Australian Journal of Crop Science   AJCS

Temporal progression of foliar plant diseases in corn hybrids

Karoliny de Souza Almeida, Anderson Rodrigo da Silva, Natanael Marcos Lemos, Walter Baida Garcia Coutinho, Jakelinny Martins Silva, Celma Cardoso Peixoto, Matheus do Carmo Leite, Milton Luiz da Paz-Lima*

Instituto Federal Goiano campus Urutaí, Lab. de Fitopatologia, CEP 75790-000, Urutaí, GO, Brazil

Abstract
The environment’s impact on foliar disease growth in annual crops and the various types of differentiation must be investigated to adapt effective disease control strategies. We studied the temporal progression of foliar disease complexes in 14 commercial corn (Zea mays L.) hybrids during the 2015/2016 crop season (Ipameri, Goiás, Brazil). The experiment consisted of 10 blocks and evaluated foliar disease severity using a diagrammatic scale. The evaluations occurred at 47, 53, 59, 74, 81 and 95 days after planting. At each time point, a plant was chosen randomly from each block (10 plants total), and the diseases causing foliar damage were identified. The areas under the disease progression curves (AUDPCs) and yields were calculated. Dependent variables were evaluated using a principal component analysis to study relationships between the hybrids and the disease severity on each leaf (biplot). Heatmaps were used to determine which leaves demonstrated the greatest disease severity and temporal disease progression, and an adjusted linear correlation model was used to predict yield relative to AUDPC. The foliar disease complex consisted of helmintosporiosis, common rust, macrospora leaf spot, cercosporiosis and maize white spot. The Ns90PRO© hybrid showed limited disease progression and; therefore, was considered more resistant and consequently had a lower AUDPC value. The Dow2B610PW© hybrid showed greater disease progression. Agroceres7098PRO2© had a greater yield and consequently a lower AUDPC value, while Lg6050PRO2© had a lower yield and a higher AUDPC value. In general, the more advanced the phenological stage, the more severe the leaf disease; however, disease progression (from plant base to plant tip) was genotype- dependent.

Pages 1731-1739 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1458
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A computational method to assist evaluation of root length of soybean based on digital image processing

Marcio Hosoya Name*, Teruo Matos Maruyama, Rosane Falate, Adriel Ferreira da Fonseca

Federal University of Paraná (UFPR), Setor Litoral, Matinhos, Paraná, Brazil
Post Graduate Program of Federal University of Paraná (UFPR), Curitiba, Paraná, Brazil
Computer Department, State University of Ponta Grossa (UEPG), Ponta Grossa, Paraná, Brazil
Department of Soil Science and Agricultural Engineering, State University of Ponta Grossa (UEPG), Ponta Grossa, Paraná, Brazil

Abstract
The evaluation of the root system is important for better understanding the effects of nutrient management on soil and plant nutrition. However, root system studies and culture are slow and show low accuracy. In this context, digital image processing may be an alternative. The objective of this research was to develop a computational method to assist evaluation of the soybean root growth. Initially, the free and open access software, available at: http://rm.deinfo.uepg.br/, was developed in Java platform with the OpenCV library supply through the plug-in JavaCV. To evaluate the software, copper wires with 10 mm, 20 mm, and 50 mm of length manually measured using callipers. They were scanned with a resolution of 300 dpi and then images were loaded in the software. Variation coefficients between 0.01 and 2.99 % were obtained. Subsequently, the samples of soybean roots were scanned and the results of developed software and Safira software were correlated with those from the line-intersect method. The determination coefficients (R² = 0.999) of the developed software, on average, were better than those obtained with Safira software (R² = 0.733), when comparing with the line-intersect method. Therefore, the proposed method was accurate for length measurements of soybean roots.

Pages 1740-1748 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1492
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Extinction coefficient and interception efficiency of the photosynthetic photon flux density in cherry tomato under levels of nitrogen in greenhouse conditions

Mariana de Oliveira Pereira, Gustavo Bastos Lyra, Guilherme Bastos Lyra, Leonardo Duarte Batista Silva, José Leonaldo de Souza, Carlos Rodrigues Pereira, Marcos Filgueira Jorge

Center of Technology and Natural Resources, Federal University of Campina Grande, Brazil
Department of Environmental Sciences, Forestry Institute, Rural Federal University of Rio de Janeiro, Brazil
Center of Agrarian Sciences, Federal University of Alagoas, Brazil
Department of Engineering, Institute of Technology, Rural Federal University of Rio de Janeiro, Brazil
School of Engineering, Fluminense Federal University, Brazil

Abstract
Cherry tomato (Perinha Água Branca cultivar) was cultivated under organic management in greenhouse conditions set up in the municipality of Seropédica, Rio de Janeiro state, Southeastern Brazil. The crop was subjected to different nitrogen doses (N) ranging from 0 to 400% based on the reference value for the crop (100 kg ha-1) applied by means of dairy cattle wastewater. In order to estimate the extinction coefficient (k) and interception efficiency (Ԑint), weekly measurements of the photosynthetic photon flux density (PPFD) were performed below (PPFDb) and above the canopy (PPFDa) and the Leaf Area Index (LAI) was estimated. The extinction coefficient k for each treatment was obtained based on the model proposed by Monsi and Saeki. Ԑint was estimated by the quotient between PPFD absorbed by the canopy (PPFDabs = PPFDa – PPFDb) and PPFDa. Statistical tests were applied to k and Ԑint to evaluate the distribution of data (Kolmorogov-Smirnov) and their significance (Kruskal-Wallis), considering the treatments applied. No statistically significant differences were observed for k (p<0.05), which indicated canopy structure uniformity. The median k value was 0.792. Similar to k, Ԑint showed no statistically significant differences (p<0.05) between treatments; however, the highest interception efficiency was achieved by treatment with 300% N (Ԑint = 0.825), which coincided with the highest leaf area index and the lowest by treatment with 100% N (Ԑint = 0.521). The nitrogen did not interfere in the plant canopy architecture; however, it provided greater leaf area index to plants submitted to nitrogen doses two and three times above that recommended for the crop. Treatment with three times the recommended nitrogen dose reached in a shorter time interval the maximum efficiency value

