In order to understand the genetic responses resulting from physiological changes that occur in plants displaying citrus variegated chlorosis (CVC) symptoms, we adopted a strategy of comparing two EST libraries from sweet orange [Citrus sinensis (L.) Osbeck]. One of them was prepared with plants showing typical CVC symptoms caused by Xylella fastidiosa and the other with non-inoculated plants. We obtained 15,944 ESTs by sequencing the two cDNA libraries. Using an in silico hybridization strategy, 37 genes were found to have significant variation at the transcriptional level. Within this subset, 21 were up-regulated and 16 were down-regulated in plants with CVC. The main functional categories of the down-regulated transcripts in plants with CVC were associated with metabolism, protein modification, energy and transport facilitation. The majority of the up-regulated transcripts were associated with metabolism and defense response. Some transcripts associated with adaptation to stress conditions were up-regulated in plants with CVC and could explain why plants remain alive even under severe water and nutritional stress. Others of the up-regulated transcripts are related to defense response suggesting that sweet orange plants activate their defense machinery. The genes associated with stress response might be expressed as part of a secondary response related to physiological alterations caused by the infection.

CitEST project resulted in the construction of cDNA libraries from different Citrus sp. tissues under various physiological conditions. Among them, plantlets of Rangpur lime were exposed to hydroponic conditions with and without water stress using PEG6000. RNA from roots was obtained and generated a total of 4,130 valid cDNA reads, with 2,020 from the non-stressed condition and 2,110 from the stressed set. Bioinformatic analyses measured the frequency of each read in the libraries and yielded an in silico transcriptional profile for each condition. A total of 40 contigs were differentially expressed and allowed to detect up-regulated homologue sequences to well known genes involved in stress response, such as aquaporins, dehydrin, sucrose synthase, and proline-related synthase. Some sequences could not be classified by using FunCat and remained with an unknown function. A large number of sequences presented high similarities to annotated genes involved with cell energy, protein synthesis and cellular transport, suggesting that Rangpur lime may sustain active cell growth under stressed condition. The presence of membrane transporters and cell signaling components could be an indication of a coordinated morphological adaptation and biochemical response during drought, helping to explain the higher tolerance of this rootstock to water stress.

Citrus is the most important fruit crop in Brazil and Citrus tristeza virus (CTV) is considered one of the most important pathogens of citrus. Most citrus species and varieties are susceptible to CTV infection. However, Poncirus trifoliata, a close relative of citrus, is resistant to the virus. In order to better understand the responses of citrus plants to the infection of CTV, we constructed expressed sequence tag (EST) libraries with tissues collected from Poncirus trifoliata plants, inoculated or not with Citrus tristeza virus at 90 days after inoculation, grafted on Rangpur lime rootstocks. We generated 17,867 sequence tags from Poncirus trifoliata inoculated (8,926 reads) and not (8,941 reads) with a severe CTV isolate. A total of 2,782 TCs (Tentative Consensi sequences) were obtained using both cDNA libraries in a single clusterization procedure. By the in silico hybridization approach, 289 TCs were identified as differentially expressed in the two libraries. A total of 121 TCs were found to be overexpressed in plants infected with CTV and were grouped in 12 primary functional categories. The majority of them were associated with metabolism and defense response. Some others were related to lignin, ethylene biosynthesis and PR proteins. In general, the differentially expressed transcripts seem to be somehow involved in secondary plant response to CTV infection.

