Australian Journal of Crop Science   AJCS

Accumulation of degree-days and chilling hours for ‘Eva’ apple tree production in temperate climate

Evandro João Rodrigues*, Nathan Felipe da Silva Caldana, Luiz Gustavo Batista Ferreira, Clandio Medeiros da Silva, Pablo Ricardo Nitsche, Daniel Soares Alves, Marcelo Augusto de Aguiar e Silva

State University of Londrina, Brazil
Rural Development Institute of Paraná – IAPAR-EMATER, Brazil
University of Guelph, Canada

Abstract
The cultivation of apple tree is highly dependent on meteorological variables, especially temperature. The link between accumulation of degree-days (DD) and accumulation of chilling hours (CH) are determinant to field success, in the context of climate change. The objective of this study was to quantify the accumulation of DD necessary during the reproductive phenological stages for cultivar IAPAR 75 Eva, considering the accumulation of CH during the period of dormancy. The study was carried out at the Experimental Station from the Rural Development Institute of Paraná IAPAR-EMATER, in the municipality of Palmas, Paraná State, Brazil. The evaluations were from 2013 to 2019, showing for each three days, the phenological phases and the value of DD and CH. The results were submitted the simple and multiple correlation by the R® software. We verified the influence of the increase in temperature on the cycle acceleration, in addition, it was verified a tendency of less requirement for DD to advance the cultivar cycle. Were verified the value of chilling hours as 281, 156, 84, 326, 96, 76 and 11 hours of chill, respectively, and the consequent accumulation of DD to breaking dormancy was appointed as 1093, 1156, 1574, 1157, 1834, 1096 and 1838 DD, respectively. We concluded that CH causes impact in DD accumulation to development of apple tree. Higher temperatures accelerate the apple tree development. With the information of CH accumulation in dormancy, it is possible estimate the quantity of DD to develop the phenological phases. This information contributes to agricultural planning for cultivar Eva farmers.

Pages 676-681 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3307
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Strategies to mitigate the emission of methane in pastures: enteric methane: A review

Juliana Medianeira Machado, Eder Alexandre Minsk da Motta, Marlon Risso Barbosa, Roberto Luis Weiler, Annamaria Mills, Fernando Ongaratto, Fabiana Moro Maidana, Paula Montagner, Dinah Pereira Abbott Rodrigues, Diógenes Cecchin Silveira

Universidade de Cruz Alta, Cruz Alta, Rio Grande do Sul, Brazil
Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
Universidad de la Republica Uruguay, Taquarembó, Uruguay
Lincoln University, Lincoln, Canterbury, New Zealand
Universidade do Estado de São Paulo, Jaboticabal, SP, Brazil
Universidade Federal de Santa Maria, Santa Maria, RS, Brazil

Abstract
The global population reached 7.9 billion in 2021, which represents a 160% increase in the number of people to be fed since 1960. Agricultural systems must sustainably meet food demand for this growing population while minimizing or mitigating potential environmental impacts, which are of growing concern to both consumers and the scientific community. High protein animal products (meat and milk) play a crucial part in human nutrition and pastures represent ~20% of the planet’s surface. Pastoral areas have a great influence on both ecological balance and human subsistence. Ruminant livestock production systems are hotly debated because of the emission of methane, which is produced during enteric fermentation of ingested food within the rumen. Methanogenesis is a naturally occurring process in the digestive system of ruminant animals and ingesting a high-quality diet has been shown to reduce methane production. An additional function of pastoral grasslands is the capacity of the soils to operate as carbon sinks. Well managed pastures absorb carbon from the atmosphere where it can add to soil organic matter directly, through residue decomposition or excrement returns. However, in Brazil and globally, the efficiency of animal productivity tends to be lower in extensively grazed farming systems. Changes to pasture and grazing management in combination with the adoption of technology is necessary to improve the quality of pastures, increase animal productivity, and consequently reduce methane emissions from ruminant livestock. This review will discuss how to improve the conversion efficiency using pasture management to reduce or mitigate enteric methane production.

