Interaction of temperature and vegetative flush maturity influences shoot structure and development of lychee (Litchi chinensis Sonn.)

Potted lychee trees (cv. Tai so) of varying vegetative flush maturity were grown under a range of temperature regimes and monitored for subsequent shoot structure and development. A combination of low temperature (15/17 or 18/13 degreesC day/night) and high vegetative flush maturity was necessary for floral initiation to occur, Exposure to high temperatures (28/23 degreesC) invariably resulted in the production of vegetative shoots, irrespective of flush maturity. Strong floral initiation was marked by the emergence of terminal particles and accompanying axillary particles. A decrea,;e in vegetative flush maturity or increase in temperature (e.g. 23/18 degreesC) resulted in a decrease in axillary shoot formation and the production of several intermediate shoot structures. These included leafy particles, stunted particles, partially emerged buds and non-emergent swollen buds, often produced on the same tree. At 23/18 degreesC, closer synchronisation of initial flush maturity was required for the production of a consistent shoot-type. Trees with synchronised mature flushes (I-2) at 23/18 degreesC resulted in the production of swollen terminal buds. Healthy trees were maintained in this state for at least 11 months. These results indicate that both temperature and flush maturity can influence subsequent shoot structure of lychee. In the absence of either a strong floral temperature (18/13 degreesC) or strong vegetative temperature (28/23 degreesC), slight differences in initial flush maturity have gteater impact on the type of emerging shoot formed. (C) 2002 Elsevier Science B.V. All rights reserved.

Regulation of woody plant development by gibberellin catabolic and signaling genes

Gibberellin (GA) is a growth promoting hormone implicated in regulating a diversity of plant processes. This dissertation examines the role of GA metabolic and signaling genes in woody plant growth and development. Transgenic modifications, expression analysis, physiological/biochemical assays, biometric measurements and histological analysis were used to understand the regulatory roles these genes play in the model woody plant, Populus. Our results highlight the importance of GA regulatory genes in woody perennial growth, including: phenology, wood formation, phenotypic plasticity, and growth/survival under field conditions. We characterize two putative Populus orthologs of the SHORT INTERNODES (SHI) gene from Arabidopsis, a negative regulator of GA signaling. RNAi-mediated suppression of Populus SHI-like genes increased several growth-related traits, including extent of xylem proliferation, in a dose-dependent manner. Three Populus genes, sharing sequence homology to the positive regulator of GA signaling gene PHOTOPERIOD-RESPONSIVE 1 (PHOR1) from Solanum, are up-regulated in GA-deficient and insensitive plants suggesting a conserved role in GA signaling. We demonstrate that Populus PHOR1-like genes have overlapping and divergent function(s). Two PHOR1-like genes are highly expressed in roots, predominantly affect root growth (e.g., morphology, starch quantity and gravitropism), and induced by short-days (SD). The other PHOR1-like gene is ubiquitously expressed with a generalized function in root and shoot development. The effects of GA catabolic and signaling genes on important traits (e.g., adaptive and productivity traits) were studied in a multi-year field trial. Transgenics overexpressing GA 2-oxidase (GA2ox) and DELLA genes showed tremendous variation in growth, form, foliage, and phenology (i.e., vegetative and reproductive). Observed gradients in trait modifications were correlated to transgene expression levels, in a manner suggesting a dose-dependent relationship. We explore GA2ox and DELLA genes involvement in mediating growth responses to immediate short-term drought stress, and SD photoperiods, signaling prolonged periods of stress (e.g., winter bud dormancy). GA2ox and DELLA genes show substantial up-regulation in response to drought and SDs. Transgenics overexpressing homologs of these genes subjected to drought and SD photoperiods show hypersensitive growth restraint and increased stress resistances. These results suggest growth cessation (i.e., dormancy) in response to adverse conditions is mediated by GA regulatory genes.

Shoot meristem maintenance is controlled by a GRAS-gene mediated signal from differentiating cells

Plant shoot development depends on the perpetuation of a group of undifferentiated cells in the shoot apical meristem (SAM). In the Petunia mutant hairy meristem (ham), shoot meristems differentiate postembryonically as continuations of the subtending stem. HAM encodes a putative transcription factor of the GRAS family, which acts non-cell-autonomously from L3-derived tissue of lateral organ primordia and stem provasculature. HAM acts in parallel with TERMINATOR (PhWUSCHEL) and is required for continued cellular response to TERMINATOR and SHOOTMERISTEMLESS (PhSTM). This reveals a novel mechanism by which signals from differentiating tissues extrinsically control stem cell fate in the shoot apex.

