Dynamics of Macronutrient Uptake and Removal by Modern Peanut Cultivars.

The productive potential of new peanut cultivars has increased over the years in relation to old cultivars, especially when compared with ones with upright growth habit. Thus, the requirement for macronutrients for these new cultivars may also have increased, making the existing fertilizer recommendation tables obsolete, thus increasing the need for further studies measuring the real macronutrient requirements of these new peanut cultivars. Our study aimed to evaluate the growth patterns and the macronutrient absorption rate throughout the biological cycle of three modern runner peanut cultivars, as well as the potential for producing dry matter, pods, and kernels, and their respective macronutrient accumulations. The experimental design was a randomized complete block with split-plots and nine replications. The experimental plots consisted of three peanut cultivars (IAC Runner 886, IAC 505, and IAC OL3), and subplots consisted of nine plant samplings (14, 28, 42, 56, 70, 84, 105, 126, and 147 days after emergence (DAE)). Our results showed that modern peanut cultivars presented nutrient accumulation around 30 to 40 days earlier than older cultivars, as well as increasing the uptake by K and Ca. IAC 505 absorbed higher amounts of macronutrients and resulted in greater dry matter production compared with IAC OL3 and IAC Runner 886. Our study demonstrated that the most appropriate time for plants to find greater availability of nutrients in the soil is 70 to 84 DAE, in addition to highlighting the need for updates on nutritional recommendations for higher yields of modern peanut cultivars.

Kinetin establish the volatile chemical profile after rhizome dormancy is released in Curcuma zedoaria (Christm.) Roscoe.

The aim of this work was to provide information about kinetin effects on chemical volatile profile of Curcuma zedoaria (Christm.) Roscoe after several days of plant dormancy release. Rhizomes of C. zedoaria were immersed in four kinetin concentrations (0, 50, 100, 150 mg ml-1, n = 12 by each concentration) for 30 min. After 240 h of treatment, root length (mm), bud break (%) and bud speed index (BSI) were measured, and three rhizomes at 24 h and 240 h were collected for chemical volatile profile analysis by application of headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Kinetin does not alter morphological aspects of the bud dormancy releasing, but drastically changes metabolic aspects of volatile production on C. zedoaria rhizomes, by the selection of several monoterpenes, such as camphene, sabinene, isoborneol, borneol, 1,8-cineole. We assume that kinetin application maintain monoterpene production as a consequence of its signaling over dormancy release.

Harvest time optimization leads to the production of native cassava starches with different properties.

The starch market is very diverse and demanding regarding the functional characteristics of the product. However, no technique based on the management of cassava root harvest time has been applied to obtain starches with different properties. Thus, in this study, cassava roots were harvested at different times and the structure and physicochemical properties of their starches were analyzed. Results indicated the time points in the first growth cycle of plants when all parameters associated with root growth were at their highest values. It was also observed that changes in the time of harvest leads to the production of starches with different granule size, crystallinity, and content of amylose and phosphorus, which resulted in changes in the thermal and pasting properties, as well as in the solubility of the starches and swelling power; that is, on the main determinant characteristics for applicability of the starches. Planned agricultural production monitoring, coupled with the analysis of the main starches characteristics for large-scale cassava crops, can provide commercial benefits for both farmers and industry, as it is possible to obtain starches with desired physicochemical characteristics for varied applications.

Methods and extractants to evaluate silicon availability for sugarcane.

The correct evaluation of silicon (Si) availability in different soil types is critical in defining the amount of Si to be supplied to crops. This study was carried out to evaluate two methods and five chemical Si extractants in clayey, sandy-loam, and sandy soils cultivated with sugarcane (Saccharum spp. hybrids). Soluble Si was extracted using two extraction methods (conventional and microwave oven) and five Si extractants (CaCl2, deionized water, KCl, Na-acetate buffer (pH 4.0), and acetic acid). No single method and/or extractant adequately estimated the Si availability in the soils. Conventional extraction with KCl was no more effective than other methods in evaluating Si availability; however, it had less variation in estimating soluble Si between soils with different textural classes. In the clayey and sandy soils, the Na-acetate buffer (pH 4.0) and acetic acid were effective in evaluating the Si availability in the soil regardless of the extraction methods. The extraction with acetic acid using the microwave oven, however, overestimated the Si availability. In the sandy-loam soil, extraction with deionized water using the microwave oven method was more effective in estimating the Si availability in the soil than the other extraction methods.

Chemical composition of potato tubers: the effect of cultivars and growth conditions.

