Australian Journal of Crop Science   AJCS

         
Late nitrogen topdressing increases nutritional and industrial quality of white oat (Avena sativa) grain

Julhana Cristina Sponchiado, Clovis Arruda Souza*, Luis Sangoi, Cileide Maria Medeiros Coelho, Deivid Luis Vieira Stefen

Department of Agronomy, Laboratory of Crop Science, Santa Catarina State University (UDESC), ZIP code 88.520.000, Lages, Santa Catarina, Brazil

Abstract

Nitrogen is a nutrient that most limits the development, biomass yield and protein composition of Poaceae. The N losses can be reduced by synchronizing fertilizer additions with plant uptake requirements. The objective of this study was to investigate the effect of N topdressing at different rates and times on grain yield and industrial quality of two white oat cultivars. The experiment was carried out under field conditions, from July to November of 2014, in a factorial design 2 x 3 x 4, with four replications. Two oat cultivars (URS Guria and URS Brava) combined with nitrogen topdressing were applied under three management systems: (i) semi-late, (ii) late and (iii) semi-late plus late, described as a growth stages (GS) GS31 (first node visible) and GS45 (booting) or split N on GS31 plus GS45 and N rates (0, 30, 60 and 90 kg ha-1), with urea as a source. White oat cultivars responded differently to nitrogen fertilization. The URS Brava cultivar showed higher hectoliter weight (HW) and crude protein in the grains (CP) and URS Guria higher number of spikelets per panicle (NSP) and plant lodging (LOD). Application of at least part of the N at the first detectable node played important role on grain yield and yield components. Splitting N fertilization in two applications, 50% at the beginning of stem elongation and 50% at booting, favored higher yield and protein content of the grains. The increase in N rates up to 90 kg ha-1 did not promote grain yield, but it provided increases in grain thickness and protein content in white oats cultivars, increasing the nutritional (more protein), industrial quality (more flakes per ton of the grains) and grain yield leading to more profit to farmer.

Pages 1355-1361 | Full Text PDF| Supplementray Data| doi: 10.21475/ajcs.20.14.09.p1844
...........................................................................................................................................................................................................................................

Genetic diversity and population structure of elite drought tolerant bread wheat (Triticum aestivum L.) genotypes

Sibusiswangaye Y. Mdluli, Hussein Shimelis*, Assefa B. Amelework

University of KwaZulu-Natal, African Centre for Crop Improvement, P/Bag X01, Scottsville 3209, Pietermariztburg, South Africa

Agricultural Research Council, Vegetable and Ornamental Plants, Private Bag X293, Pretoria, 0001, South Africa

Abstract
The objective of this study was to assess genetic diversity and population structure of 47 bread wheat genotypes obtained from the International Maize and Wheat Improvement Centre (CIMMYT) using 10 polymorphic simple sequence repeat (SSR) markers. Data was subjected to analysis for generating a dissimilarity matrix by the Jaccard index for clustering by the Neighbour-joining algorithm on DARwin 6.5 software. GenAlex Software was used to analyse the number of detected alleles (Na), number of effective alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He), genetic distance (GD), genetic identity (GI), gene flow (Nm), fixation index (F), Shannon’s Information Index (I), Analysis of molecular variance (AMOVA) and polymorphic information content (PIC). Results revealed that, at the locus level, marker Xgwm 132 had the highest Na (21), Ne (14.5), Ho (1.0) and He (0.94), while at the population level, Population III had the highest Na (21), Ne (5.59), He (0.83), and I (1.78). The mean PIC recorded was 0.80, and ranged from 0.63 (Wmc 78) to 0.93 (Xgwm 132). AMOVA revealed significant differences in genetic variation allocated within individuals (60%), across different individuals (37%) and across populations (3%) (P < 0.001). Four populations were distinguished based on pedigrees with GD ranging from 0.01 (Populations III and IV) to 0.31 (Populations II and III), while GI ranged from 0.74 (Populations II and III) to 0.99 (Populations III and IV). The selected markers successfully distinguished test genotypes with the most informative marker being Xgwm 132. Populations II and III were most distinct, thus suitable for parental selection and further drought tolerance breeding.

Pages 1362-1371 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p1943
...........................................................................................................................................................................................................................................

Application of several green manures to produce organic cabbage (Brassica oleracea var. Capitata) and their influence on soil biological properties

Thatiany da Silva Bento, Marco Antonio Camillo de Carvalho, Oscar Mitsuo Yamashita*, Rivanildo Dallacort, Ivone Vieira da Silva, Ricardo Adriano Felito, Dejânia Vieira de Araújo

Postgraduate Program in Environments and Production Systems. Mato Grosso State University, Tangará da Serra, MT, Brazil
Postgraduate Program in Amazonian Biodiversity and Agroecosystems. Mato Grosso State University, Alta Floresta, MT, Brazil
Postgraduate Program in Agriculture. Paulista State University, Botucatu, SP, Brazil

Abstract
Green manure stands out in the organic vegetable production as complementary fertilizer alternative to organic compound incorporation, contributing to reduce production costs and improve soil physical, chemical and biological features. The aim of the current study is to assess green manure and spontaneous vegetation species in cropping systems focused on the organic cabbage production, as well as their influence on soil microbial community. The treatments consisted of green manures such as black velvet beans (Stizolobium aterrimum), Crotalaria spectabilis, jack beans (Canavalia ensiformis), pigeon peas (Cajanus cajan cv. Iapar 43) and spontaneous vegetation (fallow) in two cropping systems (with and without incorporation of green manure plants). Evaluations of green manure, cabbage crop and soil microbial activity were carried out. Green manure: fresh and dry mass, nitrogen and accumulated nitrogen content; Cabbage culture: horizontal and vertical diameter of the head, commercial and total mass; Microbial soil activity: soil microbial biomass carbon, soil basal respiration and metabolic quotient. For fresh and dry mass, jack beans and pigeons pea presented higher values, indicating good performance of these materials. For both, nitrogen content and accumulated nitrogen, the jack beans were stood. Regarding cabbage culture, the spontaneous vegetation decreased the horizontal diameter of the head when the incorporation did not occur. As for the commercial mass, for jack beans the cultivation with incorporation was superior. When the incorporation of the covering plants occurred, the crotalaria spectabilis produced less commercial mass and total head mass. Still in relation to total head mass, jack beans and spontaneous vegetation had lower mass when no incorporation occurred. As to soil microbial biomass carbon the spontaneous vegetation presented higher value, differing only from black velvet beans. The use of jack beans as a cover crop associated with the incorporation system was shown to be promising for the production of cabbage.

