Australian Journal of Crop Science   AJCS

Seed morphology and surface microstructure of the genus Plectranthus L. (Lamiaceae) in Arabian Peninsula highlighting on their systematic implications

Kadry Abdel Khalik*

Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia
Botany Department, Faculty of Science, Sohag University, Sohag 82524, Egypt

Abstract

Seed coat morphology of 13 species of Plectranthus L. in Arabian Peninsula was comparatively examined using scanning and light microscopy methods. The diagnostic values for systematic were studies. Macro- and micro-morphological characteristics, including seed shape, colour, size, seed surface, epidermal cell shape, anticlinal boundaries, and periclinal cell wall are presented. Descriptions of seed size, shape, colour, surface, and seed coat types are summarised for the genus. Taxonomic phylogenetic implications of the seed coat micromorphology are also discussed in comparison with the available gross morphological and molecular data. Results of the seed character analyses offered useful data for evaluating the taxonomy of plectranthus both on subgeneric and sectional levels. Monophyly of both subgenus Burnatastrum (Briq) Codd, and Germanea (Benth.) Briq. is also supported here. The remarkable result of this study was to identify P. arabicus as a separate group. The results suggested that it should be treated as a separate subgenus because of having reddish-brown colour seeds and flat-to-convex periclinal cell wall which is distinguishable from the rest of the species. Likewise, the endemic species of P. asirensis, P. ovatus, and P. hijazensis group and P. hyemalis and P. hadiensis group should be homogeneous groups. A key for the identification of the investigated taxa based on seed characters is also provided here.

Pages 1222-1231 |  Read More Supplementary Data|  DOI: 10.21475/ajcs.2016.10.09.pne115

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Development and testing of image processing algorithm to estimate weed infestation level in corn fields

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

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, Brazil

Abstract
The challenges of modern agriculture have led to the development of localized management tools which allow the rationalization of the use and application of pesticides, a reduction in production costs and the optimization of agricultural processes. This study was carried out to develop an algorithm capable of orienting weed control in the management of a corn crop, using digital image analysis to identify the level of weed infestation in the field. The seeds of six species of weed were sown in an experimental plot of corn, and daily images were captured for 40 days for the evaluation of the level of weed infestation (low, intermediate or high). The algorithm developed was able to target information about the plants and soil accurately and discriminate the residual information as referring to either the culture or weeds. The proposed algorithm has achieved 90% accuracy in identifying the level of infestation from images already evaluated by experts. The results can thus be used as part of weed control strategy, with the incorporation of the geographic coordinates of the image making possible the construction of a map of the level of weed infestation in the different areas where the crop is growing.

Pages 1232-1237 | Read More Supplementary Data|  DOI: 10.21475/ajcs.2016.10.09.p6661
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Biplot analysis of seed yield and oil content combining ability in rapeseed (Brassica napus L.)

Gul Ghani, Raziuddin, Antonio Teixeira do Amaral Júnior*, Ibni Amin Khalil, Shahid Khan, Muhammad Adnan, Zia Ur Rahman, Muhammad Ali

Department of Plant Breeding and Genetics. The University of Agriculture Peshawar, 25130, Khyber Pakhtunkhwa, Pakistan
Laboratory of Plant Breeding, Universidade Estadual do Norte Fluminense Darcy Ribeiro 28013-602, Campos dos Goytacazes, Rio de Janeiro, Brazil
Cereal crop research institute, Pirsabaq, Nowshehra, Pakistan

Abstract
Biplot analysis was conducted to estimate the combining ability of ten parental genotypes using 7×3: Line×Tester data of 21 F1 hybrids in (Brassica napus L.) for seed yield and oil content. The data obtained from all the three replications of experimental material in randomized complete block design were subjected to analysis of variance to check the null hypothesis of the equality of means. Significant differences (P≤0.01) were found among the parents, F1 hybrids and Line×Tester interaction for the variables seed yield plant-1 and oil content. The genotypes CA-4 and DH-6 were the promising for seed yield plant-1 (36.8 g) and oil content (51.2%), respectively. Among the hybrids DH-3×CA-4 and DH-4×CA-4 were best for seed yield plant-1 (51.1 g) and oil content (52.1%). The GGE biplot displayed DH-8 and DH-2 as the best general combiners for seed yield and oil content, respectively. The best specific combiner for seed yield plant-1 was DH-3 whereas; for oil content DH-2 was ranked first. Among the testers CA-5 and CA-4 were ranked first on the basis of GCA for seed yield plant-1 and oil content, respectively. The GGE biplot graphic allowed a rapid and effective overview of General Combining Ability (GCA) and Specific Combining Ability (SCA) effects of the inbred lines; best lines and tester, as well as their performance in crosses.

