Open Access Original Research Article

Potentially Diazotrophic Endophytic Bacteria Associated to Sugarcane are Effective in Plant Growth-promotion

Maria Camila de Barros Silva Leite, Arthur Prudêncio de Araújo Pereira, Adijailton José de Souza, Pedro Avelino Maia de Andrade, Marisângela Viana Barbosa, Fernando Dini Andreote, Fernando José Freire, Júlia Kuklinsky Sobral

Journal of Experimental Agriculture International, Page 1-15
DOI: 10.9734/JEAI/2018/39963

The bioprospection of microorganisms with the potential to promote sugarcane growth has been increasingly sought, mainly to minimize the insertion of inputs that increase the costs of the production chain. The objective of this work was to isolate, identify and select endophytic bacteria from sugarcane with potential ability for plant growth promotion. Also to evaluate the influence of different levels of salinity and pH values on plant growth-promotion and to analyze the genetic diversity of the isolates by the partial sequencing of the 16S rRNA gene. Samples of stems and roots of the varieties RB 92579, RB 867515 and RB 863129 were used for collecting the bacteria associated with sugarcane. The isolation was performed in LGI-P culture medium. The isolates were evaluated for biological nitrogen fixation (BNF), indole acetic acid (IAA) production, inorganic phosphate solubilization and exopolysaccharide (EPS) production. Bacterial growth and phosphate solubilization were evaluated at different salt concentrations and pH values of the culture medium. After isolation and identification were obtained 24 isolates, been that 54% grew in nitrogen-free medium. IAA was produced in 50% and 12.5% of the isolates in medium with and without the addition of L-tryptophan, respectively. In addition, 67% of the isolates were positive for phosphate solubilization and 75% produced exopolysaccharides. The presence of salt and different pH values of the culture medium influenced the growth of the isolates and the salt concentration influenced phosphate solubilization. Seven isolates showed similarity with Burkholderia gladioli and one with Burkholderia heleia, besides many genera only of Burkholderia sp., suggesting low genetic diversity. Burkholderia heleia had a lower growth rate than Burkholderia gladioli. It was a bacterium very sensitive to high amounts of salt when the pH was higher. The root bacterial isolate G27 obtained from RB 867515 presented the highest PSI in the lowest saline concentrations and the stem isolate G15 of the same variety was able to solubilize phosphate in high salt concentration. We conclude that sugarcane interacts with potentially diazotrophic endophytic bacteria involved with plant growth-promotion and can be used as inoculants in management programs of this crop, however, it is necessary to observe soil salinity levels and monitor pH to maximize plant growth-promotion characteristics of these bacteria.


Open Access Original Research Article

Weed Control and Peanut Tolerance Using Pyroxasulfone in Oklahoma

Todd A. Baughman, W. James Grichar, Peter A. Dotray

Journal of Experimental Agriculture International, Page 1-11
DOI: 10.9734/JEAI/2018/39881

Aims: To determine the spectrum of weed control and peanut tolerance with pyroxasulfone in Oklahoma.   

Study Design:  Randomized complete block design with four replications.

Place and Duration of Study: Oklahoma State University Caddo Research Station near Ft. Cobb (35.091º N, 98.275º W) in southwestern Oklahoma during the 2013-2014 growing seasons.

Methodology: Herbicides were applied with a CO2 compressed air backpack sprayer using Teejet 110015XR nozzles that delivered 93 L ha-1 at 180kPa.  Weed control and peanut injury were visually estimated on a scale of 0 indicating no control or plant death to 100 indicating complete control or plant death, relative to the untreated control. Peanut yields were obtained by digging each plot separately, air-drying in the field for 4 to 7 d, and harvesting peanut pods from each plot with a combine.  Visual estimates of weed control and peanut yield were subjected to analysis of variance to test effects of postemergence (POST) herbicide and application timing and means were compared with Fisher’s Protected LSD test (0.05).

Results: In 2013, only treatments that controlled Urochloa texana > 85% were those that included pendimethalin plus pyroxasulfone applied preemergence (PRE) and imazapic applied late postemergence (LPOST).  Ipomoea hederacea control using either pendimethalin applied preplant incorporated (PPI) or flumioxazin applied PRE and imazethapyr applied POST was ≥ 75%.  In 2014, herbicide systems that included imazapic applied POST controlled I. hederacea at least 98% while no other herbicide systems provided better than 78% control.  Peanut stunting (4 to 13%) was observed in 2013 with all PPI and PRE treatments.  In 2013 and 2014, pyroxasulfone plus pendimethalin systems applied PRE followed by imazapic applied LPOST produced the greatest peanut stunting.

Conclusion: These results indicate that pyroxasulfone is an effective herbicide for weed control in Oklahoma peanut production.  Although no peanut yield reductions were observed, the early season stunting in isolated instances should be noted.

Open Access Original Research Article

Influence of 2,4-D Growth Regulator and Foliar Explant Source on Coffea arabica Embryogenic Calli

K. G. do Livramento, L. F. Torres, F. V. Barbosa, J. de C. e Andrade, D. E. d o Livramento, L. V. Paiva

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/JEAI/2018/39558

Aims: With the goal of obtaining Coffea arabica varieties with greater productivity and resistance, researchers in Brazil have been conducting experiments on elite plant propagation through in vitrotechniques, such as somatic embryogenesis. This large-scale multiplication method has great potential for exploration and could enable maximization of coffee propagation. The aim of the current work was to compare the effects of different 2,4-D concentrations and two pre-established methodologies for obtaining embryogenic calli of Coffea arabica, and to evaluate whether the foliar explant source can affect somatic embryogenesis.

Place and Duration of Study: The experiments were conducted in the Central Laboratory of Molecular Biology at the Federal University of Lavras, (Brazil), between 2016 and 2017.

