Open Access Case study

Identification of Resistant Germplasm to Rice Blast under Silicon Amendment in Uganda

V. M. L. Jackson, P. Rubaihayo, P. Wasswa, M. Kanaabi, A. T. Hashim

Journal of Experimental Agriculture International, Page 1-11
DOI: 10.9734/JEAI/2018/42551

Rice blast caused by Magnaporthe grisea is one of the most serious diseases of rice, causing yield losses of 50 – 100% in susceptible varieties worldwide. Durable host resistance has been hard to achieve given large pathogen diversity and capacity of pathogen to mutate. It has been suggested that silicon enhances durable resistance in partially resistant genotypes. A study was conducted to evaluate rice genotypes for their reaction to M. grisea under silicon amendments and to detect genotypes with high silicon uptake. Sixty-seven genotypes were evaluated for their reaction to Magnaporthe grisea under silicon amendments in a CRD in three replications in a screen house. Seeds were planted in soil amended with silica gel at the rate of 0, 29, and 58 g per 180 g of soil. Genotypes were inoculated with a virulent strain of Magnaporthe grisea (Namulonge isolate) 21 days after planting. Seven plants were inoculated per genotype. Data were taken on lesion size induced by blast one week after inoculation and, interpreted   from 9 to 0. Data were also taken on leaf blast severity and used to compute area under disease progress curve (AUDPC). Twenty-four genotypes were highly resistant (HR), twenty - two were resistant (R), fourteen were moderately resistance (MR), four were moderately susceptible (MS) and three were susceptible (S). Silicon concentration significantly (P <.001) impacted on the reaction of genotypes to blast. The interaction of genotypes with silicon was also highly significant (P <.001). AUDPC was significantly influenced by silicon concentration (P = 0.008). The genotypes that consistently showed resistance to rice blast disease were recommended to similar conditions. The sixty-seven genotypes were screened for the capacity to absorb silicon. Twenty-day old seedlings were placed into 50 ml plastic bottles containing one-half concentration of Kimura B solution, adjusted with 0, 5, 10 and 15 mM silicon respectively. Each bottle was wrapped with an opaque plastic membrane for 12 hours after Si application. 0.9 ml of silicon uptake solution was drawn from each bottle and silicon concentration determined. Final silicon uptake ability readings were highly significant among genotypes. The leaf blast reaction of the genotypes under silicon amendment was found to be directly proportional to their silicon uptake ability which in turn increased with the increasing amount silicon solution absorbed by the plant, from 5, through 10 to 15 Mm/L. Significant correlations of Si uptake abilities to blast disease reactions and area under disease progresses were found in this study.

Open Access Short Research Article

Study of Nitrogen Efficiency of Three Corn Cultivars in Green Ears Production

Cassiana Felipe de Sousa, Leilson Costa Grangeiro, Valdivia de Fátima Lima de Sousa, Jader Vieira Carneiro, Jorge Luis Alves Silva, Lucas Pereira Gomes

Journal of Experimental Agriculture International, Page 1-6
DOI: 10.9734/JEAI/2018/42505

Aims: The objective of this study was to evaluate the efficiency of nitrogen utilization by corn cultivars for the production of green ears.

Study Design: Treatments were constituted by the combination of two nitrogen doses (0 and 90 kg ha-1 N) and three corn cultivars (Cruzeta, Truck and AG 1051). The experimental design was the randomized block design, in a 2 x 3 factor scheme, with five replications.

Place and Duration of Study: The experiment was conducted at a garden of the Department of Plant Science of Federal Rural University of the Semi-arid, Mossoró, Rio Grande Norte state, Brazil, from February to May 2015.

Methodology: The following parameters were evaluated: plant height, insertion of the first ear, stalk diameter, number and the productivity of marketable husked/not husked green ears , and the indices of efficiency agronomic efficiency, physiological efficiency, ear production efficiency, recovery efficiency and use efficiency.

Results: It was observed that application of nitrogen increased the plant height, insertion of the first ear, dry matter, number and the productivity of green ears. Cultivars differed in terms of stem diameter, plant dry matter and prolificacy. The cultivar Truck exceeded others regarding the ear number (husked, non-husked and total). However, as for productivity, the cultivars differed significantly only in the production of marketable husked ears. There was a significant difference among the cultivars, regarding agronomic efficiency and recovery efficiency.

Conclusion: Based on the values of the nutritional efficiency indices, Cultivar AG 1051, was more effective in using nitrogen to produce green ears as compared to Cruzeta and Truck. The dose of 90 kg ha-1 N recorded the higher yield of green corn than no nitrogen application.

Open Access Original Research Article

Phosphorus Efficiency in Brazilian Soybean Cultivars

Isabeli Pereira Bruno, Alinne da Silva, Vinícius Ide Franzini, Nericlenes Chaves Marcante, Takashi Muraoka

Journal of Experimental Agriculture International, Page 1-14
DOI: 10.9734/JEAI/2018/43230

The primary goal of this study was to evaluate the phosphorus uptake and use efficiency in Brazilian soybean cultivars, besides root morphology and architecture characteristics related to phosphorus uptake, carrying out two greenhouse experiments. The experiment 1 was completely randomised, with 56 treatments (soybean cultivars) and 3 replicates. Experiment 2 was completely randomised design with three replicates, and the ten cultivars (greater and lower efficiency) were selected for this assay according to their ability to absorb phosphorus less available determined in experiment 1.

