Dentre as principais fruteiras nativas do Nordeste, especialmente aquelas encontradas no semi-árido, o umbuzeiro (Spondias tuberosa Arruda) desponta com uma alternativa importante, por ser uma fruta bem aceita pelo consumidor e por ter uma boa produção em ambientes secos. Dessa forma, o comércio dos frutos em feiras livres ou através de cooperativas proporciona uma fonte de renda complementar para os pequenos agricultores. No entanto, essa renda pode ser comprometida pelo extrativismo e o desmatamento excessivos, que tem se intensificado a cada ano. Preocupada com a redução populacional desta espécie pela ação antrópica, a Embrapa Semi-Árido vem desenvolvendo estudos sobre produção de mudas, cultivo e preservação da herança genética, através da recuperação de acessos com características morfológicas distintas e a implantação de um banco ativo de germoplasma, para disponibilizar os mais promissores para os pequenos agricultores, além de contribuir com o reflorestamento da Caatinga com uma espécie nativa. Dos fatores climáticos limitantes na produção de espécies frutíferas no semi-árido nordestino, a seca é o principal fator, aliado também ao problema crescente de salinização dos solos, que tem se agravado a cada ano. Os mecanismos utilizados pelo umbuzeiro para tolerar a seca ainda não estão completamente esclarecidos e não se conhece ainda as respostas fisiológicas frente a salinidade do solo. Desta forma, o presente trabalho objetivou avaliar as respostas fisiológicas do umbuzeiro quando submetido às condições de seca e salinidade. Para avaliar as respostas à seca, desenvolveu-se um experimento em casa de vegetação utilizando mudas enxertadas de quatro acessos de umbuzeiro (acessos BGU 44, BGU 48, BGU 50 e BGU 68) classificados como umbu-gigante, com o objetivo de avaliar as alterações no comportamento estomático, parâmetros anatômicos, relações hídricas e alguns parâmetros bioquímicos induzidos pela seca intermitente, além das possíveis variações genotípicas. Foram efetuadas mensurações da transpiração (E) e da resistência difusiva (rs) diariamente após a suspensão da rega até ocorrer o fechamento estomático, momento em que as plantas foram re-irrigadas. A rega foi suspensa novamente até ocorrer novo fechamento estomático e este ciclo foi repetido por um período de 31 dias. O potencial hídrico foliar (Yw) foi determinado em dois cursos nictimerais (no momento do primeiro fechamento estomático e ao final do período experimental). Também foram avaliados os teores de carboidratos solúveis totais (CHS), aminoácidos livres (AA), proteína (PROT) e prolina (PRO) nas folhas e nas raízes, assim como alterações anatômicas. Os acessos apresentaram regularidade no período de fechamento estomático entre as regas, demonstrando diferenças intra-específicas. Houve correlação com as variáveis ambientais sugerindo que, além da água, o comportamento estomático dos acessos BGU 44 e BGU 68 sofreram influência da Tar, UR e DPV, enquanto que o acesso BGU 50 sofreu influência do PAR e o BGU 48 não se correlacionou com os outros fatores, indicando que a água foi o fator que exerceu maior influência neste acesso. Alterações anatômicas em resposta à seca foramobservadas na densidade de estômatos (DE), reduções no índice estomático (IE) e na abertura do ostíolo (AO). O acesso BGU 48 manteve as características anatômicas inalteradas. Houve uma inversão na proporção dos tecidos do acesso BGU 44 quando sob estresse, diminuindo a espessura do parênquima lacunoso e aumentando o parênquima paliçádico. O inverso ocorreu com o BGU 68 e os demais acessos permaneceram inalterados. O horário de menor Yw para a maioria dos acessos foi entre 8h e 12h. O Yw das plantas estressadas do BGU 44 e BGU 50 foi reduzido significativamente às 8h. O BGU 68 apresentou os valores mais elevados de Yw. O prolongamento do estresse provocou reduções nos teores de CHS nas folhas de todos os acessos. Houve aumento no teor de AA nas folhas dos BGU’s 44 e 48, enquanto que os BGU’s 50 e 68 reduziram 40% e 43%, respectivamente. Ao final do período experimental esse comportamento se manteve para o BGU 44 e o BGU 50. Não houve diferença significativa para os teores de PROT nas folhas, mas houve aumento de 50% nos teores de PRO, exceto para o BGU 50. Foram verificadas alterações na concentração de CHS, AA e PRO nas raízes, com diferença entre os acessos. Os acessos BGU 68 e BGU 50 foram os mais contrastantes em condições de seca. Para avaliar as respostas do umbuzeiro ao estresse salino, foi desenvolvido um experimento utilizando-se plantas propagadas por sementes. As plantas foram cultivadas em areia lavada, regadas com solução nutritiva de Hoagland & Arnon, sem e com adição de NaCl (25, 50, 75 e 100 mM). Avaliou-se o crescimento, o Yw, E e rs. O teor de Na+, K+, Cl-, carboidratos solúveis e aminoácidos livres foram dosados nos diversos órgãos da planta. A maioria das variáveis estudadas