Pages 1238-1243 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7214
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Influence of different cover crops on the emergence and development of Digitaria horizontalis

Wéverson Lima Fonseca, Tiago de Oliveira Sousa, Adaniel Sousa dos Santos, João Batista da Silva Oliveira, Leandro Pereira Pacheco, Lisânia de Castro Medeiros, Alan Mario Zuffo*, Fernandes Antonio de Almeida

Department of Agriculture, Federal University of Piaui, 64900-000, Bom Jesus, Piaui, Brazil
Department of Agricultural and Environmental Engineering, Federal University of Mato Grosso, 78735-000, Rondonopolis, Mato Grosso, Brazil
Department of Biological Sciences, Federal University of Piaui, 64900-000, Bom Jesus, Piaui, Brazil
Department of Agriculture, Federal University of Lavras, 37200-000, Lavras, Minas Gerais, Brazil

Abstract
The physical and / or allelopathic effects caused by cover crops residue can be used to suppress the emergence and / or reduce weed growth. Based on the effects of mulch on soil surface, the objective of this study was to evaluate the influence of cover crops biomass at different residue amount levels in the emergence and development of Digitaria horizontalis. The experiment was carried out in a greenhouse from May to August, 2014, in a completely randomized design with four replications in (5 × 4) + 1 a factorial scheme, consisting of 5 cover crop species (millet cv. ADR 300 (Pennisetum glaucum), Braquiaria (Urochola brizantha), sorghum (Sorghum bicolor), cowpea (Vigna unguiculata) and Crotalaria ocroleuca) and four levels of dry mass of the corresponding plant (3, 6, 9 and 12 t ha-1) on soil surface, with another treatment without cover crop (0 t ha-1). The analyzed variables were the number of emerged plants, shoot dry mass, leaf area, root dry mass and root volume. Cover crops have proven potential to reduce D. horizontalis in all vegetative stages. The species C. ochroleuca and U. Brizantha showed a greater efficiency in reducing the number of emerged plants with a reduction of 86 % and 91 %, respectively. Amounts between 3 and 6 t ha-1 of cover crops dry mass have been sufficient to promote significant reduction in emergence and growth of Digitaria horizontalis.

Pages 1244-1248 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7624
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Early fruit thinning improves yield and quality of three low chill apples (M. domestica Borkh) cultivars in Central highlands of Ethiopia

Abayneh Melke*, Masresha Fetene, Aster Gebrekirstos, Aklilu Nigussie, Kiros Hidago, Abiy Astatke

College of natural Sciences Department of Plant Biology and Biodiversity Management, Addis Ababa University, P.O.Box 1176, Addis Ababa, EthiopiaWorld Agro forestry Centre (ICRAF) P.O.Box 30677- 00100, Nairobi, Kenya

World Agroforestry Center (ICRAF), P.O. Box 5689, Addis Ababa, Ethiopia

World Agroforestry Center (ICRAF), P.O. Box 5689, Addis Ababa, Ethiopia

Faji temperate fruits and related product development farm, Debreberhan, Ethiopia

Abstract
Three low chill apple cultivars grafted on MM-106 semi dwarf rootstock were evaluated for fruit yield and quality attributes. The trial was carried out in a five years ¬old orchard in central highlands of Ethiopia at Debrebirhan. Trees were treated as crop loads with 0 (unthinned) to 2, 3 and 4 fruits per spur to evaluate the influence of crop load on tree growth, fruit yield and quality. For the three cultivars tested, tree growth was reduced with an increasing crop load while total fruit yield per tree (kg) increased with high crop load. Average fruit weight and diameter differed significantly in all the tested cultivars, for which the highest value was recorded with the low crop load (2 fruits per spur). The mean values for fruit growth and yield indicate that fruits with marketable quality i.e. greater than 60 mm in diameter were recorded at low crop load (2 fruits per spur); for Anna, (76%), Dorsette golden, (50%) and Princesa, (64%). Similar analysis for fruit quality showed that at higher crop loads (more than three fruits per spur in cm2 TCSA); total soluble sugar concentration, titratable acidity, starch content, ripening index (RI) and red color were decreased significantly for all the tested cultivars. For lower crop load treatment, (2fruits per spur) in cm2 of trunk cross-sectional area (cm2 TCSA); fruit weight, soluble sugar contents (SSC) and red color values were significantly higher (P≤0.05) in all cultivars. Relationships between crop loads with fruit growth and yield variables revealed that fruit weight increases with low crop load (2 fruits per spur); for cultivar Anna (R2 = 0.79), Dorsette golden (R2 = 0.72) and Princesa (R2 = 0.85) were recorded. Our study also confirmed the relationships between different crop loads with quality parameters showed that trees under the heavier crop load (un thinned trees) expressed the lower percentage of soluble sugars, titratable acidity, starch contents, firmness and red color, whereas trees with lower crop loads (2 fruits per spur) showed a significant increments in these characteristics.

Pages 1249-1256 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7636
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Postharvest application of 1-MCP and ethylene influences fruit softening and quality of ‘Arctic Pride’ nectarine at ambient conditions

Sami Ullah, Zora Singh*, Ahmad Sattar Khan, Shamim Ahmed Kamal Uddin Khan, Kashif Razzaq, Alan Payne

Curtin Horticulture Research Laboratory, Department of Environment and Agriculture, Curtin University, GPO Box U1987, Perth 6845, WA, Australia
Postharvest Research and Training Centre, Institute of Horticultural Sciences, University of Agriculture, Faisalabad 38040, Pakistan
Agrotechnology Discipline, Khulna University, Khulna-9208, Bangladesh
Department of Horticulture, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan
Muhammad Nawaz Sharif University of Agriculture, Multan, Pakistan
Department of Chemistry, Curtin University, GPO Box U1987, Perth 6845, WA, Australia

