A podridão parda do pessegueiro é uma das principais doenças da cultura no Estado de São Paulo e na maioria das regiões produtoras do mundo. No Brasil, seu agente causal é o fungo Monilinia fructicola (Wint) Honey, que infecta ramos, flores e frutos tanto em pré como em pós-colheita. A compreensão do comportamento epidemiológico da podridão parda do pessegueiro em condições tropicais é fundamental para o estabelecimento de estratégias de controle mais eficientes nos pomares brasileiros. Neste contexto o presente trabalho teve como objetivo caracterizar o progresso temporal e a distribuição espacial da epidemia da podridão parda do pessegueiro, em pomares comerciais sob condições naturais de infecção. O estudo foi realizado em áreas comerciais não tratadas e tratadas com fungicidas, em dois pomares no Estado de São Paulo, em 2005 e 2006. Realizaram-se amostragens quinzenais de frutos durante 3 meses após o florescimento. Foram colhidos, pelo menos, 300 frutos por amostragem, os quais foram tratados com o herbicida gramoxone para detecção da infecção latente. A análise temporal dos dados foi realizada por regressão não-linear entre a incidência da doença e o tempo, enquanto a distribuição espacial de frutos doentes foi avaliada por meio do índice de dispersão (D) e da lei de Taylor modificada, que relacionam variâncias observada e binomial. Nos dois anos e locais estudados, a podridão parda apresentou tendência de crescimento exponencial, com baixa incidência no início das amostragens e aumento expressivo no início da maturação dos frutos. O modelo exponencial apresentou melhor ajuste aos dados, nos dois anos e locais de estudo. Em 2005, a incidência da doença chegou a valores máximos no ponto de colheita, atingindo 70% em frutos de plantas tratadas e 66,4% nos de não tratadas. Nesse ano, a incidência da podridão parda em frutos de plantas sem e com fungicidas não diferiram entre si (P>0,05), tanto nos parâmetros do modelo quanto na área abaixo da curva de progresso da doença (AUDPC). Em 2006, as curvas de progresso da doença, para frutos de plantas não tratadas com fungicidas, foram semelhantes entre si e caracterizaram-se pelo rápido aumento da incidência de infecções a partir da maturação dos frutos, chegando, na última avaliação, a 59,17% em Holambra II e 74,37% em Jarinu. O controle químico foi eficiente em 2006, havendo baixa incidência de podridão parda em frutos de plantas tratadas, durante toda safra e nos dois locais. No pomar avaliado em 2005, a agregação de frutos doentes (4,7<D<6,8) foi observada a partir da metade da safra e atribuída a pilhas de frutos mumificados na proximidade do pomar. O padrão espacial aleatório predominou na safra de 2006 nos dois pomares avaliados (0,88<D<1,52). Agregação de frutos doentes foi observada apenas por ocasião da colheita, quando a doença estava distribuída em todo o pomar, indicando haver árvores com muitos frutos doentes e outras com predominância de frutos sadios. O rápido progresso e a distribuição heterogênea da epidemia mostram a importância da eliminação das fontes de inóculo para o controle da doença. / The brown rot of peach is one of the main diseases in peach orchards in the State of São Paulo and in most peach producing regions in the world. In Brazil, brown rot is caused by the fungus Monilinia fructicola and it attacks stems, blossoms and fruits in the pre and post harvest periods. The understanding of the brown rot epidemiologic behavior in tropical conditions is essential to the establishment of more efficient control strategies in Brazilian orchards. In this context, the present work aimed to characterize the temporal progress and the spatial distribution of the peach brown rot in commercial orchards under natural infection conditions. The study was carried out in untreated and