Pages 1372-1378 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2167
...........................................................................................................................................................................................................................................

Chemical characterization and determination of in vivo and in vitro antifungal activity of essential oils from four Eucalyptus species against the Hemileia vastatrix Berk and Br fungus, the agent of coffee leaf rust

Alex Rodrigues Silva Caetano, Sara Maria Chalfoun, Mario Lúcio Vilela Resende, Caroline Lima Angélico, Wilder Douglas Santiago, Maísa Lamounier Magalhães, Danúbia Aparecida de Carvalho Selvati Rezende¹, Luana Isac Soares, David Lee Nelson4, Maria das Graças Cardoso*

Departamento de Química, Universidade Federal de Lavras (UFLA), CEP 37200-000, Lavras, Minas Gerais, Brazil
Departamento de Fitopatologia, Universidade Federal de Lavras (UFLA) CEP 37200-000, Lavras, Minas Gerais, Brazil
Empresa de Pesquisa Agropecuária de Minas Gerais, Campus Universitário, CEP 37200-000, Lavras, Minas Gerais, Brazil
Programa de Pós-Graduação em Biocombustíveis, Universidade Federal do Vale do Jequitinhonha e Mucuri, CEP 39100-000, Diamantina, Minas Gerais, Brazil
Departamento de Ciências dos Alimentos, Universidade Federal de Lavras (UFLA) CEP 37200-000, Lavras, Minas Gerais, Brazil

Abstract
Essential oils, also known as volatile oils, are substances produced through the secondary metabolism of plants. In this study, we determined the chemical composition and the in vitro and in vivo antifungal activity of the essential oils from four species of Eucalyptus, Eucalyptus citriodora, Eucalyptus camaldulensis, Eucalyptus grandis and Eucalyptus microcorys, against the Hemileia vastatrix fungus. The essential oils from these four species of Eucalyptus were extracted from their leaves by the hydrodistillation technique using a modified Clevenger apparatus. The chemical characterization was performed by gas chromatography coupled with a mass spectrometer detector and by gas chromatography using a flame ionization detector. The antifungal activities of the essential oils against H. vastatrix were studied by evaluating the percentage of spore germination using the microdilution test for in vitro assays. The curative and preventive effects were evaluated in in vivo tests. The principal constituents of the essential oil from E. citriodora were citronellal, citronellol and isopulegol, while E. camaldulensis produced 1,8-cineole, α-terpineol and α-pinene. 1,8-cineole, α-pinene and α-terpineol were obtained from E. grandis and 1,8-cineole, α-pinene and trans-pinocarveol were the principal components in the essential oil of E. microcorys. In vitro and in vivo antifungal activities against the fungus under study were observed for most of the essential oils, except the essential oil from E. microcorys, for which no preventive antifungal activity was observed. Only the curing of infection by the H. vastatrix fungus was observed with this oil.

Pages 1379-1384 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2249
...........................................................................................................................................................................................................................................

Genetic diversity among 435 barley accessions based in morpho-agronomical characteristics under irrigation in the Brazilian savannah

Vitor Antunes Monteiro, Renato Fernando Amabile, Carlos Roberto Spehar, Fábio Gelape Faleiro, Eduardo Alano Vieira, José Ricardo Peixoto, Walter Quadros Ribeiro Junior, Ana Paula Leite Montalvão*

AmBev/Maltaria Passo Fundo - 99032-680, Passo Fundo, RS, Brazil
Empresa Brasileira de Pesquisa Agropecuária/Embrapa Cerrados – BR 020, Km 18 - 73010-970, Planaltina, DF, Brazil
Universidade de Brasília/UnB – Faculdade de Agronomia e Medicina Veterinária/FAV – 70910-900 – Brasília, DF Brazil
University of Hamburg, Faculty of Mathematics, Informatics and Natural Sciences, Department of Biology, Hamburg, Germany

Abstract
The success of barley (Hordeum vulgare L.) cultivation and its adaptation to cropping systems relies on the knowledge and utilization of existing variability in germplasm banks. The objective of this work was to analyse diversity among pre-selected barley accessions to organize a working collection and to identify genotypes for a breeding program for irrigated barley in the Brazilian Savannah. The field experiment was conducted under irrigation in Planaltina, DF, Brazil. The plant population consisted of 433 accessions plus BRS 180 and BRS 195 as checks. The accessions were evaluated using fifteen morpho agronomic descriptors, in which 11 quantitative and four discrete. The interpolated control design was used for the statistical analysis. A genetic distance matrix was calculated using Gower’s coefficient. From the matrix, a grouping analysis was conducted, using the optimizing Tocher method and the graphic dispersion distance. The genetic distances varied between 0.025 and 0.572, with a mean of 0.256. The accessions were distributed in 18 groups by the Tocher method, which was directly related to the graphic dispersion. The existing genetic divergence in the collection under study helped the definition of accessions in crossing blocks from breeding programs directed to the savannah environment.

Pages 1385-1393 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2281
...........................................................................................................................................................................................................................................

Addition of preservatives to minimally processed ‘BRS Kampai’ peaches (Prunus persica L.)

Caroline Farias Barreto*, Renan Navroski, Roseli de Mello Farias, Marines Batalha Moreno Kirinus, Carlos Roberto Martins, Marcelo Barbosa Malgarim

Universidade Federal de Pelotas, Capão do Leão, RS, Brazil
Universidade Estadual do Rio Grande do Sul, São Borja, RS, Brazil
Instituto Federal de Educação, Ciência e Tecnologia Sul-Rio-Grandense, Campus Pelotas Visconde da Graça, Pelotas, RS, Brazil
Empresa Brasileira de Pesquisa Agropecuária, Clima Temperado, Pelotas, RS, Brazil

