Citrus Varieties with Different Tolerance Grades to Tristeza Virus Show Dissimilar Volatile Terpene Profiles

Plants produce considerable amounts of volatile organic compounds (VOCs) with several biological functions, including protection against biotic agents such as viruses and their vectors. In citrus species, these metabolites can be related with their different susceptibility/tolerance toward the Tristeza virus (CTV), one of the main biotic constraints for the citrus industry. The objective of this study was to compare the VOCs pattern from the leaves of a CTV-susceptible citrus variety such as Citrus aurantium and from three CTV-tolerant varieties: Citrus volkameriana, Carrizo citrange, and Forner-Alcaide no. 5. The VOCs emitted were analyzed via the headspace SPME method, while plant metabolites sequestered in the leaves were analyzed by heptane extraction followed by GC-MS. The results indicated that the majority of the VOCs emitted and sequestered in the leaves of the varieties tolerant and susceptible to CTV are constituted mainly by volatile terpenes (VTs) that exhibit strong qualitative/quantitative differences among the profiles of the four citrus species. In detail, the VOC emission indicated different patterns between C. aurantium and C. volkameriana and from both of them in comparison with Forner-Alcaide no. 5 and Carrizo citrange that exhibited more similarities, with the last two characterized by a higher presence of sesquiterpenes. The data obtained from the analysis of the VOCs sequestered in leaf tissues of the CTV-tolerant varieties indicated a higher presence of monoterpenes such as limonene, α-pinene, and p-cymene, known to be the main components of several plant extracts showing deterrent properties toward viruses and insect vectors. As VOC evaluation is a fast and noninvasive measure of phenotypic dynamics, allowing the association of plant phenotypes in accordance to plant disease resistance and/or stress tolerance, the possible implications of such differences in terms of tolerance grade to CTV and/or its related vectors are discussed.

Selection and valorization of arbuscular mycorrhizal fungi isolated from phosphate sludge basins in promoting of citrus and carob seedlings

Accumulation of phosphate sludge (PS) generated from phosphate treatment process in the open air represent an environment risk and a problem in terms of storage capacities. The use of this by-products in agriculture, is an alternative recovery technique for the phosphate. Moreover, selection of symbionts and their inoculation into the soil whether in the nursery or at field were strongly encouraged. These inoculants were selected not only for their impact on the plant, but also for their ability to persist in the soil at the expense of the residual native microflora. This can be performed to the microorganisms which could occur in the solid sludges deriving the exploitation of phosphates in a pilot site of Khouribga area. In this context, the indigenous mycorrhizal resources have been exploited through better exploration of the local floristic diversity and then a series of mycorrhizal fungi selection and production tests have been made. The mycorrhizal complex was prepared and their effect was tested in Citrus and carob plants growth in the nursery. Two mixtures of PS were carried out: 10% (S2) and 40% (S5) for Citrus plants and 20% (S3) and 40% (S5) for carob plants. The sandy soil of Maamora forest was used as a control (S1). The results shown three dominant morphotypes were detected: Rhizophagus irregularis, Funnileformis constrictum and Scutellospora calospora. The effect of the PS with the AMF-based inoculum indicate that mycorrhizal inoculation of the substrates by a raw inoculum stimulates the growth of plants specially S2, S5 and S3 for Citrus volkameriana, Carrizo citrange and carob respectively. Based on these results, this combination between PS and mycorrhizal fungi had a great effect on Citrus and carob plant in the nursery.