fungicide-sprayed commercial areas in Paranapanema and Jarinu, SP, in 2005 and 2006. Fruit samplings were performed fortnightly during 3 months after blooming. At least 300 fruits were collected in each sampling and treated with gramoxone herbicide to detect latent infection. Temporal data analysis was done by non-linear regression between disease incidence (y) and time (x). The spatial pattern of diseased fruit was assessed by the dispersion index (D) and the modified Taylor?s power law which relate observed and binomial variances. During these two years in the area studied, brown rot presented a tendency for exponential growth with low incidence in the beginning of the season and expressive increase in the beginning of fruit ripening. The exponential model presented a better fit to the data for the two year study period. In 2005, the brown rot incidence reached maximum values during the harvest: 70% in treated trees and 66,4% in untreated trees. There was no significant difference (P>0.05) in brown rot incidence in trees with or without fungicide treatment in model parameters as well as in the area under the disease progress curve (AUDPC). In 2006, the disease progress curves for treated and untreated trees were not similar. Disease progress curves for untreated trees were characterized by the rapid increase in infections incidence after the ripening of the fruit, reaching in the last evaluation, 59,17% for Holambra II and 74,37% in Jarinu. Chemical control was effective in 2006, with low brown rot incidence in treated trees throughout the harvest in both sites. In the orchard evaluated in 2005, the aggregation of diseased fruit (4,7<D<6,8) was observed in the second half of the season and attributed to piles of mummified fruit in the orchard?s vicinity. The random spacial pattern was predominant in the 2006 harvest in both orchards evaluated (0,88<D<1,52). Diseased fruit aggregations were observed only at harvest time, while the disease was spread throughout the orchard, indicating that some trees had many diseased fruits while in others the healthy fruit predominated. The quick progress and the heterogeneous distribution of the epidemics demonstrate the importance of eliminating the inoculum sources for the control of this disease.

O presente trabalho tem como objetivo avaliar o efeito da aplicação de lâminas de irrigação com níveis de adubação nitrogenada no desenvolvimento vegetativo, produtividade de palmito e na distribuição espacial do sistema radicular da pupunheira. O experimento foi conduzido dos 12 aos 34 meses após o plantio (abril/2000 a fevereiro/2002), período este que corresponde à fase de maior crescimento da cultura, no campo experimental de Irrigação e Drenagem, da Fazenda Areão da Escola Superior de Agricultura "Luiz de Queiroz" - ESALQ/USP, localizada no município de Piracicaba - S.P. à latitude de 22° 42'30"S e longitude de 47° 30'00"W. O delineamento empregado foi em blocos casualizados, com os tratamentos distribuídos em esquema fatorial 3 x 4. Os tratamentos referentes às lâminas de irrigação foram L1, L2, L3 e L4 equivalentes a 0, 50%, 100% e 120% da evapotranspiraçõo de referência determinada em função do Tanque Classe A. Os níveis de nitrogênio aplicados foram N1, N2 e N3 correspondentes a 0, 200 kg ha -1 ano -1 e 400 kg ha -1 ano -1 de N, aplicado sob a forma de nitrato de potássio, nitrato de cálcio e uréia. Foram realizadas fertirrigações semanais, pelo emprego de uma bomba injetora de diafragma. Já, as avaliações do desenvolvimento vegetativo foram feitas pelas medidas de algumas variáveis de crescimento e produtividade. A distribuição espacial do sistema radicular foi determinada pelos métodos: direto, com abertura de trincheiras e digitalização de imagens e indireto, em que a área potencial de absorção das raízes foi