Mineral nutrition of Cyclanthera pedata

O objetivo desse estudo foi o de caracterizar as limitações nutricionais para a produção de matéria seca do maxixe-do-reino, Cyclanthera pedata (L.) Schrad. Foram realizados dois cultivos sucessivos, em vasos de 3 dm3 de solo. O delineamento experimental foi inteiramente casualizado, em treze tratamentos, com três repetições. Os tratamentos foram baseados na técnica do elemento faltante (em que se omite a calagem e cada um dos macronutrientes e micronutrientes). A produção de matéria seca da parte aérea e raiz foi reduzida pela acidez do solo e baixa disponibilidade de macronutrientes, principalmente P, Ca, Mg e S; as plantas foram pouco afetadas pela baixa disponibilidade de micronutrientes.The objective of this work was to characterize the nutritional limitations for dry matter production of Cyclanthera pedata (L.) Schrad. Two successive cultivations were conducted in 3 dm3 pots with soil. The experimental design was totally randomized with 13 treatments and three replications. Treatments were based on the missing element technique (with omission of liming and each one of the macro and micronutrients). Cyclanthera pedata plants have their dry matter production reduced by soil acidity and low macronutrients availability, mainly P, Ca, Mg and S, and were little affected by low micronutrients availability

Interação entre silício e nitrogênio em arroz cultivado sob solução nutritiva Silicon-nitrogen interaction in rice cultivated under nutrient solution

O presente estudo objetivou avaliar o efeito da interação entre silício e nitrogênio nos teores de clorofila, nitrato, amônio e nitrogênio total, na produção de biomassa e nos números de perfilhos e de panículas em arroz cultivado em solução nutritiva. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 5 x 2, sendo duas concentrações de silício (0 e 50 mg L-1) e cinco as de nitrogênio (20; 50; 100; 200 e 400 mg L-1), com três repetições. No estádio de formação do colar da folha bandeira foram realizadas a leitura SPAD e as determinações dos teores de clorofila a e b, nitrogênio nítrico, amoniacal e total. No estádio de maturidade completa da panícula, foram avaliados os números de perfilhos e de panículas e determinaram-se os pesos de matéria seca de raiz e parte aérea e o acúmulo de silício na planta. Os resultados mostraram que o fornecimento de silício não alterou o perfilhamento, a produção de matéria seca e os teores de nitrogênio total. O silício elevou os valores SPAD, os teores de clorofila a e b, os teores de nitrato nas raízes e o número de panículas, especialmente em doses elevadas de nitrogênio.<br>The present study aimed to evaluate the interaction effect between silicon and nitrogen in the content of chlorophyll, nitrate, ammonium and total nitrogen, dry matter production, number of tillers and number of panicles rice-plant cultivated in nutritional solution. A factorial design 5 x 2 trial installed in a completely randomized design was used being two silicon (0 and 50mg L-1) and five nitrogen (20; 50; l00; 200 and 400 mg L-1) concentrations. In the stadium of the flag leaf collar formation SPDA reading and the a and b chlorophyll contents, ammoniacal and total nitrogen determinations in plants were detemined. During the panicle complete maturity stadium, the number of tillers and panicles were evaluated and the aerial part and root dry matter contents and silicon accumulation were determined. The outcomes show that the silicon supply did not change the tillering, the dry matter production and total nitrogen contents. The silicon increased the SPAD values, the a and b chlorophyll and the root nitrate contents, and the number of panicles, especially at high nitrogen levels

Environmental Impact of Potentially Toxic Elements on Tropical Soils Used for Large-Scale Crop Commodities in the Eastern Amazon, Brazil

The Amazon soils demand high rates of fertilizer application to express high agricultural potential, making it necessary to carry out frequent monitoring of ecological functions and biogeochemical processes in this important biome. The concentrations of As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn and contamination indexes were studied in Oxisol and Ultisols cultivated with citrus (Citrus sinensis (L.) Osbeck), oil palm (Elaeis guineensis Jacq.) and black pepper (Piper nigrum L.), at 26, 10 and 5 years of implantation, respectively. The potential risk of contamination was estimated by the enrichment (EF) and bioaccumulation (BAF) factors. Moderate enrichment of Ba, Pb and Zn (2 &lt; EF &lt; 5) and significant enrichment of As and Cu (5 &lt; EF &lt; 20) were observed. In addition, the following orders of bioaccumulation were found: oil palm—Cu &gt; Zn &gt; Hg &gt; Ni &gt; Ba &gt; Co &gt; As &gt; Cr &gt; Cd ≈ Pb; black pepper—Zn &gt; Hg &gt; Cu &gt; Ba &gt; Ni &gt; Co &gt; Pb &gt;&gt; As &gt; Cr &gt; Cd; and citrus—Hg &gt; Ni &gt; Ba &gt; Zn &gt; Co &gt; Cu &gt; As &gt; Pb &gt;&gt; Cr &gt; Cd. However, all elements are in concentrations below the prevention and investigation values established by Brazilian legislation, that is, the management practices in the crops studied are not contributing with damage to soil and human health risks