Abstract
Fruits that go through processes of sanitation, peeling, cutting and packaging, to be consumed soon afterwards, are called minimally processed fruits. Since fruit consumption is important in the human diet, consumers have looked for practicality in both preparation and consumption, a situation that includes minimally processed food. However, minimal processing can damage plant tissues, mainly by pulp browning and by accelerating changes in natural characteristics of the product. This study aimed at minimizing changes in minimally processed sliced peaches by immersing them in solutions which contained preservatives. The experiment was a completely randomized design in a 5x3 factorial scheme (5 anti-browning agents x 3 storage periods), with 4 trays per replicate and six slices of peaches in every replicate. Sliced fruits were treated with T1 = control (distilled water); T2 = ascorbic acid at 1% (m/v); T3 = sodium isoascorbate at 1% (m/v); T4 = ascorbic acid at 0.5% (m/v) + sodium isoascorbate at 0.5% (m/v); and T5 = citric acid at 0.5% (m/v) + sodium isoascorbate at 0.5% (m/v). Afterwards, they were placed on trays, covered with 9µ PVC film and stored at 4±1ºC for 0 (S1), 6 (S2) and 12 (S3) days. The following variables were evaluated: mass loss, pulp color, pulp firmness, soluble solids, titratable acidity, pH, rot spots, total phenols and antioxidant activity. The treatment that consisted of citric acid at 0.5% (m/v) + sodium isoascorbate at 0.5% (m/v) was the most efficient one to control oxidation; its values of browning indexes were the lowest ones, i. e., 15.62 (S1), 17.74 (S2) and 17.58 (S3). Besides, it kept the creamy-white color of the pulp throughout storage time.

Pages 1394-1398 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2373
...........................................................................................................................................................................................................................................

Spatial variability of soil physical attributes in sugarcane using different row spacings

Wildon Panziera, Cláudia Liane Rodrigues de Lima*, Jean Michel Moura-Bueno, Eloy Antonio Pauletto, Sergio Delmar dos Anjos e Silva, Luis Carlos Timm1, Lizete Stumpf

Federal University of Pelotas - Pelotas, Rio Grande do Sul, Brazil
Federal University of Santa Maria – Santa Maria, Rio Grande do Sul, Brazil
Research Center Embrapa Temperate Climate – Pelotas, Rio Grande do Sul, Brazil

Abstract
The aim of this study was to determine the impact of harvesting traffic by evaluating the spatial variability of soil physical attributes on a clayey Oxisol under sugarcane cultivation using different row spacing. Two areas of sugarcane production (RB855156 genotype) were planted in autumn 2013, both using conventional planting systems. Treatments were either sugarcane cultivated using: (i) single-row spacing (SR) of 1.50 m; or (ii) double-row spacing (DR) of 0.40 × 1.50 m. Areas using SR spacing occupied a total of 6 ha areas using DR spacing occupied a total of 2 ha. Assessments of soil physical attributes were performed during the summer of 2016 after the second harvest. Soil measurements in each area were done at 100 points using a grid design with dimensions of 10 m long by 5 m wide. Soil sampling was taken from the 0.00-0.10 m layer, from points distributed along the planted row and the machine’s wheel track. The following soil physical attributes were assessed: bulk density, total porosity, macroporosity, microporosity, soil penetration resistance, and water contentat field capacity. Bd and PR in the single-row spacing showed critical values for adequate sugarcane root development. The highest spatial variability of PR and Ma was found in double-row spacing, however, this spacing arrangement promoted a better soil physical conditions.

Pages 1399-1404 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2394
...........................................................................................................................................................................................................................................

Heat and drought stress and their implications on potato production under dry African tropics

Jane Muthoni, Hussein Shimelis

Kenya Agricultural and Livestock Research Organization (KALRO), Kenya
African Centre for Crop Improvement, University of KwaZulu-Natal, College of Agriculture, Engineering and Science, School of Agricultural, Earth and Environmental Sciences, Private Bag X01, Scottsxille 3209, Pietermaritzburg, South Africa

Abstract
The two most important abiotic factors affecting potato productivity in many areas of the world and especially in the dry African tropics are drought and high temperature. The situation is worsened by global warming. High temperature and drought reduce not only yields but also quality of potatoes. The effects of drought depend on the genotype, timing, duration and severity of the stress; plant emergence and tuberization are two critical periods when water stress most affects the final tuber yield. The susceptibility of potato crops to high temperature largely depends on genotype, development stage and stress duration; tuber initiation and bulking are critical stages. High temperature, particularly high night temperature, is reported to delay tuber induction, prolong tuber setting, and delay the onset of rapid tuber growth. The optimum soil temperature range for tuber initiation and tuber growth is 15–20 0C, and the colder the soil temperature, the more rapid the initiation of tubers and the greater the number of tubers formed. At high temperature more photoassimilates are partitioned to the vegetative parts than tubers resulting in acceleration of haulm growth and inhibition of tuber initiation and growth. In tropical Africa, potato production is moving to the dry mid and low altitudes due to high population pressure in the moist highlands. In these dry areas, potato production is facing the double tragedy of high temperature and water stress. This has led to low yields and poor quality since there is no available commercial potato variety which is tolerant to high temperature and water stress. Breeding for heat and drought tolerance in potatoes is hard because in most cases, especially in dry tropics, these two conditions occur concurrently. In addition, the two traits are polygenic with low inheritance making conventional breeding difficult; more progress could be achieved through molecular breeding and/or genetic engineering.

Pages 1405-1414 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2402
...........................................................................................................................................................................................................................................

Combined use of a resistance inducer (Agro-Mos®) and micronutrients for the control of Meloidogyne javanica in soybean

Monique Thiara Rodrigues e Silva*, Nathalia Silveira Conduta, Paulo Ricardo Barbosa Pontalti, Caroline Galego Comar, Antonio Nolla, Cláudia Regina Dias-Arieira

Department of Agronomy, State University of Maringá, Maringá, PR, Brazil
Department of Agronomic Science, State University of Maringá, Umuarama, PR, Brazil
Postgraduate in Biotechnology Applied to Agriculture, Paranaense University, Umuarama, PR, Brazil

Abstract
Elicitors of plant resistance are compounds that activate enzymatic processes involved in plant defense. Micronutrients also play an important role in plant responses against pathogens because they function as enzyme cofactors. Despite their well-known benefits, elicitors and micronutrients have been little investigated in nematode control. This study aimed to assess the effects of Agro-Mos® (a commercial biostimulant) and micronutrients (Zn and Mn), alone and combined, on soybean inoculated with Meloidogyne javanica. Seeds of soybean were sown in trays, treated 15 days after germination, and inoculated with 2000 eggs and juveniles of M. javanica at the time of transplanting. Treatments were as follows: 1 L/ha Agro-Mos®, 2 L/ha Metalosate® Zinc, 1.5 L/ha Metalosate® Manganese, Agro-Mos® + Zn, Agro-Mos® + Mn, and Agro-Mos® + Zn + Mn. Untreated inoculated and uninoculated plants were used as controls. At 60 days after inoculation, plants were harvested and evaluated for vegetative growth, nutrient content, and nematode parameters. All treatments were effective in reducing M. javanica population density in roots compared to the control. Agro-Mos®, Agro-Mos® + Zn, and Agro-Mos® + Zn + Mn were the most effective, reducing total nematode number and population density by 55–78% (P ≤ 0.05) in relation to the control. Agro-Mos® + Zn increased shoot dry weight. The results show that balanced fertilization can be used as part of an integrated nematode control strategy.