estimada em função da variação de umidade entre dias subseqüentes. Houve efeito significativo dos tratamentos (irrigação e adubação) para todos os parâmetros de crescimento e de produção de palmito, em grande parte dos períodos avaliados. Os tratamentos com déficit hídrico (L2) e sem irrigação (L1) apresentaram os menores crescimentos nos parâmetros avaliados acarretando uma redução de 18% a 27% na produção total de palmito. Apesar de não ter ocorrido diferenças estatísticas entre os tratamentos L3 e L4, os maiores crescimentos e produtividades foram obtidas em L3 (100% ETo). Para nitrogênio, N2 e N3 também não diferiram estatisticamente entre si, entretanto, maiores respostas foram obtidas em N2 (200 kg ha -1 ano -1 ). Portanto, levando-se em conta o crescimento da planta e os custos de aplicação de lâminas e fertilizantes, os resultados indicam que a irrigação com 100% ETo e adubação com 200 kg de N ha -1 ano -1 são as recomendadas para a pupunheira cultivada em condições agroclimatológicas semelhantes à região do presente estudo. As regressões para as lâminas de irrigação apresentaram efeitos lineares significativos para todas as variáveis analisadas, com exceção do número de perfilhos, vindo confirmar o alto consumo de água da cultura e a importância da irrigação quando cultivada em áreas com déficit hídrico. Para o nitrogênio, com exceção dos parâmetros relacionados à produção de palmito, todos os demais apresentaram efeitos lineares das regressões, ressaltando a importância do nitrogênio no desenvolvimento vegetativo da pupunheira. Todos os tratamentos (lâminas) aplicados resultaram em uma distribuição radicular (área e comprimento) bastante superficial, variando de 97,8%, 92%, 86,7% e 97,8% de raízes distribuídas até a profundidade de 0,40 m. / Peach palm (Bactris gasipaes Kunth) plants were subjected to different irrigation and N fertilizer treatments in an experiment field conducted at the Irrigation and Drainage Area (22° 42'30"S and 47° 30"00"W) of Areão Agricultural Experiment Area, ESALQ/USP, Piracicaba, SP, Brazil. The principal aim was to study the growth, development and yield of peach palm in the first plant yield cycle (April 2000 to February 2002), and also the spatial distribution of the root system. The irrigation (0%, 50%, 100% and 120% of ETo) and N fertilizer (0kg.ha -1 .year -1 , 200kg.ha -1 .year -1 and 400kg.ha -1 .year -1 ) treatments were grouped in randomized blocks resulting in a 3x4 factorial experiment. The water and N were applied through the use of a diaphragm-activated injection pump in a weekly basis. Plant parameters (as LAI obtained by the use of LAI 2000) were measured monthly to accompany the plant growth and development and the spatial distribution of the root system was evaluated by the use of a direct method (measuring by image analysis of the length and area of roots exposed by digging a soil-trench within the crop) and an indirect one (recording the moisture level differences between subsequent days). Significative differences among treatments were found in almost the total duration of the experiment. The water deficit treatments (0% and 50% of ETo) showed the lowest values of all parameters resulting in yield losses of 18% to 27%. On the other hand, the 100% of ETo treatment exhibited the highest ones, although the 120% of ETo treatment did not differ statistically from the former. Also, the 200kgN.ha -1 .year -1 and 400kgN.ha -1 .year -1 treatments did not differ statistically, showing the 200kgN.ha -1 .year -1 treatment the highest values. All parameters except offshoot number increased linearly with increasing water and except yield with increasing N. The root system in all treatments concentrated in the shallow layers of the soil with 97,8%, 92%, 86,7% and 97,8% of roots distributed until 40 cm depth.

