Root volume and dry matter of peanut plants as a function of soil bulk density and soil water stress

Soil compaction may be defined as the pressing of soil to make it denser. Soil compaction makes the soil denser, decreases permeability of gas and water exchange as well as alterations in thermal relations, and increases mechanical strength of the soil. Compacted soil can restrict normal root development. Simulations of the root restricting layers in a greenhouse are necessary to develop a mechanism to alleviate soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. This experiment aimed to assess peanut (Arachis hypogea) root volume and root dry matter as a function of bulk density and water stress. Three levels of soil density (1.2, 1.4, and 1.6g cm-3), and two levels of the soil water content (70 and 90% of field capacity) were used. Treatments were arranged as completely randomized design, with four replications in a 3×2 factorial scheme. The result showed that peanut yield generally responded favorably to subsurface compaction in the presence of high mechanical impedance. This clearly indicates the ability of this root to penetrate the hardpan with less stress. Root volume was not affected by increase in soil bulk density and this mechanical impedance increased root volume when roots penetrated the barrier with less energy. Root growth below the compacted layer (hardpan), was impaired by the imposed barrier. This stress made it impossible for roots to grow well even in the presence of optimum soil water content. Generally soil water content of 70% field capacity (P<0.0001) enhanced greater root proliferation. Nonetheless, soil water content of 90% field capacity in some occasions proved better for root growth. Some of the discrepancies observed were that mechanical impedance is not a good indicator for measuring root growth restriction in greenhouse. Future research can be done using more levels of water to determine the lowest soil water level, which can inhibit plant growth.

Efeitos da luminosidade no crescimento de mudas de Caesalpinia ferrea Mart. ex Tul. (Leguminosae, Caesalpinoideae)

Caesalpinia ferrea is a species used a lot as a medicinal plant, for urban arborization and landscape design in the state of Amapa. Yet there is not much ecophysiological information available on it. Light is an important environment factor that controls processes associates with the accumulation of dry matter, contributing thus for plant growth. The object of this research was to study the effect of different luminosity levels on the growth of seedlings of this species. The seedlings were transplanted to plastics bags containing a mixture of soil and sand (2:1), which were maintained in the full sun, under artificial shade with reduction of 50% and 70% of the luminosity and under natural shade of a closed canopy of forest. The experimental design was completely randomized with five replicates. Seedlings submitted to natural shade showed strong growth inhibition. In the full sun, the seedlings presented higher net assimilatory rate (NAR), lower shoot/root ratio (SRR) and lower leaf area ratio (LAR). The results showed little difference in the growth and biomass allocation between seedlings kept in 50 and 70% shade; the seedlings submitted to this treatment presented higher values of SRR and LAR. This indicates plasticity which influences a possible increase in light capture and is important, therefore, to keep the seedling growth and survival under low light levels. The results as a whole showed morphological and physiological adjustment to different light levels in Caesalpinia ferrea.

Efeito de níveis de fósforo no crescimento inicial, biomassa e atividade in vivo da fosfatase ácida em Lychnophora ericoides Mart

The effect of phosphorus levels on seedling growth, dry and fresh matter production, and in vivo acid phosphatase activity was studied in Lychnophora ericoides cultivated during 130 days after transplanting in a greenhouse. Experimental design was completely randomized, with four P 2O 5 levels (0; 40; 80; 160 mg dm -3 as triple superphosphate) and five replicates of four plants each. The used soil was dystrophic acid dark red latosol. Lychnophora ericoides is responsive to phosphate fertilization with modification in daily relative growth rate, dry matter production and distribution among the plant parts. Acid phosphatase activity had significant and negative correlation with total, leaf and stem dry matter production, as well as with P levels accumulated in the leaf tissue. On the other hand, acid phosphatase activity had significant and positive correlation with root/shoot ratio.

Influence of storage on chemical properties of different peats

The change of chemical properties during storage of 12 fertilized bagged peats of different origins at high temperature was investigated. The average values for N, soluble salts and EC decreased significantly, whereas the pH as well as P and K contents changed only slightly. Differences in N were observed between the peats. The contents of CAT soluble N in the two dredged frozen black peats did not change during storage. However, a decrease in N was found when water extraction was used. In the case of the 10 white peats the loss of N differed considerably, but it was independent of the method of peat harvest. The N decrease resulted mainly from reduced levels of NO3-N. Substances damaging to plant growth do not seem to have developed during storage as shown by trials on the germination and the growth of Chinese cabbage. There were no significant differences between the peats, whether stored or not.

