Use of Satellite Imagery to Predict Corn Phenology at a Regional Scale

Existing methods to report phenology are expensive, labor-intensive, time-consuming, and often not very accurate, especially at some specific crop growth stages. The objec­tive of this study was to develop large-scale phenology models via utilization of satellite imagery data and machine learning techniques for the southwest (SW) agricultural crop reporting district of Kansas. Different satellite images collected from Landsat were utilized as the main input to obtain different vegetation indices (normalized difference vegetation index, NDVI; enhanced vegetation index, EVI; green chlorophyll vegeta­tion index, GCVI; normalized difference water index, NDWI; and global vegetation moisture index, CVMI). Vapor Pressure Deficit (VPD), temperature, precipitation, and growing degree units (GDU) were evaluated for improving phenology prediction models. A large set of ground truth data with information about day of the year, crop phenology, and field location was provided by Crop Quest Inc. (Dodge City, KS) from 2014–2018 and utilized to train two different statistical models (Random Forest and Support Vector Machine) to catalog corn fields, and build a phenology evolution model for this crop

Establishment of potassium reference values using Bayesian models in grapevines

Critical levels (CL) of available potassium (K) in soils and leaves and maximum technical efficiency (MTE) doses are relevant information to define the best K fertilization strategies. The aim of this study was to determine reference values of K in leaves and soil, using Bayesian analysis, in order to maximize grape yield and must quality of ‘Chardonnay’ and ‘Pinot Noir’ grown in a subtropical climate. The vines were subjected to applications of 0, 20, 40, 60 and 80 kg K2O ha−1 year−1. The CL and MTE doses of K, in leaves and soils, were determined using Bayesian hierarchical models. The range of probability of the occurrence of CL in leaves was 15.8 to 18.9 g K kg−1 in ‘Chardonnay’ and 16.8 to 19.1 g K kg−1 in ‘Pinot Noir’ at flowering. Moreover, the range was 15.3 to 18.1 g K kg−1 in ‘Chardonnay’ and 16.1 to 18.2 g K kg−1 in ‘Pinot Noir’ at veraison. In the soil, the CL of available K for ‘Chardonnay’ was 27.4 mg K kg−1 and for ‘Pinot Noir’ it was 23.2 mg K kg−1. The increase of K in leaves and soil increased the TSS, while the TTA decreased in both cultivars after sufficiency rate. The MTE was estimated in ‘Pinot Noir’. The proposition of CL and/or MTE doses of K can help increase the efficiency of K fertilization in vineyards

Winter Wheat Yield Response to Plant Density as a Function of Yield Environment and Tillering Potential: A Review and Field Studies

Wheat (Triticum aestivum L.) grain yield response to plant density is inconsistent, and the mechanisms driving this response are unclear. A better understanding of the factors governing this relationship could improve plant density recommendations according to specific environmental and genetics characteristics. Therefore, the aims of this paper were to: i) execute a synthesis-analysis of existing literature related to yield-plant density relationship to provide an indication of the need for different agronomic optimum plant density (AOPD) in different yield environments (YEs), and ii) explore a data set of field research studies conducted in Kansas (USA) on yield response to plant density to determine the AOPD at different YEs, evaluate the effect of tillering potential (TP) on the AOPD, and explain changes in AOPD via variations in wheat yield components. Major findings of this study are: i) the synthesis-analysis portrayed new insights of differences in AOPD at varying YEs, reducing the AOPD as the attainable yield increases (with AOPD moving from 397 pl m-2 for the low YE to 191 pl m-2 for the high YE); ii) the field dataset confirmed the trend observed in the synthesis-analysis but expanded on the physiological mechanisms underpinning the yield response to plant density for wheat, mainly highlighting the following points: a) high TP reduces the AOPD mainly in high and low YEs, b) at canopy-scale, both final number of heads and kernels per square meter were the main factors improving yield response to plant density under high TP, c) under varying YEs, at per-plant-scale, a compensation between heads per plant and kernels per head was the main factor contributing to yield with different TP.Fil: Bastos, Leonardo M.. Kansas State University; Estados UnidosFil: Carciochi, Walter Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Kansas State University; Estados UnidosFil: Lollato, Romulo P.. Kansas State University; Estados UnidosFil: Jaenisch, Brent R.. Kansas State University; Estados UnidosFil: Rezende, Caio R.. Kansas State University; Estados UnidosFil: Schwalbert, Rai. Kansas State University; Estados UnidosFil: Vara Prasad, P.V.. Kansas State University; Estados UnidosFil: Zhang, Guorong. Kansas State University; Estados UnidosFil: Fritz, Allan K.. Kansas State University; Estados UnidosFil: Foster, Chris. John Deer; Estados UnidosFil: Wright, Yancy. John Deer; Estados UnidosFil: Young, Steven. John Deer; Estados UnidosFil: Bradley, Pauley. John Deer; Estados UnidosFil: Ciampitti, Ignacio Antonio. Kansas State University; Estados Unido