foi afetada em níveis de NaCl de 50 mM, reduzindo o número de folhas, a altura das plantas, o diâmetro do caule e a massa seca e aumentando a relação raiz/parte aérea (R/Pa). O potencial hídrico foliar antes do amanhecer (Ypd) foi reduzido nas plantas dos tratamentos 75 e 100 mM de NaCl. A concentração de Na+ e Cl- nas folhas aumentou em função dos níveis de NaCl aplicados, mas, o teor de K+ não foi afetado. Nos caules e raízes, houve uma saturação na retenção de Na+ e Cl- nos tratamentos acima de 50 mM. Os resultados desta pesquisa permite inferir que existem diferenças fisiológicas e anatômicas entre os acessos de umbuzeiro estudados; que eles respondem de forma diferente à seca intermitente; que a manutenção da turgescência foliar está relacionada à reserva de água nos xilopódios associado ao mecanismo de fechamento estomático eficiente e não ao acúmulo de solutos osmoticamente ativos, tanto em situação de seca como de salinidade no meio; devido à grande variação encontrada, o acúmulo de solutos orgânicos não demonstrou ser um mecanismo fisiológico indicador de tolerância à seca e a salinidade nesta espécie; o umbuzeiro tolera níveis de salinidade de até 50 mM de NaCl sem apresentar alterações fisiomorfológicas significativas na fase inicial do desenvolvimento._________________________________________________________________________________________ ABSTRACT: Among the principal native fruit trees in Northeastern Brazil, especially those found in the semi-arid areas, the umbu tree (Spondias tuberosa Arruda) represents itself as an important alternative as it well accepted by consumers and is a good produce in dry environments. Thus, the fruit trade fair or through cooperatives provides a source of supplementary income for small farmers. However, this income can be compromised by harvesting and excessive deforestation, which has intensified each year. Concern with population reduction of this species and by anthropic, Brazilian Institute for the Semi-Arid Tropic has developed studies on seedlings production, cultivation, and genetic inheritance preservation recovering genotypes with distinct morphological characteristics and deployment of a germplasm active bank provide the most promising for small producers, in addition to contributing to the reforestation of the Caatinga with a native species. Of the climatic factors limiting fruit species production in the semi-arid northeast, drought is the main factor, also allied to the growing problem of soil salinization, which has worsened each year. The mechanisms used by umbu tree to tolerate drought is not well elucidated and the physiological response before soil salinity is not yet known. Thus, the present work aimed to evaluate the physiological responses of umbu tree to drought and salt stresses. To evaluate drought responses, a project was developed in green house conditions using four grafted genotypes classified as giant umbu (BGU 44, BGU 48, BGU 50 and BGU 68) in order to evaluate the alterations on stomatal behavior, anatomical parameters, water relations and some biochemical aspects induced by intermittent drought and the possible genotypical variations. Transpiration (E) and diffusive resistance (rs) were measured daily after the beginning of the stress treatments by withholding water. When plants presented stomatal closure, the vases were re-watered and the water withhold again. This cycle was repeated for a 31 period days. The leaf water potential (Yw) was measured in four-hour intervals during a 24-hour period at the moment of the first stomatal closure and at the end of the experimental period. Total soluble carbohydrates (CHS), free amino acids (AA), protein (PROT) and proline (PRO) in leaves and roots were also measured. Certain regularity in the stomatal closure was observed among the watering period, showing differences between the species. The correlation with environmental factors suggest that, besides the water, stomatal behavior of BGU 44 and BGU 68 were influenced by Tar, RH and VPD, while the access BGU 50 were influenced by PAR and BGU 48 had no correlation with these environmental factors, suggesting that the water exerted the major influence in this genotype. Anatomical alterations in response to drought on stomatal density (DE) and reductions on stomatal index (IE) and stomatal aperture size (AO) were observed. The access BGU 48 maintained its anatomical features unaltered. There was an inversion in tissue proportion in BGU 44 under stress conditions, reducing the thickness of the spongy parenchyma and increasing palisade parenchyma. The inverse occurred with BGU 68 and theremaining genotypes continued unchanged. The lower Yw time of most of the genotypes was between 8h and 12h. The Yw of the stressed plants of BGU 44 and BGU 50 reduced significantly at 8h. The highest Yw was observed to BGU 68. The stress prolongation induced reductions in CHS