No Brasil, a palmeira pupunha tem a região amazônica como seu habitat natural. Os frutos dessa palmeira, assim como o palmito, fazem parte da dieta alimentar dos povos da região Norte. Portanto, diante da relevância de seu cultivo, os objetivos dessa pesquisa foram avaliar os níveis de desenvolvimento vegetativo da pupunheira sob diferentes fontes de adubação (orgânica (esterco bovino e esterco suíno) e mineral), em condição irrigada. Buscou-se com isso, obter qual situação que fornecerá melhores condições de desenvolvimento vegetativo em termos de: altura da planta, diâmetro do caule, tamanho da folha (comprimento da raqui), espessura da raqui e por fim número de folhas. O experimento foi conduzido na área experimental do Departamento de Engenharia de Biossistemas, na fazenda Areão, pertencente à Escola Superior de Agricultura Luiz de Queiroz ESALQ/USP, localizada no município de Piracicaba SP. Situada a uma altitude de 576 m acima do nível do mar cujas coordenadas geográficas são: 22° 42 30 latitude Sul e 47° 30 00 de longitude Oeste. O tipo de solo existente na área experimental é classificado como Terra Roxa Estruturada (Alfisolo), série Luiz de Queiroz, apresentando declividade média de 5%. Foi utilizado o delineamento experimental de blocos ao acaso em esquema fatorial 4x4 com tratamentos dispostos em faixas totalizando 4 tratamentos e 4 repetições. Cada tratamento continha aproximadamente 175 plantas. Dispostas no espaçamento de 2 m entre linhas de plantio e 1 m entre as plantas. As covas tinham em torno de 0,3 m de profundidade. O sistema de irrigação empregado foi a microaspersão. No tratamento com adubação mineral, foram aplicados: 31,2 g de uréia, 181,46 g de super fosfato simples e 11,6 g de KCl por planta. Para aplicação do adubo orgânico (esterco bovino e suíno), tomou-se como base o o elemento fósforo (essencial para desenvolvimento de raízes), no caso de esterco suíno correspondeu a 8,54 kg planta-1 e no caso do esterco bovino correspondeu a 21,34 kg planta-1. As respostas da pupunheira aos tratamentos foram avaliados a cada 2 meses, a partir do plantio, mediante medições do desenvolvimento da cultura em todas as plantas úteis de cada parcela considerando-se as características conforme recomendações de Clement e Bovi (2000). Os itens avaliados foram: diâmetro do caule da planta (medido na região do colo da planta, aproximadamente de 10 a 15 cm acima do solo, com paquímetro); altura da planta (medida da base do tronco ao ponto de inserção da folha mais nova totalmente aberta, início da flecha); número de perfilhos por planta (feito por uma contagem simples). Assim que se iniciaram as avaliações foram analisadas planta a planta, num total de aproximadamente 700 palmeiras pupunha. As avaliações se estenderam durante o mês de julho/2010 a agosto/2011. De uma maneira geral, diante dos resultados obtidos, o tratamento que obteve melhor desenvolvimento foi o tratamento com aplicação de esterco suíno, em pelo menos 4 dos 5 itens avaliados (altura de planta, comprimento da raqui, diâmetro do caule e espessura da raqui). Pode-se dizer também que tanto a adubação mineral quanto o esterco bovino deram boas respostas dentro do experimento. / In Brazil, the peach palm has the Amazon region its natural habitat. The palm fruits and palm hearts, is part of the people diet of the North region of Brazil. Therefore, given the importance of its growth, the main objective of this research were to evaluate the levels of vegetative development of peach palm under different sources of fertilizer (organic (cattle manure and swine manure) and mineral) under irrigated condition. So, was looked to get which situation will provide optimum conditions for plant growth in terms of: plant height, stem diameter, leaf size (length of rachis), rachis thickness and finally the leaves number. The experiment was carried out at the experimental site of the Department of Biosystems Engineering, on a farm belonged to the College of Agriculture \"Luiz de Queiroz\" - ESALQ / USP, Piracicaba, SP, Brazil. Located at an elevation of 576 m above sea level whose geographical coordinates are: 22 ° 42 \'30 \"South latitude and 47 ° 30\' 00\" west longitude. The soil type at the experimental area is classified as Structured Terra Roxa (alfisols) series Luiz de Queiroz, with an average slope of 5%. The adopted statistical design was in randomized blocks, in factorial scheme 4x4 with treatments arranged in strips totaling 4 treatments and 4 repetitions. Each treatment had 175 plants. Arranged in the spacing of 2 m between tree rows and 1 m between plants. The pits were around 0.3 m deep. The irrigation system was the microsprinkler. In the treatment with mineral fertilizer were applied: 31.2 g urea, 181.46 g of simple super phosphate and 11.6 g of KCl per plant. For the application organic fertilizer (swine and cattle manure) was followed by the element phosphorus (essential for root development) the sample of swine manure corresponds to 8.54 kg plant-1. In case of cattle manure sample corresponding to 21.34 kg plant-1. Responses of peach treatments were evaluated every 2 months from planting, through measurements of the development of the crop in all useful plants of each plot considering the characteristics as recommended by Clement and Bovi (2000). The items evaluated were: plant stem diameter (measured in the neck region of the plant, about 10 to 15 cm above the ground, with caliper), plant height (measured from the base of the trunk to the point of insertion of the youngest leaf fully open, beginning of the arrow), number of tillers per plant (made by a simple counting). Once started the evaluations were analyzed plant to plant, totaling approximately 700 peach palm. The evaluations were extended during the month of July/2010 to August /2011. In general, considering the results obtained, the treatment that had the best development was the treatment of swine manure application on at least four of the five items evaluated (plant height, spinal length, diameter and thickness of the spinal ). Both mineral fertilizer and the manure gave positive responses within the experiment.