Três experimentos de campo e um em vasos foram conduzidos com a cultura da soja 'Santa Rosa', para estudar os efeitos da aplicação de diferentes herbicidas, combinados com diferentes populações de plantas, sobre a nodulação, produção de grãos e teor de N em grãos. Utilizaram-se solos argiloso e muito argiloso no campo e argiloso e barrento em vasos. Os herbicidas aplicados foram o trifluralin a 0,96 kg/ha e o vernolate a 3,60 kg/ha, incorporados ao solo; alachlor a 2,40 kg; pendimethalin a 1,50 kg em dois experimentos e a 1,25 kg em um e o metribuzin a 0,63 kg em dois e a 0,53 kg em um em pré-emergência no campo. Em vasos, as doses foram as mesmas, exceto do trifluralin, que foi de 0,86 kg. Havia um tratamento sem herbicida em cada experimento. As densidades de semeadura corresponderam, no Experimento I, a 200 e 300 mil plantas/ha, no Experimento II a 200, 300 e 400 mil plantas/ha e, no III, a 150 e 250 mil plantas/ha. Em cada vaso, foram semeadas três plantas e nestes, fez-se o estudo do crescimento até 30 dias, quando se coletaram os nódulos. No campo, em pleno florescimento, foram amostrados os nódulos de cinco plantas por parcela, que foram contados e pesados após secagem. Na colheita, foram obtidos a produção de grãos e o seu teor de N. As diferentes densidades não causaram alteração no número e no peso de nódulos. Em vasos a modulação foi afetada, na fase inicial, por trifluralin, pendimethalin e vernolate, que reduziram o número e o peso de nódulos. O trifluralin reduziu esses valores no campo, na fase de máxima nodulação, em um experimento. O aumento da população causou elevação do teor de N, e de grãos na colheita, em dois experimentos. Nenhum herbicida afetou o teor desse nutriente nas folhas ou nos grãos. A produção de grãos por área foi elevada com o aumento da população de plantas. O metribuzin causou redução da produção em um experimento.

The effects of herbic ides and plant populations on nodulation and yield in soybean `Santa Rosa' were studied in three Experiments in field conditions and one in greenhouse. Clay and very clay soils were used in the field and very clay and loamy soils in pots. Trifluralin at 0,96 kg/ha and vernolate at 3,60 kg/ha, preplant incorporated; pendimethalin at 1,50 kg/ha, in two experiments, and at 1,25 in a third; alachlor at 2,40 kg; and metribu zin at 0,63 kg in two experiments and at 0,53 kg in a third, preemergence were applied in field conditions. In pots, the same rates were used, except for trifluralin which was applied at 0,86 kg/ha. A check was included in all experiments. All treatments in the field were combined with different plant densities: 200 and 300 thousand in Experiment I, 200, 300 and 400 thousand in Experiment II and 150 and 250 thousand in Experiment III. Three plants per pot were studied in the greenhouse experiment during the first 30 days. No interaction between herbicides and plant populations was observed for any of the studied parameters. The plant density increase caused increase of yield and in the N concentration in grains in two experiments. The different densities caused no change on the number or weight of nodules. Nodulation was affected, in pots, at its beginning, by trifluralin, pendimethalin and vernolate, with reduction of number and weight of nodules. Trifluralin depressed these values also in the field, in one experiment, at flower stage set. Grain yield was enhanced with population increase. Metribuzin reduced yield in one experiment.

A presente pesquisa foi conduzida em um Latossol Roxo, com 3,9% de matéria orgânica, na Usina São Carlos, município de Jaboticabal - SP com o objetivo de verificar o comportamento das principais misturas de herbicidas aplicadas em pós-emergência e suas possíveis interferências nos teores de macronutrientes, e no desenvolvimento da variedade CB 41-14. Os tratamentos utilizados com as respectivas doses do ingrediente ativo em kg/ha foram: ametryne + 2,4 - D (formulação comercial) a 1,47 - 2,03, diuron + 2,4 -D a 1,60 + 2,16; ametryne + 2,4-D a 1,60 + 2,16; alachlor + 2,4-D a 1,09 + 1,80; asulam + ioxynil - 2,4-D a 2,80 + 1,75; MCPA + 2,4-D a 0,83 + 0,83; oxadiazon + 2,4 -D a 0,50 + 2,16; ametryne + simazine + 2,4-D a 1,25 + 1,25 + 2,16; ametryne + secbumetone + 2,4-D a 2,00 + 2,00 + 2,16; diuron + hexazinone + surfatante a 0,80 + 0,45 + 0,5% e MCPA + 2,3,6-TBA + pendimethalin + surfatante a 1,50 + 0,48 + 0,66 + 0,5%. O controle das plantas daninhas foi avaliado através de contagens por espécie botânica e por avaliações visuais . Sobre a cultura os efeitos foram constatados pela contagem da brotação inicial, avaliações visuais dos efeitos fitotóxicos, análise dos teores de macronutrientes aos 5 e 8 meses, medidas do comprimento dos colmos, análise dos teores de fibra, pol, brix, % de cana e pureza, assim como valores de pol/ha, e peso de colmos por hectare. Não houve interferência das diferentes misturas de herbicidas na brotação inicial, no comprimento médio dos colmos, e nos teores de fibra, pol, brix e pureza por ocasião da colheita. Em relação às principais plantas daninhas presentes na área, que eram capim-colchão (Digitaria sanguinalis (L). Scop.) capim-coloniâo (Panicum maximum Jacq), beldroega (Portulacca oleracea L.) e caruru (Amaranthus spp), as melhores porcentagens de controle foram obtidas com as misturas de ametryne + 2,4-D, MCPA + 2,4-D, oxadiazon + 2,4-D, ametryne + secbumetone, diuron + hexazinone e MCPA + 2,3,6-TBA + pendimethalin. Aos cinco meses o teor de P foi diminuido pela mistura de ametryne + secbumetone + 2,4-D, e o teor de Ca decresceu pelas misturas de diuron + 2,4-D, ametryne + 2,4-D, alachlor + 2,4-D, asulam + ioxynil + 2,4-D, MCPA + 2,4-D, oxadiazon + 2,4-D, ametryne + simazine + 2,4-D e ametryne + secbumetone + 2,4-D. Já aos oito meses não houve diferença estatística para qualquer dos nutrientes estudados. Os teores de pol/ha e produção de colmos/ha não foram significativamente afetados por qualquer dos tratamentos quando comparados com a testemunha com capina. Todavia, todos os tratamentos apresentaram produção inferior a esta, sugerindo certa precaução com as aplicações pós-emergentes em canade-açúcar.