content in the leaves of all genotypes. There were increases in the leaves to AA in BGUs 44 and 48, while BGUs 50 and 68 were reduced by about 40% and 43% respectively. BGU 44 and BGU 50 kept this behavior at the end of the experimental period. Significant differences in PROT content were not observed, but there were increases of 50% in PRO, except to BGU 50. Alterations on CHS, AA and PRO contents in the roots were verified and varied among the different genotypes. BGU 68 and BGU 50 were the most contrasting genotypes. In order to evaluate the salt stress responses in umbu plants a project was developed using seedlings propagated by seeds. Plants were grown in washed sand with Hoagland & Arnon nutrient solution without salt and with 25, 50, 75 and 100mM NaCl. Growth, Yw, E and rs were then evaluated. Na+, K+, Cl-, soluble carbohydrates and free amino acid contents were measured in several plant organs. Most variables were affected with salinity above 50 mM NaCl showing decreases in: number of leaves, plant height, stems diameter and dry masses and increases in root to shoot ratio. Reductions in pre-dawn leaf water potential (Ypd) were observed in plants submitted to 75 and 100 mM NaCl. Salt levels applied increased Na+ and Cl- contents in leaves. However, K+ content was not affected. A saturation to retain Na+ and Cl- in stems and roots was verified in treatments above 50 mM NaCl. These results allow us to say that there are physiological and anatomical differences among umbu tree genotypes; genotypes respond differently to intermittent drought; the turgor maintenance in umbu tree is relative to water storage in the xylopodium associated with the efficient stomatal closure mechanism and not by osmotic active solutes accumulation in either drought or salt stress conditions; due to the great variation found, the organic solutes accumulations did not demonstrate to be a good physiological trait as indicator to droughtand salt-tolerance in umbu plants. This specie tolerates salt levels until 50 mM NaCl without showing significant physio-morphological alterations.

Submitted by MARCOS LEANDRO TEIXEIRA DE OLIVEIRA (marcosteixeira@ufv.br) on 2018-09-25T19:25:24Z No. of bitstreams: 1 texto completo.pdf: 3035998 bytes, checksum: f218a58188c12d02ff036d5aade6bcc3 (MD5) / Made available in DSpace on 2018-09-25T19:25:24Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3035998 bytes, checksum: f218a58188c12d02ff036d5aade6bcc3 (MD5) Previous issue date: 2018-06-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A adoção de genótipos mais produtivos e mais exigentes nutricionalmente, aliado à baixa disponibilidade de matéria orgânica (MO), fósforo (P), potássio (K), cálcio (Ca) e magnésio (Mg), baixa capacidade de troca de cátions (CTC) e elevada susceptibilidade à lixiviação dos solos sob plantios florestais, conduzem a exigência elevada em fertilizantes e justificam pesquisas que busquem racionalizar o uso desses insumos. Assim sendo, este trabalho teve como objetivos: a) determinar, com base no coeficiente de partição (Kd) e nas constantes cinéticas de absorção de K do eucalipto, o teor de K no solo no qual a planta inicia a absorção e no qual o influxo máximo (Imax) é atingido; b) obter curvas de relacionamento da produtividade com atributos químicos do solo e determinar classes de interpretação utilizando a linha de fronteira (LF); c) obter curvas de relacionamento entre o teor foliar de macronutrientes e os teores disponíveis no solo e estimar faixas de suficiência de macronutrientes para o eucalipto. Para obter o Kd foram utilizadas amostras de sete solos de localidades produtoras de eucalipto na região Centro-Leste de Minas Gerais. A partir de cada amostra foram obtidas 18 subamostras e nelas foram adicionadas soluções com seis doses de K (0, 10, 20, 40, 80 e 160 mg/L), na relação solo: solução de 1:10. As subamostras foram agitadas e no filtrado foram determinados os teores de K. Por diferença entre o aplicado e o teor no filtrado, foi calculado o K adsorvido no solo. Regressões lineares foram ajustadas entre o K adsorvido à fase sólida do solo (y) e o K em solução (x) e calculado o Kd de K para cada solo, considerando a declividade da função. Para obter o influxo de K das plantas, foram atribuídos valores de concentração junto às raízes, iniciando em 5,1 μmol/L de K (Cmin médio do eucalipto) até 250 μmol/L para atingir o Imax. Essas concentrações foram multiplicadas pelo Kd de cada solo, obtendo-se o teor de K nos solos. Foi proposto um fator de sustentabilidade considerando o teor de K em cada solo, referente ao Cmin e um fator que condiciona a máxima absorção pelas plantas de eucalipto (correspondente ao teor de K que proporcionou 98 % do Imax). Esse fator de sustentabilidade é útil para aprimorar o módulo suprimento do sistema FertiCalc-Eucalipto. Classes de fertilidade e faixas de suficiência foram obtidas usando um banco