Physical and chemical characteristics of fruits from different orange canopy/rootstock combinations grown in the brazilian semiarid

The orange trees 'Pera'/lemon 'Cravo' combination has predominated in national territory, and new oranges trees canopies/rootstock combinations citrus have been availability in breeding programs to provide for productive sector. Thus, the objective of this work was to evaluate the physical and chemical characteristics of fruits orange trees from canopy/rootstock different combinations grown in Brazilian semiarid. The experimental design was in randomized blocks, in a factorial scheme with three canopy and four rootstock cultivars, with three replications. The orange trees used were 'Pera', 'Natal' and 'Sincorá', while for the rootstocks the lemon 'Cravo Santa Cruz', the mandarin 'Sunki' Tropical selection, and the citrandarins 'Indio' and 'Riverside'. The results obtained showed that factors acted independently in mass and diameter fruit, seeds number, juice yield, skin luminosity and pulp, chromaticity and hue angle pulp, ºBrix and acids contents. However, it was different in shell thickness, chromaticity and hue angle of the shell and SS/AT ratio. Was possible conclude that 'BRS 002 – Sincorá' presented best results for physical and chemical analysis, and lemon 'Cravo Santa Cruz' and Tangerine 'Sunki' Tropical selection influenced the canopies to the best results of the physical and chemical analysis, respectively. All combinations showed low juice yield.No Brasil, a combinação laranjeira ‘Pera’ e limoeiro ‘Cravo’ têm predominado em todo o território nacional, fazendo com que os programas de melhoramento em citros invistam em medidas para disponibilizar novas combinações ao setor produtivo. Com isso, o objetivo deste trabalho foi avaliar as características físicas e químicas de frutos provenientes de diferentes combinações copa/porta-enxerto de laranjeiras cultivadas no semiárido brasileiro. O delineamento experimental foi em blocos casualizados, em esquema fatorial com três cultivares copa e quatro porta-enxerto, com três repetições. As copas utilizadas foram a ‘Pera’, a ‘Natal’ e a ‘Sincorá’, enquanto para os porta-enxertos foram utilizados o limoeiro 'Cravo Santa Cruz', a tangerineira ‘Sunki’ seleção Tropical, e os citrandarins ‘Indio’ e ‘Riverside’. Os resultados obtidos mostraram que os fatores atuaram de forma independente na massa e diâmetro do fruto, no número de sementes, no rendimento do suco, na luminosidade da casca e da polpa, na cromaticidade e ângulo de matiz da polpa, no ºBrix e nos teores de ácidos. Entretanto, foi diferente na espessura da casca, na cromaticidade e no ângulo de matiz da casca e na relação SS/AT. Foi possível concluir que a ‘BRS 002–Sincorá’ apresentou os melhores resultados para as análises físicas e químicas, e as cultivares porta-enxerto limoeiro ‘Cravo Santa Cruz’ e Tangerineira ‘Sunki’ seleção Tropical influenciaram as copas aos melhores resultados das análises físicas e químicas, respectivamente. Todas as combinações apresentaram baixo rendimento do suco

