The objective of this study was to evaluate the genetic variability of natural rubber latex traits among 44 elite genotypes of the rubber tree Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. ...Arg.. Multivariate analysis and machine learning techniques were used, targeting the selection of parents that demonstrate superior characters. We analyzed traits related to technological or physicochemical properties of natural rubber latex, such as Wallace plasticity (P
), the plasticity retention index PRI (%), Mooney viscosity (V
), ash percentage (Ash), acetone extract percentage (AE), and nitrogen percentage (N), to study genetic diversity. Multivariate unweighted pair group method with arithmetic means (UPGMA) and Tocher) and machine learning techniques K-means and Kohonen's self-organizing maps (SOMs) were employed. The genotypes showed high genetic variability for some of the evaluated traits. The traits PRI, Ash, and P
contributed the most to genetic diversity. The genotypes were classified into six clusters by the UPGMA method, and the results were consistent with the Tocher, K-means and SOM results. PRI can be used to improve the industrial potential of clones. The clones IAC 418 and PB 326 were the most divergent, followed by IAC 404 and IAC 56. These genotypes and others from the IAC 500 and 400 series could be used to start a breeding program. These combinations offer greater heterotic potential than the others, which can be used to improve components of rubber latex quality. Thus, it is important to consider the quality of rubber latex in the early stage of breeding programs.
O trabalho foi realizado com o objetivo de avaliar a produtividade de fitomassa de cinco plantas de cobertura utilizadas para produção de grãos, sementes e forragem, em diferentes densidades de ...semeadura, e da vegetação espontânea, na Região Noroeste do Estado de São Paulo. Os experimentos foram instalados em Votuporanga, SP e Selvíria, MS, em março de 2008, após o preparo convencional do solo. O delineamento experimental utilizado foi o de blocos casualizados com quatro repetições, utilizando as seguintes plantas de cobertura em diferentes densidades de semeadura que constituíram os tratamentos: Sorghum bicolor: 6, 7 e 8kg ha-1, Pennisetum americanum: 10, 15 e 20kg ha-1, Sorghum sudanense: 12, 15 e 18kg ha-1, híbrido de Sorghum bicolor com Sorghum sudanense: 8, 9 e 10kg ha-1, Urochloa ruziziensis: 8, 12 e 16kg ha-1. Também se utilizou um tratamento controle com vegetação espontânea. Avaliou-se a fitomassa das diferentes coberturas no momento da colheita/corte das coberturas, na pré-semeadura e no florescimento das culturas da soja e do milho. A utilização de plantas de cobertura mostrou-se mais benéfica que se deixar as áreas em pousio. Concluiu-se que as plantas de cobertura avaliadas mostraram-se como boas opções de plantas de cobertura para a região Noroeste do Estado de São Paulo. Além Disso, as diferentes densidades de semeadura de cada planta de cobertura não influenciaram na produtividade de fitomassa da mesma planta de cobertura
IAC VR211 and IAC VM211 were developed for growing in Brazil with the aim of responding to the domestic and export market. The cultivars have a mean cycle of 85 days and yield potential of 2,191 kg ...ha-1 for IAC VR211 and 1,603 kg ha-1 for IAC VM211.