Kinetic parameters govern of the uptake of nitrogen forms in "Paulsen" and "Magnolia" grapevine rootstocks.

Grapevine rootstocks are selected according to graft compatibility, pathogen tolerance and water stress. However, morphological and kinetic parameters of nutrient absorption, such as nitrate (NO3 −) and ammonium (NH4 +), usually are not considered. The study aimed to select, based on morphological and kinetic absorption parameters, grapevine rootstocks with greater efficiency of N-forms absorption. The study was performed with two grapevine rootstocks (?Paulsen 1103? and ?Magnolia?), grown in Hoagland nutrient solution in a greenhouse. After 21 d, they were placed in 0.05 mol L-1 CaSO4 solution for 20 d to exhaust nutrient internal reserves. The rootstock with highest NO3 − and NH4 + uptake efficiency was ?Paulsen 1103?, since it presented lower Cmin and Km values in the two N forms, allowing N extraction by roots, even in low concentrations in solution, due to the higher transporter affinity for NO3 − and NH4 + in roots from rootstock. ?Paulsen 1103? rootstock also presented better photosynthetic performance and root development, collaborating for greater growth and mass production than 'Magnolia' rootstock. On the other hand, ?Magnolia? rootstock showed higher NO3 − and NH4 + Cmin and Km values than ?Paulsen? rootstock, which shows lower transporters affinity for these ions. Results demonstrate the importance of the use of NO3 − and NH4 + uptake kinetic parameters in grapevine rootstock selection programs, since these may serve as indicator of plant's ability to absorb NO3 − and NH4 + in low concentrations

Forecasting maize yield at field scale based on high-resolution satellite imagery

Estimating maize (Zea mays L.) yields at the field level is of great interest to farmers, service dealers, and policy-makers. The main objectives of this study were to: i) provide guidelines on data selection for building yield forecasting models using Sentinel-2 imagery; ii) compare different statistical techniques and vegetation indices (VIs) during model building; and iii) perform spatial and temporal validation to see if empirical models could be applied to other regions or when models' coefficients should be updated. Data analysis was divided into four steps: i) data acquisition and preparation; ii) selection of training data; iii) building of forecasting models; and iv) spatial and temporal validation. Analysis was performed using yield data collected from 19 maize fields located in Brazil (2016 and 2017) and in the United States (2016), and normalized vegetation indices (NDVI, green NDVI and red edge NDVI) derived from Sentinel-2. Main outcomes from this study were: i) data selection impacted yield forecast model and fields with narrow yield variability and/or with skewed data distribution should be avoided; ii) models considering spatial correlation of residuals outperformed Ordinary least squares (OLS) regression; iii) red edge NDVI was most frequently retained into the model compared with the other VIs; and iv) model prediction power was more sensitive to yield data frequency distribution than to the geographical distance or years. Thus, this study provided guidelines to build more accurate maize yield forecasting models, but also established limitations for up-scaling, from farm-level to county, district, and state-scales.Publicado originalmente en: Rai A. Schwalbert, Telmo J.C. Amado, Luciana Nieto, Sebastian Varela, Geomar M. Corassa, Tiago A.N. Horbe, Charles W. Rice, Nahuel R. Peralta, Ignacio A. Ciampitti. Forecasting maize yield at field scale based on high-resolution satellite imagery. Biosystem Engineering. 171: 179–192 DOI: https://doi.org/10.1016/j.biosystemseng.2018.04.020Sociedad Argentina de Informática e Investigación Operativ