Parâmetros genéticos da mandioca quanto à tolerância ao deficit hídrico

The objective of this work was to evaluate the effect of drought on genetic parameters and breeding values of cassava. The experiments were carried out in a completely randomized block design with three replicates, under field conditions with (WD) or without (FI) water deficit. Yield of storage roots (RoY), shoot (ShY), and starch (StY), as well as the number of roots (NR), and root dry matter content (DMC) were evaluated in 47 cassava accessions. Significant differences were observed among accessions; according to heritability, these differences had mostly a genetic nature. Heritability estimates for genotypic effects () ranged from 0.25±0.12 (NR) to 0.60±0.18 (DMC), and from 0.51±0.17 (NR) to 0.80±0.21 (RoY and StY) for WD and FI, respectively, as a consequence of greater environmental influence on WD. Selective accuracy was lower in WD, and ranged from 0.71 (NR) to 0.89 (RoY, DMC, and StY). However, genetic gains were quite high and ranged from 24.43% (DMC) to 113.41% (StY), in WD, and from 8.5% (DMC) to 75.70% (StY) in FI. These genetic parameters may be useful for defining which selection strategies, breeding methods, and experimental designs are more suitable to obtain cassava genetic gains for tolerance to drought.O objetivo deste trabalho foi avaliar o efeito do deficit hídrico sobre os parâmetros e os valores genéticos da mandioca. Os experimentos foram realizados em delineamento de blocos ao acaso com três repetições, em campo com (CD) ou sem deficit hídrico (SD). A produtividade de raízes (PR), da parte aérea (PA) e de amido (PAM), assim como o número de raízes (NR) e a massa de matéria seca das raízes (MS) foram avaliados em 47 acessos de mandioca. Observaram-se diferenças significativas entre os acessos; conforme a herdabilidade, estas diferenças foram em sua maioria de natureza genética. As estimativas de herdabilidade dos efeitos genotípicos () variaram de 0,25±0,12 (NR) a 0,60±0,18 (MS) e de 0,51±0,17 (NR) a 0,80±0,21 (PR e PAM) para CD e SD, respectivamente, em decorrência da maior influência ambiental sobre o CD. A acurácia seletiva foi menor no CD, com variação de 0,71 (NR) a 0,89 (PR, MS e PAM). No entanto, os ganhos genéticos foram elevados, de 24,43% (MS) a 113,41% (PAM) no CD, e de 8,5% (MS) a 75,70% (PAM) no SD. Estes parâmetros genéticos podem ser úteis para definir estratégias de seleção, métodos de melhoramento e delineamentos experimentais mais apropriados, para a obtenção de ganhos genéticos em mandioca quanto à tolerância à seca

Photosynthesis and mechanisms of protection against photooxidative stress in Coffea arabica L. grown in the field under two irradiance levels

O cafeeiro é originário de ambientes sombreados, fato gerador de uma crença bem estabelecida de que se trata de uma espécie de sombra. No entanto, em muitos locais, o café é cultivado a pleno sol, com produções satisfatórias. O objetivo deste trabalho foi, pois, identificar potenciais mecanismos de fotoproteção, bem como avaliar como eles se ajustam diurna e sazonalmente. As plantas foram cultivadas no campo, sob dois níveis de irradiância (50 e 100% da luz natural incidente), analisando-se folhas das faces do renque completamente expostas à luz, em três épocas contrastantes: agosto e dezembro de 2003 e outubro de 2004. A fotossíntese líquida e a condutância estomática apresentaram valores baixos e similares nas plantas de ambos regimes de luz em todas as épocas, especialmente à tarde. Tendência semelhante foi observada para a atividade da carboxilase/oxigenase da ribulose-1,5-bisfosfato, amostrada ao meio-dia. Observou-se fotoinibição crônica em agosto e uma discreta fotoinibição dinâmica em dezembro e em outubro nas plantas de ambos tratamentos. As concentrações de clorofilas e carotenóides totais foram menores em agosto nas plantas de ambos regimes de luz. O ângulo foliar foi sempre maior nas plantas a pleno sol em relação às sob sombra. Na maioria das amostragens, a taxa de transporte de elétrons foi semelhante em plantas de ambos tratamentos. Em laboratório, observou-se, na medida em que incrementava a irradiância, redução na fração de energia utilizada na fase fotoquímica da fotossíntese e aumentos concomitantes e consistentes na fração dissipada na forma de calor e na fração da energia não utilizada na fase fotoquímica e tampouco dissipada como calor. Isto foi observado até a irradiância actínica de 1500 μmol(fótons) m - 2 -1 s sem, contudo, verificar-se um padrão claro entre plantas a pleno sol e sob sombra. Não se observaram diferenças entre essas plantas acerca das atividades das enzimas antioxidantes: dismutase do superóxido (SOD), catalase (CAT), peroxidase do ascorbato (APX) e redutase da glutationa (GR). Comparativamente, maior atividade da SOD e da APX ocorreram em outubro, da CAT, em outubro/dezembro, enquanto a da GR foi similar entre as épocas avaliadas. Verificou-se tendência de maiores níveis de ascorbato nas plantas a pleno sol que naquelas sob sombra, mas apenas em agosto tais diferenças foram significativas. De modo geral, danos celulares de pequena magnitude, caracterizados por aumentos discretos no extravasamento de eletrólitos e acúmulo de aldeído malônico, foram mais evidentes em agosto e em outubro em relação a dezembro, embora similar entre plantas de ambos tratamentos. Em suma, nas condições deste experimento, o cafeeiro apresentou alta plasticidade fisiológica de seu aparelho fotossintético às variações da irradiância.Coffee is native to shady environments, a fact that has been associated with a general belief that it is a shade species. However, in many places, coffee grows well without shade and even out-yields shaded coffee. The aim of this work was to identify potential mechanisms of photoprotection as well as to evaluate how they are able to adjust diurnally and seasonally. The plants were grown in the field under two irradiance levels (50 and 100% of incident natural light). Sampling and measurements were made using outer leaves from the sun-faced sides of the coffee hedgerow in three contrasting times: August and December 2003 and October 2004. Regardless of the treatments, net photosynthesis and stomatal conductance were very low, particularly in the afternoon. A similar trend was observed for the activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, as analyzed at midday. Chronic photoinhibition was found in August, whereas a slight, dynamic photoinhibition was observed in December and October, irrespective of light treatments. Concentrations of chlorophylls and total carotenoids were smaller in August than in December or October, regardless of light conditions. Leaf angle was always steeper in plants under full sunlight in relation to those under shade. On most occasions, electron transport rate was similar in plants under both irradiance treatments. Under laboratory conditions, there was a reduction in the fraction of absorbed light used in photochemistry which was accompanied by increases in the fraction of absorbed light dissipated as heat as well as in that fraction neither used in photochemistry nor dissipated thermally. This was observed until applying an actinic irradiance of 1500 μmol (photons) m -2 s -1 , but no clear difference between sun leaves and shaded ones was noted, however. Activities of key antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR), were similar between plants from both light treatments. Comparatively, larger activity of SOD and APX occurred in October, that of CAT in October/December, while GR activity was similar among the evaluated periods. A trend for higher reduced ascorbate pool was observed in plants grown in the open than in those grown under shade, but only in August such differences reach statistical significance. In a general way, discrete cellular damages, characterized by slight increases both in electrolyte leakage and malondialdehyde accumulation, were more evident in August and in October as compared to December, but such damages were similar between plants from both irradiance treatments. Summing up, the photosynthetic apparatus of the coffee tree, under the present experimental conditions, showed a high physiological plasticity to varying irradiance.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Physiological aspects of coffee growth and production