Uso do regulador de crescimento etil-trinexapac em arroz de terras altas

This work was developed with the objective of evaluating the use of trinexapac-ethyl doses (0, 75, 150, 225 and 300 g of the a.i. ha -1) and application times (active tillering, between active tillering and floral differentiation and at floral differentiation) in upland rice crop development and yield. The experiment was carried out in Selvíria-MS, during the agricultural year of 2006/07. Application of 150 g ha -1 of trinexapac-ethyl in Primavera rice cultivar at panicle initiation differentiation reduces plants height, 0.40 m on average comparing to other times, with lodging absence. Trinexapac-ethyl promotes lange number of abnormal grains, reduction of grain yields in doses above 150 g ha -1, when applied in panicle initiation differentiation stadium. Application of 150 g ha -1 of trinexapac-ethyl at any time does not interfere in crop yield.

Fig tree orchard formation using organic fertilization

The present work aimed at evaluating the effects of cattle manure fertilization on the growth and yield of fig trees. The cultivar 'Roxo de Valinhos' was used. One-, two-, three-and four-year-old trees were treated with cattle manure containing 0, 25, 50, 75, 100, 125 and 150% of the recommended nitrogen level per plant. The experiment was carried out using randomized blocks with 7 treatments, 5 replicates and 5 plants per experimental plot. The evaluated characteristics were: plant height, stem diameter, secondary branch length and diameter, yield per plant (kg plant-1), besides some quality characteristics of fruits such as pH, titratable acidity, soluble solids and texture. Manure application enhanced plant growth and fruit production. Significant differences were observed only for soluble solids content, pH and texture, which varied according to the crop cycle. After four crop cycles (2002/03, 2003/04, 2004/05 and 2005/06), the best results (about 5.0 kg of fruits per plant) were obtained with 100% of the recommended nitrogen dose, which corresponded to 14.3 kg of cattle manure per plant, in the last crop cycle (2005/2006).

Doses de Nitrogênio na Produção de rabanete fertirrigado e determinação de clorofila por medidor portátil nas folhas

The relative chlorophyll determination is used to predict the need for nitrogen fertilization aiming to increase production in various cultures. The objective of this study was to evaluate the soil nitrogen dose response added to the soil via fertigation in radish production and the relation between chlorophyll and cultivar Redondo Vermelho leaf nitrogen content. Transverse diameter of root, leaf area, green index, leaf N contents, shoots (stem) production, number of commercial and noncommercial roots, and the total commercial mass roots were evaluated. The N doses didn't interfere in the radish production and the readings taken with portable chlorophyll meter are not very accurate in ascertaining the level of N on radish plant growth.

Mango flower induction in the brazilian northeast Semi-arid with gibberellin synthesis inhibitors

Mangoes in the Brazilian semi-arid stands out in the national scenario due to high yields and fruit quality, and also to the possibility of all-year production taking advantage of the climatic conditions as well as management technique (irrigation, pruning and growth regulators application) for plant growth and blossom control. Paclobutrazol soil drench applied is normally used for production management of mangoes. This research deals with the evaluation of the effect of foliar applied growth regulators to mango, cultivar 'Kent', as regard to their efficiency for blossom management, in order to allow off season mango production. Three growth regulators (prohexadione-Ca, trinexapac-ethyl and chlormequat chloride) were foliar applied, at two dosages and compared to paclobutrazol applied as soil-drench. In order to compare the effects of the treatment, data were recorded related to panicle emission (percentage and length), period of time until blossom and production, yield (number and plant weight) and post-harvest quality of the fruit (total soluble solids, titratable acidity, pH, firmness, flesh and skin color and appearance). The results showed that prohexadione-Ca and chlormequat chloride induced a 15-day early harvest, while paclobutrazol, alone or combined with prohexadione-Ca, allow to harvest 25 days in advance, when compared to trinexapac-ethyl and control trees. Growth regulators foliar applied and paclobutrazol applied as soil-drench delayed mangoes fruit ripening in post-harvest.