Nutrição mineral de plantas de maxixe-do-reino Mineral nutrition of Cyclanthera pedata

O objetivo desse estudo foi o de caracterizar as limitações nutricionais para a produção de matéria seca do maxixe-do-reino, Cyclanthera pedata (L.) Schrad. Foram realizados dois cultivos sucessivos, em vasos de 3 dm³ de solo. O delineamento experimental foi inteiramente casualizado, em treze tratamentos, com três repetições. Os tratamentos foram baseados na técnica do elemento faltante (em que se omite a calagem e cada um dos macronutrientes e micronutrientes). A produção de matéria seca da parte aérea e raiz foi reduzida pela acidez do solo e baixa disponibilidade de macronutrientes, principalmente P, Ca, Mg e S; as plantas foram pouco afetadas pela baixa disponibilidade de micronutrientes.The objective of this work was to characterize the nutritional limitations for dry matter production of Cyclanthera pedata (L.) Schrad. Two successive cultivations were conducted in 3 dm³ pots with soil. The experimental design was totally randomized with 13 treatments and three replications. Treatments were based on the missing element technique (with omission of liming and each one of the macro and micronutrients). Cyclanthera pedata plants have their dry matter production reduced by soil acidity and low macronutrients availability, mainly P, Ca, Mg and S, and were little affected by low micronutrients availability

Açaí Biochar and Compost Affect the Phosphorus Sorption, Nutrient Availability, and Growth of Dioclea apurensis in Iron Mining Soil

Organic materials, such as biochar and organic compost, can reduce P sorption mechanisms and improve soil fertility, benefiting the reclamation of areas impacted by mining. This study evaluated how the chemical properties of Fe mining soil, the adsorption of P onto this substrate, and the growth of the native plant Dioclea apurensis, were affected by the application of açaí biochar (BC), organic compost (OC), and different P doses. Substrate collected from mining soil piles was incubated for 30 days with BC or OC. Each mining substrate with or without the addition of BC or OC received five doses of P (0, 40, 80, 120, and 240 mg∙kg−1 P). The addition of BC or OC promoted an increase in pH and nutrient availability (P, K, Ca, and B) in Fe mining soil. However, plants grown in the unamended mining soil (W) showed higher growth. The maximum P adsorption capacity decreased as a function of the addition of BC. We conclude that the application of BC reduced P sorption, while the application of either OC or BC altered the chemical properties of the soil and caused contrasting effects on P dynamics in Fe mining soil, and these treatments also affected plant growth

Biochar and conventional compost reduce hysteresis and increase phosphorus desorbability in iron mining waste

Phosphorus (P) fixation in the soil reduces the utilization of this element by plants and can be one of the main problems for fertilization management in soils containing Fe oxides. As a strategy to minimize the effects of P retention, organic materials, such as biochar or commercial composts, may be useful tools to maintain P availability and delay immobilization of this element in the soil, thereby benefiting, for example, the rehabilitation of areas impacted by Fe mining. The objective of this study was to evaluate the kinetics of P sorption and desorption and the hysteresis index in red mining waste from Fe mining subjected to açaí biochar and commercial compost amendments. Therefore, a substrate collected from Fe mining waste piles in the Carajás Mineral Province was incubated for 30 days with açaí biochar, commercial compost, and açaí biochar + commercial compost at a ratio of 90 % mining waste and 10 % organic amendment (w/w). The P sorption and desorption kinetics were evaluated in a solution containing 10 mg L -1 P at times from 0.5 to 48 h; the data were modeled according to a pseudo-first-order equation considering two types of reaction sites, and the hysteresis index was obtained by the difference between the sorption and desorption isotherms. Treatment of the mining substrate with açaí biochar reduced P sorption, while P desorption was increased by up to 60 % by applying biochar and/or commercial compost. Açaí biochar also reduced the hysteresis of P sorption from 78 to 54.8 %, in addition to slowing P fixation in this substrate. Thus, this study showed that açaí biochar and commercial compost may maximize the benefits of phosphate fertilization during the rehabilitation of areas impacted by Fe mining. However, as these composts can cause different effects on P dynamics in mining waste, their effects on other elements, such as micronutrients, whose availability may be affected, are important to be evaluated