Impact of root and shoot temperature on bud dormancy and floral induction in lychee (Litchi chinensis Sonn.)

Potted lychee trees (cv. Tai so) with mature vegetative flushes were grown under three day/night temperature regimes known to induce floral (18/13degreesC), intermediate (23/18degreesC) and vegetative (28/23degreesC) shoot structures. Heating roots respective to shoots accelerated bud-break and shoot emergence, but reduced the level of floral initiation in emergent shoots. At 18/13degreesC, root temperatures of 20 and 25degreesC decreased the period of shoot dormancy from 9 weeks to 5 and 3 weeks, respectively. A root temperature of 20degreesC also increased the proportion of both leafy and stunted panicles to normal leafless panicles, and reduced the number of axillary panicles accompanying each terminal particle. A root temperature of 25degreesC produced only vegetative shoots. At 23/18degreesC, heating roots increased the proportion of vegetative shoots and partially emerged buds to leafy and stunted particles as well as accelerating bud-break. Cooling of roots in relation to the shoot resulted in non-emergence of buds at both 28/23 and 23/18degreesC. Bud-break did not occur until root cooling was terminated and root temperature returned to that of the shoot. At 23/18degreesC, subsequent emergent shoots had a greater proportion of leafy panicles relative to control trees. At 28/23degreesC, all emergent shoots remained vegetative. Lychee floral initiation is influenced by both root and shoot temperature. Root temperature has a direct effect on the length of the shoot dormancy period, with high temperatures reducing this period and the subsequent level of floral initiation. However, an extended period of dormancy in itself is not sufficient for floral initiation, with low shoot temperatures also a necessary prerequisite. (C) 2003 Elsevier B.V. All rights reserved.

Starch, growth, and development in cuttings of rootstock "Paulsen 1103" from plants infested with ground pearl.

ABSTRACT The ground pearl, Eurhizococcus brasiliensis, is considered an important pest of vineyards in southern Brazil, with affected plants exhibiting leaf chlorosis, reduction in vigor, fading, and death. This study evaluated the quality of hardwood cuttings produced from plants infected (I) and not infected (NI) by ground pearl. ?Paulsen 1103? (Vitis berlandieri × Vitis rupestris) plants were grown for 29 months in brick-built raised beds either infested or not infested by ground pearl; then, 12 one-year-old branches with a maximum of 12 buds each were cut from each plant, subdivided into three portions (4 buds cutting-1), and subjected to destructive and nondestructive testing. Destructive testing comprised determining fresh and dry weight, length, internode diameters, and percentage of starch. Nondestructive testing comprised assessing the potential for bud sprouting and shoot development. Each mother plant in the I and NI beds was considered a replicate, with a total of 360 cuttings per treatment. It was observed that cuttings from infected plants had significantly lower (P<0.05) internode diameter, length, and fresh and dry weight than those of the uninfected plants. The percentage of starch content of the cuttings did not differ significantly. All cuttings showed the same percentage (100%) of bud breaking and no changes in growth and development of seedlings regardless of source. Given these results, it was concluded that vines of ?Paulsen 1103? infested with ground pearl produce smaller cuttings than those of uninfected plants but with no reduction in bud break percentage or seedling development. Key words: Margarodidae, Vitaceae, insect?plant interaction, carbohydrates. RESUMO A pérola-da-terra, Eurhizococcus brasiliensis, tem sido considerada uma importante praga dos vinhedos no sul do Brasil, sendo que as plantas atacadas manifestam clorose foliar, redução no vigor, definhamento e morte. Este trabalho teve por objetivo avaliar a qualidade de estacas lenhosas produzidas a partir do contraste de videiras infestadas (I) e não infestadas (NI) por pérola-da-terra. Após 29 meses de cultivo em canteiros de alvenaria, em presença ou ausência de pérola-da-terra, cada planta da variedade ?Paulsen 1103? (Vitis berlandieri × Vitis rupestris) foi submetida à retirada de 12 ramos de ano, com no máximo 12 gemas cada, sendo subdivididos em três porções 4 gemas estaca-1) e submetidos a avaliações destrutivas e não destrutivas. As destrutivas consistiram em determinar massas fresca e seca, comprimento, diâmetro de entrenós e percentual de amido. As avaliações não estrutivas consistiram em testar o potencial de brotação e desenvolvimento das estacas. Cada planta matriz dos canteiros I e NI foi considerada uma repetição, totalizando 360 estacas por tratamento. As estacas das plantas infestadas tiveram uma redução (P<0,05), em relação às não infestadas, em diâmetro, comprimento e massas fresca e seca. Não houve contraste significativo do percentual de amido avaliado das estacas. Quanto à brotação, destaca-se que todas as estacas apresentaram o mesmo percentual (100%), independente da origem, sem alterações no desenvolvimento e crescimento das mudas. Diante desses resultados, salienta-se que videiras ?Paulsen 1103? infestadas por pérola-da-terra produzem estacas menores, porém não há comprometimento no percentual de brotação e desenvolvimento das mudas, quando comparadas com plantas não infestadas. Palavras-chave: Margarodidae, Vitaceae, interação inseto-planta, carboidrato