The aim of the study involved evaluating the chemical composition of tubers of five potato cultivars that were grown under the same cultural practices in soils with low, medium, and high availability of phosphorus. The experimental designs corresponded to a randomized block with four replicates. Tuber samples were analyzed in terms of moisture, ash, protein, lipid, total sugar, fiber, starch, and phosphorus contents. The results suggested that increased availability of phosphorus in soil allowed the production of tubers with higher dry matter content, lower total sugar content, and a higher percentage of starch and protein. Hence, the aforementioned parameters constitute important factors corresponding to the nutritional and industrial quality of potatoes. Increased phosphorus availability in soil can promote significant changes in the composition of potato tubers, and thereby in potential uses of tubers.

Nitrogênio no crescimento da planta e na qualidade de raízes da mandioquinha-salsa / Nitrogen on plant growth and storage root quality of Arracacha

RESUMO: O nitrogênio (N) é o segundo nutriente mais absorvido pela mandioquinha-salsa. No entanto, ainda existem dúvidas sobre a influência que esse nutriente pode exercer sobre o crescimento da planta e a qualidade das raízes de reserva. Assim, objetivou-se com este trabalho avaliar a influência da adubação nitrogenada no crescimento da planta e na qualidade físico-química e nutricional das raízes de mandioquinha-salsa. O experimento foi conduzido em um Latossolo Vermelho distrófico de textura arenosa, no delineamento experimental de blocos ao acaso, com quatro repetições. Os tratamentos foram constituídos pelas doses de 0, 50, 100 e 200kg ha-1 de N. O crescimento das partes vegetativas da planta de mandioquinha-salsa aumentou linearmente com a adubação nitrogenada, mas a massa média e a produtividade das raízes de reserva aumentaram até as doses estimadas de 121 e 148kg ha-1 de N, respectivamente. A adubação nitrogenada aumentou os teores de amido e de proteína das raízes e diminuiu os teores de açúcares totais, porém, sem influenciar a qualidade nutricional delas.

ABSTRACT: Nitrogen (N) is the second most absorbed nutrient by Arracacha. However, there are still doubts about the influence that this nutrient can have on plant growth and the quality of the storage roots. Thus, the aim of this research was to evaluate the influence of nitrogen fertilization on plant growth and physical-chemical and nutritional quality of storage roots of Arracacha. The experiment was conducted on an Oxisol of sandy texture, in a randomized complete block design, with four replications. The treatments consisted of rates of 0, 50, 100, and 200kg ha-1 N. Growth of vegetative parts of Arracacha increased linearly with nitrogen fertilization, but the storage root mean weight and the yield of storage roots increased up to estimated rates of 121 and 148kg ha-1 N, respectively. Nitrogen fertilization increased the starch and protein content of the storage roots and reduced the content of total sugar, but without affecting the nutritional quality of the same.

Crescimento e produtividade de duas cultivares de feijão em função de doses de ácido 2,3,5-triiodobenzoico / Growth and yield of two common bean cultivars as affected by 2,3,5-triiodobenzoic acid rates

RESUMO:O crescimento excessivo da parte aérea do feijoeiro pode aumentar o acamamento das plantas e promover fechamento muito rápido da cultura, limitando a produtividade de grãos. O uso de reguladores de crescimento, como o ácido 2,3,5-triiodobenzoico (TIBA), pode reduzir o crescimento das plantas, porém, não existem informações sobre o uso dessa tecnologia na cultura do feijão. Objetivou-se com este trabalho avaliar o efeito de doses de TIBA (0, 8, 16, 32, 64 e 128g do i.a. ha-1) sobre o crescimento e a produtividade de grãos de duas cultivares de feijão ('IAC Alvorada' e 'IAC Jabola'). O delineamento experimental foi o de blocos ao acaso, em esquema de parcelas subdivididas, com quatro repetições. A aplicação de TIBA reduziu o comprimento da maior haste de ambas as cultivares, até a dose média estimada de 100g ha-1 de TIBA. A altura de inserção da primeira vagem foi reduzida apenas na cultivar IAC Alvorada até a dose de 88g ha-1 de TIBA. A aplicação de TIBA reduziu em 10% o número de grãos por vagem. A utilização de TIBA não afetou a produtividade de grãos, sendo uma alternativa para diminuir o porte das plantas de feijão.

ABSTRACT:The excessive aboveground growth of common bean can increase plant lodging and promote very rapid canopy closing, limiting grain yield. The use of growth regulators, such as 2,3,5-triiodobenzoic acid (TIBA), can reduce plant growth, however, there is no information on the use of this technology in the common bean crop. The objective of this study was to evaluate the effect of TIBA rates (0, 8, 16, 32, 64, and 128g a.i. ha-1) on growth and grain yield of two common bean cultivars ('IAC Alvorada' and 'IAC Jabola'). The experimental design used was randomized blocks, in a split plot scheme, with four replications. The application of TIBA reduced the stem length of both cultivars, to the average estimated rate of 100 g ha-1 TIBA. Height of insertion of the first pod was reduced only in IAC Alvorada up to rate of 88 g ha-1 TIBA. Application of TIBA reduced by 10% the number of grains per pod. The use of TIBA did not affect grain yield, being an alternative to reduce the size of the common bean plants.