Pages 1749-1755 | Ful Text PDF| doi: 10.21475/ajcs.19.13.11.p1497
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Yield of maize grain and tropical grass species under intercropping management system using nicosulfuron herbicide in off-season cultivation

Armindo Neivo Kichel, Luiz Carlos Ferreira de Souza, Ademar Pereira Serra*, Roberto Giolo de Almeida

Embrapa Beef Cattle, Campo Grande, Mato Grosso do Sul, Brazil
Universidade Federal da Grande Dourados (UFGD), Post-Graduation Program in Agronomy, City of Dourados, State of Mato Grosso do Sul, Brazil

Abstract
This research aimed to evaluate the maize grain yield and forage of grass species under intercropping system using nicosulfuron herbicide. In order to assess the parameters related to maize, a randomized block design was defined. The treatments were arranged in a (5 × 2+ 1) × 2 factorial design with four repetitions resulting in 11 treatments, where maize was cultivated under intercropping condition with different forage species (5) (Brachiaria brizantha cv. Marandu, Piatã, Xaraés, Brachiaria ruziziensis and Panicum maximum cv. Mombaça) and maize monoculture (1) as control treatment, with and without nicosulfuron herbicide application (2) in two growing seasons (2014 and 2015). The off-season intercropping of maize with tropical forage grasses with and without herbicide suppression decreased maize grain yield. The suppression with nicosulfuron herbicide decreased the dry matter production of forage grasses. Intercropping of P. maximum cv. Mombaça with maize showed higher decrease in maize grain yield. On the other hand, it showed higher forage grasses production for livestock feeding. B. brizantha cv. Piatã was the forage which less affected maize grain yield under intercropping, even with absence of nicosulfuron suppression. Off-season maize under intercropping with tropical forages can be used to recover degraded pastures; increasing forage dry matter production for livestock, remaining the soil covered with straws with possibility of no-till seeding for the next cultivation.

Pages 1756-1763 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1498
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Genetic analysis for biological nitrogen fixation (BNF) in cowpea

Sirando Lima Seido*, Carlos Antonio Fernandes Santos, Paulo Ivan Fernandes Júnior, Danillo Olegário Matos da Silva, Michael Paul Timko

Universidade Federal Rural de Pernambuco, Departamento de Agronomia, Recife, PE, Brazil
Embrapa Semiárido, Petrolina-PE, Brazil
Universidade Estadual de Feira de Santana, Departamento de Ciências Biológicas, Feira de Santana-BA, Brazil
Department of Biology, University of Virginia, Charlottesville, VA 22904 USA

Abstract
This work aimed to estimate the genetic parameters of biological nitrogen fixation (BNF) in cowpea to guide the development of efficient cultivars in N2 fixation. Inoculation was performed with a mix of three Bradyrhizobium strains. Two soil inoculations were performed with 1mL of the inoculum, at sowing and at five days after seedlings emergence. Plants were harvested and evaluated at 40 days after sowing. The means and variances of parents F1 and F2 and the BCs IC-1 (inefficient) × BRS Marataoã (efficient) (cross 1) and IC-1 × BRS Pujante (efficient) (cross 2) were analyzed. Segregation analyses for efficient and non-efficient plants indicate that BNF is controlled by two genes with dominant-recessive epistatic effect. Narrow-sense heritability estimates for crosses 1 and 2 were, respectively, 90% and 78% for shoot dry matter (SDM); 78% and 58%, for number of nodules/plant (NN); 86% and 58%, for nodule fresh matter (NFM); and 85% and 71%, for accumulated nitrogen (AN). Gene number estimates for SDM, NN, NFM, AN ranged from two to nine by the Mather and Jinks’ method, and from one to two, by the Lande’s method, in both crosses. SDM x NFM and NFM x AN had significant and positive correlations, while NN showed significant negative correlation with AN and SDM. BNF efficiency in cowpea can be easily achieved using autogamous breeding methods.

Pages 1764-1769 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1534
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Spraying deposits using different nozzles and application volumes for pest management of cotton at reproductive stage

Augusto Guerreiro Fontoura Costa*, Cleber Daniel de Goes Maciel, Thiesli Rogoski, Adelardo José Silva Lira, Enelise Osco Helvig

Empresa Brasileira de Pesquisa Agropecuária - Embrapa Algodão. Rua Oswaldo Cruz, 1143. Campina Grande, PB, Brazil. Zip code: 58428-095
Universidade do Centro-Oeste (Unicentro). R. Simeão Camargo de Varela Sá, 03. Guarapuava, PR, Brazil. Zip code: 85040-080
Instituto Matogrossense do Algodão. Rodovia BR163, km 726. Sorriso, MT, Brazil. Zip code: 78890-000

Abstract
With the growing need for greater operational capacity, information about the effect of application volume and spray nozzles on the quality of pesticide application are essential to obtain greater efficiency in pest management in cotton crops. This study aimed to assess the effect of the spraying volume and nozzles on the deposition of spray solution on cotton crops at the reproductive stage. The treatments of the first experiment correspond to the 55, 67, 140 and 194 L ha-1 volumes obtained by variation of the displacement speed using the XR11004 flat fan nozzle. In the second assay the treatments corresponded to the applications of MGA9004 (hollow cone), XR11004 (flat fan), AIXR11004 (air induction flat fan) and CVIA04 (air induction hollow cone) nozzles with 120 L ha-1. An artificial brilliant blue food dye (FD&C 1) was used as a tracer (2.5 g L-1) to determine the deposited volumes on the leaves of the upper, middle and lower third of cotton plants. The results showed that increase in the application volume contributed to obtain the larger deposits in the upper third of the cotton crop during its reproductive phase, especially up to 140 L ha-1, but did not exhibit a significant increase of the deposition in the middle and lower thirds of the plants. The MGA9004, XR11004 and AIXR11004 nozzles provided the largest deposits in the three plant sectors. The flat fan nozzles resulted in greater uniformity of deposits in the upper and middle thirds of the plants.

