the Chinese traditional medicinal plant Atractylodes macrocephala

We developed an efficient plant regeneration protocol for rapidly propagating Atractylodes macrocephala Koidz, an important traditional Chinese medicinal plant, via shoot organogenesis. Shoot multiplication was induced on Murashige-Skoog (MS) medium supplemented with various concentrations of N-phenyl-N-1, 2, 3-thidiazol-5-ylurea (TDZ), 6-benzylaminopurine (BA) and α-naphthaleneacetic acid (NAA). Rooting was induced on half-strength MS medium supplemented with NAA and indolebutyric acid (IBA). The maximum mean number of shoots (5.61) was obtained from a single explant by the combined effect of 1.08 μmol/L NAA and 2.25 μmol/L TDZ. The longest roots and a minimum number of roots were produced when they were cultured in a medium without plant growth regulators. The shortest roots and the largest number of roots were observed in the medium supplemented with 2.7 μmol/L NAA.

Rooting success using IBA auxin on endangered Leucadendron laxum (PROTEACEAE) in different rooting mediums

Leucadendron laxum (Marsh rose Leucadendron) was tested for its rooting ability as an endangered plant species for reintroduction into the natural habitat, using IBA liquid hormone preparations and four growth media. The treatments included a control, 500, 1000, 2000 and 4000 ppm concentrations. Four growth media, namely: bark and polystyrene; peat moss and polystyrene; bark, river sand and polystyrene; and perlite and river sand were tested in an environmentally controlled greenhouse with bottom heat. The experiments used a randomised block design with 10 cuttings per treatment and 4 replicated four times. The results showed that the bark, sand and polystyrene medium had the highest (45%) significant survival rate when supplied with IBA at 500 ppm. The application of 1000 ppm of IBA in bark, sand and polystyrene medium significantly increased the number of roots per cutting (5) and produced the longest roots (4 cm). The bark and polystyrene medium supplied with zero IBA had the largest number of roots per cutting (6.5). The comparison of the four growth media showed that bark and polystyrene was the best medium that produced the highest and most significant callusing formation (30%), % of cuttings that rooted (28%), cuttings with a higher survival rate (57%), and cuttings with a higher number of roots (3.5) and the longest roots (7.35 mm). With regard to various IBA treatments tested across all treatments, the IBA supplied at 1000 ppm produced greater root numbers when compared with all other treatments.

Enraizamento de estacas herbáceas da seleção 8501-1 de goiabeira submetidas a lesão na base e a concentrações de AIB

This work aimed to evaluate the influence of different concentrations of indolebutiric acid (IBA) on the rooting potential of 0- cm long herbaceous cuttings of guava selection 850 - , submitted or not to basal lesions. The cuttings were prepared in two ways (with or without basal lesions) and submitted to four concentrations of IBA (0 mg L- , ,000 mg L- , ,000 mg L- and 3,000 mg L- ). After the lesions were made, the cuttings were placed to root in plastic boxes containing carbonized rice husk. The experiment was randomized with five replicates in 2 x 4 factorial arrangement, where each plot was composed by 0 cuttings. After 85 days, the following variables were evaluated: foliar retention (%); rooted cuttings (%); cutting survival rate (%); cuttings with callus but without roots (%); root number per cutting; root length per cutting and wet and dry root matter per cutting (g). There is no significant contrast amongst the IBA different concentrations related to the percentage of rooted cuttings, but there is a significant difference related to the root number per cutting and wet and dry root matter per cutting where the doses of ,000 and 3,000 mg L- showed the highest averages; the basal lesions do not bring improvements on the cutting rooting potential; the 3,000 mg L- IBA concentrations resulted in the largest number of roots per cutting.

Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca Welw. and Khaya ivorensis A. Chev

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30–50 cm2 had the best rooting percentage and cuttings with about 30 cm2 had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10–30 cm2 leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting.

Rooting success using IBA auxin on endangered Leucadendron laxum (PROTEACEAE) in different rooting mediums

Leucadendron laxum (Marsh rose Leucadendron) was tested for its rooting ability as an endangered plant species for reintroduction into the natural habitat, using IBA liquid hormone preparations and four growth media. The treatments included a control, 500, 1000, 2000 and 4000 ppm concentrations. Four growth media, namely: bark and polystyrene; peat moss and polystyrene; bark, river sand and polystyrene; and perlite and river sand were tested in an environmentally controlled greenhouse with bottom heat. The experiments used a randomised block design with 10 cuttings per treatment and 4 replicated four times. The results showed that the bark, sand and polystyrene medium had the highest (45%) significant survival rate when supplied with IBA at 500 ppm. The application of 1000 ppm of IBA in bark, sand and polystyrene medium significantly increased the number of roots per cutting (5) and produced the longest roots (4 cm). The bark and polystyrene medium supplied with zero IBA had the largest number of roots per cutting (6.5). The comparison of the four growth media showed that bark and polystyrene was the best medium that produced the highest and most significant callusing formation (30%), % of cuttings that rooted (28%), cuttings with a higher survival rate (57%), and cuttings with a higher number of roots (3.5) and the longest roots (7.35 mm). With regard to various IBA treatments tested across all treatments, the IBA supplied at 1000 ppm produced greater root numbers when compared with all other treatments.