de dados de áreas cultivadas com eucalipto, contendo informações de produtividade, teores foliares e de atributos químicos do solo. Foram elaborados gráficos de dispersão relacionando o Incremento Médio Anual em volume de tronco (IMA relativo), com os teores de MO, P, K, Ca e Mg no solo. Nesses gráficos foram estabelecidas as LF e obtidas as equações para estimar as classes de fertilidade do solo. Teores foliares de N, P, K, Ca e Mg foram plotados com os teores de MO, P, K, Ca e Mg no solo. Usando o método do Diagrama de Quadrantes do Relacionamento planta-solo (DQRps), foi traçada uma linha horizontal e uma vertical separando a nuvem de pontos em quatro quadrantes. Com os pontos dos quadrantes III e I, foram ajustadas equações de regressão. Para obtenção das faixas de suficiência foliar, os valores dos níveis críticos e ótimos de MO, P, K, Ca e Mg do solo, obtidos pela LF, foram substituídos nas equações geradas pelo método do DQRps. Os teores de K no solo para as plantas iniciarem a absorção e atingirem 98 % do Imax foram mais elevados nos solos mais argilosos. O modelo proposto utilizando as constantes cinéticas e o Kd do K permitiu definir a faixa de teores no solo em que as plantas de eucalipto absorvem esse nutriente. As faixas adequadas de teores no solo determinadas pela LF, para obter uma produtividade de 47,7 m 3 /ha/ano, foram: 24,75-38,28 g/kg de MO; 9,7-14,35 mg/dm 3 de P; 100,0-150,35 mg/dm 3 de K; 0,77-1,47 cmol c /dm 3 de Ca; e 0,25-0,43 cmol c /dm 3 de Mg. As faixas de teores foliares determinadas pelo DQRps foram: 19,4-21,3 g/kg de N; 1,0-1,2 g/kg de P; 8,5-10,6 g/kg de K; 4,8-6,1 g/kg de Ca; e 1,9-2,4 g/kg de Mg. / The adoption of more productive and nutrient-demanding genotypes, in addition soils with low availability of organic matter (OM), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg), as well as low cation exchange capacity (CEC) and high leaching susceptibility of soils under forest plantations, lead high fertilizer demand and justify research that seeks to rationalize the use of these inputs. Therefore, the objectives of research were to: a) determine, based on the partition coefficient (Kd) and eucalyptus kinetic constants of K absorption, the soil K content in which plants start absorption and in which the maximum influx (Imax) is reached; b) obtain productivity relationship curves with soil chemical attributes and determine classes of interpretation using Boundary Line (BL); c) obtain relationship curves between macronutrient leaf contents and soil available contents in order to estimate macronutrient sufficiency ranges for eucalyptus. In order to obtain Kd, of seven soil samples from eucalyptus producing sites were collected in Eastern region of Minas Gerais state. Each sample was obtained 18 sub-samples and solutions with six K rates (0, 10, 20, 40, 80 and 160 mg/L) were added to there, in ratio soil: solution of 1:10. The sub-samples in solution containing these K rates were shaked and after wards filtered and K contents were determined in the filtered solutions. Was calculated by the difference between K applied initial and K contents in the filtered, soil adsorbed K. Regressions were adjusted between soil K adsorbed (y) and K in solution (x). Potassium Kd for each soil, is considered to be the functions slope. In order to obtain K influx by plants, concentration values were assigned to the solution near the roots, starting at 5.1 μmol/L of K (mean value of Cmin for eucalypt) up to 250 μmol/L in order to reach maximum influx. These concentrations were multiplied by the Kd of each soil, and this allowed us to obtain soil K content. A sustainability factor was proposed considering soil K content of each soil that corresponds to Cmin and a factor that conditions eucalyptus maximum influx (considering the K content that provided 98% of the Imax). This sustainability factor is useful to improve the system supply module of FertiCalc-Eucalyptus. Fertility classes and sufficiency ranges were obtained using a database of areas cultivated with eucalyptus, containing information on yield, leaf contents and soil chemical attributes. Scatter plots were drawn relating the mean annual increment in trunk volume (relative MAI) with soil OM, P, K, Ca and Mg. In those graphs and equations were to used estimate soil fertility classes. Leaf contents of N, P, K, Ca and Mg were plotted with soil contents of OM, P, K, Ca and Mg. Using the Quadrant Diagram of the Plant-Soil Relationship (QDpsR) method, a horizontal and vertical lines were drawn separating the cloud of points in four quadrants. With the points at the quadrants III and I, regression equations were fitted. In order to obtain foliar sufficiency ranges, soil values of critical and optimal levels of OM, P, K, Ca and Mg, obtained by BL, were substituted in the equations generated by the QDpsR method. Soil levels of K that allow plants to initiate nutrient absorption and reach 98% of the Imax to dye the Imax were higher in clayey soils. The proposed model, using kinetic constants and potassium Kd, allowed to define the range of soil contents in which the eucalyptus plants absorb this nutrient. The appropriate soil content ranges determined by BL for a productivity of 47.7 m 3 /ha/year were: 24.75-38.28 g/kg of OM, 9.7-14.35 mg/dm 3 of P, 100.0-150.35 mg/dm 3 of K, 0.77-1.47 cmol c /dm 3 of Ca, and 0.25-0.43 cmol c /dm 3 of Mg. Leaf content ranges determined by QDpsR are: 19.4-21.3 g/kg of N, 1.0-1.2 g/kg of P, 8.5-10.6 g/kg of K, 4.8-6.1 g/kg of Ca, and 1.9-2.4 g/kg of Mg.