Uniconazole on mango floral induction cultivar 'Kent' at submedio são francisco region, Brazil

In order to provide efficient crop management which enables the scaling of the production of mango in semi-arid conditions and achieve a greater precision in the recommendation, evaluating the effect and the influence of uniconazole foliar spray, on the emission of vegetative flushes in the cultivar 'Kent', field tests were carried out in a productive orchard. Treatments tested were three uniconazole dosages, 500, 1,000 and 1,500 mg L-1, with one, two or three respective foliar sprayings. Another treatment with paclobutrazol was used at 2.0 g a.i./m of canopy diameter, with a single application via soil and a control (without spraying of plant growth regulators), where spreader-sticker was added and the pH was adjusted. With 30, 60 and 90 days after the first spraying of the flowering inducer the growth of branches were evaluated, as well as the percentage of flowering in all treatments after 120 days of first spraying. The sprayings started in the orchard after the emission of the second vegetative flush after pruning of production, through airassisted sprayer with flow rate of 1,000 L ha-1. The experimental design was done through randomized blocks with four replications, using three plants per plot. It was observed that paclobutrazol was significantly highlighted in relation to other treatments and that the uniconazole with one, two and three foliar sprayings presented inhibition of the vegetative growth in mango 'Kent' and showed, even at low proportions, signs of flowering.

Efeito da densidade de semeadura e de reguladores vegetais sobre os caracteres morfofisiológicos da folha bandeira do trigo

The objective of this work was to study the morphological and physiological characteristics of the wheat flag leaf as affected by increasing sowing densities and plant growth regulators application. The experimental design was a split-plot with completely randomized blocks and four replications. Plots were consisted by four sowing densities (30, 50 70 and 90 plants m-1) and the split-plots by plant growth regulators: a product composed by auxin+gebberellin+cytokinin (Ax+GA+CK), Trinexapac-Ethyl e (Ax+GA+CK) + Trinexapac-Ethyl, and a control without application. Dry mass accumulation, plant height, morphological characteristics, SPAD index, nitrogen and photosynthetic pigments contents in the flag leaf were determined. The increase in the sowing density resulted in lower dry mass accumulation and SPAD index of the flag leaves. Trinexapac-Ethyl caused increase in the SPAD index, but the chlorophyll content of the flag leaf was reduced. The SPAD index values were more correlated with the nitrogen than the chlorophyll contents. Ax+GA+CK did not affect flag leaf characteristics in wheat plants.

Doses de potássio em cobertura na cultura da abóbora

Although there are recommendations for the fertilization of commercial squash crops, studies which connect the effect of topdressing potassium fertilization and yield are still rare. Thus, this study aimed at evaluating topdressing potassium doses on squash (Mirian hybrid) yield, in an experimental farm of the Universidade Estadual Paulista Júlio de Mesquita Filho, in São Manuel, São Paulo State, Brazil. The experimental design was randomized blocks, with five treatments (0.0 kg ha-1, 50.0 kg ha-1, 100.0 kg ha-1, 200.0 kg ha-1 and 400.0 kg ha-1 of K2O) and six replications. Plant growth parameters, yield and fruit quality were evaluated. After harvesting, plant (leaves + stem) and soil macronutrients were submitted to chemical analysis and data to variance and regression analysis. It was concluded that the highest yield resulted from the topdressing dose of 199.0 kg ha-1 of K2O. A reduction in calcium and magnesium contents in the plant canopy and a higher K+ content in the soil were observed for increasing K2O levels.

Fertilizing lychee plants with phosphorus at time of planting in Brazil

The objective of this research was to study the effects of P fertilizers applied at time of planting on lychees' nutritional status and on plant growth. The treatments consisted of five doses of P: zero, 50, 100, 200, and 300 g of P2O5 per plant, furnished by triple superphosphate. Plant diameter was evaluated during two years and the plants' nutritional status on the second year. The second year foliar levels of macro and micronutrients (with the exception of Zn) were increased by the P fertilizer. The orchard's initial development, especially during the second year, was also influenced by the fertilizer. The P doses of 164 and 158 g of P2O5 per plant resulted in the largest plant diameter after the first and the second year, respectively. These doses were found to be associated with a foliar P level of <1.4 g kg-1. © 2012 Renato de Mello Prado et al.