Doctor of Philosophy / Department of Biology / Jyoti Shah / Phloem-feeding insects like aphids feed on a variety of crop plants and limit plant productivity. In addition they are vectors for important plant viruses. Efforts to enhance plant resistance to aphids have been hampered by lack of sufficient understanding of mechanisms of plant defense against aphids. I have utilized a plant-aphid system consisting of the model plant Arabidopsis thaliana and the generalist aphid, Myzus persicae Sulzer (green peach aphid [GPA]), to study plant response to aphids. These studies have demonstrated an important role of premature leaf senescence in controlling aphid growth in Arabidopsis. Molecular and physiological studies suggest that the Arabidopsis PAD4 (PHYTOALEXIN DEFICIENT 4) gene modulates the GPA feeding-induced senescence process. Furthermore, in comparison to the wild type plants, GPA growth was higher on pad4 mutant plants, suggesting an important role for PAD4 in plant defense against GPA. In contrast, constitutive expression of PAD4 in transgenic Arabidopsis enhanced basal resistance against GPA. Unlike its involvement in plant defense against pathogens, the role of PAD4 in Arabidopsis resistance to GPA is independent of its involvement in phytoalexin biosynthesis and of its interaction with EDS1, a PAD4-interacting protein. Instead, the heightened resistance to GPA in these PAD4 constitutively expressing plants was associated with the rapid activation of leaf senescence. The association of premature leaf senescence in basal defense against GPA is supported by our observation that in comparison to the wild type plant, GPA growth was restricted on the Arabidopsis hypersenescence mutants, ssi2 and cpr5. Gene expression studies suggested some overlap between plant responses to pathogens and aphids, for example, activation of genes associated with the salicylic acid (SA) signaling pathway. However, the characterization of aphid performance on Arabidopsis SA biosynthesis and signaling mutants have ruled out the involvement of SA signaling in controlling aphid growth.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Amygdalin, a controversial anti-cancer agent, is a cyanogenic glycoside plant compound found in apricot and peach kernels. Both amygdalin and its patented form, Laetrile®, have been promoted and sold as "vitamin B-17", although neither compound is a vitamin. No consensus on the efficacy of amygdalin regarding the treatment of different cancers has been reached. Cancer is now the third leading cause of death worldwide. More than 7.6 million deaths were estimated to have occurred in 2007 and by 2030 it is projected to increase to 17 million cancer deaths per year. Cancers of the lung, breast, colon/rectum, liver and prostate are no longer largely confined to Western industrialized countries but are among the most common cancers worldwide (Thun et al. 2010). In South Africa it is estimated that one in every four males and one in every five females will be affected by a cancer diagnosis in their lifetime. The most common cancers in males are prostrate, lung, oesophagus, bladder and colorectal and in females they are cervix, breast, colorectal, oesophagus and lung (Haggar & Boushey 2009). Colon cancer is one of the most prevalent cancers worldwide, especially in western societies and is nutrition dependent (Klenow et al. 2009). It is one of the leading causes of death in both men and women in industrialised western countries. Colon cancer development involves both hereditary factors and lifestyle factors which include absence of physical exercise, unbalanced nutrition and long term smoking (Forman et al. 2004; Heavey et al. 2004). Colon cancer is traditionally treated by the resection of the colon, chemotherapy, radium therapy, and pharmaceutical hormonal drugs (Willson et al. 1987; Padussis et al. 2004)). Epidemiological studies supports evidence that colon cancer is preventable by adjusting the diet (Forman et al. 2004) and a protective effect is attributable to polyphenols and foods such as fruits and vegetables (Araújo et al. 2011). It was reported by Ruan et al. (2006) that the addition of Chinese Herbal Medicine in conjunction with chemotherapy notonly raised the efficacy of the chemotherapeutic drug, but also reduced the toxic side-effects. The aim of this research was to carry out a comparative in vitro study of the anti-tumour effect of the Chinese , South African