Pages 1770-1776 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1549
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Could 137Cs remediation be accomplished with stable cesium (CsCl) on tropical soils?

Riviane Maria Albuquerque Donha*, Mário Roque, Antônio Enedi Boaretto, Antonio Sergio Ferraudo, Elcio Ferreira Santos, Fernando Giovannetti Macedo, Wanderley José Melo, José Lavres Junior

UNESP – São Paulo State University, Postal Code 79560-000, Jaboticabal, SP, Brazil
USP – University of São Paulo, Center for Nuclear Energy in Agriculture. Postal Code 13416-000, Piraicaba, SP, Brazil
Brasil University, Postal Code 13690-000, Descalvado, SP, Brazil

Abstract
Stable cesium can be considered as the best element for desorption of soil radio-cesium. It is considered an element that slightly absorbed by plants, so that the application of high doses to the soil could increase the absorption of 137Cs, which is desired for the remediation of contaminated soils. There is shortage of knowledge on remediation of tropical and subtropical soils contaminated with 137Cs. The aim of this work was to evaluate the use of 133Cs for the remediation of Brazilian tropical and subtropical soils contaminated with 137Cs. In addition, we investigated the Cs uptake by bean plants (Phaseolus vulgaris L.) grown in Cs contaminated soil. The experiment was carried out in pots under greenhouse conditions. Seven soil types were used in the experiment (Oxisol, Udox, Psamment, Ochrept; Aquoll; Udox and Udult), which received the application of four doses of 133Cs (0, 5, 10 and 20 mg/pot in a completely randomized design arranged in a factorial scheme (7 soil types x 4 doses of 133Cs) with three replicates. An increase in transfer factor values of 137Cs was observed for both shoot growth and grains, as well as in percentage of total activity of 137Cs removed from the soil regarding to addition of stable cesium levels in all soils. The results showed that psamment soil presented higher specific activity of 137Cs in the soil and grains, as well as for the transfer coefficient from soil to shoot growth and grains. The application of stable cesium chloride to soil did not cause any effects on dry matter production of shoot growth and grains. The addition of 133Cs increased the transfer from soil 137Cs to the plant regardless of soil type, proving the efficiency of this practice for the remediation of soils contaminated with radioactive Cs. In addition, the plants of common bean were efficient for use in phytoremediation.

Pages 1777-1785 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1562
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Potato cultivars as a source of starch in Brazil: physicochemical characteristics of the starches and their correlations

Emerson Loli Garcia, Ezequiel Lopes do Carmo, Joaquin Gonçalves de Pádua, Célia Maria Landi Franco, Magali Leonel*

São Paulo State University (UNESP), Center for Tropical Roots and Starches (CERAT), Botucatu, São Paulo, Brazil
Institute of Education, Science and Technology, Tocantins, Brazil
Agricultural Research Corporation of Minas Gerais, Technological Center of Potatoes and Strawberries, Belo Horizonte, MG, Brazil
Department of Food Engineering and Technology, Institute of Biosciences, Language, and Physical Sciences, São Paulo State University (UNESP), São José do Rio Preto, São Paulo, Brazil

Abstract
As a source of starch, potato remains unexploited in Brazilian industries, where they typically utilize corn and cassava. Considering the emerging need for using potato as a source of commercial starch, this study evaluated starches extracted from seven cultivars of potatoes with limited commercial usage in Brazil. Potatoes were grown under the same environmental conditions and cultural practices. After harvesting, the potato tubers were processed for the extraction of starch. The proximate composition, amylose content, resistant starch, minerals, as well as pasting and thermal properties of extracted starch samples were analyzed. Starch characteristics varied with the cultivar. Using correlation analysis, we demonstrated that minerals have a robust effect on starch characteristics. Moreover, positive correlations were observed between phosphorus, potassium, magnesium, resistant starch, viscosity peak, breakdown, and gelatinization enthalpy. Calcium had a positive correlation with the amylose content and the percentage of starch retrogradation. Starch samples showed important differences in their physicochemical properties, which are advantageous for industrial applications allowing a larger diversification and incentive to the production of potato for industry in Brazil.

Pages 1786-1792 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1567
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Comparison of wheat growth-response to endophytic Beauveria bassiana (Hypocreales: Cordycipitaceae) derived from an insect versus plant host

Lisemelo F. Motholo, Mardé Booyse, Justin L. Hatting*, Toi J. Tsilo, Oriel M. M. Thekisoe

Agricultural Research Council – Small Grain, Private Bag X29, Bethlehem, 9700, South Africa
Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
Agricultural Research Council – Biometry, Private Bag X5013, Stellenbosch, 7599, South Africa