AMMONIUM AND NITRATE IN SOIL AND RATOON SUGARCANE GROWN IN FUNCTION OF NITROGEN ON OXISOL

After harvest, sugarcane residues left on the soil surface can alter nitrogen (N) dynamics in the plant-soil system. In Oxisols, the nitrogen fertilizer applied had its effects on the levels of ammonium and nitrate in the soil, N concentration in the plant leaves, and on the growth and productivity of second ratoon plants. The N rates tested were of 0, 60, 120, 180, and 240 kg ha-1. Each treatment was replicated four times. Four months after the experiment was started, ammonium and nitrate concentration in the soil, N levels in plant leaves, and plant growth were evaluated. Productivity was evaluated 11 months after the experiment was set. By increasing the content of mineral N in soil, plant growth variables reflected differences in the production of stems; however, it did not affect foliar N. The use of leaf analysis was not important to assess the nutritional status of nitrogen in the ratoon sugarcane. Nitrogen concentration in soil was affected by nitrogen fertilization, but not the N content in leaves. The rate of 138 kg N ha-1enabled greater production of sugarcane stalks (140 t ha-1). © 2013 Copyright Taylor and Francis Group, LLC.

Acúmulo de biomassa em variedades de cana-de-açúcar inoculadas com diferentes estirpes de bactérias diazotróficas

The objective of this study was to evaluate the contribution of inoculation with diazotrophs, applied both individually and in combination, in commercial varieties of sugarcane. The experiment was carried out at the experimental grounds of Embrapa Agrobiologia, in Seropédica, Rio de Janeiro, Brazil. The experimental design was of randomised blocks, with sub-divided plots and six replications. Six varieties of sugarcane with six treatments were used: control, control with nitrogen, inoculation of the individual strains: BR 11512, BR 11724 and BR 11411, in addition to inoculation with a cocktail consisting of five strains of diazotrophs. Differences were observed between varieties and between treatments, and an interaction observed between the treatments and varieties. For all the parameters evaluated, no response was observed in the sugarcane varieties RB855536 and RB92606. In the variety RB918639, the only difference was in the accumulation of green biomass. No difference was observed between the treatments for total nitrogen accumulation. The most responsive variety to inoculation was RB867515, differing in the accumulation of fresh and dry biomass. This study showed that inoculation promotes the accumulation of biomass, the contribution being different for the varieties and strains of bacteria, suggesting an interaction between the factors studied. The variety RB867515 is promising for use in studies of inoculation with diazotrophs.

Improvement of grapevine iron nutrition by a bovine blood-derived compound

Iron (Fe) is essential for chlorophyll formation and plant growth. Irondeficiency chlorosis is a major nutritional disorder in several fruit trees cultivated in calcareous and alkaline soils, reducing fruit yield and quality and causing heavy economic losses. Since chelated Fe, the most widespread fertilizers used for preventing or curing Fe deficiency, pose risks of environmental pollution, the development of sustainable agronomic alternatives represents a priority for the fruit industry. In this work, we investigated the effectiveness of a bovine blood-derived product (BB; 0,125% Fe) for preventing Fe-deficiency in grapevine plants. During the vegetative season 2011 potted plants of five graft combinations: Sangiovese/S4O, Cabernet Sauvignon/S4O and Cabernet Sauvignon/140 Ruggeri, 140 Ruggeri/Cabernet Sauvignon, Vitis riparia/Cabernet Sauvignon were grown on calcareous soil. Soil treatments included: 1) Control; 2) Fe-EDDHA (Fe 6%); 3) Bovine-Blood (5 g/L); 4) Bovine-Blood (20 g/L). With the exception of Cabernet Sauvignon/S4O plants, Fe-EDDHA increased SPAD units (leaf chlorophyll content). Bovine-blood at low concentrations had similar or higher SPAD units than Fe-EDDHA. Increasing concentration resulted in further increases in SPAD units only in some graft combinations. Data highlight the efficiency of Fe blood-compound in the prevention of grapevine Fe-deficiency over one growing season.