Abstract
Fruit softening in nectarine is a limiting factor for their extended postharvest life with best quality. Effects of postharvest exogenous applications of 1-MCP (1 µL L-1), ethylene (10 µL L-1) or 1-MCP (1 µL L-1) followed by ethylene (10 µL L-1) at 20 ± 1 oC for 12 h on ‘Arctic Pride’ nectarine were investigated for changes in fruit softening and quality during ripening at ambient temperature (20 ± 1o C; 60-65% RH). Untreated fruit were kept as control and stored at the same conditions i.e. 20 ± 1o C; 60-65% RH. 1-MCP application significantly reduced ethylene production and activities of fruit softening enzymes, including pectin esterase (PE), endo-1,4-β-glucanase (EGase), endo-polygalacturonase (endo-PG), exo-polygalacturonase (exo-PG) as compared to ethylene treatment or control. A significant reduction in fruit weight loss, fruit softening, total sugars and organic acids was also observed with the application of 1-MCP as compared to ethylene-treated or control fruit. Exogenous application of 1-MCP maintained individual sugars (glucose, fructose and sucrose) and organic acids (malic, shikimic, succinic, and citric acid) at higher levels and delayed ripening of nectarine fruit as compared to ethylene or untreated fruit during ripening. In conclusion, 1-MCP application delayed fruit ripening by inhibiting ethylene production and the activities of fruit softening enzymes and maintained the quality of nectarine fruit as compared to ethylene-treated or control fruit during ripening.

Pages 1257-1265 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7648
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Expression of rice genes homologous of Arabidopsis genes previously related to drought tolerance

Fernanda Raquel Martins Abreu, Karinne Evaristo de Deus, Wendell Jacinto Pereira, Ricardo Diógenes Dias Silveira, Rosana Pereira Vianello, Claudio Brondani*

School of Agronomy and Food Engineering, Federal University of Goias, Goiania, GO, 74001-970, Brazil
Institute of Biological Science, Federal University of Goias, Goiania, GO, 74001-970, Brazil
Biotechnology Laboratory, Embrapa Arroz e Feijão, Santo Antonio de Goias, GO, 75375-000, Brazil

Abstract
The identification and validation of candidate genes related to traits of interest is a time consuming and expensive process and the homology among genes from different species can facilitate the identification of genes of the target species from the genomic information of a model species. This study aimed to quantify the expression of homologous rice genes previously related to drought tolerance in Arabidopsis. Five genes (CPK6, PLDα, GluR2, CesA8, and EIN2) were identified in rice by the homology of the amino acid sequence between rice and Arabidopsis. The genotypes Douradão (drought tolerant) and Primavera (drought susceptible) were subjected to a water deficit experiment, and subsequently evaluated for gene expression by qPCR for the five homologous and Lsi1 genes. The qPCR analysis clearly showed that the five homologous genes were expressed in rice, which is an indication that these genes could preserve their function in rice as a response to drought. In Douradão, of the five homologous genes, all but OsGluR2 displayed an increase in the average expression in drought treatment when compared to the control, while in Primavera, the average expression of the five genes did not differ between the control and drought treatment. In Douradão, the OsPLDα1, which showed the higher expression level in drought in relation to the control (10.82), significantly increased the gene expression in the leaf and root tissues as a response to drought, in both vegetative and reproductive stages, whereas in Primavera, this gene was suppressed in both tissues and stages under drought. Therefore, the OsPLDα1 gene was the most important in relation to drought response and is an interesting candidate for further studies in developing rice cultivars that are more tolerant to this stress.

Pages 1266-1272 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7652
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Management of wheat rusts at different growth stages using Nativo 300 SC (trifloxystrobin 100g/L+tebuconazole 200g/L) fungicide

Ruth Wanyera, Mercy Wamalwa, Mercy Odemba, Hannington Wanga, Philister Kinyanjui, Victoria Onyango, James Owuoche

Kenya Agricultural and Livestock Research Organization, P.O. Private Bag, Njoro 20107, Kenya
Egerton University, P. O Box 536, Egerton, Kenya

Abstract
Rusts (stem, yellow and leaf) remain the most important diseases of wheat worldwide due to their ability to cause severe yield losses in susceptible varieties. Timing of fungicide application in the integrated management of rusts on wheat is critical. This study was conducted to determine the wheat growth stage at which fungicide application can effectively control/reduce the damages caused by rust diseases. Field experiments were conducted in 2013 and 2014 in three locations; Njoro, Eldoret and MauNarok. Three doses of Nativo 300 SC (trifloxystrobin 100g/L+tebuconazole 200g/L) fungicide were applied at seven different growth stages of wheat variety Duma as split plot arrangement using a randomized complete block design with three replications. Results showed significant (P<0.01) differences among growth stages for stem rust infection, grain yield, grain and test weights. Area Under Disease Progress Curve (AUDPC) was significant for stem and yellow rusts in MauNarok and for leaf rust in Njoro. Significant (P<0.01) effects of environments and fungicide were observed on grain yield, grain and test weights. Environment × growth stage interaction were significant (P<0.01) on AUDPC for stem rust, grain yield, grain and test weights. Fungicide application at tillering and flowering growth stages (GS) increased grain yield by 66.3%, grain weight by 41.6% and test weight by 17.27%. Therefore, wheat rusts can effectively be controlled by applying fungicide at tillering and flowering growth stages.