Abstract
Beauveria bassiana (Hypocreales) is a cosmopolitan entomopathogen, infecting >700 insect species. Although traditionally associated with insects, endophytic colonisation of plants is also known. Endophytism may protect plants against insects/diseases and enhance plant growth. Both insect- and plant-derived (endophytic) ‘sources’ of B. bassiana may be present in an agroecosystem, both of which may be in contact with plants. Here, growth response, viz., root length, shoot height, fresh root biomass, fresh and dry shoot biomass of wheat, Triticum aestivum L. (Poaceae), is reported following inoculation with B. bassiana (strain PPRI 7598). The strain was passaged and re-isolated from an insect (IN) versus plant (PL) substrate. When five wheat cultivars were inoculated with either B. bassiana PPRI 7598IN or -PL isolates through seed imbibition, a significantly higher level of endophytism (roots, stems and leaves, combined) was recorded with 7598IN (29.74%) compared to 7598PL (26.13%). Cultivar Baviaans responded best to endophytic colonisation (plant parts combined) at 33.54%, followed by Tugela (31.34%), Kariega (27.87%), Gariep (25.67%) and Elands (21.28%). On average, B. bassiana-treated plants showed a 71% growth increase over control plants. In topically sprayed bioassays, 7598IN caused 57% mortality to D. noxia, compared with 50% by 7598PL; also recording a significantly shorter mean time to aphid mortality (4.14 days) versus 7598PL (4.58 days). A significantly higher level of overt mycosis (58.2%) was noted with 7598IN compared with 7598PL (47.9%). Results underscored several positive aspects associated with endophytic B. bassiana in wheat, creating new and exciting IPM possibilities.

Pages 1793-1802 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1585
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Physical quality of a Cerrado-biome soil cultivated with three management strategies in forest planted with rubber tree (Hevea brasiliensis)

Yuri Luiz Augusto dos Santos*, Adriana Aparecida Ribon, Clarice Backes, Alessandro José Marques Santos, Larissa Gabriela Marinho da Silva, Amanda Romeiro Alves, Leonardo Rodrigues Barros, Vladia Correchel, Samara Santos Viana, Nara Rúbia de Morais Arantes

Universidade Estadual de Goiás, São Luis de Montes Belos – Brazil
Universidade Federal de Goiás, Goiânia – Brazil
Universidade Federal de Santa Maria, Santa Maria – Brazil
Instituto Federal Goiano, Rio Verde - Brazil

Abstract
The rubber tree is a species native to the Amazon biome of great economic importance. Analyzing the soil physical attributes allows for quantifying the impact of different management practices on the soil properties and the yield of rubber plantations. The present experiment was developed on Red-Latosol soil cultivated with rubber tree (Hevea brasiliensis) since 2013. The experiment was set up as a factorial (2x3) design with two rubber-tree clones (PB 312 and RRIM 600) and three management strategies (organomineral fertilizer - poultry litter; mowing followed by mineral fertilizer application; green manure - pigeonpea [Cajanus cajan], as a cover crop) applied annually, with five replicates. Treatments were applied annually but the soil samples were collected at two times: firstly in 2015 (T1) and subsequently on 2016 (T2). Results revealed a reduction of microporosity, macroporosity, and total porosity and an increase in soil density with depth. However, no significant difference was detected across the management strategies for any of the evaluated traits. The different management strategies did not significantly influence the rubber-tree trunk circumference, suggesting a need for further evaluations throughout the entire development of individuals so that the response of this species can be quantified.

Pages 1803-1809 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1730
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The effect of novel biodegradable films on agronomic performance of zucchini squash grown under open-field and greenhouse conditions

Di Mola Ida, Cozzolino Eugenio, Ottaiano Lucia, Duri Luigi Giuseppe, Riccardi Riccardo, Spigno Patrizia, Leone Vincenzo, Mori Mauro

Department of Agricultural Science University of Naples “Federico II” via Università 100, 80055 Portici Napoli Italy
CREA-Research Centre for Cereal and Industrial Crops, via Torrino 2, 81100 Caserta Italy
ARCA 2010 S.c.a.r.l., via G. Leopardi 18, Teverola Caserta Italy

Abstract
The soil mulching is an important agricultural practice for increasing crop productivity and earliness. Mulching can be made with natural or synthetic materials. The common films being used these days are usually made of low density polyethylene (LDPE), but its disposal can represent a serious environmental and economic problem. The biodegradable mulching can overcome these problems. Two experiments were carried out comparing the effects of biodegradable and LDPE mulching films on yield and quality of zucchini (Cucurbita pepo L.) grown in two environments (open-field vs. greenhouse). In both the environments a randomized complete block design was adopted. The treatments composed of no-mulched crop (control), soil covered by 15 microns black biodegradable film (MB15) and soil covered by 50 microns black LDPE film. The results showed that MB15 was able to maintain discrete technical proprieties until the end of cycle, especially in greenhouse, assuring a sufficient heating of soil, similar to LDPE. The soil heating promoted crop development. Furthermore, earliness was increased (84 in greenhouse vs. 99 days in open air) in greenhouse. The early production of zucchini grown on MB15 was similar to the one in LDPE production in greenhouse. The total marketable yield of plants grown on both films was not different but it was lower in open air. The biodegradable film significantly improved fruits quality, with higher values of firmness and total soluble solid than fruits grown on LDPE.

Pages 1810-1818 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1796
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Evaluation of bag-of-features (BoF) technique for weed management in sugarcane production

Wesley E Santiago*, Neucimar J Leite, Bárbara J Teruel, Manoj Karkee, Carlos AM Azania

Federal University of the Valleys Jequitinhonha and Mucuri, Minas Gerais, Brazil
University of Campinas, São Paulo, Brazil
Center for Precision and Automated Agricultural Systems and Department of Biological Systems Engineering, Washington State University, Prosser, Washington, USA
IAC - National Pride in the Lands of São Paulo

Abstract
Weeds interfere in agricultural production, causing a reduction in crop yields and quality. The identification of weed species and the level of infestation is very important for the definition of appropriate management strategies. This is especially true for sugarcane, which is widely produced around the world. The present study has sought to develop and evaluate the performance of the Bag-of-Features (BoF) approach for use as a tool to aid decision-making in weed management in sugarcane production. The support vector machine to build a mathematical model of rank consisted of 30553 25x25-pixel images. Statistical analysis demonstrated the efficacy of the proposed method in the identification and classification of crops and weeds, with an accuracy of 71.6% and a Kappa index of 0.43. Moreover, even under conditions of high weed density and large numbers of overlapping and/or occluded leaves, weeds could be distinguished from crops This study clearly shows that the system can provide important subsidies for the formulation of strategies for weed management, especially in sugarcane, for which the timing of weed control is crucial.