Pages 682-690 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3457
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Vegetative growth and yield of two watermelon varieties (Citrullus lanatus) as influenced by different organic fertilizers

Tahir Dalorima, Siti Zaharah Sakimin, Ramisah Mohd Shah*

Laboratory of Crop Science, Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

Abstract
The demand for watermelon for consumption in a fresh form as a source of minerals and vitamins is on the increase. Consequently, any agronomic approach to promoting the productivity and quality of watermelon is a technique that needs to be studied. Thus, an experiment was conducted at Universiti Malaysia Terengganu’s research farm to compare the impact of various types of organic fertilizer’s (cow manure, sheep manure, poultry manure, goat manure, fish waste, vermicompost, and dolomite) on the growth and yield of two watermelon varieties. A total of sixty-four (64) experimental pots were arranged in a CRD layout and in factorial design of which eight organic fertilizers were used as main factors, and two varieties (V) of watermelon as sub-factors, which was replicated four times. Results of this study showed that the New Dragon variety treated with poultry fertilizer produced significantly higher results in vine length at 4 WAP (79.84 cm), the number of leaves (26.0), LAI (0.77), chlorophyll content at 6 and 8 WAP (60.1 and 66.6 SPAD respectively), days to 50% flowering (20.0 days) and weight of fruits (15.2 t/Ha). Moreso, the seaweed-extract treated New Dragon watermelon variety produced a significantly higher number of female flowers (3.75). Summarily, the New Dragon variety (red-fleshed) recorded higher results for both growth and yield characteristics than the Golden Delight (yellow-fleshed) variety of watermelon. Correlation analysis between morphological and yield parameters showed that yield parameters positively correlated with growth and development. It is recommended that the New Dragon variety of watermelon treated with poultry manure gives the best results.

Pages 691-699 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3463
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Boron and zinc coating of Brachiaria brizantha cv. MG5 seeds

Amanda Justino Acha*, Henrique Duarte Vieira

Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes - RJ, 28013-602, Brasil

Abstract
Brachiaria brizantha cv. MG5 has been increasingly used in pasture establishment to intensify production systems and increase yield and quality of forage. However, Brazilian soils are deficient in Boron and Zinc, which are essential elements for plant growth and development. Thus, to improve physical and chemical quality of brachiaria seeds, doses of boric acid (H3BO3) and zinc sulfate (ZnSO4.7H2O) were added to the calcium silicate and sand coating of the seeds, using a rotary coater. We tested 11 independent treatments in laboratory and greenhouse, where the seeds were evaluated for physical and physiological quality and the initial growth of the plants. At the end of the evaluations, the collected data were submitted to statistical analysis. There was an increase of up to 320% in seed mass with the seed-coating method tested. The treatment with 10 g H3BO3 + 5 g of ZnSO4.7H2O.kg-1/seeds enhanced plant growth and did not affect the physiological quality of the seeds. Thus, the seeds are ready to be tested in the implementation of pastures. The combinations of 25g H3BO3 + 5 g of ZnSO4.7H2O.kg-1 /seeds and 25g H3BO3 + 15g of ZnSO4.7H2O.kg-1 /seeds reduced seed vigor and are not suitable for seed coating of Brachiaria brizantha cv. MG5.

Pages 700-705 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3523
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Combining quantitative and qualitative descriptors to predict genetic diversity in Capsicum

Mariane Copati*, Lívia Torres, Françoise Dariva, Herika Pessoa, Gabriella Almeida, Ana Carolina Nascimento, Moysés Nascimento, Carlos Nick

Departamento de Agronomia, Universidade Federal de Viçosa, Viçosa, MG, Brasil
Departamento de Biologia, Universidade Federal de Viçosa, Viçosa, MG, Brasil
Departamento de Estatística, Universidade Federal de Viçosa, Viçosa, MG, Brasil

Abstract
The objective of the present study was to assess the accuracy of analyzing quantitative and qualitative descriptors separately or combined to differentiate Capsicum accessions. We assessed 47 Capsicum accessions from the UFV Vegetable Germplasm Bank (BGH-UFV) with botanical classification previously known. The experiment was arranged in a randomized block design with four replicates. Variables consisted of 16 morphological descriptors proposed by the IPGRI. Analysis of quantitative descriptors alone was performed by calculating the Mahalanobis distance matrix (D1), while qualitative descriptors alone were analyzed using the simple coincidence index (D2). The joint analysis consisted of the sum of the distance matrices D1 and D2, and the joint calculation of both descriptors using Gower’s algorithm. Association between the distance matrices was assessed by Mantel’s correlation test, and accession clustering was performed using the UPGMA method. There was genetic variability amongst Capsicum accessions for both quantitative and qualitative traits. Accession clustering was more accurate when performed using the distances obtained by the simple coincidence index (qualitative descriptors alone) and the Gower’s algorithm (qualitative and quantitative descriptors combined).