Pages 1273-1280 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7676
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Genetic diversity of mango accessions (Mangifera indica) using new microsatellite markers and morphological descriptors

Elaini Oliveira dos Santos Alves, Francisco Pinheiro Lima Neto, Carlos Antônio Fernandes Santos, Ierla Carla Nunes dos Santos Ribeiro, CláusioAntônio Ferreira de Melo, Ioná Santos Araújo Holanda, Anete Pereira de Souza, Ronan Xavier Corrêa*

UESC, Universidade Estadual de Santa Cruz, Departamento de Ciências Biológicas, Centro de Biotecnologia e Genética, Rodovia Jorge Amado, km 16, CEP 45662-900 – Ilhéus, BA, Brazil
Embrapa Semiárido, Empresa Brasileira de Pesquisa Agropecuária. BR 428 KM 152. Zona Rural 56300970 - Petrolina, PE - Brazil - Caixa-postal: 23
UFERSA, Universidade Federal Rural do Semiárido, Av. Francisco Mota, Bairro Costa e Silva, CEP 59.625-900 -Mossoró, RN Brazil
UNICAMP, Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Biologia Vegetal CEP 13083-862, Campinas, São Paulo, Brazil
UNICAMP, Universidade Estadual de Campinas, Centro de Biologia Molecular e Engenharia Genética, CEP 13083-875, Campinas, SP, Brazil

Abstract
Genetic diversity estimates based on morphological and molecular data can provide different information on the relationship between cultivars of a species. This study aimed to develop new microsatellite markers as additional tools in genetic studies on mangoes (Mangifera indica L.), and to analyze the genetic variability of 20 mango cultivars based on morphological descriptors and microsatellite markers. We aimed to better understand the cultivars enhanced breeding histories and to support crossbreeding planning. Positive clones were selected from a DNA library enriched for microsatellite regions for sequencing and primer design. Four plants of each of the 20 accessions were used for observations, based on 48 morphological descriptors. Twenty accessions were analyzed using 27 microsatellite markers, of which 16 were developed during this study. The clusters, based on the morphological descriptors by Ward-MLM strategy and the microsatellite markers, suggested that Brazilian mango cultivars have extensive genetic diversity and are related to cultivars with different provenances, demonstrating their different enhanced breeding histories.

Pages 1281-1287 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7729

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Evidence of association among floral and fruit traits and its implication on fruit size and shape in tomato (Solanum lycopersicum)

Nungu S.I, Uguru M.I

Department of Botany, University of Dar es Salaam, Dar es Salaam, Tanzania
Department of Crop Science, University of Nigeria, Nsukka, Nigeria

Abstract
The relationship and the magnitude of association among floral and fruit characters in tomato were investigated in this study. The mean value of fruit weight showed significant and positive correlation with all the floral traits with the exception of length of flower and style. The number of locules per fruit had the highest correlation value (r = 0.984**) with fruit size. Path coefficient analysis revealed that number of locules per fruit has the highest positive direct effect (p = 0.8086**) on fruit size. This was closely followed by ovary diameter (p = 0.7942**) and stigma diameter (p = 0.7685**). On the other hand, style length had the highest negative direct effect (p = -0.9147**) on fruit size. The fruit shape index showed significant positive correlation with the ovary shape index (r = 0.835**) and the seed shape index (r = 0.718**). However, fruit shape index was negatively and significantly correlated with ovary diameter (r = -0.601*), fruit diameter (r = -0.576*) and the seed diameter (r = -0.519*). The association mapping using 25 SNPs markers detected 9 markers with significant association with mean fruit weight, fruit length, fruit diameter, number of locule and fruit shape index. The SNP marker, Solyc11g039870 exhibited significant association with both fruit diameter, number of locules per fruit and fruit shape index. The variation in fruit diameter explained by the marker, Solyc11g039870 was higher than the variations in the number of locules per fruit and fruit shape index.

Pages 1288-1296 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7730
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Combining ability in elephant grass (Pennisetum purpureum Schum.) for energy biomass production

Bruna Rafaela da Silva Menezes*, Rogério Figueiredo Daher, Geraldo de Amaral Gravina, Antônio Vander Pereira, Messias Gonzaga Pereira, Flávio Dessaune Tardin, Verônica Brito Silva, Erina Vitório Rodrigues, Maria do Socorro Bezerra Araújo, Maria Lorraine Fonseca Oliveira, and Brunno de Oliveira Almeida

Universidade Federal Rural do Rio de Janeiro, 28013-600, Seropédica, RJ, Brazil
Universidade Estadual do Norte Fluminense, 28013-600, Campos dos Goytacazes, RJ, Brazil
Embrapa Gado de Leite, 36038-330, Juiz de Fora, MG, Brazil
Embrapa Agrossilvipastoril, 78550-970, Sinop, MT, Brazil

Abstract
The objective of this study was to estimate and evaluate the general and specific combining abilities of hybrid combinations for energy biomass production, adopting the methodology of Griffing as adapted by Geraldi and Miranda Filho in evaluation cuts referring to two periods, the wet and dry seasons, and in relation to total dry matter yield (TDMY). The experiment was conducted at Pesagro Rio, located in Campos dos Goytacazes, RJ, Brazil, in a randomized block design with three replicates. Crosses were performed in a partial diallel system. Treatments consisted of 10 parents, 25 hybrid combinations, and 1 control. Three evaluation cuts were made: two in the wet season and one in the dry season. The following traits were evaluated: plant height, stem diameter, leaf width, number of tillers, percentage of dry matter, dry matter yield, and TDMY. Regarding the general combining ability effects, the parents “Cameroon-Piracicaba” and “Mercker” showed outstanding positive values. Of the hybrid combinations, “Cubano Pinda”x“Mercker”, “Cameroon-Piracicaba”x“Três Rios”, “Cameroon-Piracicaba”x“Mercker 86-México”, “IAC-Campinas”x“Três Rios”, “IAC-Campinas”x“Mercker 86-México”, and “Guaçu IZ.2”x“Roxo” showed superior productive performance. Hybrids can be obtained with superior energy biomass production to that of the currently available elephant grass cultivars.