Publicación a texto completo no autorizada por el autor / El estudio se realiza en dos etapas: en cobertor como protección a las heladas ocasionales, y en campo agrícola. De las colectas se encuentra que en el valle del Mantaro se desarrollan tres especies de Amaranthus: A. caudatus, A. cruentus y A.hybridus, ésta última con una variante adicional. Luego del tratamiento agrícola en el campo se determina que la obtención de mayor masa foliar útil se logra en la defoliación durante la floración, tanto en el cultivar como en las especies silvestres, asimismo, esta correlación se mantiene en las interacciones de los factores. La especie silvestre de mayor rendimiento foliar es A. hybridus, seguido de A. cruentus y A. hybridus variante 1. La fertilización orgánica es favorable para incrementar los rendimientos y es efectivo como tratamiento agrícola. El rendimiento de hojas secas de cada especie mantiene una correlación con el de las hojas frescas, de lo que se deduce que el contenido de agua es específico. La defoliación afecta significativamente a los factores de producción, especialmente si se realiza antes de la floración. Del tratamiento agrícola en el cobertor se determina que, el mayor peso de hojas por planta y por parcela, tanto fresca como seca, se obtiene con la defoliación durante la floración en A. caudatus y A.hybridus, manteniendo este orden en las interacciones. Sin embargo, la defoliación antes de la floración afecta positiva y significativamente en la altura de la planta, especialmente en A. hybridus y A. cruentus; esto se mantiene en las interacciones, pero sólo para esta evaluación. Además, A. caudatus es afectado negativamente en sus factores de producción, excepto para el rendimiento foliar. Para el peso de semillas por planta y por parcela, los testigos y la defoliación antes de la floración no presentan diferencia estadística, especialmente en las especies silvestres, lo que indica que puede ser utilizado con doble finalidad. Haciendo una comparación entre las dos condiciones se determina que, la producción tanto de hojas como de semillas, ya sea por planta como por parcela, es mayor en el campo agrícola que en el cobertor, a excepción de la longitud del tallo y la longitud de la panoja. El contenido de nutrientes de las hojas y las semillas de las especies silvestres, según el análisis proximal, son iguales o mejor que las de A. caudatus y otras hortalizas conocidas, por lo que se les puede considerar como plantas promisorias para los agricultores. / Tesis

The services that urban trees provide to human society and the natural environment are widely recognized, but urban trees are in jeopardy due to climate change and urban stressors. With drought as a major threat in many areas, it is important for the future of urban forestry to select species composition based upon performance under water stress. Certain leaf functional traits can help horticulturalists more accurately predict water usage of urban trees. Comprehension through rigorous experimentation is lacking, partly due to the thousands of mostly exotic species. Previous studies suggest that species whose leaves have a denser arrangement of smaller stomata and a higher leaf mass per area (LMA) are better adapted to low water availability. We sampled 70 urban tree species California and analyzed their stomatal length, stomatal density, and LMA. We compared the traits with water use data from the Water Use Classification of Landscape Species to assess possible correlations. All pairwise trait comparisons show significant correlation (P < 0.05), and LMA is significantly higher in low water use species compared to medium water use species (P= 0.0045). After using independent contrasts to incorporate phylogenetic relationships, significance was lost, implying that basal divergences are responsible for observed trends. Other potential explanations for differences in species water usage are foliar longevity (deciduous vs. evergreen) and stomatal distribution (amphistomatous vs. hypostomatous). Low water use species are more likely to be evergreen and amphistomatous compared to medium water use species. Consideration of all these traits in combination with good management practices can help ensure future success of urban forests.