Nitrogen supply method affects growth, yield and must composition of young grape vines (Vitis vinifera L. cv Alicante Bouschet) in southern Brazil.

The aim of this study was to evaluate yield and chemical composition of the must in grapevines subjected to Nitrogen (N) supply methods in sandy soils. The vineyard cultivar was ?Alicante Bouschet? (Vitis vinifera L.) grafted on 1103 Paulsen rootstock, in southern Brazil. The treatments consisted of the application of 20+20 kg N ha−1 without irrigation (NWI), 20+20 kg N ha−1 followed by irrigation (NFI), 20+20 kg N ha−1 via fertigation (NF), 20 kg N ha−1 via fertigation (½NF), and a control (C) without N application. The study was conducted during four crop seasons. Leaves were collected at flowering and veraison to determination N concentration. Stem diameter, grape yield and its components were determined. In the must were evaluated the total soluble solids (TSS), pH, total titratable acidity (TTA) and total anthocyanins (TA). The concentration of nitrate and ammonium in soil solution was determined. N application followed by irrigation or N supplied via fertigation provided to the vines larger stem diameters and leaf N concentrations, in most crop seasons. Grapevines submitted to N application via fertigation or followed by irrigation presented higher yields than conventional application without irrigation, and between two and three times higher than the control. N supply methods little affected total soluble solids contents. The application of N to the soil, regardless of the N supply method, decreased the anthocyanin concentration in the grape must, due to the dilution effect on the pulp/skin ratio, promoted by the yield increase

Chemical properties and protective effect of Rosmarinus officinalis: mitigation of lipid peroxidation and DNA-damage from arsenic exposure

Recent studies have implicated dietary factors in the cause and prevention of important diseases, with strong evidence that plant’s compounds can protect against these diseases. Moreover, food security and environmental contamination are topics in focus at the moment. In this view, contamination by arsenic (As) has received much attention as well as some spices with medicinal properties. Among these plants, the use of Rosmarinus officinalis L. has demonstrated antioxidant properties besides being used for circulatory disorders. Therefore, we measured the mitotic index of Allium cepa L. and characterized the antioxidant effects to determine the capacity of R. officinalis to ameliorate arsenic-induced DNA damage. R. officinalis extract showed no mutagenic effects and exhibited antimutagenic potential, reducing the DNA damage, anaphase-telophase briges and micronuclei chromosome aberrations that result from treatment with the arsenic. Additionally, reduction in arsenic- induced lipid peroxidation was also observed

Photosynthetic activity and grape yield of 'Alicante Bouschet' (Vitis vinifera L.) grapevines submitted to nitrogen supply methods and doses.