and Turkish apricot (Xing ren / Armeniacea Semen) and Chinese and South African peach (Tao ren / Persica Semen) kernel extracts on the HT-29 colon cancer cell line.All the extracts significantly reduced cell viability and inhibited proliferation in the HT-29 cancer cells after 24 hours with the lipophilic and total fractions of CAK being the most effective. After 72 hours, it is clear that the inhibitory effects have been abolished and replaced by a stimulatory effect as the cell viability is higher in the treated cultures than the untreated controls. Results show that the total and the hydrophilic fractions of all the kernels increased cell viability more than the lipophilic fractions. It cannot be said with certainty that it was the amygdalin metabolite cyanide that affected the cell viability or induced apoptosis on its own. If hydrolysis of amygdalin indeed happened and cyanide was produced, it would affect the cells by shutting down aerobic respiration. Since cancer cells have more β- glucosidases and less rhodanese than normal cells, it is a possibility that the HT-29 cancer cells had some rhodanese to convert cyanide into a relatively harmless compound thiocyanate. It could be that in vitro this conversion, in light of the low enzyme levels in the HT-29 cancer cells, happened slowly and that the effect was only seen after 48 hour. However, this does not explain the overall inhibition even by the lipophilic fractions that should not contain any amygdalin or the eventual stimulatory effect, observed from 48 hour onwards.The S phase block observed, was mostly seen after 24 hour exposure to organic extractions, with the SAK showing 86% of cells in the S phase in contrast to the aqueous extractions which only slightly increased the S phase fraction. This could indicate that synergistic and/or additive effects between polyphenolic compounds may also be responsible for the reduction of cell viability, proliferation and apoptosis. All the kernels and the various fractions affected cell viability and to an extent cell cycle progression, but more studies is needed to establish the most effective kernel and specific fraction or signature active component. Inhibition of cell viability and proliferation and the induction of apoptosis could be an important preventive approach in chemoprevention. Understanding how dietary components regulate proliferation and cell survival could play a critical role in development of new enriched agents that can prevent and treat cancer with reduced risk of toxicity.

Phloem transport is along hydrostatic pressure gradients generated by differences in solute concentration between source and sink tissues. Numerous species accumulate raffinose-family oligosaccharides (RFOs) in the phloem of mature leaves to accentuate the pressure gradient between source and sinks. In this study, metabolic engineering was used to generate RFOs at the inception of the translocation stream of Arabidopsis thaliana, which transports predominantly sucrose. To do this, three genes, GALACTINOL SYNTHASE, RAFFINOSE SYNTHASE and STACHYOSE SYNTHASE, were expressed from promoters specific to the companion cells of minor veins. Two transgenic lines homozygous for all three genes (GRS63 and GRS47) were selected for further analysis. Sugars were extracted and quantified by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), and 21-day old plants of both lines had levels of galactinol, raffinose, and stachyose approaching 50% of total soluble sugar. All three exotic sugars were also identified in phloem exudates from excised leaves of transgenic plants whereas levels were negligible in exudates from wild type leaves. Differences in starch accumulation or degradation between wild type and GRS63 and GRS47 lines were not observed. Similarly, there were no differences in vegetative growth between wild type and engineered plants, but engineered plants flowered earlier. Finally, since the sugar composition of the phloem translocation stream is altered in these plants, we tested for aphid feeding. When green peach aphids were given a choice between WT and transgenic plants, WT plants were preferred. When aphids were reared on only WT or only transgenic plants, aphid fecundity was reduced on the transgenic plants. When aphids were fed on artificial media with and without RFOs, aphid reproduction did not show differences, suggesting the aphid resistance is not a direct effect of the exotic sugars.