Tissue culture parameters in sweet orange cultivars

The objective of this work was to establish tissue culture parameters for gene transfer in sweet orange cultivars. Epicotyl explants with different ages were cultured with 6-benzylaminopurine (BAP), kanamycin and hygromycin. Shoots were cultured with alpha-naphthaleneacetic acid (NAA) alone or in combination with indole-3-butyric acid (IBA). The requirement of BAP for shoot development was genotype-specific. Epicotyl explants from 35-day-old seedlings produced significantly more shoots per explant in 'Pêra'. Kanamycin inhibited shoot regeneration for the most cultivars. The percentage of shoots that produced roots in 'Pêra' was significantly higher in medium with NAA and IBA than with NAA alone.

Auxin-mediated plant architectural changes in response to shade and high temperature.

The remarkable plasticity of their architecture allows plants to adjust growth to the environment and to overcome adverse conditions. Two examples of environmental stresses that drastically affect shoot development are imminent shade and high temperature. Plants in crowded environments and plants in elevated ambient temperature display very similar phenotypic adaptations of elongated hypocotyls in seedlings and elevated and elongated leaves at later developmental stages. The comparable growth responses to shade and high temperature are partly regulated through shared signaling pathways, of which the phytohormone auxin and the phytochrome interacting factors (PIFs) are important components. During both shade- and temperature-induced elongation growth auxin biosynthesis and signaling are upregulated in a PIF-dependent manner. In this review we will discuss recent progress in our understanding of how auxin mediates architectural adaptations to shade and high temperature.

In vitro organogenesis of rangpur lime

Rangpur lime (Citrus limonia Osbeck) in vitro organogenesis was studied based on explant type and cytokinin culture media supplementation. Four explants types collected from epicotyl or hypocotyl regions of in vitro germinated seedlings were evaluated. The epicotyl-derived explants consisted of epicotyl segments and the hypocotyl-derived explants consisted of the entire hypocotyl segment, the hypocotyl segment attached to a cotyledon fragment, and the hypocotyl segment divided longitudinally. The explants were cultured on EME culture medium supplemented with benzylaminopurine (0, 0.5, 1.0, or 1.5 mg L-1). The evaluation was performed after 6 weeks. Best results considering both the explant responsiveness and number of shoots developed per explants were obtained when epicotyl segments-derived explants were evaluated. Considering the explant responsiveness of hypocotyl segments-derived explants no difference was detected between the entire hypocotyl segment and the hypocotyl segment attached to a cotyledon fragment. Moreover, the percentage of responsive explants decreased when hypocotyl segments divided longitudinally were tested. No difference was detected for the number of shoots developed per explant considering the three types of hypocotyl-derived explants. Culture media supplementation with BAP was not essential for Rangpur lime in vitro organogenesis. However, adventitious shoot development was stimulated in concentrations between 0.5 - 1.0 mg L-1.

CLONAL PROPAGATION OF NEEM (Azadirachta indica A. Juss.) VIA DIRECT AND INDIRECT IN VITRO REGENERATION

ABSTRACTThe study was conducted with shoot tip explants of neem (Azadirachta indica A. Juss) to identify a viable regenerative process. Shoot tips were obtained from neem embryos cultured alternatingly in DKW medium supplemented with BAP and medium without hormones. Initial shoot development was influenced by cotyledon presence. Basal callus, excised from in vitro stem base, also presented organogenic potential. In some cases, plant lines, obtained from each seed, presented different characteristics. The most common characteristic observed in vitro was callus formation at the stem base. However, the rarest characteristics were stem callus formation and leaf senescence. The regenerated shoot tips were further subculture and rooted on a medium supplemented with IBA so that complete plants could be obtained. The rooted plants were transplanted to a greenhouse and successfully acclimatized. No significant differences in in vivo development were observed between neem plants from callus and from shoot tip propagation.