Methodology: The calli of Coffea arabica cv. Catiguá MG2 were obtained using two well-known methodologies and from two explant sources: seedling leaves cultivated both in vitro and in a greenhouse. The quality of potentially embryogenic calli was verified by morphological analysis by light microscopy, and the quantity was determined by analysis of variance.

Results: After five months of culture, all treatments generated potentially embryogenic calli. The calli were histologically characterized as having a homogeneous tissue consisting of small isodiametric cells and aggregates displaying a dense cytoplasm and clear nuclei. Numerous small starch grains were also noted.

Conclusion: The plant leaf explants grown in vitro showed a high percentage of potentially embryogenic calli after inoculation in a culture medium containing a low 2,4-D concentration. Morphological characteristics may therefore be used as structural markers to select embryogenic cultures.

Open Access Original Research Article

Influence of Bio-regulators on the Fruit Quality and Yield Attributes of Phalsa (Grewia subinaequalis DC)

Gurpinder Kaur, Maninderjit Singh, Manpreet Singh

Journal of Experimental Agriculture International, Page 1-6
DOI: 10.9734/JEAI/2018/38465

Aims: To examine the influence of bioregulators on the fruit quality and yield attributes of phalsa.

Study Design: Randomised Block Design.

Place and Duration of Study: Phalsa orchard, Department of Horticulture, Khalsa College, Amritsar during 2015-2016.

Methods: The present study comprised of ten treatments which replicated thrice. The treatments were consisted of Gibberellic acid (GA3 @ 50, 100 and 150 ppm), Naphthalene Acetic Acid (NAA @ 25, 50 and 75 ppm), Ethrel (@ 250, 500 and 1000 ppm) and control. The thirty plants of uniform vigour were randomly selected for the study and these were applied with different concentrations of NAA and GA3 at fruit set whereas ethrel was sprayed at 20 to 25 days before fruit harvest. Uniform sized mature fruits were harvested and a sample of ten randomly selected fruits were being taken from each replication for fruit physical and biochemical analysis and then average was worked out for each parameter. The observations were recorded viz., fruit length (cm), fruit breadth (cm), fruit weight (g), fruit colour, total soluble solids (TSS%), titratable acidity (%), TSS: acid ratio, reducing sugars (%), total sugars (%), ascorbic acid (mg/100 g pulp), stone length (cm), stone breadth (cm), stone weight (g), harvesting span (days), number of pickings and fruit yield per plant (kg).

Results: The results revealed that GA150 ppm treated plants yielded fruits with maximum fruit length (1.26 cm), fruit breadth (1.43 cm), fruit weight (1.20 g), reducing sugars (7.49 %), ascorbic acid (31.10 mg/100 g pulp) and yield (3.48 kg/plant). Minimum stone length (0.50 cm), stone breadth (0.33 cm) and stone weight (0.045 g) were recorded in fruits obtained from plants treated with NAA 25 ppm. Ethrel 1000 ppm significantly improved TSS (20.23%), fruit colour (purple black), total sugars (12.79 %) whereas reduced the titratable acidity (1.54 %), harvesting span (22.81 days) and number of pickings (3.90).

Conclusion: The results of the present study concluded that plants treated with GA3 150 ppm registered a significant improvement in fruit physical and biochemical parameters and also fruit yield per plant was increased. The fruits obtained from the plants treated with NAA 25 ppm had small sized and minimum weighed stone. Whereas the yield attributes were enhanced with the application of ethrel 1000 ppm in terms of advancement of harvesting and also reduction in number of pickings. Hence ethrel 1000 ppm may be applied to improve the fruit quality parameters as well as yield parameters and also to fetch the premium price in the market due to their attractive colour appearance than control.

Open Access Original Research Article

Development and Validation of a Solid-Liquid Extraction with Low Temperature Partitioning (SLE/LTP) Method for Determination of the Herbicide Indaziflam in Brazilian Soils by High Performance Liquid Chromatography (HPLC-UV/Vis)

Ana Cecilia Romero Ramírez, Matheus F. F. Teixeira, Antônio Augusto Neves, Maria Eliana L. R. Q ueiroz, Antonio Alberto da Silva, Ivan Ferreira Furtado, André Fernando de Oliveira

Journal of Experimental Agriculture International, Page 1-8
DOI: 10.9734/JEAI/2018/39554

Given the increased use of herbicides in intensive agriculture, it is essential to understand the dynamics of new products in the soil and in the wider environment, in order to avoid problems of contamination. One of the herbicides recently registered in Brazil is indaziflam (C16H20FN5). Although various analytical techniques are available for the determination of herbicides in soils, there have been few studies concerning indaziflam. In the present study, a solid-liquid extraction with low-temperature partitioning (SLE/LTP) method was developed, optimized, and validated for the identification and quantification of this herbicide in the soil by high-performance liquid chromatography with ultraviolet detection (HPLC-UV/Vis). Samples (4 g) of clayey and sandy Red-Yellow Latosol soils were conditioned with charcoal (1% w/w) obtained from the pyrolysis of sugarcane bagasse and were fortified with 2 mg L-1 of indaziflam. Extraction was performed using 4 mL of ultrapure water (pH 7.0) and 10 mL of acetonitrile (ACN)/ethyl acetate (EtOAc) in a proportion of 8.1:1.9 mL. The mixture was vortexed and then frozen at -20 °C. The supernatant was filtered, evaporated to dryness, and then recovered in 1.5 mL of ACN, prior to analysis by HPLC-UV/Vis. The recoveries of the herbicide were between 79.56 and 106.41% and the coefficients of variation were between 0.9 and 14.4%, in conformity with the parameters established by national regulatory agencies. The method provided selective, efficient, and accurate determination of indaziflam in the soils studied.