Leonardo Angelo de Aquino

Elaboração e validação de escala diagramática para quantificação da mancha de ramularia do algodoeiro

This study aimed to elaborate and validate a diagrammatic scale to assess areolate mildew on cotton leaves. The proposed scale showed disease levels of 0.05, 0.50, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0 and 67.20%. The scale showed to be adequate to evaluate areolate mildew due to an increase in accuracy, precision, and reproductibility during disease evaluations.

Produtividade, qualidade e estado nutricional da beterraba de mesa em função de doses de nitrogênio

Nitrogen is a fundamental element for the yield and quality of vegetables, but there is little information about its application to table beet crop. This work aimed to evaluate the yield, quality and nutritional status of N of the table beet as affected by the rate of N. Four rates of nitrogen were applied (0; 100; 200 and 400 kg ha-1 N) in a randomized block design with four replicates. 28 days after the transplant (dat), the nutritional N status was evaluated through the leaves content of NO-3-N and chlorophyll by the SPAD meter. At harvest (56 dat), the traits evaluated were: leaf area, yield of fresh (FW) and dry weight (DW) of storage roots and leaves contents of NO-3-N and total-N at the leaves, and storage roots and °Brix in the storage roots. With the increase of the doses of N, all the selected characteristics were increased. The NO-3-N and SPAD units at the 28 dat (95% of the maximum yield) were 2,575 mg kg-1 of DW and 44.7, respectively. Considering the quantitative and economic aspects of the yield of storage roots, the rate of 343 kg ha-1 N was the maximum economical efficiency rate. If considering the quantitative and qualitative aspects together, the 193 kg ha-1 of N was the recommended rate.

Estimativa da área foliar do girassol por método não destrutivo

Simple, rapid, and non-destructive methods that help to estimate leaf area accurately are very important to assess plant growth under field conditions. The objective of this study was to adjust equations to estimate the area of a single sunflower leaf and also the area of total leaves per plant as a function of linear measurements of them. It was also verified the possibility of using common models for the sunflower cultivars BR-122 and M-734. Six plants of each cultivar in the early stage of flowering and full flowering were harvested. The area of each leaf was determined by the direct method. The length along the midrib and the width perpendicular to leaf insertion in the petiole were determined. Linear, quadratic, cubic, exponential, and potential models were adjusted. The potential models Ŷi = 1.6329Xi1,7164 and Ŷi = 0.5405Xi1,0212 using the width measurements and width x length, respectively, were the most adequate to estimate the leaf area. The model Ŷi = 5.1014Xi2,4383 allowed to precisely estimate the total leaf area according to the number of leaves per plant. The accuracy of the adjusted equations to estimate each leaf are and total leaves area was not reduced when common models were adjusted to the two cultivars used.

Características agronômicas e o estado nutricional de cultivares de girassol irrigado

This work aimed to assess nutritional status, agronomic characteristics, and productivity of sunflower cultivars under irrigation. Embrapa 122 V-2000, Helio 250, Helio 251, Helio 253, Helio 358, Helio 360, IAC Iarama, and Dow Agroscience M 734 and MG 02 cultivars were sown in randomized block design with four replications. The number of leaves per plant in full bloom was higher in hybrid Helio 250, Helio 251, Helio 253, Helio 358, Helio 360 and Dow Agroscience MG 734 and M 02 related to open-pollinated cultivars Embrapa 122 V-2000 and IAC Iarama. Foliar contents of N, P, K, Ca, Mg, and S were 40.91, 3.51, 35.91, 33.91, 6.23, and 7.88 g kg-1, respectively. Embrapa 122 V-2000 and IAC-Iarama cultivars showed an average content of P in the index leaf lower than the other cultivars. Foliar contents of Zn, Cu, Fe, and Mn were 75.15, 24.11, 98.39, and 348.10 mg kg-1, respectively. Mean content of B in index leaf of hybrid and open-pollinated varieties was 119.25 and 140.35 mg kg-1, respectively. Helio 250, Helio 251, Helio 253, Helio 358, Helio 360, and Dow Agroscience M 734 and MG 02 cultivars had higher productivity than Embrapa 122 V-2000 and IAC Iarama.

Is abscisic acid involved in the drought responses of Brazilian Green Dwarf coconut

SUMMARYAbscisic acid (ABA) accumulation in leaves of drought-stressed coconut palms and its involvement withstomatal regulation of gas exchange during and after stress were investigated. Two Brazilian GreenDwarf coconut ecotypes from hot/humid and hot/dry environments were submitted to three consecutivedrying/recovery cycles under greenhouse conditions. ABA accumulated in leaflets before significantchanges in pre-dawn leaflet water potential ( PD ) and did not recover completely in the two ecotypesafter 8 days of rewatering. Stomatal conductance was influenced by ABA under mild drought and by PD under severe drought. There were no significant differences between the ecotypes for most variablesmeasured. However, the ecotype from a hot/dry environment showed higher water use efficiency afterrepeated cycles of water stress. INTRODUCTION Water availability is the environmental factor that most strongly affects plant growthand yield worldwide (Nemani et al. , 2003). Increased irrigation inputs are not a viableoption because water resources are either scarce or too expensive. Plants can sensewateravailabilityaroundtherootsandrespondbysendingchemicalsignalstotheshootto elicit several adaptive responses, such as decrease in leaf expansion and stomatalclosure (Wilkinson and Davies, 2002). Abscisic acid (ABA) has been suggested as amajor signalling molecule in the response of plants to drought stress. As the soil dries,ABA is produced at the root tips and transported via the transpiration stream to theleaf where it reduces stomatal conductance. It is well known that these responses canoccur without any change in shoot water relations (Wilkinson and Davies, 2002).The area cultivated with dwarf coconut palm (