studies were conducted to better understand the influence of temperature on the rest period of dormant peach and apricot buds. Gleason Elberta peach and Chinese apricot trees in the field at Howell Experiment Station in Ogden were used to evaluate rest intensity, respiration, and cold hardiness in relation to temperature. A rest intensity curve was obtained for both species using various concentrations of gibberellic acid. It was found that temperature had no direct effect on the depth of rest and that the depth of rest had no measurable influence on respiration and cold hardiness. Respiration of flower and leaf buds was not affected by temperature until after the rest period was over and the temperature rose above 40 F. However, cold hardiness was directly affected by temperature during the rest period. As the temperatures dropped the cold hardiness increased in both species. Lovell peach seedlings were placed in 5 gallon containers and placed in controlled temperature chambers. At 3 different periods, 3 trees were removed from 9 different temperature treatments. It was found that 40 F was generally more effective in breaking rest than was 32 F. Light did not seem to affect the rest period significantly.

Nutrient concentrations in plant tissues are directly correlated with the nutritional status and productivity of fruit trees. Plant tissue testing is one of the most effective and accurate methods to determine nutritional status of perennial plants. Tissue test analyses were performed on tart cherry (Prunus cerasus) and peach (Prunus persica) leaves to validate tissue sufficiency levels used in Utah and to determine optimal timing of tissue sampling for prediction of harvest nutrient status, focusing on phosphorus (P), potassium (K), calcium (Ca), iron (Fe), and zinc (Zn). Sufficiency limits that were adopted in Utah were developed in the 1960s from research data accumulated from the primary fruit growing regions in the United States. Limited research has been conducted under Utah growing conditions. Tissue nutrient concentrations over time correlated well with current sufficiency limits and observed nutrient deficiencies in the field. Tissue concentrations of P, K, Fe, and Zn were found to be chronically low in Utah orchards. Plant tissue data demonstrates that mid-season sampling can predict nutrient status at harvest. Mid-season sampling also allows time for corrective adjustments to maintain sufficiency levels and reach optimal fruit production. Nutrient management practices are commonly applied annually to increase yield, fruit quality, and overall health of an orchard. Yield was measured on previously treated tart cherry orchards to determine residual effect on tree nutrient status. Orchards were treated 2 to 3 years prior with rate-response formulations of P and K; one has since adopted recommended fertilizer rates for optimizing tart cherry production in Utah and the other continued with their less aggressive management practices. The less aggressively managed orchard showed trends across treatments, but differences were not significant. Annual fertilizer applications may not immediately show effect during year of application, but long term management is essential for overall productivity of orchards.