Os efeitos promovidos pelas plantas de cobertura nos atributos químicos do solo são bastante variáveis, dependendo de fatores como espécie utilizada, manejo dado à biomassa, época de plantio e corte ...das plantas, tempo de permanência dos resíduos no solo, condições locais e interação entre esses fatores. Este trabalho foi realizado com o objetivo de avaliar a absorção de nutrientes por cinco plantas de cobertura, que foram utilizadas para produção de grãos, sementes e forragem, em diferentes quantidades de sementes por hectare e pela vegetação espontânea, bem como para o efeito sobre as propriedades químicas de dois Latossolos, cultivadas em rotação com as culturas da soja e do milho. Os experimentos foram instalados em Votuporanga, SP, e Selvíria, MS, em março de 2008, após o preparo convencional do solo. O delineamento experimental utilizado foi o de blocos casualizados com quatro repetições, utilizando as seguintes plantas de cobertura em diferentes quantidades de sementes por hectare que constituíram os tratamentos: sorgo granífero: 6, 7 e 8 kg ha-1; milheto: 10, 15 e 20 kg ha-1; capim-sudão: 12, 15 e 18 kg ha-1; híbrido de sorgo com capim-sudão: 8, 9 e 10 kg ha-1; e Urochloa ruziziensis: 8, 12 e 16 kg ha-1. Também se utilizou um tratamento-controle com vegetação espontânea. Após o manejo das coberturas, no primeiro ano de estudo, foi semeada a soja e, no segundo ano, semeou-se o milho, ambos em sistema de semeadura direta. Avaliaram-se a produtividade de matéria seca das diferentes coberturas, a absorção de nutrientes pelas coberturas e as alterações químicas no solo. Constatou-se que em solos argilosos, com elevado teor de alumínio no solo, como em Selvíria, o capim-sudão, com 18 kg ha-1 de sementes, e o sorgo granífero, com 6 kg ha-1, em associação a calagem, contribuem para redução do teor de alumínio e da acidez potencial e para elevação da saturação por bases. As diferentes quantidades de sementes de cada planta de cobertura não influenciaram a produtividade de matéria seca da mesma planta de cobertura, mas interferiram na absorção de nitrogênio do híbrido de sorgo com capim-sudão, com 10 kg ha-1 de sementes, apresentando menor absorção que com 8 kg ha-1 de sementes, e também no teor de matéria orgânica no solo, com o capim-sudão, com 15 kg ha-1 de sementes, propiciando maior teor que o de 18 kg ha-1 de sementes.
To address the problems of acidity in the surface and subsurface layers and improve soil chemical fertility, three methodology of surface application of hydrated lime (HL) (4Ca(OH)
2
Mg(OH)
2
) ...(ensure that calcium (Ca)
+2
occupied 70%, 60%, and 50% of cation exchange capacity (CEC) in the 0.0-0.2 m layer) were evaluated in a Typic Hapludalf in conventional pasture system (CPS), no-till system (NTS), and agropastoral system (APS) in Brazil. The results support the following conclusions: (a) the application of HL corrects surface and subsurface acidity and improve the soil chemical fertility: increasing pH and magnesium (Mg)
2+
content in the CPS, NTS, and APS in the 0.0-0.2 m and 0.2-0.4 m layers; increasing base saturation (BS) and Mg
+2
/CEC in the CPS, NTS, and APS in the 0.0-0.2 m layer; increasing Ca
+2
content, CEC, and Ca
+2
/CEC in the NTS and APS in the 0.0-0.2 m layer; reducing total acidity in the CPS, NTS, and APS in the 0.0-0.2 m layer and in the NTS and APS in the 0.2-0.4 m layer; reducing total acidity and increasing Mg
+2
/CEC in the NTS and APS in the 0.2-0.4 m layer.
Quantifying the wood volume of forest stands is essential for planning sustainable forest management. The most efficient means of quantifying wood volume is volumetric equations. Many models for ...adjusting volumetric equations have been developed and tested, but their suitability for agrosilvipastoral systems remains unclear. To address this gap, we assessed the ability of six volumetric models to generate estimates of the total volume with bark of eucalyptus hybrids Grancam 1277 and Urograndis H-13. The trees were cultivated in an agrosilvipastoral system in an Arenic Hapludult in the municipality of Votuporanga, Sao Paulo State, Brazil, which is within the Cerrado biome. For Urograndis H-13, the Takata model was most accurate for quantifying volume, as it gave the highest F test (178.38) and adjusted coefficient of determination (0.93) values and the smallest standard error (0.06). The nonlinear and linear Schumacher-Hall models were most accurate for Grancam 1277, as this model gave the highest F test (54.59) and adjusted coefficient of determination (0.8) values and the smallest standard error (0.07).
Pearl millet Pennisetum glaucum (L.) R. Br. is grown as a forage, cover and grain crop in Brazil. Historically, forage production has the most important use, but during the last 30 years, the use as ...a cover crop in no-till soybean Glycine max (L.) Merrill production systems has expanded greatly and is currently used on over 5 million ha. Grain production as livestock feed is presently of minor importance but expanding. This review cites 125 references and documents pearl millet research conducted in Brazil which is largely published in Portuguese. The review addresses recommended pearl millet production practices for different uses, including stand establishment, row spacing and plant population, fertiliser and pest management, and the use of pearl millet in rotation and as a cover crop between soybean or maize (Zea mays L.) production to reduce crop losses from nematode infestation. It is concluded that greater research investment in crop improvement, fertiliser and pest management, nematode management, and forage/grain utilisation is needed to fully take advantage of pearl millet to meet feed, food and soil improvement needs in Brazil. In addition, creation of a database on pearl millet production, marketing and utilisation to assist farmers and grain merchandisers, and increased extension programming on pearl millet production is needed.