Pages 706-801 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3525
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Weed management with post-emergent herbicides in intercropped castor and common bean cultivation

Fenelon Lourenço de Sousa Santos*, Itamar Rosa Teixeira, Gisele Carneiro Silva, Marcos Eduardo Araújo, Paulo César Corrêa, Paulo César Timossi

Plant Production Department, State of University of Goiás, Ipameri-GO, Brazil
Federal University of Viçosa, Viçosa-MG, Brazil
Federal University of Jataí, Jataí-GO, Brazil

Abstract
The objective of this work was to evaluate the possibility of using herbicides registered for the cultivation of beans in castor crop when intercropped with beans and the influence of weeds in the crops. A randomized block design was used in a 2 x 4 + 1 factorial scheme with three replications. The herbicides chosen were: (A) fluazifop-p-butyl + fomesafen (125 + 125 g ai L-1) and (B) bentazon + imazamox (600 + 28 g ai L-1). They were applied in four different dosages (0.5; 1.0; 2.0 and 4.0 L ha-1) of the commercial product, plus a control as no weed management. The number of racemes per plant, number of berries per raceme, weight of one hundred grains and castor yield were evaluated. In the bean crop, the number of pods per plant, number of grains per pod, weight of one hundred grains and grain yield were evaluated. Weed competition reduced crop yields by 65.5% for castor beans and 71.87% for beans when intercropped. The results suggest that intercropping of beans with castor is viable and weed management can be carried out with the herbicides evaluated in this study, respect to the doses. The herbicides demonstrate selectivity for BRS Paraguaçu castor crop, showing higher productivity at doses of 612.25 g ai ha-1 and 1506.4 g ai ha-1 of the herbicides fluazifop-p-butyl + fomesafen and bentazon + imazamox, respectively.

Pages 802-808 | Full Text PDF| Supplementary Data PDF| doi: 10.21475/ajcs.22.16.06.p3565
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Contribution of root system architecture and function in the performance of tropical maize (Zea mays L.) genotypes under different moisture regimes

P.H. Zaidi*, K. Seetharam, M.T. Vinayan, Zerka Rashid, L. Krishnamurthy, B.S. Vivek

Asia Regional Maize Program, CIMMYT Int., Hyderabad (Telangana), India
International Crop Research Institute for Semi-arid Tropics, Hyderabad (Telangana), India

Abstract
Understanding how roots respond to increasing rate of evapotranspiration in warmer days and exposure to dry spells is crucial for saving productivity of rainfed crops, including maize, grown in Asian tropics. In a semi-automatic root phenotyping facility (lysimetric system) a set of 100 elite and diverse tropical maize inbred lines were phenotyped under managed drought stress (DT) and well-watered (WW) conditions. Plants were grown in PVC (Polyvinyl chloride) cylinder of 30.0 cm diameter and 150.0 cm length. In drought experiment, last irrigation was applied based accumulated growing degree days (∑GDD) criteria to achieved reproductive stress DT, whereas optimal moisture was maintained in WW trials. Data recorded on various root structural and function traits in both DT and WW trials. Significant phenotypic variability was observed for various root traits, including both structural and functional traits, under both the moisture regimes. Correlation studies showed that grain yield of early maturity group of genotypes was positively and significantly associated with all the root structural traits under drought, whereas, in case of medium and late maturity group of entries root structural traits showed either weak positive or significant negative correlation with grain yield under drought. Though, root functional traits of all the maturity group of genotypes showed positive and significant correlations with both grain yield and total biomass under both well-watered drought stress. Regression analysis showed that water uptake had significant positive relationship with total biomass in all the three-maturity group of genotypes. However, grain yield seems to be less dependent directly on the total amount of water uptake. We conclude that contribution of various traits in root system architecture under drought or well-watered conditions vary with maturity of genotypes. However, root functional traits, such as water uptake and transpiration efficiency are equally important across maturity groups and water availability regimes.