The effects of temperature, defoliation, light, and certain fall cultural practices on rest and hardiness of Gleason Elberta peach buds were studied. The influence of these factors on abscisic acid concentration in peach buds and a possible role of ABA in rest and hardiness of peach buds were also investigated. Peach leaf buds enter rest in early fall, reach a rest intensity peak in early winter, then break rest as a chilling requirement is met. Complete defoliation before rest has begun will cause some leaf and flower buds to grow, while defoliation after rest has begun will not cause visible bud growth. Effective chill-unit accumulation in the fall apparently did not begin until after a certain amount of leaf abscission had occurred. A GA3 application on August 15, 1974, delayed leaf abscission, and also caused an extension of the rest period. Early fall defoliation was correlated with a reduction in rest intensity and a reduction in the rest period of leaf buds. A result of this study indicates the possibility of the existence of a rest promoting substance that was apparently translocated from a side of a tree exposed to ambient temperatures to a warm greenhouse covered side. Decreasing temperatures caused an increase in flower bud hardiness, however, other factors also had effects on hardiness. An extended day-length treatment caused flower buds to acclimate more slowly than those on untreated trees during the early fall period. The light affect was not evident as colder temperatures prevailed. Buds on trees that were kept warm, acclimated to the same level as buds on trees kept at cooler but non freezing temperatures. However, it took the warm buds approximately four months longer to acclimate. Buds on trees that were exposed to below freezing temperatures acclimated to a much lower level than those on trees not exposed to freezing temperatures. Fall pruning and heavy fertilization with ammonium nitrate did not reduce cold hardiness enough to be measured. However, buds on vigorous, large diameter twigs were more hardy during the early winter period than buds on twigs of smaller diameter. The August 15 and September 19 GA3 treated trees and the early defoliated trees had a delay in acclimation during the fall period, although they did eventually acclimate to the same level as the untreated buds. Abscisic acid concentration in peach leaf and flower buds was low before rest began, increased sharply during the rest inception period, and decreased in concentration before the end of rest. ABA may be a controlling factor in the inception of rest in peach. There was no apparent relationship between ABA concentration and cold hardiness of Gleason Elberta peach flower buds.

The unveiling of small RNA (sRNA)-mediated gene regulatory pathways has profoundly shaped our understanding of the complexity of gene regulation. In eukaryotes, sRNAs have been found to control cellular metabolism, growth and differentiation, to maintain genome integrity, and to combat viruses and mobile genetic elements. To gain insight into the roles of small RNAs in apple and peach, we conducted sRNA-seq, computational analysis and molecular experiments to genome-widely characterize their microRNAs (miRNAs) and trans-acting siRNA (tasiRNA) pathways. We identified totally 75 miRNAs or families, including 23 conserved, 10 less-conserved and 42 apple-specific ones, and 118 miRNA target genes in apple. Two classical trans-acting siRNA (tasiRNA) pathways, miR390-TAS3 and miR828-TAS4, were characterized with similar but unique tasiRNA biogenesis profiles and target specificities. Importantly, miR159, miR828 and miR858 can collectively target up to 81 MYB genes potentially involved in diverse aspects of plant growth and development. In contrast to the location of the miR159 target site in a sequence-divergent region, the target sites of miR828 and miR858 are located in the region encoding the conserved R3 repeat domain of MYB proteins. 10 out of the 19 miR828-targeted MYBs undergo the biogenesis of various phased siRNA (phasiRNA), which potentially regulate diverse genes outside the MYB family. In peach, totally 94 miRNAs or families and 80 target genes were identified. Similar pathways of tasiRNA (miR828-TAS4 and miR390-TAS3) or phasiRNA (miR828-MYB-siRNA) processing were also characterized in peach. Taking advantage of reverse computation and public available deep-sequencing data, we demonstrated that the miRNA-TAS-PPR-siRNA pathway is a highly dynamic and widespread feature of eudicots. Nine eudicot plants, representing six different plant families, have evolved similar tasiRNA pathways to instigate phasiRNA production from PPR �genes, which are triggered by different 22-nt miRNAs, including miR7122, miR1509, and fve-PPRtri1/2 and through distinct mechanistic strategies, like miRNA direct-targeting or indirect-targeting through TAS-like genes, one-hit or two-hit, or even two layers of tasiRNA-TAS interactions. We found that the MIRNA genes of these miRNA triggers show great identity with the Arabidopsis MIR173, implying a common origin of this group of miRNAs (super-miR7122). Combined results from phylogenetic analyses and conservation extent profiling revealed that the super-miR7122 was potentially evolved from another miRNA superfamily (super-miR4376), which probably originated from the miR390. Additionally, the miR482/2118-NB-LRR-siRNA pathway was found to be conserved, but evolved with distinct features, in apple and peach. Taken together, widespread and complex miRNA and tasiRNA regulatory networks have been adapted in apple and peach. They add another crucial layer of regulation on gene activity and stability, and must exert essential functions in all aspects of plant life. / Ph. D.