Seeds enriched with zinc (Zn) are ususally associated with better germination, more vigorous seedlings and higher yields. However, agronomic benefits of high‐Zn seeds were not studied under diverse ...agro‐climatic field conditions. This study investigated effects of low‐Zn and high‐Zn seeds (biofortified by foliar Zn fertilization of maternal plants under field conditions) of wheat (Tritcum aestivum L.), rice (Oryza sativa L.), and common bean (Phaseolus vulgaris L.) on seedling density, grain yield and grain Zn concentration in 31 field locations over two years in six countries. Experimental treatments were: (1) low‐Zn seeds and no soil Zn fertilization (control treatment), (2) low‐Zn seeds + soil Zn fertilization, and (3) Zn‐biofortified seeds and no soil Zn fertilization. The wheat experiments were established in China, India, Pakistan, and Zambia, the rice experiments in China, India and Thailand, and the common bean experiment in Brazil. When compared to the control treatment, soil Zn fertilization increased wheat grain yield in all six locations in India, two locations in Pakistan and one location in China. Zinc‐biofortified seeds also increased wheat grain yield in all four locations in Pakistan and four locations in India compared to the control treatment. Across all countries over 2 years, Zn‐biofortified wheat seeds increased plant population by 26.8% and grain yield by 5.37%. In rice, soil Zn fertilization increased paddy yield in all four locations in India and one location in Thailand. Across all countries, paddy yield increase was 8.2% by soil Zn fertilization and 5.3% by Zn‐biofortified seeds when compared to the control treatment. In common bean, soil Zn application as well as Zn‐biofortified seed increased grain yield in one location in Brazil. Effects of soil Zn fertilization and high‐Zn seed on grain Zn density were generally low. This study, at 31 field locations in six countries over two years, revealed that the seeds biofortfied with Zn enhanced crop productivity at many locations with different soil and environmental conditions. As high‐Zn grains are a by‐product of Zn biofortification, use of Zn‐enriched grains as seed in the next cropping season can contribute to enhance crop productivity in a cost‐effective manner.
Efficiency of Nitrogen Use in Sunflower Coêlho, Ester dos Santos; Souza, Almir Rogério Evangelista de; Lins, Hamurábi Anizio ...
Plants,
09/2022, Volume:
11, Issue:
18
Journal Article
Peer reviewed
Open access
The large variation in the response of sunflower to nitrogen fertilization indicates the need for studies to better adjust the optimum levels of this nutrient for production conditions. Our ...objectives were to analyze the agronomic yield of sunflower cultivars as a function of nitrogen fertilization; indicate the cultivar with high nitrogen use efficiency; and measure the adequate N dose for sunflower through nutritional efficiency. The completely randomized block design with split plots was used to conduct the experiments. The treatments included five nitrogen rates being allocated in the plots and the four sunflower cultivars. To estimate the nutrient use efficiency in the sunflower, we measured agronomic efficiency (AE), physiological efficiency (PE), agrophysiological efficiency (APE), apparent recovery efficiency (ARE), and utilization efficiency (UE). The results indicate that all cultivars had a reduction in AE due to the increase in N doses in the first crop. For PE, the highest values were observed for Altis 99 during the 2016 harvest. In that same harvest, Altis 99 had the highest APE. The dose of 30 kg ha−1 provided greater ARE for all cultivars in both crops, with greater emphasis on BRS 122 and Altis 99. The cultivation of cultivars Altis 99 and Multissol at a dose of 30 kg ha−1 in is recommended semiarid regions.
‘IAC Sempre Verde’ is a medium-seeded runner-type peanut highly resistant to late leaf spot and rust, the main diseases in peanut cultivation in Brazil. The newly released cultivar showed remarkable ...yield advantage over controls when diseases were not controlled and represents the first possibility for peanut cultivation under “Organic” management.
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