Rootstock Influence on Growth and Mineral Content of Citrus limon and Citrus sinensis cv. Valencia Inoculated with Candidatus Liberibacter Asiaticus

Huanglongbing (HLB) reduces the growth and development of citrus and induces changes in secondary metabolites such as flavonoids, limonoids, and polyamines. Likewise, infected plants have a deficient absorption of nutrients such as zinc, potassium, manganese, and copper. Therefore, the objective of this study was to evaluate the influence of different rootstocks on morphology and mineral changes of Citrus limon and Citrus sinensis cv. Valencia plants inoculated with Candidatus Liberibacter asiaticus. In a greenhouse of the Experimental Station-Autonomous University of Tamaulipas, the Candidatus Liberibacter asiaticus bacteria were inoculated to Citrus limon plants (growing on Citrus volkameriana, Citrus macrophylla, and Citrus aurantium rootstocks) and Citrus sinensis cv. Valencia (growing on Citrus volkameriana and Citrus aurantium rootstocks). The experiment was established under a completely randomized design with 45 graft/rootstock repetitions. In each graft/rootstock combination, the plant height and stem diameter were determined using a tape measurer and a Vernier, respectively. In addition, the nutrient content of foliar samples was determined by an X-ray fluorescence spectrometer. In both citrus species, the C. aurantium rootstock promoted a higher concentration of the bacteria. On the other hand, the rootstock that showed the best agronomical results after inoculation with the bacteria was C. volkameriana, presenting the least variation in mineral content and conferring greater plant height (15%) and stem diameter (23%). In contrast, the presence of Ca. Liberibacter asiaticus decreased S content and increased Cu concentration in C. lemon plants. Similarly, plants infected with C. sinensis presented higher Fe content. Finally, in both species, no significant differences were observed for Mn, P, and Zn concentration.

Effect of Rootstock and Harvesting Period on the Bioactive Compounds and Antioxidant Activity of Two Orange Cultivars (‘Salustiana’ and ‘Sanguinelli’) Widely Used in Juice Industry

Oranges are a rich source of bioactive compounds with recognized benefits for human health. To guarantee high quality and production levels, citrus farms usually employ the combination of selected cultivars with well adapted rootstocks. This study analyzes the impact of four different citrus rootstocks (Forner-Alcaide no.5, ‘Cleopatra mandarin’, Citrus volkameriana and Carrizo citrange) on the bioactive compounds and antioxidant activity of two orange cultivars (‘Salustiana’ and ‘Sanguinelli’) widely used in the orange juice industry. For the hydrophilic fraction, the phenolic compound, anthocyanin, and organic acid profiles were determined by HPLC-DAD-HRMS, and the antioxidant activity by ABTS, DPPH, and ORAC assays. Besides, the total carotenoids and ABTS concentrations were calculated for the hydrophobic fraction. A set of three flavanones, one flavone, and eight anthocyanins were tentatively identified and quantified in the orange cultivars tested. The predominant phenolic compounds obtained in both orange cultivars were hesperidin and narirutin, while cyanidin-3-O-(6″-malonyl) glucoside followed by cyanidin-3-O-rutinoside and cyanidin-3-O-glucoside were the main anthocyanins found in the ‘Sanguinelli’ cultivar. Citric acid, followed by malic, oxalic, and ascorbic acids were the main organic acids. The higher amount of antioxidant compounds was found in fruit from the Forner-Alcaide no.5 rootstock. These results indicate that Forner-Alcaide n.5 affects positively the phenolic and organic acid composition and the antioxidant capacity of ‘Sanguinelli’ and ‘Salustiana’ cultivars, and is therefore a good option for the sector based on the healthy promoting properties.

Arbuscular mycorrhizal inoculation in Citrus volkameriana Tan & Pasq

Objective. We evaluated the effect of arbuscular mycorrhizal inoculation in Citrusvolkameriana Tan & Pasq plants with the application of Glomus spp Zac- 19 (G.claroides, G. diaphanum and G. albidum) to assess growth under greenhouseconditions without fertilizer application.Methodology. The evaluated treatments were inoculation with 2,4,6,8, and 10 g ofinoculum, plus a control without inoculation in an experimental design of completerandomized blocks with three replications. Variables were plant height, stem diameter,number of leaves, foliar area, dry weight, and mycorrhizal colonization.Results. A statistically significant response (p?0.01) to inoculation wasobserved, registering higher growth of mycorrhizal plants. The inoculation wasconsidered appropriate for all the levels evaluated. The outstanding treatment was 10 gof inoculum that produced plants with 110.16 cm in height for the last sampling; 38.56leaves per plant; 1.13 cm stem diameter; 35.95 g dry weight of root; 76.88 g dry weightof the aerial part of the plant; 225.03 cm 2 of leaf area per plant and 88.87% ofmycorrhizal colonization.Conclusions. The application of 10 g per plant to the roots of Citrus volkameriana fromthe Glomus Zac-19 arbuscular mycorrhizal consortium promoted the production of morevigorous plants for grafting, without the application of chemical fertilizer.