Pages 1819-1825 | Full Text PDF| Supplementary Data PDF| doi: 10.21475/ajcs.19.13.11.p1838
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Herbage production, botanical and plant-part composition of mixed black oat (Avena strigosa Scherb.) annual ryegrass (Lolium multiflorum Lam.) pastures under different management strategies

André Brugnara Soares*, André Luis Finkler da Silveira, Tangriani Simioni Assmann, Daniel Schmitt

Agronomy Department, Federal University of Technology Paraná, Campus Pato Branco, Via do Conhecimento km 01, municipality of Pato Branco, PR, Brazil
Agronomic Institute of Paraná, Rodovia BR 158, nº5.517, Brazil
Santa Catarina State University, Avenida Camões 2090, Lages, SC, Brazil

Abstract
Mixing annual ryegrass and black oat can improve forage production in subtropical and temperate areas with integrated crop-livestock systems. Thus, we evaluated the forage production dynamics of mixed annual ryegrass-black oat pastures under different management strategies based on canopy height and supplement level. Pastures were continuously stocked with Boer goats at two grazing heights (12 or 21 cm); animals received or did not receive energy supplements (0 and 15 g kg-1 of body weight). These treatments were applied using a factorial scheme (2 × 2) and randomized block design with three replications. We evaluated the herbage accumulation rate (kg of DM h-1 day-1) using the exclusion cage technique, herbage mass (HM, kg of DM ha-1) using the double sampling technique, and botanical and plant-part composition (%) of destructive samplings. Supplementation had no effect on the parameters measured (P ≤ 0.05). Annual ryegrass become the predominant species during the experimental period and mainly at the lowest canopy height. Total herbage production during the 131 days of pasture utilization was 10,280 kg of DM ha-1. The herbage accumulation rate was similar between the two canopy heights; however, it varied throughout experimental period. Leaf lamina mass was lower in treatments 12 cm up to 102 after sowing; after that, they were equivalent. At the end of the study, herbage mass was 2720 kg DM ha-1 with the 21-cm treatment and 2170 kg DM ha-1 with the 12-cm treatment. It is recommended to maintain mixed annual ryegrass-black oat pastures at 12 cm in height. Reasons are discussed throughout the text.

Pages 1826-1832 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1855
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The release of macronutrients from second crop corn straw and their behaviour in a red-yellow latosol

Edilson Cavalli*, Anderson Lange, Cassiano Cavalli, Mirelly Mioranza, Onã da Silva Freddi, Estêvão Vicari Mellis

Postgraduate courses in tropical and subtropical agriculture, Agronomic institute -IAC, Campinas, São Paulo, Brazil
Institute of Agrarian and Environmental Sciences, Federal university of Mato Grosso, Sinop, Mato Grosso, Brazil
Postgraduate courses in Geoscience (Geochemistry), Federal University Fluminense, Niteroi, Rio de Janeiro, Brazil
Agronomic institute -IAC, Campinas, São Paulo, Brazil

Abstract
Crop residues left on the soil function as a nutrient reservoir and as a ground cover in agricultural systems. The aim of the present study is to assess the chemical alterations in the soil after the decomposition of different amounts of straw from corn as second crop. The climate of the region is classified as hot tropical and the soil is categorized as Red-Yellow Latosol (Typic hapludox) in the cerrado-amazon ecotone. The experiment was set up in randomized blocks in September 2013 after harvesting the second crop corn, comprised of corn straw rates (0, 14.18 and 42.54 t ha-1) with six repetitions. The content of macronutrients, H+Al, pH and base saturation in the soil profile were assessed. The straw rates were added to litter bags and stored on the soil, where they were kept for 154 days throughout the rainy period. Subsequently, the soil characteristics were assessed in layers 0 to 0.05, 0.05 to 0.10, 0.10 to 0.15, 0.15 to 0.20 and 0.20 to 0.40 m. The Ca+2 and Mg+2 elements were only released by the straw on the first 0.05 m of soil. However, K circulated in the soil profile reaching depth of 0.40 m. There was reduction in K+ saturation in treatments without straw. No alterations were observed in the other nutrients and studied attributes. According to the results, it is important to distribute the cultural remains of maize homogeneously in the area during harvesting to avoid the appreciation of soil fertility spots, especially of K.

Pages 1833-1838 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1863
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Fertilization with potassium (K) in the soybean-corn succession affects behavior of plants and in the soil (oxisol)

Edilson Cavalli*, Anderson Lange, Cassiano Cavalli, Ivan Bedin, Antonio Carlos Buchelt, Estêvão Vicari Mellis

Postgraduate courses in tropical and subtropical agriculture, Agronomic institute -IAC, Campinas, São Paulo, Brazil
Institute of Agrarian and Environmental Sciences, Federal university of Mato Grosso, Sinop, Mato Grosso, Brazil
Rural Producer, Agronomist, Master in Agronomy, Sorriso, Mato Grosso, Brazil
Postgraduate courses in agronomy, Paulista State University-UNESP, Jaboticabal, São Paulo, Brazil
Agronomic institute -IAC, Campinas, São Paulo, Brazil