The great majority of sandy soils present low nitrogen availability, generally below vines physiological demand, and therefore nitrogen fertilizer application, such as urea, is necessary. However, when urea is applied on the soil surface, the vine can use only a small amount of N. Thus, management strategies such as fertigation can increase N utilization by vine, reflecting in a greater photosynthetic activity and grape yield. The objective of this study was to evaluate the influence of nitrogen supply methods and doses on photosynthetic activity and grape yield of 'Alicante Bouschet' grapevines cultivated in sandy soil. The experiment was carried out in Santana do Livramento, in the southern region of Brazil, in a vineyard planted in 2011. The cultivar was 'Alicante Bouschet' grafted on '1103 Paulsen'. The experimental design was of randomized blocks in a bifactorial arrangement (dose x method). The N source used was urea (45 % N). The 0, 20, 60 and 100 kg N·ha-1 doses were applied on the soil surface, without irrigation (NWI) and via fertigation (NF). Photosynthetic activity, N concentration in leaves and grape yield during two growing seasons were evaluated. The application of N doses in soil increased N concentration in grapevine leaves by up to 53 % in NF and 18 % in NWI methods but did not affect yield. Strong correlations between yield and water use efficiency were also observed, evidencing a certain synchronism between the physiological demand of the grapevine and the offer of the adequate N dose by a more efficient method

Calagem, adubação e estado nutricional em videiras.

A área cultivada com videira no Brasil e, especialmente, no Sul do país, como no Rio Grande do Sul (RS) e Santa Catarina (Se), tem aumentado nos últimos anos. Porém, na maioria dos casos os solos são ácidos e possuem baixa fertilidade natural. Por isso, torna- se necessário, quando diagnosticada a necessidade, a aplicação de corretivos da acidez do solo e adubações. Mas, estas práticas devem ser realizadas seguindo as recomendações técnicas oficiais recomendadas para a cultura da videira, pois normalmente afetam a produção e qualidade da uva, bem como do mosto e de seus subprodutos, como o vinho, sucos e espumantes. Considerando esta problemática, no presente capítulo serão apresentadas informações técnicas sobre calagem, adubações e composição nutricional de videiras. Além disso, serão apresentados resultados de pesquisa mais recentes sobre a dinâmica de nutrientes em solos de vinhedos, bem como o impacto de nutrientes sobre as características físicas e químicas do vinho, temática ainda pouco estudada no Brasil. Com todas as informações esperamos contribuir para um sistema de produção vitivinícola mais produtivo, com uvas e seus subprodutos com melhor qualidade requisitada pelo consumidor, mas com baixo potencial de risco ambienta I

Critical levels of nitrogen in leaves of grapevine grown on sandy soils in southern Brazil using Bayesian models

Sandy soils in southern Brazil have low levels of soil organic matter, and consequently, low nitrogen (N) availability to grapevines. Therefore, it is necessary to apply N fertilizers to achieve satisfactory yield. However, the N critical levels (CL) in leaves of grapevines grown in subtropical regions is not sufficiently known. The study aimed to determine the critical levels and sufficiency ranges (SR) of N in leaves for grapevine cultivars grown on sandy soils in southern Brazil using Bayesian models. Leaf data from different long-term calibration experiments in southern Brazil were used. The grapevine cultivars sampled were ‘Chardonnay’, ‘Pinot Noir’, ‘Cabernet Sauvignon’ and ‘Alicante Bouschet’, which were grafted onto 1103 Paulsen rootstock. About 600 observations of N concentration in leaves collected during flowering and veraison and the respective grape yield were used. The relative production was calculated from the highest yield obtained for each cultivar and each crop season and from that, the other proportions were established. The concentration of total soluble solids (TSS) and anthocyanins was evaluated at harvest. Linear regression with a plateau at the 95% percentile was implemented to quantify the relationship between N concentration in leaves and grape yield, TSS, and anthocyanins. The critical concentration of N in leaves was assumed to be the point at which the adjusted line reaches the plateau. The CL and SR of N in leaves collected during flowering and veraison for yield were 19.2, 18.8 to 19.5 g N kg-1 and 25.4, 24.3 to 27.2 g N g kg-1, respectively. The CL for the TSS and anthocyanins were 18.4 and 25.2 g N kg-1 at flowering, and 25.2 and 26.2 g N kg-1 at veraison. The proposition CL and SR of N in leaves allow to accurately verify the potential yield and the grape quality