Pages 1415-1419 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2414
...........................................................................................................................................................................................................................................

Safflower genotypes affected by nitrogen fertilization in subtropical conditions

Paulo de Lima Bueno, Reginaldo Ferreira Santos, Doglas Bassegio, Cristiano Fernando Lewandoski, Claudia Luiza Maziero, Diane Maschio de Souza, Samuel Nelson Melegari de Souza, Caroline Beal Montiel

Universidade Estadual do Oeste do Paraná, UNIOESTE, CEP 85819–1 30, Cascavel, PR, Brazil

Abstract
Nitrogen fertilization is one of the main management systems that affects safflower (Carthamus tinctorius) production. However, the response of safflower to nitrogen fertilization may vary depending on the genotype and growing conditions. The objective of this study was to evaluate the influence of nitrogen fertilization on yield components, oil content, and protein content of safflower genotypes in subtropical conditions. Two experiments were performed to evaluate the effect of nitrogen fertilization (0 and 160 kg ha–1) on six safflower genotypes. The experiment was designed in randomized blocks, in a 2 × 6 factorial design, with six repetitions. The height of the plants, yield, and oil and protein contents were determined 170 and 160 days after emergence in 2017 and 2018, respectively. The oil content and protein content of safflower genotypes were affected by nitrogen fertilization, but this effect varied depending on the genotype. Genotype 4 dominated with a grain yield of 1088 kg ha–1 and an oil yield of 215 kg ha–1. Nitrogen fertilization increased the grain yield, oil content, and protein content; thus, it is appropriate for the cultivation of safflower off-season in autumn-winter in subtropical conditions. Safflower genotype 4 could be a promising oilseed crop for southern Brazil when fertilized with 100 kg ha–1 of N.

Pages 1420-1426 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2420
...........................................................................................................................................................................................................................................

Morphophysiology of ornamental sunflower plant irrigated with saline water and application of silicon

Lunara de Sousa Alves, Mário Leno Martins Véras*, Nelto Almeida de Sousa, Fernanda Ferreira de Araújo, Edinete Nunes de Melo, Ewerton Gonçalves de Abrantes, Adriana Pricilla Jales Dantas, Thiago Jardelino Dias, Ana Carolina Bezerra, Márcia Paloma da Silva Leal

Federal University of Paraíba, Department of Phytotechnics and Environmental Sciences, Highway BR 079 – km 12, 58397-000, Areia, PB, Brazil
Federal Institute of Amapá, Highway BR 210 – km 103, 68997-000, Porto Grande, AP, Brazil
Federal University of Santa Maria, Building 77, Room 05, Roraima nº 1000, Camobi Neighborhood, 97105-900, Santa Maria, RS, Brazil
Federal University of Viçosa, Department of Phytotechnics, Avenue Peter Henry Rolfs, University Campus, 36570-900, Viçosa, MG, Brazil
Federal University of Paraíba, Soil and Rural Engineering Department, Highway BR 079 – km 12, 58397-000, Areia, PB, Brazil"

Abstract
The use of saline water in agriculture is an alternative, especially in regions with water scarcity, such as the Brazilian Northeast semiarid. However, salt stress considerably reduces plant growth and development. In this sense, the objective was to evaluate the morphophysiological responses of the ornamental sunflower irrigated with saline water under application of silicon. The experimental design was entirely randomized conducted in a factorial 4 x 5 with 6 replicates, related to four electrical conductivity of the irrigation water (ECw): 0.5; 1.5; 2.5 and 3.5 dS m-1 five silicon rates: 0, 50, 100, 150 and 200 mg L-1, proceeding to the evaluation of: plant height, stem diameter, number of leaves, absolute and relative growth rates, initial fluorescence, maximum fluorescence, variable fluorescence, maximum efficiency of the photochemical process in FSII, potential quantum yield of photosystem II, stomatal conductance and instant efficiency in the use of water. The gradual increase of ECw reduces growth, chlorophyll fluorescence a and stomatal opening of the ornamental sunflower plants. The application of silicon above 100 mg L-1 promotes a decrease in ornamental sunflower stomatal conductance. It is recommended to irrigate ornamental sunflower plants with water of 0.5 dS m-1 associated with the application of 100 mg L-1 of silicon.

Pages 1427-1432 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2440
...........................................................................................................................................................................................................................................

Grain yield, stability and bacterial brown spot disease of dark red kidney dry bean (Phaseolus vulgaris L.) genotypes across six environments in South Africa

Venâncio Salegua*, Rob Melis, Deidré Fourie, Julia Sibiya, Cousin Musvosvi

University of KwaZulu-Natal, School of Agricultural, Earth and Environmental Sciences, Private Bag X01, Scottsville 3209, Pietermaritzburg, South Africa
Agricultural Research Council - Grain Crops Institute, Private Bag X1251, Potchefstroom 2520, South Africa

Abstract
Dry bean (Phaseolus vulgaris L.) is grown under an extensive range of agro-climatic conditions and is an essential source of protein and income globally. This study aimed to identify and evaluate yield performance, stability, and bacterial brown spot (BBS) disease resistance of fourteen dark red kidney genotypes across environments in South Africa namely Carolina, Clarens, Cedara, Middelburg, Potchefstroom, and Warden. Analysis of variance (ANOVA), additive main effects and multiplicative interaction (AMMI) and the genotype plus genotype by environment interaction (GGE-biplot) analysis were used to evaluate grain yield performance, stability, and BBS disease resistance. The AMMI ANOVA revealed that mean squares for grain yield and BBS severity for the environment, genotype, and genotype by environment interaction were highly significant (P<0.001). Four interaction principal components (IPCA1 - 4) for grain yield and IPCA1 for BBS severity were highly significant (P<0.001, P<0.01). Genotype G12 showed broad adaptation for both high grain yield, low BBS severity across the six environments, while genotypes G08, G06, G03, G02, G05, and G04 had specific adaption for high grain yield and low BBS severity. These genotypes recorded grain yield above the best check cultivar, both with (1.43 t ha-1), and BBS severity below the grand mean (31.90%) and the best check (48.89%). The genotypes identified with either broad or specific adaptation can be released in the environments they are adapted to, or used as parents in breeding programmes aiming to improve grain yield and BBS disease resistance of dry bean for farmers in South Africa.