Abstract
The potassium fertilizer recommendations are almost entirely made by the main culture in the field, without taking into account the predecessor and successor cultures. The nutrients in crop residues represent a reserve for subsequent crops. Therefore, knowledge of the absorption and cycling capacity of nutrient through the culture, and efficient fertilization should consider the entire system are important. This study aimed to evaluate the effect of potassium levels in soybean and corn, changes in nutrient stocks in the soil profile, absorption and accumulation in plant tissues and soybean, corn and Urochloa crop production during the two agricultural years. The study was performed in an oxisol in the cerrado-amazon ecotone, with potassium rates (0, 40, 80, 160 and 320 kg ha-1 K2O). The rates applied in soybean (first crop) and three harvests of residual effect of the applied doses (maize-soybeans-maize) were evaluated. After harvesting the first crop, plots were subdivided (with or without the presence of Urochloa in corn spacing) in order to understand effect of Urochloa to increase the potassium cycling in the system. The grain yield and dry matter of Urochloa, extraction, and export of nutrients and their concentration in the leaf were evaluated. During the experiment, the chemical changes caused in the soil were also evaluated. In the first year, corn yield and the cumulative grain yield of the other crops were increasingly influenced by K2O rates. The rates provided increased K concentration and a decrease in Ca and Mg in plant materials. The Ca and Mg elements showed a decreased trend in the soil influenced by the applied rates of up to 130 days after fertilization. The K showed higher levels influenced by rates even after 619 days. We do not recommend the application of high doses of K due to the large losses caused by leaching.

Pages 1839-1847 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1869
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Biochemical composition of pigeonpea genotypes in Kenya

Juliana J. Cheboi, Miriam G. Kinyua, Paul K. Kimurto, Oliver K. Kiplagat, Fredrick Ng’an’ga and Sita R. Ghimire*

Department of Plant Science and Crop Protection, University of Nairobi, P.O Box 29053-00625, Nairobi, Kenya
Department of Biotechnology, University of Eldoret, P.O Box 1125-30100, Eldoret, Kenya
Department of Crops, Horticulture & Soils, Egerton University, P.O Box 536-20115, Njoro, Kenya
Biosciences eastern and central Africa, International Livestock Research Institute, P.O Box 30709 – 00100, Nairobi, Kenya

Abstract
Pigeonpea is an important crop in semi-arid tropics and sub-tropics. The improvement and utilization of this crop in East Africa can enhance food and nutrition security. A study was carried out to examine variation in biochemical composition (crude protein, total phenols, total flavonoid and total anti-oxidant activity) of 55 pigeonpea genotypes grown in Kabete field station during the long rains of April-September 2017. The experiment was set up in a randomized complete block design with three replications. After harvest, 100g of dry seed samples were collected for biochemical analyses. The biochemical analyses were performed at nutrition platform of Biosciences eastern and central Africa- International Livestock Research Institute (BecA-ILRI) Hub, Nairobi, Kenya. Treatment means were separated based on Tukey test using Genstat, SAS and R software. The genotypes varied significantly (P≤0.05) for all the parameters measured with a mean of 20.88 g/100g, 46.21 mg/100g, 23.98 mg/100g and 38.13 mg/100g for crude protein, total phenol, total flavonoid and total anti-oxidant activity, respectively. Advanced elite materials out performed for all parameters analyzed except for crude protein with a mean of 59.57 mg/100g, 26.64 mg/100g and 30.23 mg/100g for total phenols, total flavonoid and total anti-oxidant activity, respectively. The total antioxidant activity had significantly positive correlation (P≤0.05) with total phenol, total flavonoid and crude protein. Similarly, total phenol and total flavonoid had significantly positive correlation (≤0.05). The results revealed that the advanced elite materials contain high phenolics and antioxidant activity that contribute to lowering oxidation of free radicals due to their redox properties. Therefore, these germplasm are valuable genetic resources for improving pigeonpea varieties for nutritional qualities.

Pages 1848-1855 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1886
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Salt-induced changes in solutes, pigments and essential oil of two basil (Ocimum basilicum L.) genotypes under hydroponic cultivation

André Dias de Azevedo Neto*, Renata Velasques Menezes, Hans Raj Gheyi, Petterson Costa Conceição Silva, Alide Mitsue Watanabe Cova, Rogério Ferreira Ribas, Marcos de Oliveira Ribeiro

Center of Exact and Technological Sciences, Federal University of Reconcavo of Bahia, Cruz das Almas, Brazil
Center of Agricultural, Environmental and Biological Sciences, Federal University of Reconcavo of Bahia, Cruz das Almas, Brazil

Abstract
The aim of this study was to evaluate the effect of salt stress on the contents of inorganic and organic solutes, pigments and essential oil in two basil genotypes cultivated in hydroponic system. The experiment was carried out in a greenhouse. Treatments were distributed in randomized blocks, in a 2 × 2 factorial arrangement, corresponding to two contrasting genotypes (‘Toscano folha de alface’ (TFA) and ‘Gennaro de menta’ (GM)) and two salt levels (0 - control and 80 mM NaCl), with six replicates. The Na+, Cl- and K+ accumulation in the leaves, stem and roots did not differ between genotypes. Salt stress increased free amino acids accumulation in the leaves of the TFA genotype. The proline content increased in the roots of both genotypes. However, in GM genotype, the proline content (3.12 mmol g-1 dry mass (DM)) was around 2-fold greater when compared to TFA genotype (1.48 mmol g-1 DM). The salt stress increased the photosynthetic pigments content only in the GM genotype. Inorganic solutes and photosynthetic pigments content are not good indicators of salt-tolerance in the studied genotypes. Under salt stress, there was increase in oil content in GM genotype, while the TFA genotype showed a decrease compared to control treatment. In spite of showing lower oil content, the TFA genotype showed higher yield and productivity of essential oil compared to GM under salt stress conditions.