Neste trabalho, foram investigadas alterações no crescimento vegetativo, na produção, na "seca de ramos", nas trocas gasosas, no metabolismo de carboidratos, nos teores de nitrogênio e pigmentosem folhas e segmentos de ramos de plantas de café cultivadas em renques orientados na posição norte-sul, sob condições de campo, ao longo de dois anos. Foram realizadas avaliações em ramos em três classes de razão área foliar/número de frutos (RAF) [0 a 6 (R1); 6,1 a 14 (R2); >14 cm2 fruto-1 (R3)], em 2006-2007, e RAF >20 cm2 fruto-1, em 2007-2008, nas posições leste inferior (LI), leste superior (LS), oeste inferior (OI) e oeste superior (OS) da copa. As avaliações de crescimento foram realizadas de novembro de 2006 a março de 2007, e de novembro de 2007 a maio de 2008. As avaliações de trocas gasosas, metabolismo do carbono, nitrogênio e pigmentos foram realizadas em março de 2007 e em março de 2008, enquanto a produção de frutos foi avaliada em abril de 2007 e em maio de 2008, e a seca de ramos, em julho de 2007 e 2008. A taxa de crescimento dos ramos foi maior, enquanto a produção e a seca de ramos foram menores, na medida em que a RAF aumentou, em todas as posições avaliadas, em 2006-2007. Em 2007-2008, a taxa de crescimento dos ramos foi maior nos estratos superiores em comparação aos inferiores, tanto nas posições leste como na oeste do renque. Em 2007, a produção total de frutos e de frutos normais nas faces leste e oeste foi maior no estrato superior em relação ao inferior, enquanto a produção de frutos-bóia foi maior em OS que em OI. Entre as faces do renque, tanto a produção total de frutos, a de frutos normais e a de frutos-bóia, bem como a morte de ramos, no estrato superior, foram maiores na face leste em comparação com a oeste. A produção total de frutos foi sobremodo maior em 2006-2007 que em 2007-2008, em todas as posições e faces avaliadas. Não se puderam associar diferenças de produção entre os tratamentos com diferenças de taxas de fotossíntese, com variações na composição isotópica do carbono e nem com diferenças de disponibilidade de carboidratos, fato que poderia ser explicado pela perda da autonomia dos ramos, particularmente nos períodos de alta demanda de assimilados pelos frutos. Em consonância com estes resultados, nenhuma alteração substancial nas atividades de enzimas-chave associadas ao metabolismo do carbono foi verificada. Não se pôde, também, associar seca de ramos com disponibilidade de minerais e carboidratos, nem com estresse oxidativo. Em adição, não se verificaram variações de bienalidade de produção entre faces do dossel; possivelmente, maior produção da face leste poderia estar associada com maior disponibilidade de luz, nas condições deste experimento. Registra-se, ainda, que a manutenção das trocas gasosas, ao longo do dia, pode estar muito mais associada a baixas demandas evaporativas da atmosfera do que propriamente com retroinibição da fotossíntese. Nesse sentido, os estômatos parecem responder fortemente ao aumento do déficit de pressão de vapor; porém, ritmos endógenos também podem estar associados ao fechamento estomático, especialmente no fim da tarde.In this work, changes in vegetative growth, crop production, branch die-back, gas exchange, carbohydrate metabolism, nitrogen and pigment concentration were investigated in leaves and branch segments in coffee trees grown (north-south orientation) under field conditions along two years. Samplings and measurements were conducted using outer leaves from the upper and lower strata from east- and west-faced sides of a coffee hedgerow in branches of three classes of leaf-to-fruit ratio (0 to 6; 6.1 to 14; >14 cm2 fruit-1) in 2006-2007 and leaf-to-fruit ratio >20 cm2 fruit-1 in 2007-2008. Growth evaluations were accomplished from November 2006 to March of 2007 and from November 2007 to May 2008. Evaluations of gas exchange, carbon metabolism, nitrogen and pigment concentration were accomplished in March 2007 and March 2008, while crop yield was evaluated in April 2007 and May 2008, and branch die-back in July 2007 and July 2008. Branch growth rate was larger, whereas production and branch die-back were smaller with increasing leaf-to-fruit ratio regardless of canopy positions in 2006-2007. In 2007-2008, branch growth rate was larger in the upper strata in comparison with the lower strata in both east and west positions of the hedgerow. In 2007, total crop yield and production of welldeveloped fruits in east and west faces were both larger in upper strata than in the lower strata, while the production of partially-empty fruits was larger in upper than in lower strata in the east canopy position. Among the faces of the row, total crop yield and production of well-developed- and partially-empty-fruits, as well as branch dieback in the upper strata, all were larger in the east face than in the west one. Total crop yield was remarkably larger in 2006- 2007 than in 2007-2008 regardless of canopy position. Relationships among crop production with photosynthetic rates, carbon isotope composition and carbohydrate concentration could not be found, which could be explained by the loss of branch autonomy, particularly in periods of high demand of assimilates by the fruits. In support to these results, substantial alteration in activities of key enzymes associated with carbon metabolism was not verified. Relationships among branch die-back with availability of minerals and carbohydrates as well as with oxidative stress were also not found. In addition, variations in biennial production were not verified among the faces of the tree canopies. Possibly, larger production of the east face could be associated with larger light supply. Maintenance of gas exchange along the day could be largely associated with lower atmospheric demand than with feedback inhibition of photosynthesis. In this sense, stomata seemed strongly responsive to increasing evaporative demand; however, endogenous rhythms might also be associated with stomatal closure, especially at the end of afternoon.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Agronomic responses of grapevine ‘Chenin Blanc’ as a function of training systems and rootstocks