Pages 809-818 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3572
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Genetic variability during in vitro establishment of bacurizeiro (Platonia insignis Mart.): an Amazon species

Tácila Rayene dos Santos Marinho*, Thais Roseli Corrêa, Karina da Silva Vieira, Irislene Souza Albuquerque, Givago Lopes Alves, Marcos Vinícius Marques Pinheiro, Fabrício de Oliveira Reis, Fábio Afonso Mazzei Moura de Assis Figueiredo , José Ribamar Gusmão Araújo, Tiago Massi Ferraz

Graduate Program in Agroecology State University of Maranhão, 65055-310 São Luís, MA, Brazil
Graduate Program in Agriculture and Environment, State University of Maranhão, 65055-310 São Luís, ma, Brazil

Abstract
As a Brazilian Amazon fruit, bacuri tree (Platonia insignis Mart.) has been pointed out as an important species to the sustainable management and development of the Amazon region. However, since it is not yet domesticated, techniques regarding its propagation are still incipient. This study aimed to evaluate the genetic control of traits related to in vitro establishment of Platonia insignis accessions from different regions of the Maranhão state, Brazil. Immature fruits were collected over different sites for explants obtention. The in vitro responsiveness of the genotypes was evaluated by assessing the percentage of explant oxidation (OXI), pinkish-colored defense structures (PCDS), callogenesis (CAL), radicle (ROOT) and shoot forming (SHOOT). Callus was classified according to its callogenic potential, namely as: globular-friable, with higher embryogenic potential; undefined structure [cell mass], with lower embryogenic potential; and white spongy-like callus, absent of embryogenic potential. The estimates of genetic parameters were accomplished via REML (Restricted Maximum Likelihood)/BLUP (Best Unbiased Linear Prediction) mixed model. The outputs showed high genetic variability within the studied population. Additionally, accessions AC.7, AC.2, AC.1, AC.6, and AC.8 showed as more efficient by considering characteristics related to the in vitro regeneration, thereby presenting a superior callogenesis ability; lower susceptibility to oxidation; and higher capacity for root and shoot formation. This was the first study to investigate the relationship among genetic parameters and selecting accessions of P. insignis for in vitro regeneration, thus providing support for studies related to micropropagation and domestication of this species.

Pages 819-825 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3575
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Dynamics of Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae) in Tahiti acid lime (Citrus latifolia) orchards under different fertilizer applications

Alirya Magda Santos do Vale Gomes, Raimunda Nonata Santos de Lemos*, Gislane da Silva Lopes, Cristina Silva Carvalho, Fabrício de Oliveira Reis, José Ribamar Gusmão Araujo, Janaina Marques Mondego, Ester Azevedo do Amaral, Adriano Soares Rêgo

Graduate Program in Agroecology, State University of Maranhão, São Luís, Maranhão, Brazil
State University of Maranhão. São Luís, Maranhão, Brazil

Abstract
Citrus black fly Aleurocanthus woglumi Asbhy is an important citrus pest because it causes significant losses in production. The objective of this study was to evaluate the incidence and distribution of A. woglumi egg laying, eggs and nymphs on Citrus latifolia (Tahiti acid lime) plants grown under different fertilizer applications. The experiment was carried out in a citrus orchard in the municipality of Paço do Lumiar, MA, Brazil. A randomized block design in a 3×5×3 factorial arrangement (three evaluation times, five treatments, and three plant strata) was used with 4 replications. The experimental unit consisted of three plants and treatments with different fertilizations were applied to the soil: T1: control (no fertilizer application); T2: organic fertilizer (bovine manure); T3: organic fertilizer + potassium silicate (K2O3Si); T4: NPK; T5: NPK + K2O3Si. The number of egg laying, eggs and nymphs of A. woglumi was evaluated in the basal, mid and apical strata of C. latifolia plants at 30, 60 and 90 days after fertilizer application. Reductions in the number of eggs and nymphs were observed in treatments with organic fertilization + K2O3Si and NPK + K2O3Si. Citrus latifolia plants treated with K2O3Si were less susceptible to A. woglumi and plants fertilized with NPK present higher susceptibility (p<0.05). There was a higher incidence of egg laying, eggs and 1st instar nymphs in the apical stratum and 2nd, 3rd and 4th instar nymphs in the basal and mid strata in C. latifolia (p<0.05). The addition of K2O3Si to organic and mineral fertilization is recommended as a viable alternative to reduce the population level of A. woglumi in citrus plants.

Pages 826-832 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3576
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Influence of precipitation on reproductive phenophases in Moringa oleifera Lam.