Aplicação do fósforo e da irrigação na absorção e exportação de nutrientes pelo algodoeiro

This work aimed to evaluate the effect of phosphorus application in rainfed and irrigated crop on shoot dry matter, the absorption and nutrient exportation, and yield of cotton crop. The experiment was carried out in a Psament in the northeren part of Minas Gerais State, Brazil. The experimental design was in randomized blocks with four replications in a factorial arrangement of two doses of P2O5 x two cropping systems. Two additional treatments in each system without phosphorus application completed six studied treatments. Accumulation of dry biomass, absorption and exportation of nutrients, and yield of seed cotton were evaluated. Phosphorus levels did not influence the accumulation of shoot dry biomass. P supply increased the exportation of P, Ca, Mg, S, and Mn under irrigated and of N, K, and Fe regardless of the cropping system. Irrigation increased the dry biomass of leaves, stems, and shoots at 80 days after emergency, and the absorption of N, P, K, Ca, Mg, S, Cu, Fe, Mn, Zn, and B, as well as their exportation by the crop. There was an increase in the number of bolls per plant, fiber yield and productivity through the irrigation use. Increasing productivity with P application was conditioned to irrigation.

Influence of Boron on Sunflower Yield and Nutritional Status

ABSTRACT Sunflower has been mentioned in the literature as a plant that requires large amounts of boron (B) to achieve a successful crop. This study aimed at evaluating the influence of sunflower fertilization with boron on the soil nutrient concentration, index leaf, seed yield, fatty acids’ composition of sunflower oil, and oil content. Cultivar M734 was selected for boron fertilization at 0, 3, 6, 9, and 12 kg ha−1 rates. The maximum economic return was obtained with 3.13 kg ha−1. Neither oil content nor fatty acid composition was affected by boron. With proper irrigation, the M734 cultivar was able to absorb boron in the 0 − 40-cm layer, ultimately producing about 3000 kg ha−1 of seeds in soils with only 0.30 mg kg−1 of boron. Based on these results, it is suggested that the boron fertilization program be expanded to include the soil strata at 0−20 cm and 20−40 cm.

Parcelamento do fertilizante fosfatado no algodoeiro em sistema de cultivo irrigado e de sequeiro

The objective was to evaluate the application of phosphorus doses in parcels in the cotton crop in the systems of cultivation under irrigation and rainfed, being aimed the higher efficiency of phosphate fertilization, in comparison to the traditional application, only at sowing. The experiment was carried out in Quartzanic Neossoil, in the North region of Minas Gerais. The adopted design was randomized blocks, with three replicates. The treatments were the doses of 50 and 120 kg ha-1 of P2O5 applied in four ways: PS, P1, P2 and P3 [100/0; 75/25; 50/50; 25/75% of the dose of phosphate fertilizer applied, respectively at the sowing and at 35 days after the emergence (DAE)], in the irrigated and rainfed crops. Two additional treatments, without P, in the crop without and with irrigation, completed the eighteen studied treatments. The increase of the P doses increased the dry mass of aerial part and the number of reproductive structures at 80 DAE, the relative efficiency of the phosphate fertilization and the productivity of cotton in bull. The response to P doses occurred only under irrigation. The parceled application of the phosphate fertilizer did not increase the efficiency of the fertilization in the cotton farm in Quartzanic Neossoil.

Foliar Diagnosis Indexes for Corn by the Methods Diagnosis and Recommendation Integrated System (DRIS) and Nutritional Composition (CND)

ABSTRACT Foliar analysis has been an important method for diagnosing the nutritional status of plants. Therefore, this work aimed to determine benchmarks (norms) for interpretation of results of foliar analysis by the methods of Diagnosis and Recommendation Integrated System (DRIS) and Nutritional Composition (CND) and to determine the order of nutritional limitation and the potential response to fertilization (PRA) of corn cultivations. Leaves were sampled and the productivity was determined in 64 different sites in the crop season 2011/2012, and 66 sites were sampled in the crop season 2012/2013. The yields were divided in two sub-populations: high productivity (equal or above 11.795 kg ha−1) and low productivity (less than 11.795 kg ha−1). The normal ranges obtained by DRIS and CND methods were similar. The amplitudes of ideal ranges were smaller when compared to the sufficiency ranges found in the Brazilian literature. The development of benchmarks (norms) at regional levels increases reliability in diagnoses.

Parcelamento de fósforo em algodoeiro irrigado

Most regions where cotton is cultivated in Brazil present low soil fertility, especially concerning the available phosphorus (P). This study aimed to evaluate the phosphorus split application on irrigated cotton, for reaching a higher phosphate fertilization efficiency, in comparison to the traditional application at sowing. The experiment was conducted in Quartzarenic Neosol with 22 mg dm -3 of P (medium availability), in the north region of the Minas Gerais State, Brazil. The design used was randomized blocks, in a (4x3) + 3 factorial scheme, with three replications. Treatments consisted of P 2 O 5 doses (0 kg ha -1 , 30 kg ha -1 , 60 kg ha -1 , 120 kg ha -1 , and 180 kg ha -1 ) and three split applications (80% and 20%; 60% and 40%; 40% and 60% of the P dose applied respectively at sowing and at 35 days after emergence (DAE)), plus the application of 0 kg ha -1 , 60 kg ha -1 , and 120 kg ha -1 of P 2 O 5 at sowing. The P source was the granulated triple superphosphate, and the P content in the shoots increased according to the doses applied. Nutrient contents in the index leaf, except for P, were not influenced by P levels and split applications. The P content in the index leaf and the number of cotton bolls per plant increased with the increment of P doses, but were not affected by the phosphate fertilizer split application. The application of 40% of the P dose at sowing and the remaining amount split at 35 DAE decreased the cotton boll yield, with no significant effect for the other split applications.