Pages 1297-1305 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7747

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Soil physical quality after the fifth and sixth harvest of sugarcane in Brazilian Cerrado

José Luiz Rodrigues Torres*, Venâncio Rodrigues e Silva, Renato Lara de Assis, Zigomar Menezes de Souza, Dinamar Márcia da Silva Vieira, Amanda Yamada Tamburús

Federal Institute of Mining Triangle (IFTM) – Uberaba, MG, Brazil
IFTM Uberaba, MG, Brazil, Scientific Initiation scholar of PIBIC/CNPq, PET/MEC, Brazil
Federal Institute of Goiano, Iporá, GO, Brazil
State University of Campinas, Faculty of Agriculture Engineering, Campinas, São Paulo, Brazil
Environmental Management, IFTM Uberaba, MG, Brazil

Abstract
On most cultivated areas with sugarcane the crop cycle allows between five to seven ratoon crops. The longevity of the plantation is determined by physical changes in soil during this period. This study evaluated the changes to soil physical properties after the fifth and sixth harvest of sugarcane using physical quality indicators. The experimental design was completely randomized blocks with two treatments, each with four replications: treatment 1 - sugarcane after the fifth ratoon crop; treatment 2 - sugarcane after the sixth ratoon crop. The physical attributes of soil: soil penetration resistance (PR), soil density (Sd) volumetric water content (VWC), macroporosity (Ma), microporosity (Mi) and total porosity (TP) were evaluated at six depths; while stability of aggregates (AS), mean weight diameter (MWD) and geometric mean diameter (GMD) were evaluated at four depths. Degradation of soil physical properties after the fifth and sixth ratoon crop was detected in this study. The area had a compacted layer between 0.10 and 0.30 m of depth. The correlations between soil density and the other parameters prove their importance as indicators of soil quality, and the need to evaluate soil moisture prior to tillage or harvest of the crop.

Pages 1306-1311 | Read More|  DOI: 10.21475/ajcs.2016.10.09.p7776
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The effects of nitrogen and neighbouring crops on maturation and timing of seed dispersal in Hordeum spontaneum Koch. and Brassica kaber (DC.)

Sadegh Taghizadeh*, Saeid Bahari, Ali Behpouri

Department of Agroecology, Darab Faculty of Agriculture and Natural Resources, Shiraz University, Iran
Department of Crop Production and Plants Breeding, College of Agriculture, Shiraz University, Iran

Abstract
Reproductive development and then timing of seed dispersal in many weeds is positively correlated with intensity/availability of environmental resources. In this study, we investigated the effects of nitrogen availability and the type of the crop on timing of weed seed dispersal. Two agricultural weeds; wild barley (Hordeum spontaneum Koch.) and wild mustard (Brassica kaber (DC.)) were grown in wheat and oilseed rape crops under a range of nitrogen levels. H. spontaneum seeds that developed under no or low nitrogen levels (0 and 60 kg ha-1) reached their final maturation stage sooner than those that developed under high nitrogen levels (120 and 240 kg ha-1), resulting in an earlier seed dispersal (109 and 76 degree-days where grown in wheat and oilseed rape cropping systems, correspondingly). In all nitrogen levels, H. spontaneum seeds developed in wheat crop reached their maturation stage sooner, and were then dispersed sooner than those developed in oilseed rape cropping system. The results of this study could help growers to make the best decision on weed management through management of seed dispersal. High nitrogen application, for example, with an early harvest may mean that a significant proportion of seeds are taken up to the combine harvester traveling long distances as grain impurity. In contrast, low nitrogen application with a late harvest may result in the majority of seeds falling to the ground and increasing subsequent crop interference. Therefore, an infested crop should be harvested as early as possible to reduce the quantity of weed seeds entering the seed bank.

Pages 1312-1318 | Read More| DOI: 10.21475/ajcs.2016.10.09.p7799
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Fruit biometry, germination and seed vigor of Mimosa setosissima Taub.: Conservation of a rare Cerrado species

Daniel Cardoso Brandão, Lucas Marquezan Nascimento, Carlos de Melo e Silva-Neto, Anna Carla Souza Luccas, Aniela Pilar Campos de Melo*, Leandra Semensato, Larissa Leandro Pires, Alexsander Seleguini

Sector of Horticulture; Federal University of Goiás; Campus Samambaia, Zip Code: 74900-000; Goiânia, GO – Brazil
Group Conhecer; Scientific Center Conhecer; Zip Code: 74.280-110; Goiânia, GO - Brazil