The aim of this research was to study the influence of training system and rootstock on the yield, vigor and physiology of the ‘Chenin Blanc’ grapevine at São Francisco Valley, northeastern Brazil. An experiment was carried out on eight harvests, from 2013 to 2017, in Petrolina, in the state of Pernambuco. Grapevines were grown under two training systems, lyre and espalier, and five rootstocks: ‘IAC 572’, ‘IAC 313’, ‘IAC 766’, ‘Paulsen 1103’ and ‘SO4’, using a split-plot randomized block design, with training systems assigned to the main plot and the rootstock assigned to the subplot. Lyre favored an increase in the number of bunches, branches and leaf mass in the harvest of the first semester of the year, while in the second semester there were increases of 40 % in the number of bunches and 10 % in leaf mass. Lyre promoted more balanced vines, showing a better ratio between production and pruning weight (Ravaz index). The rootstocks ‘IAC 766’, ‘IAC 313’ and ‘IAC 572’ increased yield and bunch mass under both training systems, while ‘SO4’ reduced yield and vigor. The stomatal conductance and instantaneous efficiency of water use were not influenced by either the training system or the rootstock. Under tropical conditions in the São Francisco Valley, ‘Chenin Blanc’ grapevine may be grown under the lyre training system, preferably on the ‘IAC 766’ rootstock, to obtain high yields and balanced grapevines