Pages 1433-1442 | Full Text PDF| Supplementray Data PDF| doi: 10.21475/ajcs.20.14.09.p2464
...........................................................................................................................................................................................................................................

Root and shoot growth in safflower as affected by soil compaction

Caroline Beal Montiel*, Deonir Secco, Araceli Ciotti Marins, Luiz Antônio Zanão Junior, Jeikson Rafael Deggerone, Doglas Bassegio

Universidade Estadual do Oeste do Paraná, UNIOESTE, CEP 85819130, Cascavel, PR, Brazil
Agronomic Institute of Paraná, IAPAR, CEP 85825000, Santa Tereza do Oeste, Paraná, Brazil

Abstract
Soil compaction, induced by no-tillage practices, can negatively impact soil properties important for plant growth. Compacted soils can restrict root growth depth, resulting in reduced crop yield. Although safflower (Carthamus tinctorius) has a deep root system, yield may still be affected by soil compaction. Therefore, this study aimed to evaluate safflower root and shoot growth when submitted to soil compaction in an Oxisol soil under controlled (greenhouse) and field conditions. Five soil bulk density measures were performed in a greenhouse (1.1, 1.2, 1.3, 1.4 and 1.5 Mg m–3). Four compaction levels (established by the number of passes of a farm tractor: 0, 1, 3, and 5 passes consecutively) were performed to evaluate the effect of soil compaction in the field. Root and shoot growth were measured after harvesting the plants. Safflower root growth was reduced when soil compaction increased from 1.1 to 1.5 Mg m–3 under controlled (greenhouse) conditions. In field conditions, we observed a decrease in root length, and fresh and dry matter in roots and shoots of safflower as the soil compaction increased to 5P (1.28 Mg m–3). The results of our study suggest safflower root and shoot growth can be impacted by soil compaction which could affect crop yield.

Pages 1443-1448 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2466
...........................................................................................................................................................................................................................................

Allelopathic effect of Sphenoclea zeylanica Gaertn. on rice (Oryza sativa L.) germination and seedling growth

Ramida Krumsri, Hisashi Kato-Noguchi, Thanatsan Poonpaiboonpipat*

Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan
Department of Agricultural Science, Faculty of Natural Resources and Environment, Naresuan University, Phitsanulok, Thailand, 65000

Abstract
The allelopathic effect of Sphenoclea zeylanica Gaertn., a broadleaf paddy weed that hinders rice production in Thailand, was investigated. Different parts of S. zeylanica were used to determine their inhibitory effect on seed germination, and shoot and root length of rice in a laboratory. Aqueous extracts of leaves and stems had an inhibitory effect on rice germination and seedling growth more than 50% that of control at concentrations higher than 50 g L-1, whereas all concentrations of root extracts had no effect on rice seeds. At the concentration of 100 g L-1, leaf and stem extracts completely (100%) inhibited rice seed germination. The inhibitory effect was increased with increasing concentrations. Additionally, leaf extracts contained higher total phenolics (7.36 mg GE g-1 DW) and total flavonoids (254.19 µg QE g-1 DW) than extracts of other parts. In glasshouse conditions, soil incorporation with dried whole plant residue had a significant inhibitory effect on rice emergence, seedling height, and dry weight when compared with extracted residue at an equal concentration. The decomposition of S. zeylanica in the soil was also evaluated regarding rice seedling growth. The maximum inhibition was achieved 1-3 days after the application of plant residues. At the 30th day, the inhibition disappeared, suggesting that residue decomposition in the soil has been finished. These results support that S. zeylanica has an allelopathic effect on paddy fields, which may cause a reduction in rice growth and yield.

Pages 1450-1455 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2494
...........................................................................................................................................................................................................................................

Effect of seaweed (Ecklonia maxima) extract and legume-derived protein hydrolysate biostimulants on baby leaf lettuce grown on optimal doses of nitrogen under greenhouse conditions

Ida Di Mola*, Eugenio Cozzolino, Lucia Ottaiano, Maria Giordano, Youssef Rouphael, Christophe El-Nakhel, Vincenzo Leone, Mauro Mori

Department of Agricultural Sciences, 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

Abstract
In recent years, the demand for green leafy vegetables is increasing. In order to satisfy this trend, the leafy crops are cultivated under high energetic input, especially high doses of nitrogen (N) fertilization that leads to a nitrate accumulation in leaves, sometimes overcoming the legal threshold set by the European Community for their commercialization. The nitrate in leaves can be dangerous for human health because in the human body it can be converted into nitrite, which can cause methemoglobinemia or create cancer-causing compounds. In order to overcome this problem, a correct N management is needed, especially using technical means which can improve the nitrogen use efficiency. In this study, we evaluated the possible effect of two important plant biostimulants on yield and quality traits (nitrate, antioxidants activity, carotenoids) of baby leafy lettuce, grown in a greenhouse with three levels of nitrogen input. Nitrogen doses were 0, 10 (sub-optimal) and 20 (optimal) kg ha-1, N0, N10 and N20 respectively. The biostimulants were Ecklonia maxima seaweed extract (3 ml per liter) (named Bio 1), legume-derived protein hydrolysate (Bio 2) and non-treated control (Control). The treatments were distributed in a randomized complete-block design with three replications (3 N levels x 3 Biostimulant applications x 3 replications). Biostimulant applications of seaweed extracts and legume-derived protein hydrolysate improved yield and LAI: 13.4% and 12.0% increase over non treated plants, respectively. The highest yield was reached at 20 kg N ha-1. Application of foliar biostimulants stimulated the antioxidant systems of plants, improved leaves color and increased chlorophyll and carotenoids content. The nitrate concentration in leaves was increased under higher levels of N fertilization, meeting the EC legal limit at N20 treatment in plants sprayed by E. maxima seaweed extract. Therefore, in our growth conditions, it seems possible to reduce nitrogen input at 10 kg N ha-1, by applying additional applications of biostimulants to reduce the yield gap upon application of N20 treatment.