Abstract
Mimosa setosissima is a tree species, considered rare once its occurrence is restricted to the Cerrado biome. Studies on this species may contribute to its conservation. Thus, the objective of this study was to characterize the fruits (physically) and seeds (physiologically) of M. setosissima to provide supporting information for the commercial and conservational propagation of the species. The pods (n=200 fruits) of M. setosissima were collected from plants present in the Cerrado Rupestre of the Serra dos Pirineus State Park, Goiás, Brazil. The fruit were separated into two maturation classes regarding to the color and texture of the pods (brown and green). The pods of each maturity stage were characterized by the following attributes: fresh weight, length, width, thickness, number of seeds, number of normal and abnormal seeds (dead/rotten/damaged/broken). A germination test was used to evaluate the physiological potential of seeds. The germination test applied in a factorial (2 × 2) randomized design, with two fruit ripening stages (brown and green) and two substrates (between paper and paper roll and on paper in a gerbox) (temperature 25ºC; 12-hour photoperiod; humidity 75%). The morphobiometrics of M. setosissima fruit depends on the maturity stage, where an increased growth was observed in brown fruits. The substrate “between paper and paper roll” is more appropriate to conduct the germination test of seeds M. setosissima. Seeds coming from green pods have a physiological performance higher than that of brown seed pods.

Pages 1319-1323 | Read More| DOI: 10.21475/ajcs.2016.10.09.p7814
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Evidence of extensive positive selection acting on cherry (Prunus avium L.) resistance gene analogs (RGAs)

Antonios Zambounis*, Ioannis Ganopoulos, Evangelia Avramidou, Filippos A. Aravanopoulos, Athanasios Tsaftaris, Panagiotis Madesis*

Laboratory of Genetics and Plant Breeding, Faculty of Agriculture, Forestry & Natural Environment, Aristotle University of Thessaloniki, P.O. Box 261, Thessaloniki GR-54124, Greece
Laboratory of Forest Genetics and Tree Breeding, Faculty of Agriculture, Forestry & Natural Environment, Aristotle University of Thessaloniki, P.O. Box 238, Thessaloniki GR54006, Greece
Institute of Applied Biosciences, CERTH, Thermi, Thessaloniki, 570 01, Greece

Abstract
The cherry tree (Prunus avium L.), is an important tree species which is intensively plagued by many phytopathogenic fungal species. Resistance gene analogs (RGAs) are the largest class of resistance (R) genes and are pivotal components at breeding projects, serving as useful functional markers linked to R genes. In order to assess the evolutionary pressures acting upon P. avium RGAs candidates, their 173 homologues that have previously been deposited in GenBank were mined. Their proteins were clustered according to their blast(p) similarities in 12 MCL (Markov Cluster Algorithm) tribes, resulting in unique and well supported paralogous gene groups (PGGs). The extent to which these genes exhibit evidence of adaptive, positive selective pressures, which are causing excessive fixation of non-synonymous mutations, was determined using a series of maximum likelihood analyses using the PAML package. The results postulate existence of robust evidence of positive selection, acting in almost all of the clustered PGGs across their phylogenies. Furthermore, analyses revealed that the majority of the positively selected amino acid residues sites are localized widely across these RGAs sequences. We speculate that the clustered distribution of these RGAs might also be pronounced of high birth and death genes rates with diversifying episodes acting on their NB-ARC domains, putatively affecting their ligand-binding specificities. Such evolutionary insights shed light on how these NBS-encoding RGAs in P. avium are being evolved, assigning them as the foremost surveillance mechanism against rapidly evolving fungal pathogens, and providing breeders with effective tools for fast-tracking the development of varieties with more durable resistance.

Pages 1324-1329 | Read More Supplementary Data| DOI: 10.21475/ajcs.2016.10.09.p7825
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Nitrogen recovery, use efficiency, dry matter yield, and chemical composition of palisade grass fertilized with nitrogen sources in the Cerrado biome

Elisângela Dupas*, Salatiér Buzetti, Flávio Henrique Silveira Rabêlo, André Luís Sarto, Nicole Colombari Cheng, Marcelo Carvalho Minhoto Teixeira Filho, Fernando Shintate Galindo, Raíssa Perreira Dinalli, Rodolfo de Niro Gazola

Department of Plant Health, Rural Engineering, and Soils, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Ilha Solteira, Sao Paulo State, Zip Code 15385-000, Brazil
Laboratory of Plant Mineral Nutrition, Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, Sao Paulo State, Zip Code 13418-900, Brazil
André Luis Sarto ME - Serviços Agrícolas, Ivinhema, Mato Grosso do Sul State, Zip Code 79740-000, Brazil
Luiz de Queiroz College of Agriculture, Department of Soil and Plant Nutrition, Piracicaba, Sao Paulo State, Zip Code 13418-900, Brazil

Abstract
The high cost and the low efficiency of fertilizers, especially nitrogen (N), are of major concerns in agriculture. This study aimed to evaluate the effect of N fertilizers sources in Urochloa brizantha cv. Marandu (palisade grass). The study was conducted in Cerrado of Brazil to evaluate dry-matter yield (DMY), recovery of applied N (RAN), N use efficiency (NUE), and chemical composition of palisade grass in response to sources of N (ammonium nitrate, ammonium sulfate, ammonium sulfate-nitrate, urea, urea with urease inhibitor, polymer-coated urea, and control) in seven harvests (100 kg ha-1 N were applied after each harvest). The N fertilization increased DMY and growth of palisade grass compared to control (without N fertilization). However, there was not any difference in DMY due to N sources. Application of ammonium sulfate-nitrate increased RAN. The urea, urea with urease inhibitor, and polymer-coated urea improved NUE. Concentration of neutral detergent fiber (NDF) was decreased, while concentrations of acid detergent fiber (ADF) and cellulose were not affected by the fertilizers. Crude protein (CP) content was increased with N supply, but CP fractions A and B were not changed, except in the fifth period of growth. The results indicated protected fertilizers (ammonium sulfate-nitrate, urea with urease inhibitor, and polymer-coated urea) are more recommended for the cultivation of palisade grass in the Cerrado biome of Brazil.