Performance of cassava intercropped with maize, soybean and cowpea in the forest zone of Ghana<BR><BR>La performance du manioc intercultive avec le maïs, le soja et le niebe dans la zone forestiere du Ghana

Experiments were conducted in the forest zone of Ghana from 1997 to 1999 to assess the performance of two cassava varieties intercropped with maize, soybean and cowpea at different spatial arrangements. The cassava varieties were “Gblemoduade” and “Ankra” and spatial arrangements were (S1) one row cassava, one row maize, one row soybean, two rows cowpea; (S2) one row cassava, one row maize, two rows soybean, three rows cowpea; and (S3) one row cassava, one row maize, three rows soybean, four rows cowpea. Cowpea rows were planted in the minor season into cassava as a succeeding crop to maize and soybean after their harvest in the major season. Intercropping reduced root yield by 22-37% in “Gblemoduade” and 43-51% in “Ankra” compared to sole crops. “Gblemoduade”, on the average, yielded two and half times greater than Ankra under intercrop (24.8 vs 9.1 t ha -1 ) and monocrop (36.9 vs 17.4 t ha -1 ) as a result of larger number of roots, heavier and bigger roots than “Ankra”. Cassava yield decreased as the number of rows of soybean or cowpea increased. Root yields were similar for S2 and S3 (22.3 and 23.2 t ha -1 for “Gblemoduade” and 8.6 and 8.9 t ha -1 for “Ankra”, respectively), but were smaller than yields at S1 (28.8 t ha -1 and 9.9 t ha -1 for “Gblemoduade” and “Ankra”, respectively). “Gblemoduade” was more aggressive (a strong competitor) than “Ankra” in the system while, both cassava varieties increased in aggressivity with decreased number of soybean or cowpea rows in the mixture (i.e. S1=S2 > S3). Among the crops, maize was more competitive to cassava than soybean and cowpea. Thus, the performance of cassava can be improved by planting 1 row each of cassava, maize and soybean followed by 2 rows of cowpea (after maize and soybean harvest) and by growing the improved variety “Gblemoduade”. Keywords : intercropping, cassava, maize, soybean, cowpea Agricultural and Food Science Journal of Ghana Vol. 3 2004: 193-202

In vitro root induction in weedy amaranthus species to obtain mitotic chromosomes

Mitotic chromosome analysis has proven to be an important tool in monitoring the potential for genetic exchange among related plant species. One major obstacle to using mitotic chromosome analysis in any species is obtaining large numbers of clear, well-spread metaphase chromosomes necessary to perform cytological techniques such as chromosome banding and fluorescent in situ hybridization. The ability to obtain good chromosome spreads is in part determined by the number and morphology of the roots, which contain the metaphase tissue. Many Amaranthus species produce very thin, delicate roots. The technique used in the process described herein provides for much more substantial roots, allowing for higher probability of obtaining well-spread metaphase chromosomes. Seeds were planted in a soilless mixture, and then cuttings and leaves were taken from the plants. The cuttings were sterilized and placed in Murashige and Skoog (MS) media, while leaf tissue was analyzed by flow cytometry, both pre- and post-propagation, to obtain DNA contents. No changes in DNA content were observed. The in vitro procedure produced significantly larger roots than were produced in soilless mix. Furthermore, all of the in vitro roots observed had 32 chromosomes of normal morphology. In vitro root propagation allowed large numbers of roots to be obtained from a single plant, thereby resulting in increased probability of obtaining cells with metaphase chromosomes that reflected the original plants' chromosome numbers and therefore may be used for molecular cytogenetic analysis.

Tree fern growth strategy in the Late Devonian cladoxylopsid species Pietzschia levis from the study of its stem and root system

Portions of stems from five new anatomically preserved specimens of Pietzschia levis from a new Late Devonian plant locality of eastern Tafilalt, Anti-Atlas (Morocco), were analyzed to complete the preliminary reconstruction previously done with a single specimen. The basal part of the longest new specimen consists of an obconical portion of stem surrounded by a thick mantle of adventitious roots. Roots are connected to the peripheral strands of primary xylem specific to the stele of Pietzschia stems. Roots grow outwardly; they cross the cortex and the broad central pith at a steep angle and emerge from the stem lower down. The number of roots produced at one level increases conspicuously from the base towards the distal end of the obconical portion of stem. By contrast, cross-sectional dimensions of roots at their origin level decrease distally. Individual roots increase in diameter, and their stele gets more lobed as they grow through stem tissues. The large number of roots at the specimen base and their wider dimensions at this level contribute to the conspicuous enlargement of the stem base. Patterns assessed from the reconstruction of the Pietzschia levis root system may be close to those of the older cladoxylopsids Pseudosporochnales comprising an upright trunk. Growth strategies in the small-statured species P. levis and in younger arborescent ferns of the Psaronius type are compared. They differ mainly in the relative lengths of epidogenetic vs. apoxogenetic growth phases of the stem.