The study was carried out at Center of Nuclear Energy in Agriculture, University of São Paulo, Brazil, between February 2011 and August 2012. The isotopic dilution technique was used in the first experiment to assess the phosphorus availability in the soil and to determine the ability of plants to access labile phosphorus by measuring the specific activity of plants grown in soil labeled with radioactive phosphorus. Nine cultivars showed greater phosphorus uptake and used efficiency. The second experiment evaluated the root morphology and architecture. The cultivars with greater uptake efficiency have root morphology and architecture characteristics that favour acquisition of phosphorus from soil compartments that are inaccessible to other cultivars. Phosphorus uptake by plants was not affected by soybean seeds phosphorus content. Identification of these cultivars is very important because it could enable soybean farming in low fertility soils, reducing fertiliser dependence.

Open Access Original Research Article

Potassium Silicate in the Acclimatization of Arabica Coffee Seedlings under Shaded and Full Sun Conditions

Paulo Fernando Marques Cavalcanti-Filho, Diego Corona Baitelle, Sílvio de Jesus Freitas, Waldinei Souza da Silva, Paulo Cesar dos Santos, Sávio da Silva Berilli, Silvério de Paiva Freitas

Journal of Experimental Agriculture International, Page 1-7
DOI: 10.9734/JEAI/2018/43307

Aims: The objective of this study was to evaluate the effect of the application of potassium silicate (K2SiO3) on the acclimatization of arabica coffee seedlings, under shaded and full sun conditions.

Study Design:  Randomized block design, with the treatments arranged in the subdivided portions scheme, with 13 replicates.

Place and Duration of Study: The experiment was conducted from November 2016 to February 2017 in the greenhouse, at the State University of Norte Fluminense Darcy Ribeiro - UENF, in the municipality of Campos dos Goytacazes - RJ, Brazil.

Methodology: The experiment was conducted in randomized blocks, with the treatments arranged in the subdivided portions scheme, with 13 replicates. The plots referred to two forms of acclimatization (shading and full sun), and the subplots were arranged to two nutrition conditions (application of K2SiO3 or not). The biometric, physiological and nutritional parameters of the plants were evaluated. The means of the collected data were submitted to analysis of variance and compared by the Tukey test at 5% of probability.

Results: A significant interaction between the acclimatization and application of K2SiO3 was observed in the SPAD index and potassium contents in the leaves. The SPAD index was higher when K2SiO3 was applied in both the acclimatization methods; and K2SiO3 application resulted in higher potassium contents in the shaded seedlings. Regarding the biometric variables, an increase in the fresh and dry matter of the aerial part was observed, when the K2SiO3 was used. In relation to the physiology, there was a beneficial effect in relation to the gradual acclimatization of the seedlings for all the parameters evaluated; while K2SiO3 increased only the chlorophyll contents in the leaves.

Conclusion: The application of K2SiO3 might be effective in making the seedlings rustic, thereby increasing the tolerance against insolation.

Open Access Original Research Article

Light-emitting Diodes (LED) as Luminous Lure for Adult Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)

Izabela Nunes do Nascimento, Gemerson Machado de Oliveira, Mileny dos Santos de Souza, Gilmar da Silva Nunes, Antonio Carlos Leite Alves, Heloísa Martins de Araújo, Jacinto de Luna Batista

Journal of Experimental Agriculture International, Page 1-8
DOI: 10.9734/JEAI/2018/43402

The capture of insects through luminous sources can represent another option for integrated pest management (IPM). The purpose of this study was to verify the attractiveness of different-colored Light-Emitting Diodes (LED) on adult Spodoptera frugiperda. The research was conducted at the Entomology Laboratory of Plant Breeding and Environmental Sciences Department, Federal University of Paraíba’s Agricultural Sciences Center – CCA/UFPB, Areia-PB. An environment composed of two plastic containers connected by a PVC pipe was assembled for this study. Adult subjects of S. frugiperda were inserted into one of these containers, and the opposite container was used to house the lamp. Ultra LED lamps were used as light source. Different colors of light viz., yellow, green, white, red, and blue, each one of them with specific wavelengths, illuminance, and exposure period were used. The study revealed that the attractiveness rate for adult subjects of S. frugiperda varied by the LED lamp colors and the exposure period. The green-colored lamp showed a greater attractiveness rate (31.22 and 49.91% at the times of 24 and 48 hours, respectively), which was followed by the white- and yellow-colored lamps. The red (25.75%) and blue (7.4%) colors, with an exposure period of 48 hours, showed the lower rates. The attractiveness of S. frugiperda gradually increased over the exposure period for the treatments with the green, yellow, white, and red colored LEDs. The green LED lamp, followed by the yellow and white LED, was proved to be the most attractive ones for adults of this species.