João Luciano de Andrade Melo Junior*, Luan Danilo Ferreira de Andrade Melo, João Correia de Araújo Neto, Keven Willian Sarmento Galdino da Silva, Larice Bruna Ferreira Soares, Vilma Marques Ferreira, Reinaldo de Alencar Paes, Jaqueline Figueredo de Oliveira Costa, Ivanildo Claudino da Silva, Priscila Cordeiro Souto, Lívia Francyne Gomes Chaves

Engineering and Agricultural Sciences Campus, Federal University of Alagoas, BR-104, Rio Largo - AL, 57100-000, Brazil
Federal University of Agreste of Pernambuco, Av. Bom Pastor, s/n - Boa Vista, Garanhuns - PE, 55292-270, Brazil

Abstract
Phenology works as an indicator of the response of plants to local climatic and edaphic conditions, enabling a better understanding of the dynamics of the species. The seasonal climate also influences the occurrence of periodic rhythms of growth and reproduction (phenophases). Moringa oleifera Lam., belong to the Moringaceae family, is widely distributed in tropical countries and easily adapts to semiarid conditions, having medicinal value as a forage, flavoring, in the cosmetics, honey, fuel and in the treatment of water purification through the coagulant solution made from the seeds. The objectives of the present work were to study the phenological behavior of M. oleifera and to relate the variations in phenophases with climatic factors, precipitation and temperature. For collection of phenological data, ten trees were selected, and the records were carried out between the first half of August 2020 and the first half of July 2021. The observations were carried out at fortnightly intervals, recording the presence and absence of the flowering and fruiting phenophases including flowering – period in which the tree is in full flowering; fructification – which starts from the moment that small fruits are visible after the fertilization of the flowers and ends with the dispersal of seeds. The Fournier intensity index was determined using a semiquantitative interval scale of five categories (0 to 4), with an interval of 25% between each category. The phenological data of intensity of each phenophase (flowering and fruiting) were related to precipitation and average temperature fortnightly using Spearman's correlation. The flowering and fruiting phenophases of M. oleifera intensified in August, September and December 2020, showing Fournier intensity peaks of 47.5 and 77.5, 72.5 and 92.5, and 35 and 55 %, respectively, and April and June 2021, in the monthly intervals of greater rainfall, with percentage rates of 82.5 and 95, 77.5 and 80%, respectively. In general, we found that M. oleifera produced seeds between the first half of August and the first half of September, and the second half of December 2020, and the second half of April and the first half of June 2021. Thus, it can be stated that the production of fruits by M. oleifera is interrupted in the months with less rainfall (October to November 2020, and January to February 2021). The intensity and duration of the flowering and fruiting phenophases in M. oleifera are synchronized with the temporal distribution of the precipitation pulses in that habitat.

Pages 833-837 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3629
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Effects of temporary agroforestry systems and weeding techniques on the control of invasive species in Atlantic Forest restoration

Altemar de Rezende, Priscilla de Paula Loiola, Alessandra dos Santos Penha, Maysa Mariano Aguiar de Oliveira, Patrícia Andrea Monquero

Center for Agricultural Sciences (CCA), Federal University of São Carlos (UFSCar), Rodovia Anhanguera km 174, P.O. Box 153, 13.600-970, Araras, SP, Brazil
Graduate Program in Agriculture and Environment (PPGAA), Federal University of São Carlos (UFSCar), Rodovia Anhanguera km 174, P.O. Box 153, 13.600-970, Araras, SP, Brazil
São Paulo State University (UNESP), Institute of Biosciences, Rio Claro, São Paulo, Department of Biodiversity, Phenology Lab, Brazil

Abstract
The restoration of tropical forests is greatly in demand but is limited by the lack of feasible technologies. Forest restoration can be associated with a temporary, productive herbaceous layer. Here, we compared the use of temporary agroforestry systems (tAFS) with conventional forest restoration through seedling planting. We quantified the growth estimators of native forest tree species and the effectiveness of the two methods for controlling invasive grasses. Seedlings of 20 native tree species were planted in 72 rows of 60 m each, totaling 1148 individuals. The restoration methods of planting tree seedlings only or trees coupled with herbaceous species (annual crops), along with weed control methods (mechanical and chemical), were systematically established in 12 plots (7920 m2 for conventional techniques and 7920 m2 for tAFS) per treatment (3960 m2 each) and analyzed in a nested design using generalized mixed models. The chemical control of weeds was conducted using herbicides, and the mechanical control consisted of semimechanized mowing. The tAFS showed greater relative growth in both the height and diameter of native trees in comparison with the conventional method. Within the conventional restoration technique, chemical management led to an increased height of native trees and a decreased invasive biomass, but tAFS showed no differences between the invasive control methods. tAFS was efficient in ensuring the success of the tree seedlings and diminishing the invasive biomass, concomitant with the production of annual crops in tropical forest restoration.