Pages 1856-1864 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p2015
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Morpho-physiological responses of chili peppers (Capsicum annuum) to short-term exposure of water-saturated rhizosphere

Erna Siaga, Jun-Ichi Sakagami, Benyamin Lakitan*, Shin Yabuta, Hasbi Hasbi, Siti Masreah Bernas, Kartika Kartika, Laily Ilman Widuri

Graduate School, Universitas Sriwijaya, Palembang 30139, Indonesia
Faculty of Agriculture, Kagoshima University, Korimoto, Kagoshima 8900065, Japan
College of Agriculture, Universitas Sriwijaya, Inderalaya 30662, Indonesia
Research Center for Sub-optimal Lands (PUR-PLSO), Universitas Sriwijaya, Palembang 30139, Indonesia

Abstract
Chili pepper is frequently grown by local farmers at riparian wetland during dry season in Indonesia. However, during the last decade, unpredictable distribution and intensity of rainfall have increasingly threatened chili pepper production at the wetlands due to untimely water-saturated rhizosphere (WSR) occurrences. WSR is a condition when all pores within root zone were filled with water. This condition can be simulated by adding water into growing substrate until a thin layer of water was visible above substrate surface. Two Indonesian varieties (Laris and Romario) and one Japanese variety (Takanotsume) were used in this study. Aim of this study was to evaluate morpho-physiological effects of short-term (4 days) WSR exposure in chili pepper. Results of this study revealed that roots suffered more than aerial organs as indicated by the increase of shoot/root ratio from 4.56 at pre-exposure to 7.03 at end of the exposure. Total leaf area significantly reduced since larger older leaves were replaced by newly developed smaller leaves. Relative water content (RWC) in all organs was decreased, but did not reach a detrimental level. Leaf RWC was decreased from 83.6% at pre-exposure to 77.8% after the exposure; however, leaf RWC was able to rebound to 81.5% after 7 days of recovery. Photosynthetic and transpiration rates sharply decreased, associated with decrease in stomatal conductance during WSR exposure. Chlorophyll fluorescence also sharply declined. Gas exchange parameters did not significantly recover after 7 days of recovery in all varieties. Meanwhile, SPAD values were not affected by WSR exposure.

Pages 1865-1872 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p2046
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Estimation of productivity gain by irrigated and fertilized forage palm plants (Opuntia ficus-indica (L.) Mill. and Nopalea cochenillifera (L.) Salm-Dyck): systematic review and meta-analysis

Rener Luciano de Souza Ferraz*, Patrícia da Silva Costa, José Dantas Neto, Pedro Roberto Almeida Viégas, Alberto Soares de Melo, Flávio da Silva Costa, Aldair de Souza Medeiros, Ivomberg Dourado Magalhães, Antônio Suassuna de Lima, Constantino Antônio Cavalcante Júnior, Vera Lúcia Antunes de Lima

State University of Paraíba, Center for Agrarian and Environmental Sciences, Lagoa Seca, 58117-000, Paraíba, Brazil
Federal University of Campina Grande, Academic Unit of Agricultural Engineering, Campina Grande, 58109-970, Paraíba, Brazil
Federal University of Sergipe, Department of Agronomic Engineering, São Cristóvão, 49100-000, Sergipe, Brazil
State University of Paraíba, Coordination of the Post-Graduate Program in Agricultural Sciences, Campina Grande, 58429-570, Paraíba, Brazil
Federal University of Amapá, Field Education Coordination, Mazagão, 68940-000, Amapá, Brazil
Federal University of Alagoas, Department of Plant Production, Maceió, 57072-900, Alagoas, Brazil
Fellow of CNPq Research Productivity, level 1C, Brazil
Fellow of CNPq Research Productivity, level 2, Brazil
Fellow of CNPq Research Productivity, level 1D, Brazil

Abstract
Population expansion increases the water use for food production, which has stimulated farmers to cultivate vegetable with improved water use efficiency. The purpose of this meta-analysis study was to estimate the productivity gain of irrigated and fertilized forage palm plants (Opuntia ficus-indica (L.) Mill. and Nopalea cochenillifera (L.) Salm-Dyck) compared to non-irrigated ones. A systematic review was done and productivity average, tendency and dispersion measures were carried out from a search carried out between October 23 and 27, 2017, without any restriction of date and location and use of filters. Data were submitted to normality, hierarchical grouping, and meta-analysis tests. It has been observed that irrigated forage palm plant presents an increasing production of 53.54 t ha-1 year-1 when compared to non-irrigated and 80.25 t ha-1 year-1, with higher irrigation levels, and 26.83 t ha-1 year-1 with smaller water levels, with the possibility of even higher yields, especially in semiarid regions.

Pages 1873-1882 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p2095
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Phytometric characteristics and chlorophyll index of “Paiaguás” grass (Urochloa brizantha) as a function of wood ash doses and soil water stress

Maria Débora Loiola Bezerra, Edna Maria Bonfim-Silva, Tonny José Araújo da Silva, André Pereira Freire Ferraz, Ana Paula Alves Barreto Damasceno

Federal University of Mato Grosso - UFMT, Faculty of Agronomy and Zootechny, 2367 Fernando Corrêa da Costa Avenue, Cuiabá, 78060-900, Brazil
Federal University of Mato Grosso - UFMT, Institute of Agricultural and Technological Sciences, 5055 Students Avenue Rondonópolis, 78.735-901, Brazil

Abstract
The objective of this study was to evaluate the phytometric characteristics and chlorophyll index of paiaguás grass (Urochloa brizantha) fertilized with wood ash doses and soil water availability. The experiment was carried out in a randomized complete block in a 5x5 fractional factorial scheme (five doses of wood ash: 0, 8, 16, 24 and 32 g dm-3, and five soil water stresses: 4, 8, 16, 32 and 64 kPa), with four replicates. The experimental design was based on the modified central compound, in which 13 combinations of wood ash doses and soil water availability were studied. Each experimental unit consisted of a pot containing 8.7 dm3 of soil and five plants. Three harvests were performed every 30 days after planting, in a 90-day experimental period. At each harvest, plant height, leaf angle, leaf area, stem diameter, and chlorophyll index (SPAD reading) were evaluated. The best results for the phytometric characteristics and chlorophyll index of paiaguás grass were observed in the wood ash dose of 21 g dm-3. There was a reduction of growth and grass chlorophyll content in the soil water tension of 41.20 kPa.