Since man first grew crops on calcareous soils he has probably been troubled with what we today call lime-induced chlorosis. This chlorosis has determined whether he grew certain desirable ornamentals or crops or whether he had to substitute others which were less desirable. Lime-induced chlorosis is spread world wide. It has been reported in the vine and fruit growing regions of Europe, in the chernozem soils of Russia, and many other areas where the rainfall is relatively low and the soil is relatively high in calcium carbonate. In the United States it most frequently occurs where the average annual rainfall is less than 30 inches. The conditions causing chlorosis are not stable, for it varies from year to year and even from week to week with changing conditions in climate and soil. An estimated 500,000 acres of crops grown in the western United States on calcareous soils are subject to moderate to severe chlorosis. This physiological malady has challenged the technical ingenuity of outstanding plant and soil scientists. The exact cause or causes have never been isolated; consequently no permanent preventative measures or cures can, as yet, be recommended.

In an effort to reduce application costs and to integrate plant health management strategies in soybean, growers may combine POST herbicides with foliar fertilizers or cytokinin mixtures. Field experiments were conducted at the Delta Research and Extension Center in Stoneville, MS in 2015 and 2016 to evaluate soybean [Glycine max (L.) Merr.] injury, weed control, and agronomic performance when combining blended or single-nutrient foliar fertilizers with POST herbicide applications. Field experiments were also conducted at the Delta Research and Extension Center in Stoneville, MS in 2015 and 2016 to evaluate the influence of cytokinin mixtures on soybean injury and weed control when combined with common POST soybean herbicides.

Through proper irrigation scheduling and management of damaged cotton, sustainable agricultural withdrawal from the Mississippi River Valley Alluvial Aquifer can be achieved while maximizing net returns. This research was conducted to 1) develop a sensor based irrigation strategy that maximized cotton lint yield and quality, irrigation, and water use efficiency (IWUE) and 2) quantify the effects of timing of damage, intensity, and foliar N on cotton growth and development. Lint yield, fiber quality, and IWUE were optimized using a season-long irrigation threshold of -90 kPa and irrigation terminated 2-weeks before cracked boll. Regardless of cotton variety (early- or late-maturing) or timing of damage, plant height, number of nodes, and lint yield were negatively correlated with the intensity of damage. Moreover, the application of foliar nitrogen to damaged cotton had no effect on plant growth, lint yield, or fiber quality, regardless of N application timing. These data indicate that lint yield, and fiber quality are optimized when cotton varieties are selected based on yield potential, irrigated at -90 kPa threshold, and irrigations are terminated two weeks before cracked boll.

No description available.

Frogeye leaf spot (FLS), caused by Cercospora sojina Hara, is a foliar disease of soybean (Glycine max (L.) Merr.). FLS has re-emerged as an important disease due to the widespread QoI-resistant fungal population in Mississippi. Growers have transitioned from a stand-alone QoI fungicide to a multi-mode of action fungicide. One disadvantage of certain MOA’s is phytotoxicity. Phytotoxicity is a concern among soybean growers as to whether or not yield is lost. Disease, phytotoxicity, green stem, yield, plant morphology, and grain quality were analyzed to determine the impacts of fungicide phytotoxicity. Yield was significantly and negatively correlated as a result of phytotoxicity. Numerical differences in phytotoxicity severity were observed among all cultivars. Phytotoxicity severity were greatest in the Hornbeck 4950 LL with an average of 26.9%. Tank-mixing dodine with Manniplex B Moly, Megafol, and Veritas decreased phytotoxicity by 8.5, 2.7, 11.4% compared to dodine as a stand-alone treatment, respectively.

No description available.