Pages 838-845 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3633
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Viability and vigor of Moringa oleifera Lam. seeds using the tetrazolium test

João Luciano de Andrade Melo Junior*, Luan Danilo Ferreira de Andrade Melo, Vilma Marques Ferreira, Larice Bruna Ferreira Soares, João Correia de Araújo Neto, Jaqueline Figueredo de Oliveira Costa, Reinaldo de Alencar Paes, Lívia Francyne Gomes Chaves, Priscila Cordeiro Souto, Ary Michel Medeiros da Silva, Ivanildo Claudino da Silva, Keven Willian Sarmento Galdino da Silva

Engineering and Agricultural Sciences Campus, Federal University of Alagoas, BR-104, Rio Largo - AL, 57100-000, Brazil
Federal University of Agreste of Pernambuco, Av. Bom Pastor, s/n - Boa Vista, Garanhuns - PE, 55292-270, Brazil

Abstract
To evaluate the physiological potential of the seeds, the tetrazolium test would be an interesting alternative, as it is a quick test that provides a detailed analysis of viability and vigor. Therefore, it is necessary to define pre-conditioning conditions, such as temperature and duration of soaking, concentration of the tetrazolium solution, and method of exposing the seeds to staining. Moringa oleifera Lam., belonging to the family Moringaceae, is widely distributed in tropical countries and easily adapted to semi-arid conditions, possessing medicinal value, as forage, condiment, in the cosmetics industry, melliferous, fuel, and in water purification treatment through the coagulant solution made from seeds. Based on the above, the objectives of the present work were to establish the most appropriate procedure for conducting the tetrazolium test to evaluate the viability and vigor of M. oleifera seeds. Only the cotyledons containing the embryo were placed in 50 mL plastic cups and immersed in a solution of 2,3,5-triphenyl chloride tetrazolium salt at concentrations of 0.05; 0.075 and 0.1% for staining periods of 1, 2, and 3 hours in a Biochemical Oxygen Demand chamber at 30 ºC in the dark. The seeds were evaluated one by one for tissue condition (firm or flaccid) and seed color, and by the location and size of the lesions on the cotyledon and embryonic axis. For the standardization of the tetrazolium test, the Completely Randomized Design was used in a 3x3+1 factorial scheme (three concentrations of tetrazolium solution x three staining periods + control = germination test) with four repetitions of 25 seeds. M. oleifera seeds were found to have a high germination rate (100%), there was no significant difference between the control and the percentage of viable seeds (TZ) for the 2 and 3 hours staining periods, immersed in tetrazolium solution at concentrations of 0.075 (96%) and 0.05% (99%), respectively. The most appropriate procedure for conducting the tetrazolium test to assess the viability and vigor of M. oleifera seeds is to use a concentration of 0.05% for 3 hours of salt immersion.

Pages 846-849 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3636
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Performance of soybean crop in response to palisadegrass pasture desiccation and nitrogen fertilization under integrated crop-livestock system

Flávia Werner*, Alvadi Antonio Balbinot Junior, André Sampaio Ferreira, Julio Cezar Franchini, Henrique Debiasi, Marcelo Augusto de Aguiar e Silva

Londrina State University, Rodovia Celso Garcia Cid, PR 445, Km 380, Caixa Postal 6001, 86051-980, Londrina, Paraná state, Brazil
Embrapa Soybean, Rodovia Carlos João Strass, Distrito de Warta, CEP 86001-970, Londrina, Paraná state, Brazil

Abstract
The desiccation (burn down) time of high-biomass pasture in no-tillage system and nitrogen (N) fertilization of pasture and soybean can influence the crop performance under crop-livestock system. The objective of this study was to evaluate the effect of desiccation times of palisadegrass pasture combined with three N fertilization levels of pasture and two N fertilization levels of soybean on crop yield, yield components and grain oil and protein concentration. Three N rates in the U. brizantha cv. BRS Piatã pasture were evaluated (0; 150 and 300 kg ha-1 of N as urea) in three different experiments. In each experiment, five pasture desiccation periods (60; 45; 30; 15 and 1 days before soybean sowing) and two levels of N fertilization of soybean (30 kg ha-1 of N distributed as urea at sowing + a control without urea) were evaluated. A randomized complete block design with five replications was used for each experiment. After statistical analysis of each experiment, a joint analysis of the three experiments was performed, allowing the comparison of the three rates of N in the pasture. The time interval between Urochloa brizantha pasture desiccation and soybean sowing did not influence soybean yield, yield components or the grain oil and protein concentrations, regardless of N fertilization of pasture and soybean. N fertilization of pasture induced a taller soybean plant height, insertion height of first pod, increased lodging, and reduced yield, but did not change the grain oil and protein concentration, regardless of the pasture desiccation time and N fertilization of soybean. Soybean grain yield was negatively affected by N fertilization of the crop, regardless of fertilization levels and desiccation times of the previous pasture.