Pages 1883-1891 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p2100
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Evaluation of some bread wheat genotypes popular in Saudi Arabia under drought stress

Soleman M. Al-Otayk, Abdulrahman A. AL-Soqeer, Abd Elsalam M. Menshawy and Mohamed I. Motawei

Plant Production and Protection Dept., College of Agriculture and Veterinary Medicine, Qassim University, Saudi Arabia

Abstract
Six bread wheat genotypes were evaluated in three separate irrigation regime experiments to compare the response of agronomic performance and to identify genotypes with high yield potential under drought stress. The first irrigation treatment (I3) was given normal water irrigation (about 7000 m3 ha-1, according to recommendation for Qassim Region). The second (I2) and third (I1) treatments were given 2/3 and 1/3 of water amount of the first treatment, respectively. Factorial experiments in randomized complete block design with three replications were conducted during 2009/2010 and 2010/2011 seasons in the arid environment of central region of Saudi Arabia. Measurements were taken on days to heading, plant height, number of spikes m-2, number of kernels spike-1, 1000-kernel weight and grain yield. The drought susceptibility index (DSI) and water utilization efficiency (WUE) were calculated. The results revealed that effect of irrigation regime was highly significant for all traits, except days to heading. All studied characters were significantly decreased by reducing the amount of irrigation water. Grain yield showed maximum sensitivity as affected by moisture-stress. Means over environments indicated the existence of sufficient genetic variability among the genotypes for all the characters studied. Giza 171 recorded the highest values for most yield characters, while genotype 'Sama' was the lowest for the most yield characters. Giza 171, Sakha 93 and IC-1 recorded highest grain yield and WUE, based on average over irrigation treatments. Giza 171, Sakha 93 and IC-2 can be considered as drought stress tolerant genotypes.

Pages 1892-1900 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1330
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Growth and production of soybean in response to spatial arrangement in savannah climate

Artur Sousa Silva*, Amanda Soares Santos, Assussena Carvalho Miranda, Odália Carolinne Mota de Sousa, Cibele Divino Aguiar, Jeissica Taline Prochnow, Fabio Mielezrski

University Federal of Piauí, Campus Profª Cinobelina Elvas, Bom Jesus, PI, Brazil
University Federal of Paraíba, Areia, PB, Brazil

Abstract
The management of spatial arrangement in soybean culture (Glycine max L., Merrill) from seeding density and row spacing is an important tool that contributes to yield growth. The objective of this study was to evaluate the influence of spatial arrangement in the development and the production components of soybean in the Piauí Cerrado savanna. The experimental design was completely randomized, with subdivided plots and four replicates. The main plots consisted of different row spacing (17.5 cm, 25 cm, 50 cm and 76 cm) and subplots consisted of plant populations as follows: recommended (280,000 plant/ha); 50% below recommended; 50% and 100% higher than recommended. The subdivided plots had six lines of five metres in length. The highest growth component values (plant height, stem diameter and number of nodes) were observed in the larger spacing (50 cm and 76 cm) and lower populations (recommended and 50% below recommended). The highest component yield values (number of grains per pod, number of grains per plant, number of pods per plant, weight of one thousand seeds and productivity) were observed in the larger spacing (50 cm and 76 cm) and in the recommended population for the cultivar.

Pages 1901-1907 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p1480
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Shading improves initial growth and quality of Parkia multijuga Benth. seedlings

Noemi Vianna Martins Leão*, Elizabeth Santos Cordeiro Shimizu, Sérgio Heitor Sousa Felipe

Embrapa Amazônia Oriental, Laboratório de Sementes Florestais, Belém, PA, Brazil
Universidade Federal de Viçosa, Laboratório de Cultura de Tecidos/BIOAGRO, Viçosa, MG, Brazil

Abstract
During the production of forest seedlings, light quantity can indicate the degree of tolerance of tree species to shading conditions and provide information to obtain seedlings with a higher quality standard. The objective of this study was to evaluate the effect of different levels of shading on the emergence and the quality standard of Parkia multijuga Benth. seedling, a timber species that can be used in landscaping and restoration of degraded areas. The experimental design was completely randomized, consisting of three treatments: full sunlight (control; 2050 µmol m2 s2), 50 (1025 µmol m2 s2), and 70% (615 µmol m2 s2) shading obtained with black polyethylene screens. The results showed that the applied treatments did not significantly influence the emergence percentage. However, under unshaded conditions (i.e., full sunlight), the seeds displayed a higher velocity index and a shorter mean time of seedling emergence. On the other hand, the different levels of shading (50 and 70%) improved the growth performance (e.g., higher shoot height, collar diameter, number of leaves) and quality (e.g., higher Dickson Quality Index (DQI)) of P. multijuga seedlings. Furthermore, seedlings under 50 and 70% shading displayed a significant increase in the total biomass compared to those exposed to the full sunlight condition (243 and 195%, respectively). In addition, the DQI was higher in plants grown at 50 and 70% shading in comparison with the full sunlight treatment (145 and 85%, respectively). The shading level of 50% is recommended for the production of P. multijuga seedlings with the highest quality standard in the nursery beds in Brazilian Amazon.

Pages 1908-1913 | Full Text PDF| doi: 10.21475/ajcs.19.13.11.p2352