Pages 1456-1464 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2511
...........................................................................................................................................................................................................................................

Spatial variability in soybean associated with soil fertility variations in a no-tillage system

Michel Esper Neto*, Evandro Antonio Minato, Anderson Takashi Hara, Silas Maciel de Oliveira, Edner Betioli Junior, Antonio Carlos Andrade Gonçalves, Tadeu Takeyoshi Inoue, Marcelo Augusto Batista

Maringá State University, UEM – PR – Av. Colombo, 5790, Zona 7, CEP 87020-900 Maringá – PR, Brasil

Abstract
Understanding the spatial variability of soil fertility is necessary for preventing nutrient losses or excessive agricultural inputs. The aim of this research was to evaluate the spatial variability of the chemical characteristics of a Typic Hapludox cultivated with soybean for 110 days at different depths and the impacts of these characteristics on crop yield. Soil samples were collected at a total of 80 points in an area of 5000 m2 . The contents of P, Ca, Mg, S, Cu, Fe, Zn and Mn were analyzed, in addition to pH and H+Al. The data were evaluated through descriptive statistics and geostatistical tools, and kriging maps were made based on semivariogram adjustments. Most of the soil fertility variables showed moderate or strong spatial dependence. The statistical moments obtained for the distributions showed that the symmetry of the distributions allowed the use of geostatistics techniques. In general, the greater the soil depth was, the lower the nutrient levels were. The soybean yield range (29.5 m) was similar to the P range in the 0.0-0.20 m soil layer (29.2 m). P influenced the soybean yield the most, as expressed by the similarity between the two kriging maps. In regions with more phosphorus at deeper soil layers, higher soybean yields were obtained.

Pages 1465-1472 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2551
...........................................................................................................................................................................................................................................

Pretreatment of maize seeds with different magnesium nanoparticles improves the germinating performance and storability

Cristiane SEGATTO, Clovis Arruda SOUZA*, Cristiano Reschke LAJÚS, Márcio Antônio FIORI, Luciano Luiz SILVA, Humberto Gracher RIELLA, Cileide Maria Medeiros COELHO

Santa Catarina State University, Agronomy Department, Crop Plant Laboratory, Lages, Santa Catarina, Brazil.
Universidade Comunitária da Região de Chapecó, Chapecó, Santa Catarina, Brazil
Federal University of Santa Catarina, Faculty of Chemical Engineering, Florianópolis, Santa Catarina, Brazil

Abstract
The objective of this study was to evaluate the effect of treatment with simple or coated nanoparticle and concentrations on storage time and the germination parameters in corn seeds. The treatments composed of three magnesium sources, magnesium oxide nanoparticles and nanoparticles in the form of (MgO NPs), magnesium carbon oxide core-shell nanoparticles (MgO@C NPs) and magnesium nitrate [Mg(NO3)2]. Six concentrations 0 (control) 37.5, 75, 150, 300 and 600 mg.L-1 were applied. The treated seeds were submitted to germination tests, after different storage times: 0, 30, 60, 90 and 150 days and then the normal and abnormal seedlings were evaluated. The results indicate that the treatment process with simple or coated nanoparticles with optimal concentration value, between 75 and 150 mg.L-1 of Mg, can approximately increase 6% of normal seedlings in conjunction with the storage time (90-150 days). The exposure of the seeds to magnesium nitrate resulted in less normal plants, possibly due to the saline and toxic effect of this source. The best germination performance of seeds pretreated with simple or coated nanoparticles can be achieved at the concentration of 75 mg.L-1 and for the storage time of 150 days. There might be some negative effect for magnesium nitrate depending on concentration and storage time.

Pages 1473-1478 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2558
...........................................................................................................................................................................................................................................

Effect of brassinoesteroid hormone on oxidants activity of two contrasting cowpea cultivars subjected to saline stress

Rafael Sales Ohashi, Glauco Andre dos Santos Nogueira*, Kerolém Prícila Sousa Cardoso, Ana Ecídia de Araújo Brito, Liliane Corrêa Machado, Jéssica Taynara da Silva Martins, Thays Correa Costa, Cândido Ferreira de Oliveira Neto, Ricardo Shigueru Okumura, Júlia Karoline Rodrigues das Mercês, Joaquim Alves de Lima Junior

Universidade Federal Rural da Amazônia, Presidente Tancredo Neves avenue, 2501, Belém city, Brazil
Universidade Estadual do Oeste do Paraná, Universitária street, 1619, Cascavel city, Brazil
Universidade Federal de Santa Maria, Roraima avenue, 1000, Santa Maria city, Brazil

Abstract
The aims of this study were to study the biochemical metabolism alterations generated by saline stress in two cowpea cultivars: BRS Guariba (moderately tolerant) and BR3 Tracuateua (sensitive), and to investigate the action of brassinosteroid in attenuation of oxidative stress. The results for water content and damage index in cell membranes were similar. Plants with 24-Epibrassinolide hormone maintained their water content satisfactory and without any membrane extravasation, whereas, for plants with salinity these variables decreased considerably. The results showed that salinity increased sodium (Na+) contents and reduced potassium (K+) content, which caused water increases allowing a higher dilution of sodium ions (Na+), avoiding cellular toxicity. The antioxidant defense system of these plants (catalase, superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase) were activated mainly in characterization of salt stress, increasing their concentrations trying to avoid toxicity. The association of brassine and salinity caused reduction of lipid peroxidation characterized by malondialdehyde variable. These results corroborated the efficacy of the brassine hormone in cowpea plants under saline stress, characterizing as a plant plasticity.

Pages 1479-1486 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2603
...........................................................................................................................................................................................................................................