Pages 1330-1338 | Read More| DOI: 10.21475/ajcs.2016.10.09.p7854
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Growth-promoting activity of indigenous Trichoderma isolates on wheat seed germination, seedling growth and yield

Behzad Hajieghrari, Mohammadreza Mohammadi

Department of Agricultural Biotechnology, College of Agriculture, Jahrom University, PO BOX 74135-111, Jahrom-IRAN
Department of Plant Protection, Faculty of Agriculture, Varamin Branch, Islamic Azad University, Varamin, Tehran-IRAN

Abstract
Apart from their biocontrol potential, Trichoderma rhizosphere-competent strains stimulate plants growth via several direct mechanisms that affect various growth parameters. In this study, effect of five indigenous isolates (T. harzianum T 969, T. harzianum T 447, T. hamatum T 614, Trichoderma sp. isolate T and Gliocladium virens G525.) on wheat (variety Moghan 3) seed germination, seedling vigor and plant growth was examined through seeds treatment by the conidia and culture filtrate of the isolates. In the field experiments various growth parameters including rootlet and shoot length, stem height and weight, root length and weight, total leaf area, head and tiller number and 1000 grain weight as well as the plant total chlorophyll content and stomata conductance response were evaluated. In overall, seed germination rate was increased. The highest seed germination rate (95.8%) was observed for T. harzianum T969 non-sterilized cultural filtrate treatment and after 96 hours. The isolate G. virens G525 spore treatment decreased the rate by 54.5%. Although all isolates colonized on rootlets but no significant effect on the seedlings growth was observed. Isolate T. hamatum T614 caused necrotic reaction on rootlets, revealing its parasitic rather than symbiotic activity. In the field experiments, the isolates had significant effect on parameters such as stomata conductance, 1000 grain weight, ear fresh and dry weights, ear length and stem and root dry weight but they showed no significant effect on other evaluated parameters. Some isolates improved the affected parameters and some had negative effects which are discussed.

Pages 1339-1347 | Read More| DOI: 10.21475/ajcs.2016.10.09.p7857
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Stable reference genes for studies of gene expression in Prunus persica under water stress

Leticia Neutzling Rickes*, Elsa Kuhn Klumb, Letícia Carvalho Benitez, Eugenia Jacira Bolacel Braga, Valmor João Bianchi

Institute of Biology, Departament of Botany, University Federal of Pelotas, Campus Universitário, s/n C.P. 345, Capão do Leão, RS, Brazil

Abstract
Strategies which allow the unequivocal identification of genes expressed in response to different treatments and/or stress conditions are important to obtain reliable results in plant physiology studies. However, in order to analyze the expression levels of target genes through RT-qPCR technique, it is essential to use model genes with uniform expression levels under specific experimental conditions. The present study aimed at investigating the stability of reference genes in peach leaves cultivar scion Chimarrita grafted onto ‘Aldrighi 1’ and ‘Tsukuba 2’ rootstock, subjected to water deficit for a 9-day period. The experiment was conducted in a completely randomized design with four treatments that correspond the evaluations period: zero (control), 4th, 7th, and 9th stress day of water deficit. For each treatment three biological replicates was used. Eight reference genes were analyzed, among them: ACT, CYP2, Ef-1α, GAPDH, TUA, TUB, UBQ10 and 18SrRNA. For the normalization and validation of RT-qPCR data were used the four major software programs currently available: geNorm, NormFinder, BestKeeper, and Comparative ΔCT. The results showed that there was no influence of different plant grafting combinations in the expression of all reference genes evaluated, yet genes TUA and CYP2 had the most stable expression in the leaves of the peach plants under water deficit for 9-d, whereas genes Ef-1α and ACT were the least stable ones for the same stress conditions.

Pages 1348-1356  | Read More| DOI: 10.21475/ajcs.2016.10.09.p7864
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Development of a mini core collection from Sri Lankan traditional rice for flowering time variation

Elpitiya Udari Uvindhya Rathnathunga, Gamini Senanayake, Nimal Dissanayake, Saman Seneweera, Sudarshanee Geekiyanage*

Board of Study in Agriculture, Faculty of Graduate Studies, University of Ruhuna, Matara, Sri Lanka
Department of Agricultural Biology, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka
Address during the research period: Rice Research and Development Institute, Bathalagoda, Sri Lanka
Centre for Systems Biology, University of Southern Queensland, Toowoomba, QLD 4350, Australia