Bazı Turunçgil Anaçlarında Tuza Tolerans için In vitro Testleme

Just because of geographical spread, citrus species generally grow in places sensitive to salinity. Testing methods have a significant role in breeding and cultivar development programs. This study was conducted to investigate in vitro salt response of Cleopatra mandarin (Citrus reshni Tan.), sour orange (Citrus aurantium L.), rough lemon (Citrus jambhiri Lush.), Volkamer lemon (Citrus volkameriana Tan & Pasq.), Carrizo citrange (Poncirus trifoliata L. Raf. X Citrus sinensis L. Osbeck) and trifoliate orange (Poncirus trifoliata Raf.) rootstocks at different NaCl concentrations. Seeds were germinated in MS medium with 0, 45, 90 and 135 mM NaCl concentrations. In general, the greatest germination rates in all salt concentrations in Volkamer lemon and sour orange rootstocks and the lowest values were observed in rough lemon and trifoliate orange rootstocks. Present findings revealed that in vitro conditions could reliably be used in salt tolerance tests of citrus rootstocks.

INOCULACIÓN DE Citrus volkameriana Y Citrumelo swingle CON HONGOS MICORRIZÓGENOS (HMA), BAJO TÉCNICAS DIFERENTES DE DESINFECCIÓN DE SUSTRATO

Se evaluó el efecto de la inoculación con hongos micorrizógenos sobre el crecimiento ydesarrollo de dos especies de cítricos utilizados como portainjertos en la fase de semillero y al momento del trasplante a bolsas de vivero. En los años 2003 y 2004, se realizaron dos ex-perimentos en un diseño completamente al azar con 10 repeticiones, en un vivero comercial en Alajuela, Costa Rica. Los portainjertos utilizados fueron Citrus volkameriana y Citrumeloswingle. El sustrato se desinfectó siguiendo cuatro técnicas diferentes. Se midieron la altura de la planta, el diámetro del tallo a la base, biomasa aérea, biomasa de raíces, tiempo a in-jertación y colonización de raíces. De los resultados obtenidos se concluye que cuando se utilizaron agroquímicos (Basamid y PCNB) para desinfectar el sustrato de vivero, se afectó negativamente la simbiosis micorrícica. Las técnicas de desinfección naturales (agua calien-te y solarización) fueron más amigables con la relación mutualista. Se obtuvo una respuesta significativa de la inoculación en todas las variables medidas cuando se inoculó con una po-blación nativa de HMA. La mejor fecha para inocular fue al momento de realizar el semillero de Citrus volkameriana y Citrumelo swingle. Los árboles inoculados con población nativaacortaron de dos a tres meses su “período a injertación”, comparados con los no inoculados; de esta manera, se logró un ahorro en los gastos de mantenimiento de más de un 20%. Ade-más con este tratamiento se obtuvieron plantas más uniformes y con mejor desarrollo.