Agro-morphological characterization of horned melon (Cucumis metuliferus) accessions from selected agro-ecological zones in Kenya

Marline Hanny Owino*, Bernard Mukiri Gichimu and Phyllis Wambui Muturi

Department of Agricultural Resource Management, University of Embu, P.O. Box 6 – 60100, Embu, Kenya

Abstract
Morphological characterization of genotypes is fundamental in providing information on their genetic status to guide on their conservation and improvement. The objective of this study was to determine agro-morphological diversity within horned melon in Kenya. The study was carried out in two seasons at the University of Embu in Kenya. The study characterized 19 horned melon accessions collected from different agro-ecological zones in Eastern, Central and Western regions in Kenya. The experiment was laid out in a randomized complete block design with three replications. Morphological characterization of the accessions was based on melon descriptors from International Plant Genetic Resources Institute (IPGRI) with slight modifications. Significant differences were observed in all the quantitative traits except the number of branches and main vine length. However, qualitative variations were only observed in fruit shape, rind colour and seed shape. Principle Component Analysis (PCA) showed that fruit weight, main vine length and days to maturity had the highest contribution to the observed diversity. Cluster analysis separated the accessions into seven groups with between classes diversity of 79.20% and within classes diversity of 20.80%. The diversity observed can be exploited by plant breeders for genetic improvement of the crop.

Pages 1487-1496 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2642
...........................................................................................................................................................................................................................................

Water use efficiency, plant growth and vegetative traits of rubber (Hevea brasiliensis) seedlings grown using different growing media and water levels

Monsuru Adekunle Salisu*, Zulkefly Sulaiman, Ridzwan Che Rus, Mohd Yusoff A. Samad, Norhanizan Usaizan, Yusuff Oladosu and Paiman

Department of Agricultural Science, Faculty of Technical and Vocational, Sultan Idris Education University 35900 Tanjung Malim, Perak, Malaysia
Institute of plantation studies, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia (UPM), UPM, Serdang 43400, Malaysia
Department of Agrotechnology, Faculty of Agriculture, Universitas PGRI Yogyakarta. Jl. PGRI Sonosewu no. 117, Yogyakarta, Indonesia

Abstract
The aim of this study was to evaluate the effects of soilless media and water levels on growth and physiological response of rubber plant. The four water levels were I50: 50%, I75: 75%, I100: 100% and I150: 150%) with three replications per water treatment and four soilless media. Water levels were determined as irrigation needed for the root zone in growing media to rise to field capacity I100:100%, at field capacity (FC). The experiment was laid out in randomized complete block design (RCBD) in factorial arrangement 3 x 4 with three replications. Soilless medium contains proportion of vermiculite, perlite, coconut husk, empty fruit bunch (EFB) compose, Christmas Island Rock Phosphate (CIRP), peat moss, urea-N and burnt rice husk coded as M1. Vermiculite, perlite, coconut husk, EFB, CIRP, peat moss, urea-N, sugarcane bagasse coded as M2. M3 is a commercial soilless medium and 100% soil was designated as control. The M1 significantly influenced almost all plant growth traits, noticeable in biomass production. Growth of plants in M1 corresponded to higher water use efficiency WUEinstantaneous and WUEintrinsic, the M1 increased plant growth like LAR, biomass production and root morphological traits. Shoot dry weight of the plant was greater (14.66 g/plant) when 150% was applied and significantly different from M2 (10.36 g/plant), M3 (4.73 g/plant) and M4 6.22 g/plant. Lower water level 50%, applied in plant grown in M1 (31.94 g/plant) recorded highest total shoot fresh weight (SFW). The results showed suitability of the soilless medium M1 and the 50% water level for rubber nursery planting. Consequently, it is recommended for planting where management and control of irrigation water are considered necessary in rubber plantation.

Pages 1497-1505 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2643
...........................................................................................................................................................................................................................................

Physico-chemical characterization of wines produced by different rootstock and Vitis vinifera cv. Tannat clones in vineyards of subtropical climate region

Willian dos Santos Triches*, Daniel Pazzini Eckhardt, Elisandra Nunes da Silva, Marcos Gabbardo, Fabio Clasen Chaves, Jessica Fernanda Hoffmann, Giovana Paula Zandoná, Cesar Valmor Rombaldi

IFSP, Instituto Federal de São Paulo, Campus São Roque CEP: 18136-540, São Roque-SP, Brazil
UFPel, Universidade Federal de Pelotas, CEP: 96010-000, Pelotas-RS, Brazil
Unipampa, Universidade Federal do Pampa, Campus Dom Pedrito, CEP: 96450-000, Dom Pedrito-RS, Brazil

Abstract
Tannat wine trees are well characterized in Uruguay and the French region of Madiran for their high colour and phenolic concentrations. In addition to the cultivar, the rootstock, clone and region of production can influence the phenolic concentrations of wines. In this context, this study evaluated the rootstocks 'SO4' (Vitis berlandieri x Vitis riparia), 'Gravesac' ('161-49C' x '3309C') and '3309C' (Vitis riparia x Vitis rupestris) grafted with Tannat cultivar clones ('Californian', '944', '717', '398' and '794') to assess the physicochemical, phenolic and sensorial composition of the wine produced in the Campanha Gaúcha (RS) region, Southern Brazil, in a subtropical climate region. A vineyard planted in 2007 was used in this study (for 3 years during 2015, 2016 and 2017). The wine composition and the sensorial profile were evaluated as dependent variables. This study showed that the rootstocks and the Tannat clones did not influence the dependent variables evaluated and that the genetic materials and their combinations presented high oenological potential, providing wines with high alcohol content, colour and phenolic compound concentrations. This study suggests the diversification of rootstocks and clones as a way of increasing genetic variability, avoiding the cultivation of a single rootstock and clone.

Pages 1506-1518 | Full Text PDF| Supplementray Data PDF| doi: 10.21475/ajcs.20.14.09.p2644
...........................................................................................................................................................................................................................................