Productive and morphogenetic responses of buffel grass at different air temperatures and CO2 concentrations

The objective of the present trial was to evaluate the productive and morphogenetic characteristics of buffel grass subjected to different air temperatures and CO2 concentrations. Three cultivars of buffel grass (Biloela, Aridus and West Australian) were compared. Cultivars were grown in growth chambers at three temperatures (day/night): 26/20, 29/23, and 32/26 °C, combined with two concentrations of CO2: 370 and 550 µmol mol-1. The experimental design was completely randomized, in a 3 × 3 × 2 factorial arrangement with three replications. There were interactions between buffel grass cultivars and air temperatures on leaf elongation rate (LER), leaf appearance rate (LAR), leaf lifespan (LL) and senescence rate (SR), whereas cultivars vs. carbon dioxide concentration affected forage mass (FM), root mass (RM), shoot/root ratio, LL and SR. Leaf elongation rate and SR were higher as the air temperature was raised. Increasing air temperature also promoted an increase in LAR, except for West Australian. High CO2 concentration provided greater SR of plants, except for Biloela. Cultivar West Australian had higher FM in relation to Biloela and Aridus when the CO2 concentration was increased to 550 µmol mol-1. West Australian was the only cultivar that responded with more forage mass when it was exposed to higher carbon dioxide concentrations, whereas Aridus had depression in forage mass. The increase in air temperatures affects morphogenetic responses of buffel grass, accelerating its vegetative development without increasing forage mass. Elevated carbon dioxide concentration changes productive responses of buffel grass

Spondias tuberosa trees grown in tropical, wet environments are more susceptible to drought than those grown in arid environments

In this study, we investigated the different responses of Spondias tuberosa (umbu) trees, which grow in two different ecological life zones in northeast Brazil: tropical wet and tropical arid ecosystems. We evaluated the responses of plants grown under humid and dry conditions by measuring photosynthesis, water status, fluorescence parameters, carbon isotopes and antioxidant systems activity. The highest net photosynthesis values were recorded simultaneously with the lowest VPD values. The highest internal-to-ambient CO2 concentration and the absence of typical changes in the fluorescence parameters suggested the onset of a nonstomatal limitation in photosynthesis. Our results showed that umbu plants can adjust their antioxidant activity during the dry season as a defensive strategy against the deleterious effects of water stress. This evidence is supported by the observed modifications in the pigment concentrations, increased accumulation of hydrogen peroxide and malondialdehyde, high levels of electrolyte leakage, increased antioxidant activity, and decreased carbon isotope discrimination in the umbu trees during the dry season. Supported by multivariate analysis of variance, significantly effect of interaction between categorical “months of collect and location” predicts a strong “dry season effect” on our dataset. Taken together, our data show that umbu trees grown in a wet tropical environment are more susceptible to drought compared with their tropical arid counterparts