Abstract
Sri Lankan traditional rice germplasm (Oryza sativa indica) consists of a wide variety of morphology and days to flowering (DF). The objective of this research was to develop a mini core collection representing the DF variation of the total collection. Three hundred and eighty four rice accessions from 53 Sri Lankan traditional rice varieties were evaluated for morphological and flowering time variation. The experiment was carried at Rice Research and Development Institute, Bathalagoda, Sri Lanka during the late short day season (Maha), 2012/2013.Three hundred and forty five accessions flowered and 39 accessions did not flower during the experimental period of 210 days. Two principal component analyses (PCA) were performed and subsequently 2 dendograms were developed for flowered and not flowered accessions. Sixty eight percent of total observed variation was explained through 6 principal components (PC’s) by DF and fourteen quantitative morphological characters of 345 flowered accessions. Seventy nine percent of total observed variation of not flowered 39 accessions was explained through 4 PC’s by 9 quantitative morphological characters. Ninety accessions were selected from 2 dendograms for development of a mini core collection; out of which 85 accessions represented flowered accessions based on minimum and maximum DF variation in each cluster of the dendogram. Five randomly selected accessions represented each cluster of not flowered accessions. Minimum and maximum DF values of both total collection and mini core collection were 56 and 189 days, respectively. Average DF of total flowered collection and mini core collection was 79.16 ± 0.95 and 87.95 ± 3.1, respectively. A similar trend in the regression relationship between DF and plant height and, DF and leaf length of the leaf prior to flag leaf was observed in total flowered collection and mini core collection, indicating the representation of mini core collection for flowering time variation.

Pages 1357-1367 | Read More Supplementary Data| DOI: 10.21475/ajcs.2016.10.09.p7864
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Growth, yield and fruit quality of ‘Maçã’ banana under different rates of phosphorus fertilization

Ana Carolina Batista Bolfarini*, Sarita Leonel, Magali Leonel, Marco Antonio Tecchio, Marcelo de Souza Silva, Jackson Mirellys Azevedo Souza

UNESP-São Paulo State University, Botucatu School of Agronomy (FCA/UNESP), Horticulture Department, Fruit Laboratory, Rua José Barbosa de Barros, CEP 18610-307, Botucatu, SP, Brazil
UNESP-São Paulo State University, Center of Tropical Roots and Starches, Lageado Experimental Farm s/n, CEP 18610-307 Botucatu, SP, Brazil

Abstract
The aim of this study was to evaluate the agronomic performance and fruit quality of ‘Maçã’ banana cultivar. A field experiment was conducted to study the effect of phosphorus (P) on the cultivar. The study area presents a subtropical climate, where the mean temperature is 22°C; and the mean rainfall is 1377 mm. The experiment was conducted from November 2012 to May 2014. The experiment design was totally randomized, consisting of six treatments (0, 40, 60, 80, 100 and 120 kg P2O5 ha-1) and seven repetitions. The results indicated that plant height, pseudo-stem diameter, number of live leaves, yield and fruit numbers per bunch increased at 51, 45, 44, 34 and 40 kg P2O5 ha-1, respectively. The shortest harvest cycle was of 480 days at 60 kg P2O5 ha-1. In unripe bananas, RSC improved 13% at 47 kg P2O5 ha-1; while the highest level of P, Ca and Mg were obtained at 74, 41 and 58 kg P2O5 ha-1, respectively. During banana ripening, maximum fruit firmness (3.07 N) was achieved at 63 kg P2O5 ha-1. Application of triple superphosphate fertilizer (at 34 kg P2O5 ha-1) increased yield, without changing physicochemical characteristics.

Pages 1368-1374 | Read More| DOI: 10.21475/ajcs.2016.10.09.p7892
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Garlic extract and hydrogen cyanamide on ‘Tupy’ blackberry bud sprouting, flowering and harvest

Sarita Leonel*, Daniela Mota Segantini, Marco Antonio Tecchio, Rafael Bibiano Ferreira, Jackson Mirellys Azevêdo Souza, Marcelo Garcia Ribeiro Auricchio

Department of Horticulture, Universidade Estadual Paulista (UNESP), Botucatu, Brazil

Abstract
Considering the reduction of synthetic compounds used in sustainable fruit production system, this work aimed to evaluate and compare the effects of applying garlic extract and hydrogen cyanamide (C22H19Cl2NO3) in the bud sprouting, flowering and harvesting of blackberry. The research was conducted during the season of 2011 and 2012. The experiment design was randomized in split plots, consisting of 12 blocks. Each plot corresponded to the six treatments with hydrogen cyanamide, garlic extract and control (0%); and subplots were formed from the two crop seasons. ‘Tupy’ blackberry were 2 and 3 years-old, trained to 1.2m high espalier-type trellis with 4 lateral canes retained in a T configuration, with a spacing of 0.6 m between plants and 4.0 m between rows. The plants were pruned in August and the treatments applied immediately afterwards: 4% hydrogen cyanamide (standard product) and garlic extract in doses of 4.0%, 8.0%, 12.0% and 16.0%, and control. Both products were applied only once; and separately by using knapsack sprayer in the early morning hours. The hydrogen cyanamide 4% performed best, bringing forward more uniform bud sprouting and fruit harvesting. The intervals between: pruning and bud sprouting and pruning and harvesting were 14.5 and 87.5 days, respectively. The evaluated garlic extract concentrations showed similar values of production compared with the other treatments, except at 16% in 2011, being the highest concentration used on cultivated blackberry at São Manuel, São Paulo state, Brazil.

Pages 1375-1380 | Read More| DOI: 10.21475/ajcs.2016.10.09.p7900

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