Pages 850-855 | Full Text PDF| doi: 10.21475/ajcs.22.16.06.p3644
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Genetic diversity of avocado (Persea americana Mill.) germplasm in Vietnam using RAPD and ISSR molecular markers

Thao Thi Ninh*, Hien Thi Doan, Mai Thi Nguyen, Tran Tu Tran, Phong Dinh Duc Dang, Son Truong Dinh, Hai Thanh Nguyen, Hue Thi Nong, Canh Xuan Nguyen

Faculty of Biotechnology, Vietnam National University of Agriculture, Hanoi, Vietnam
Western Highlands Agriculture and Forestry Science Institute, Dak Lak, Vietnam

Abstract
Avocado is a significant cash crop in Vietnam, while little is known about its genetic diversification. Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were performed to investigate the genetic diversity of twenty-eight imported and domestic avocado cultivars being maintained at Western Highlands Agriculture and Forestry Science Institute, Dak Lak, Vietnam. 18 RAPD and 15 ISSR primers produced 3183 and 2807 scorable bands, of which 83.92% and 71.72% were polymorphic, respectively. The RAPD markers exhibited an average PIC of 0.27 and Rp index of 12.63 whereas the mean PIC and Rp values of ISSR primers were 0.21 and 13.37, respectively. The correlation between RAPD and ISSR markers was low (r = 0.338), suggesting that the ability to resolve genetic variation among varieties may relate to the number of detected polymorphisms rather than the marker employed. Nevertheless, the correlation between ISSR and combined data was high (r = 0.791) and the correlation between RAPD and combined matrices was even higher (r = 0.897). This indicates that RAPD markers have slightly higher efficiency over ISSR to resolve genetic variation among 28 avocado cultivars. High genetic diversity among 28 avocado cultivars was revealed with the Jaccard’s similarity coefficient ranging from 0.623 to 0.913 based on combined data analysis. The UPGMA dendrogram generated from combined RAPD and ISSR data grouped Vietnamese domestic and imported avocado cultivars into three different groups at 72% similarity. These results could be applied to the avocado conservation and breeding programs.

Pages 856-862 | Full Text PDF| Supplementary Data PDF| doi: 10.21475/ajcs.22.16.06.p3667
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Genetic differentiation in weedy (O. sativa f. spontanea) and wild rice (O. rufipogon) revealed by DNA sequence in the QTL SD7-1/Rc locus

Preecha Prathepha

Department of Biotechnology, Faculty of Technology, Mahasarakham University, Kantarawichai District, Maha Sarakham province Thailand 44150

Abstract
The QTLSD7-1/Rc is a pleiotropic locus that controls seed dormancy and pericarp color in rice. DNA sequence variation in promoter region, exon1, and intron 1 in wild rice from Thailand and Laos, weedy rice accessions from Thailand, as well as cultivated rice were investigated using re-sequencing DNA technique. For promoter region, three types of DNA variation were observed including variation in number of nucleotide (T)n (n=9,10,11), five SNPs and 19-bp indel. For coding region exon 1, no DNA sequence variation was observed. For non-coding region intron1, weedy rice had the 10-bp insertion in the region, but there was the deletion in wild rice. In addition, deletion of 34-bp in intron1 was observed in all wild rice accessions examined, while weedy rice had the 34-bp insertion. Haplotype analysis of weedy rice indicated that the pairwise nucleotide diversity parameter, Pi (ℼ) and the level of the Watterson estimator (Өw) in the DNA sequences were 0.00401 and 0.0048, respectively. This finding enhances knowledge of the DNA sequence

Pages 863-869 | Full Text PDF| Supplementary Data PDF| doi: 10.21475/ajcs.22.16.06.p3672