Genetic parameters for drought-tolerance in cassava

The objective of this work was to evaluate the effect of drought on genetic parameters and breeding values of cassava. The experiments were carried out in a completely randomized block design with three replicates, under field conditions with (WD) or without (FI) water deficit. Yield of storage roots (RoY), shoot (ShY), and starch (StY), as well as the number of roots (NR), and root dry matter content (DMC) were evaluated in 47 cassava accessions. Significant differences were observed among accessions; according to heritability, these differences had mostly a genetic nature. Heritability estimates for genotypic effects () ranged from 0.25±0.12 (NR) to 0.60±0.18 (DMC), and from 0.51±0.17 (NR) to 0.80±0.21 (RoY and StY) for WD and FI, respectively, as a consequence of greater environmental influence on WD. Selective accuracy was lower in WD, and ranged from 0.71 (NR) to 0.89 (RoY, DMC, and StY). However, genetic gains were quite high and ranged from 24.43% (DMC) to 113.41% (StY), in WD, and from 8.5% (DMC) to 75.70% (StY) in FI. These genetic parameters may be useful for defining which selection strategies, breeding methods, and experimental designs are more suitable to obtain cassava genetic gains for tolerance to drought

Potassium doses on the ecophysiological characteristics of ‘Syrah’ grapevine grown at São Francisco River Valley, Brazil

The nutrients availability can lead to changes on grapevines physiological behavior, which results in a great importance of studies regarding the application of potassium doses. The aim of this research was to evaluate the ecophysiological behavior of grapevine cultivar ‘Syrah’ growing under different potassium doses by fertigation, according to the determination of gas exchange, chlorophyll a, fluorescence and pigments index. Five years old plants, grafted on ‘Paulsen 1103’ rootstock, in a trellis system and planted at theBebedouro Experimental Field, located in Petrolina, PE, Brazil, were evaluated. The experiment was composed by five potassium doses (0, 20, 40, 80 and 160 kg ha-1), applied by fertigation. The potassium sources were potassium sulfate, potassium nitrate and potassium chloride. The evaluations of the ecophysiologyical parameters were performed at four different times (07am, 10am, 1pm and 3pm) throughout the day on the flowering stage and the first and second fruit growth stages, determining gas exchange and chlorophyll a fluorescence and the pigments index was evaluated at the same grapevines leaves one time. Considering each evaluation period, it was observed that, according to the magnitude of the results for gas exchange, chlorophyll a fluorescence and pigments index, is not possible to indicate the best potassium dose. The climatic conditions during each period of evaluation influenced most the eco-physiological variables than the applied potassium doses, while the changes on pigments index were due to leaves development during the plant cycle.A disponibilidade de nutrientes proporciona alteração no comportamento fisiológico das plantas, tornando de grande importância o estudo da aplicação de diferentes doses de potássio em videira de vinho. O objetivo desta pesquisa foi avaliar o comportamento ecofisiológico da videira ‘Syrah’ cultivada em diferentes doses de potássio aplicadas via fertirrigação, analisando as trocas gasosas, a fluorescência da clorofila a e o índice de pigmentos. Foram utilizadas plantas com cinco anos de idade, enxertadas sobre ‘Paulsen 1103’, cultivadas em espaldeira e implantadas no Campo Experimental de Bebedouro, Petrolina-PE. O experimento foi constituído de cinco doses de potássio (0, 20, 40, 80 e 160 kg ha-1) aplicados via fertirrigação utilizando como fontes o sulfato de potássio, o nitrato de potássio e o cloreto de potássio. As avaliações foram realizadas em quatro horários (07:00, 10:00, 13:00 e 15:00 h) ao longo dia na fase de florescimento e nas 1ª e 2ª fases de crescimento do fruto, consistindo em determinar os parâmetros de trocas gasosas, da fluorescência da clorofila, enquanto o índice de pigmentos foi avaliado nas mesmas datas e nas mesmas folhas de videira uma única vez. Considerando-se cada data de avaliação de forma independente, se observou que a magnitude dos resultados dos parâmetros de trocas gasosas e da fluorescência da clorofila a obtidos neste trabalho não sofreram influência das doses de potássio e que as condições climáticas reinantes em cada período de avaliação influenciaram mais as respostas ecofisiológicas do que as doses de potássio aplicadas, enquanto a alteração no índice de pigmentos foi em função do desenvolvimento das folhas ao longo do ciclo