EVALUACIÓN DE CUATRO PATRONES PARA CÍTRICOS INJERTADOS CON LIMA PERSA (Citrus latifolia TAN) BAJO CONDICIONES DE CAÑAS, GUANACASTE

La lima Persa se ha convertido en una alternativa de diversificación agrícola para losagricultores del Distrito Riego Arenal de nuestro país por sus excelentes expectativas demercado y comportamiento agronómico bajo estas condiciones y también a nivel nacionalen general. Esta lima al igual que todas las especies cítricas de importancia comercial enel mundo se propagan principalmente por injerto, lo cual afecta una serie de características fitosanitarias y agronómicas del cultivo que también están condicionadas por el tipo de sue-lo, clima y aspectos de manejo del árbol. A raíz de ésto, se decidió establecer una parcela bajo condiciones del Pacífico Seco (Estación Experimental Enrique Jiménez Núñez Cañas/ Guanacaste) para evaluar la interacción de cuatro patrones de cítricos: volkameriana (Ci-trus volkameriana Pasq), taiwanica (Citrus taiwanica), citrumelo [(Poncirus trifoliata (L) Raf X Citrus paradisi Maca)] y mandarina cleopatra (Citrus reshni Hort X tan) injertados con unclon de lima Persa seleccionado en la Estación Experimental Enrique Jiménez Núñez librede enfermedades virosas. Se analizó el rendimiento de fruta fresca, longevidad de árboles,características de crecimiento de árboles, calidad interna y tamaño de fruta y absorción denutrientes en hoja y fruta en las distintas interacciones lima Persa/patrón. Se encontró quela mayor cantidad de fruta fresca se obtuvo sobre Citrus volkameriana al cabo de tres años de la siembra. Sin embargo, a los cinco años más del 50% de las plantas de lima Persa in-jertadas sobre este patrón presentaban decaimiento o habían muerto. Asimismo, la interac-ción que presentó la mayor eficiencia productiva a los cinco años, fueron los árboles injer-tados sobre mandarino cleopatra. Los parámetros de calidad interna obtenidos en frutas cosechadas sobre distintos patrones fueron muy similares en tres años de evaluación. Eltamaño de fruta sí varió significativamente, encontrándose los mayores calibres y pesos de limas cuando se cosecharon sobre citrumelo.También, se encontraron diferencias significa-tivas en la absorción de nutrientes en hoja y fruta de lima injertada sobre los distintos pa-trones bajo las condiciones de este estudio.

Indice

ARTÍCULOSMétodos de siembra y uso de atrazina en el establecimiento delpasto Brachiaria brizantha cv. Diamantes 1, en el trópico húmedode Costa Rica. Moisés Hernández, Franklin Herrera ... ... ... 1Efecto de la dosis y formulación de Metahrizium anisopliae enel combate de cercópidos en el pasto Brachiaria (Brachiariaruzizensis). Yannery Gómez ... ... ... ... ... ... ... ... ... ... ... ...11Evaluación de la eficacia biológica de los fungicidas BAS510(Boscalid) y BAS 516 (Boscalid + Pyraclostrobin) para el control de Botrytis cinnerea en el cultivo de tomate (Lycopersicum escu-lentum). Bernardo Mora ... ... ... ... ... ... ... ... ... ... ... ... ...23 Inoculación de Citrus volkameriana y Citrumelo swingle con hon-gos micorrizógenos (HMA), bajo técnicas diferentes de desinfec-ción de sustrato. Susana Shweizer, Eduardo Salas ... ... ... ...35 Identificación de trips (Thysanoptera: Thripidae) en el cultivo de mango (Mangifera indica L.). Ruth León, Jimmy Gamboa, Ri-cardo Elizondo ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...47 Evaluación de cuatro patrones para cítricos injertados con lima persa (Citrus latifolia Tan.) bajo condiciones de Cañas, Guana-caste. Sergio Hernández ... ... ... ... ... ... ... ... ... ... ... ... ...53 Análisis de estabilidad de cultivares de maíz (Zea mays L.) enambientes de Costa Rica. Nevio A. Bonilla ... ... ... ... ... ... ...63NOTAS TÉCNICASEvaluación agronómica de cereales forrajeros de uso potencialen sistemas de producción de leche de altura. María Mesén,William Sánchez ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...73Evaluación de leguminosas de los géneros Vicia, Lotus y Trifoliumen la zona alta de la provincia de Heredia, Costa Rica. MaríaMesén, William Sánchez ... ... ... ... ... ... ... ... ... ... ... ... ...79