The present research was conducted in the São Carlos Sugar Mill. Jaboticabal - SP in a oxisol (Latossolic B) containing 3,9% organic matter. with the obje tive to study the behavior of the main post-emergence herbicide mixtures, in the sugarcane crop for weed control, and their interferences on the macronutrient levels and development of CB 41-14 variety. The treatments in kg of active ingredient per hectare were: ametryne + 2,4-D (comercial formulation) at 1,47 -t 2,03; diuron + 2,4-D at 1,60 + 2,16: ametryne + 2,4-D at 1,60 + 2,16; alachlor + 2,4-D at 1,09 + 1,08; asulam + ioxynil 2,4 -D at 2,8 + 1,75; MCPA + 2,4-D at 0,83 + 0,83; oxadiazon 2,4-D at 0,50 + 2,16; ametryne + simazine + 2,4-D at 1,25 1,25 + 2,16; ametryn + secbumeton + 2,4 -D at 2,00 + 2,00 + 2,16; diuron + hexazinone + surfactant at 0,80 + 0,45 + 0,5% and MCPA + 2,3 ,6 -TBA + pendimethalin + surfactant at 1,50 + 0,48 + 0,66 + 0,5% . The weed control was evaluated by counting the surviving weeds, and by visual evaluation according to the scale of the "AssociacionLatinoamericana de Malezas" (ALAM). The effects on the crop were evaluated by counting the fresh-emerging sugarcane plants, visual evaluating of herbicide injuries, analysis of macronutrients levels in the leaves at 5 and 8 months after planting, measures of the lenght of the culms, analysis of fibers, brix, purity and poi and the values of pot/ha and weight of culms/ha. Any interference of the herbicide mixtures. was not observed on the ini tial growth, the average lenght of the culms, the fiber, pol, brix or purity. The best weed control was obtained by the mixtures ametryn + 2,4-D, MCPA + 2,4-D, oxadiazon + 2,4-D, ametryn + secbumeton, diuron + hexazinone and MCPA + 2,3,6 TBA + pendimethalin, and the principal weeds present in the area were Digitaria sanguinalis (L .) Scop, Panicum maximum Jacq., Portulacca oleracea L. and Amaranthus spp. The P content level was reduced by ametryn + secbumeton t 2,4-D and the Ca reduced by diuron + 2,4-D, ametryn ; 2,4-D, alachlor + 2,4-D, asulam + ioxynil + 2,4-D, MCPA + 2,4-D, oxadiazon + 2,4-D, ametryn + simazine + 2,4-D and ametryn + secbumeton + 2,4-D at 5 months. At 8 months no effect on the macronutrient levels was observed. The values of po l/ha and weight of culms/ha were not affected by the treatments when compared with the hoed control, but all treatments yielded less than the hoed control.