Qualidade de tubérculos de batata da cultivar 'Atlantic' afetada pela adubação fosfatada / Quality of potato tubers from cultivar 'Atlantic' as affected by phosphorus fertilization

To evaluate the influence of phosphorus (P) fertilization on the potato tuber quality of the cultivar 'Atlantic' experiments were conducted in soils with medium (36 mg dm-3) and high (70 mg dm-3) P availability. The treatments consisted of five P2O5 rates (0, 125, 250, 500, and 1,000 kg ha-1). The experiments were conducted in a randomized block design, with four replications. Only in soil with medium P availability, the phosphorus fertilization decreases protein, but increases starch content of the tubers until rate of 595 kg ha-1 P2O5. Phosphorus fertilization increases the tuber size and marketable yield, but in a more expressive and until higher rates in soil with medium P concentration, in which the influence of tuber size on marketable yield is higher. In two conditions of P availability, the phosphorus fertilization has greater influence on the tuber size and the production of processed material (dry matter yield of tubers) than on the quality characteristics of tubers that influence in the quality frying.

Para avaliar a influência da adubação fosfatada sobre a qualidade dos tubérculos de batata da cultivar 'Atlantic' foram conduzidos experimentos em solos com médio (36 mg dm-3) e alto (70 mg dm-3) teor de P disponível. Os tratamentos foram constituídos por cinco doses de P2O5 (0, 125, 250, 500 e 1.000 kg ha-1). Os experimentos foram conduzidos no delineamento experimental de blocos casualizados, com quatro repetições. Apenas no solo com média disponibilidade de P a adubação fosfatada diminui os teores de proteína, mas aumenta o teor de amido dos tubérculos até a dose de 595 kg ha-1 de P2O5. A adubação fosfatada aumenta o tamanho dos tubérculos e a produtividade comercial, porém de forma mais expressiva e até maiores doses em solo com médio teor de P, em que a influência do tamanho do tubérculo sobre a produtividade comercial é maior. Nas duas condições de disponibilidade inicial de P, a adubação fosfatada tem maior influência sobre o tamanho dos tubérculos e a produção de material processado (produtividade de matéria seca de tubérculos), do que sobre as características de qualidade dos tubérculos, que podem influenciar na qualidade da fritura.

Eficiência de utilização de nutrientes por cultivares de batata / Absorption and nutrients use efficiency by potato cultivars

O uso de cultivares eficientes na utilização de nutrientes é fundamental para aumentar a produtividade e reduzir os custos de produção. Objetivou-se com esse experimento avaliar a absorção e a eficiência de utilização de nutrientes em cinco cultivares de batata. O experimento foi conduzido na safra de inverno de 2008, em Latossolo Vermelho, no município de Itaí-SP. Utilizou-se delineamento em blocos ao acaso, em esquema de parcela subdividida, com quatro repetições. As parcelas foram constituídas pelas cinco cultivares e as subparcelas por épocas de coletas, realizadas no momento do plantio e a cada sete dias após a emergência. Aos 97 dias após o plantio (DAP) calculou-se a eficiência de utilização de nutrientes para produção de matéria seca (MS) total e aos 122 DAP calcularam-se as eficiências de utilização de nutrientes para produção de tubérculos frescos e de MS dos mesmos. As cultivares Asterix e Mondial apresentaram maior produção de MS, produtividade de tubérculos frescos e maior acúmulo de nutrientes. A eficiência de utilização de nutrientes para a produção de MS total e MS de tubérculos foi semelhante entre as cultivares, mas, a cultivar Ágata foi mais eficiente na utilização de nutrientes para a produção de tubérculos frescos.

The use of cultivars efficient in nutrient use is essential to increase yield and reduce production costs. The objective of this study was to evaluate absorption and nutrients use efficiency on five potato cultivars. The experiment was conduced in Itaí, São Paulo State, Brazil, in winter cropping season of 2008 on Oxisol. The experimental design was randomized blocks with split-plots and four replications. Plots comprised the five potato cultivars and subplots were established by sampling times, performed at planting and every seven days after emergence. At 97 DAP was calculated the nutrients use efficiency for dry matter production and at 122 DAP were calculated the nutrients use efficiency for fresh tuber and tuber dry matter yield. Mondial and Asterix cultivars showed greater dry matter production, higher fresh tubers yield and nutrients accumulation. Nutrients use efficiency for total dry matter and tubers dry matter, was similar among cultivars, but Ágata was more efficient in nutrients use efficiency for fresh tubers yield.