Crescimento radicular e aéreo de cultivares de arroz de terras altas em função da calagem

This work aimed to evaluate root growth, shoot development and nutrient absorption efficiency by rice cultivars Caiapo and Maravilha as affected by lime application. The experiment was carried out in a greenhouse, with treatments set up by Caiapo and Maravilha cultivars in combination with the base saturation (V%) of 10%, 40% and 70%. The experiment was in a randomized complete block design, with four replications. The number of tillers, root length, root dry matter, leaves and stems, leaf content and macronutrients absorption efficiency were evaluated. Comparing cultivars, Maravilha cultivar presented higher root dry weight, root length, number of stems, dry matter of stems and shoot than Caiapo cultivar, as well as accumulated more nutrients in the shoots. on the other hand, nutrient contents were higher in the cultivar Caiapo compared to Maravilha. Maravilha cultivar shows greater root and shoot growth while Caiapo shows higher nutrient absorption efficiency from the soil. The base saturation of 40% is the most effective for both cultivars.

Performance of constructed wetland system for public water supply

The project is being conducted in the town of Analândia, São Paulo, Brazil. The constructed wetlands system for water supply consists of a channel with floating aquatic macrophytes, HDS system (Water Decontamination with Soil - Patent PI 850.3030), chlorinating system, filtering system and distribution. The project objectives include investigating the process variables to further optimize design and operation factors, evaluating the relation of nutrients and plants development, biomass production, shoot development, nutrient cycling and total and fecal coliforms removal, comparing the treatment efficiency among the seasons of the year; and moreover to compare the average values obtained between February and June 1998 (Salati et al., 1998) with the average obtained for the same parameters between March and June 2000. Studies have been developed in order to verify during one year the drinking quality of the water for the following parameters: turbidity, color, pH, dissolved oxygen, total of dissolved solids, COD, chloride, among others, according to the Ministry of Health's Regulation 36. This system of water supply projected to treat 15 L s-1 has been in continuous operation for 2 years, it was implemented with support of the National Environment Fund (FNMA), administered by the Center of Environmental Studies (CEA-UNESP), while the technical supervision and design were performed by the Institute of Applied Ecology. The actual research project is being supported by FAPESP.

Upland rice growth and mineral nutrition as affected by cultivars and sulfur availability

A better understanding of the differential growth of upland rice (Oryza sativa L.) cultivars with increasing soil S availability could help improve rice yield under upland conditions. The objective of this study was to evaluate root and shoot growth and nutrition of upland traditional and modern rice cultivars as affected by S availability. The experimental design was completely randomized in a 3 (rates of S) × 3 (cultivars) factorial with four replications. Low availability of S in the soil reduces root and shoot development and the efficiency of N, P, and S uptake, as well as the concentration and content of these nutrients in rice cultivars. At 0 mg dm-3 of S, rice cultivars prioritize root growth over shoots, and the traditional cultivar does so with greater intensity. Our results suggested that more development of traditional cultivars under low S availability facilitates its adaptation in soils under this condition. On the other hand, the intermediate and modern cultivars are more responsive to S fertilization. Moreover, S fertilization allows significant increases in upland rice growth and must be considered in cropping systems aiming for high yields. © Soil Science Society of America.

Influência associada do estresse hídrico e do alumínio na germinação e crescimento inicial do guandu (Cajanus cajan (L.) Millsp.)

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Aspectos fitotécnicos e fitoquímicos de acessos de Hebanthe eriantha (Poir.) Pedersen - Amaranthaceae

Pós-graduação em Agronomia (Horticultura) - FCA

IN VITRO ORGANOGENESIS OF RANGPUR LIME

Rangpur lime (Citrus limonia Osbeck) in vitro organogenesis was studied based on explant type and cytokinin culture media supplementation. Four explants types collected from epicotyl or hypocotyl regions of in vitro germinated seedlings were evaluated. The epicotyl-derived explants consisted of epicotyl segments and the hypocotyl-derived explants consisted of the entire hypocotyl segment, the hypocotyl segment attached to a cotyledon fragment, and the hypocotyl segment divided longitudinally. The explants were cultured on EME culture medium supplemented with benzylaminopurine (0, 0.5, 1.0, or 1.5 mg L-1). The evaluation was performed after 6 weeks. Best results considering both the explant responsiveness and number of shoots developed per explants were obtained when epicotyl segments-derived explants were evaluated. Considering the explant responsiveness of hypocotyl segments-derived explants no difference was detected between the entire hypocotyl segment and the hypocotyl segment attached to a cotyledon fragment. Moreover, the percentage of responsive explants decreased when hypocotyl segments divided longitudinally were tested. No difference was detected for the number of shoots developed per explant considering the three types of hypocotyl-derived explants. Culture media supplementation with BAP was not essential for Rangpur lime in vitro organogenesis. However, adventitious shoot development was stimulated in concentrations between 0.5 - 1.0 mg L-1.