O efeito de EPTC (S-etildipropiltiolcarbamato) sobre o desenvolvimento e a absorção de macronutrientes até o florescimento e os seus teores nas sementes e vagens, na colheita, foi estudado em dois experimentos de campo com a cultura do feijão, var. Carioca. O EPTC foi aplicado em pré-plantio com incorporação nas doses de 0, 1, 2, 4, 8 e 16 kg/ha em dois experimentos em solos argiloso e barrento. A avaliação da ação do herbicida sobre o desenvolvimento da cultura se fez pela obtenção de pesos de matéria seca de folhas, caules e vagens, durante o ciclo e número de plantas e produção de sementes na colheita. No início do florescimento foram analisados os teores de N, P, K, Ca, Mg e S em folhas e caules e, na colheita, em vagens e sementes. O EPTC, nas doses de 1, 2 ou 4 kg/ha não afetou o desenvolvimento da cultura, não alterou o teor de nutrientes em folhas ou caules, no início do florescimento, nem o teor nos grãos ou vagens, na colheita. Também não alterou a população de plantas ou a produção de grãos. As doses de 8 e 16 kg/ha de EPTC causaram redução de crescimento, de absorção de nutrientes, número de plantas por área e produção de sementes. O ciclo da cultura foi alongado. Os teores de nutrientes foram mais elevados, em geral, nas folhas, caules e vagens. Com essas doses ocorreu maior acúmulo de K nas vagens na colheita. Nenhuma das doses de EPTC, em qualquer dos experimentos, causou alteração nos teores de macronutrientes nas sementes.

The effect of EPTC, on growth and the macronutrient content in leaves and stems, at flowering set, and in seeds and pods, at harvest, in common beans CV. Carioca was studied. The EPTC was applied pre-plant incorporated at the dosages of 0, 1, 2, 4, 8 and 16 kg/ha in two experiments on clay and loamy soils. The influence of the herbicide on the crop growth was evaluated by means of fresh and dry matter weights of leaves, stems and pods at different periods of the crop cycle and by the stand and seed production. In both experiments the concentration of N, P, K. Ca, Mg and S were analysed in leaves and stems at the flowering set. The content of the same nutrients in seeds and pods were determined at harvest. Rates of 1, 2 or 4 kg/ha of EPTC did not affect the crop growth or the nutrient content in leaves, stems, seeds or pods. Rates of 8 and 16 kg / ha reduced the plant growth, nutrient absorption, stand and yield, but the nutrient concentration was enhanced in leaves, stems and pods. With these rates of EPTC the K content in pods was signifficantly higher. None of the applied rates of EPTC caused changes in the macronutrients concentration in the seeds at harvest.

Foi estudado o efeito das deficiências de nitrogênio, potássio, boro e zinco, isoladas ou combinadas de diversos modos no cafeeiro cultivado em solução nutritiva. Alem das descrições dos sintomas de deficiência foram feitas análises químicas dos diversos órgaos das plantas; verificou-se também o efeito das deficiências no crescimento.

Young coffee plants were grown in nutrient solution from which the following elements were omitted, singly or in several combinations: nitrogen, potassium, boron and zinc. The choice of these elements was basee on the high frequency of occurrence of their deficiencies under field conditions in Brazil. The effect of single or multiple deficiencies was studied under several aspects, namely: growth, visual symptons, mineral composition. The following conclusions can be drawn: (1) symptons of deficiency of nitrogen, potassium, boron and zinc can be identified even when occurring simultaneously; (2) the concentration of nitrogen, potassium, boron and zinc is markedly influenced by their supply in the substrate, as well as by the concentration of other elements in the medium; (3) cases of multiple deficiency should be taken into consideration when interpreting results of leaf analysis.

Foi verificado, usando-se plantas de 11 anos de idade da variedade "Bourbon vermelho" submetidas a um ensaio fatorial NPK 2x2x2 que a incidência dos sintomas de desfolhamento e secamento sub-terminal ("pescoço pelado", "pescoço de galinha","cin turamento") é função inversa do uso de nitrogênio na adubação, estando negativamente correlacionada com o teor de nitrogênio nas folhas.

A differential incidence of subterminal die-back was observed in the several tratments of a NPK 2x2x2 factorial experiment whose plants are 11 years old. In each tratment the number of affected individuals was counted. Leaf samples were collected and the macronutrient content therein was determined. The statistical analysis of the results has shown that: a) The use of nitrogen has significantly reduced the number of abnormal plants. b) A negative highly significant correlation coefficient was found between leaf nitrogen and number of affected individuals. c) It is likely, therefore, that nitrogen manuring in an efficient way to prevent and/or cure the abnormality studied.