Hand-held mechanical device improves thinning efficiency of peach trees

Daniel Spagnol, Marcos Antônio Giovanaz, Bruno Carra, Everton Sozo de Abreu, José Carlos Fachinello, Marcelo Barbosa Malgarim, Paulo Mello-Farias, Mateus da Silveira Pasa

Universidade Federal de Pelotas, Faculdade de Agronomia Eliseu Maciel, CEP 96010-900, Capão do Leão, Rio Grande do Sul, Brasil
Instituto Nacional de Investigación Agropecuaria, INIA Las Brujas, C.C. 33085, Rincon del Colorado, Departamento de Canelones, Uruguai

Abstract
The objective of this study was to evaluate the effect of mechanical-manual thinning at different developmental stages in the thinning efficiency and productive performance of ‘Sensação’ peach trees. The experiment was performed during the 2013 and 2014 growing seasons, in a commercial orchard located in Morro Redondo (RS), Brazil. Plant material consisted of 7-year-old peach trees grafted on Capdeboscq rootstock and trained as an open-vase system. The experiment was arranged as a randomized block design, with five three-trees replications. In order to reduce the effect of personal experience, the treatments and measurements were applied by the same person in a set of replications throughout the experiment. Treatments consisted of: control I [without thinning (WT)]; control II [hand thinning (HT) 40 days after full bloom (40 DAFB)]; MmT at full bloom (FB): 50% of open flowers; MmT at the end of bloom (EB): 80-100% of open flowers; MmT at petal fall (PF); and MmT at the green fruit (GF) stage (fruit with ~1 cm of diameter). The MmT was performed using a hand-held portable device. The parameters assessed were: percentage of thinning, fruit set, thinning time, work economy, production per tree, fruit mass, estimated yield and fruit size distribution. The use of the MmT at the stages tested reduces thinning time of ‘Sensação’ peach trees, resulting in labor saving, as well as increases the percentage of fruit in category (CAT) 1. The MmT when performed at GF results in a higher percentage of thinning. The treatment MmT at FB increases the average fruit mass.

Pages 1519-1524 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2683
...........................................................................................................................................................................................................................................

Nutritional composition of a selected white food-grade waxy sorghum variety grown in Mediterranean environment

Paola Pontieri*, Jacopo Troisi, Roberta Romano, Graziano Pizzolante, Scott R. Bean, Michael Tilley, Mario Motto, Mariarosaria Aletta, Fabio Del Giudice, Mario Sicardi, Pietro Alifano, Luigi Del Giudice

Istituto di Bioscienze e BioRisorse-UOS Portici-CNR c/o Dipartimento di Biologia, Sezione di Igiene, Napoli 80134, Italy
Theoreosrl - Spin off of the University of Salerno - Via degli ulivi, 3 Montecorvino Pugliano (SA) Italy
Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali (DICAM), Università di Bologna 40131, Italy
ZooPlantLab, Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
USDA-ARS, CGAHR, Manhattan, KS 66502, USA
Fondazione per le Nuove Tecnologie per la Vita, Bergamo, Italy
DCSRSI SPR BIBLIOTECA – Napoli 80131, Italy
Bioteam Laboratory. via Girolamo Santacroce. Napoli 80129, Italy
Dipartimento di Scienze Economiche e Statistiche - Via Cinthia n°45 - Monte S.Angelo, Università di Napoli Federico II, Napoli 80126, Italy
Dipartimento di Scienze e Tecnologie Biologiche e Ambientali. Università del Salento. Lecce 73100, Italy

Abstract
A white food-grade waxy sorghum Tw variety, grown in two Mediterranean sites (named Tw1M and Tw1S) was evaluated for nutrient composition and fatty acid- and mineral concentrations in order to determine the suitability of producing waxy sorghum for human uses in southern Italy. The nutritional values of the grains of the Tw inbred line grown in the two trial fields were substantially the same, except for slight differences in ash level and accordingly slight variation in mineral composition. In samples from both locations, a higher percentage of K was observed among the nutritionally essential macro-elements, and higher percentages of Zn, Fe, Mn, Cu, Al among the nutritionally essential micro-element along with a strong difference in Cd content was among trace elements. Across both sites linoleic, oleic and palmitic were the most abundant fatty acids, while very slight variations in the content of minerals were found among the two samples examined. These results demonstrate the importance of developing agronomically productive waxy sorghum varieties suitable for growth in non-traditional sorghum producing regions both as a food and feed crop (i.e. with good nutritional quality) and for utilization in new products at the industrial level.

Pages 1525-1532 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2783
...........................................................................................................................................................................................................................................

Agronomic performance of maize and Brachiaria grasses cultivated at monocropping and intercropping in a compacted Latossolo

Aline Borges Torino, Lucas Freitas do Nascimento Júnior, Marlete Ferreira de Brito, Jordaanny Danyelly Pereira Lima, Wainer Gomes Gonçalves, Kátia Aparecida de Pinho Costa, Eduardo da Costa Severiano*

Federal Institute of Education, Science and Technology of Goias, Rio Verde Campus, Rod, Sul Goiana Km 01, Cx. P. 66, CEP 75.901-970, Rio Verde, Goias, Brazil

Abstract
Obtaining adequate yields by intercropping maize and grasses in soils with poor physical quality is a challenge for managing crop-livestock systems in the Cerrado region. The aim of the present study was to verify the viability of maize in intercropping with Brachiaria grasses in the second crop season in a physically degraded Latossolo. The experiment was carried out in accordance with a split-plot completely randomized block design with four replications. Seven treatments (T) were evaluated in the plots: Brachiaria brizantha cv. Paiaguas (p), Brachiaria brizantha cv. Xaraes (x), Brachiaria ruziziensis (r) and maize (m) as monocrops (Tp1, Tx1, Tr1 and Tm1) and maize in intercropping with each of the three Brachiaria species (Tp2, Tx2 and Tr2). Two grass management systems were evaluated in each subplot: with (M1) and without simulated grazing (M2) of the grasses. Soil physical quality was estimated by the least limiting water range of undisturbed soil samples collected at layers of 0-0.05, 0.05-0.10 and 0.10-0.20 m. Crop agronomic yield evaluations were carried out for maize, and both the forage biomass and mulch biomass of the grasses were evaluated. Water deficit during the reproductive crop phase and soil compaction explained the low productivity observed in the experiments. The replacement of the maize crops with pasture during the second crop season is indicated in physical degradation soil conditions. Use of the Brachiaria ruziziensis grass in the intercropping system under simulated pasture grazing resulted in a satisfactory forage yield in the off-season and was the best alternative for oversowing in the intercropping systems. Mulch biomass production in intercropping systems with simulated grazing did not reach adequate amounts for soil cover, and suppression of the last cut could potentially result in increased biomass accumulation and system viability. Overall, it is recommended that maize cultivation during the second crop season in Brazil be preceded by a soil compaction diagnosis.

Pages 1533-1540 | Full Text PDF| doi: 10.21475/ajcs.20.14.09.p2773