Water Requirement Estimation of One-Whorl Rubber (Hevea brasiliensis Müll. Arg.) Planting Materials

Fulfilling water requirement is one of the important factors for a successful production of rubber tree planting materials. Research on the irrigation requirement for young rubber trees is crucial to determine the amount of water required for an optimum plant growth. The aim of this study was to determine the amount of water needed by one whorl rubber planting material to compensate the amount of evapotranspiration, as well as to estimate the crop coefficient value (kc). The research was conducted at the Indonesian Rubber Research Institute on July 2021. Daily evapotranspiration (ETc) of rubber planting materials of clone “PB 260”, “RRIC 100”, and “IRR 112” planted in polybag size 13 cm x 35 cm were measured by weighing the planting materials daily. Evapotranspiration for the reference crop was collected from the Indonesian Rubber Research Institute climatological station. Our study showed that the amount of water required by each rubber planting material was 92.21 mL per day per polybag when the mean of daily reference evapotranspiration (ETo) was 3.67 mm per day. Therefore, the crop coefficient (kc) of one whorl rubber planting material arranged sparsely was ± 0.32. This kc value can be used as a base to calculate water requirement of one whorl rubber planting material based on the daily reference evapotranspiration (ETo).

Dynamics of Nocturnal Evapotranspiration and Its Biophysical Controls over a Desert Shrubland of Northwest China

Knowledge about the dynamics and biophysical controlling mechanism of nocturnal evapotranspiration (ETN) in desert-dwelling shrub ecosystem is still lacking. Using the eddy covariance measurements of latent heat flux in a dried shrubland in northwest China, we examined the dynamics of ETN and its biophysical controls at multiple timescales during growing-seasons from 2012 to 2014. The ETN was larger in the mid-growing season (usually in mid-summer) than in spring and autumn. The maximum daily ETN was 0.21, 0.17, and 0.14 mm night−1 in years 2012–2014, respectively. At the diel scale, ETN decreased from 21:00 to 5:00, then began to increase. ETN were mainly controlled by soil volumetric water content at 30 cm depth (VWC30), by vapor pressure deficit (VPD) and normalized difference vegetation index (NDVI) at leaf expanding and expanded stage, and by air temperature (Ta) and wind speed (Ws) at the leaf coloring stage. At the seasonal scale, variations of ETN were mainly driven by Ta, VPD, and VWC10. Averaged annual ETN was 4% of daytime ET. The summer drought in 2013 and the spring drought in 2014 caused the decline of daily evapotranspiration (ET). The present results demonstrated that ETN is a significant part of the water cycle and needs to be seriously considered in ET and related studies. The findings here can help with the sustainable management of water in desert ecosystems undergoing climate change.

ANÁLISE ECONÔMICA DA UTILIZAÇÃO DE SILÍCIO NO CULTIVO DE COUVE-FLOR EM AMBIENTE PROTEGIDO NA REGIÃO NOROESTE DO PARANÁ

ANÁLISE ECONÔMICA DA UTILIZAÇÃO DE SILÍCIO NO CULTIVO DE COUVE-FLOR EM AMBIENTE PROTEGIDO NA REGIÃO NOROESTE DO PARANÁ GUSTAVO SOARES WENNECK 1; RENI SAATH2; ROBERTO REZENDE2; ANDRÉ FELIPE BARION ALVES ANDREAN1; DANILO CÉSAR SANTI1 E DANIELE DE SOUZA TERASSI1 1 Discente do Programa de Pós-graduação em Agronomia, Universidade Estadual de Maringá (UEM), Av. Colombo, 5790, Zona 7, CEP:87020-900, Maringá, Paraná, Brasil. E-mail:[email protected]; [email protected]; [email protected]; [email protected]. 2 Professora do Departamento de Agronomia, Universidade Estadual de Maringá (UEM), Av. Colombo, 5790, Zona 7, CEP:87020-900, Maringá, Paraná, Brasil. E-mail:[email protected]; [email protected] 1 RESUMO O estudo teve como objetivo analisar a viabilidade econômica do cultivo de couve-flor em ambiente protegido sob diferentes condições de disponibilidade hídrica e quantidades de silício (Si) na região noroeste do Paraná. O trabalho foi desenvolvido em ambiente protegido, com três condições de reposição hídrica (40, 70 e 100% da evapotranspiração diária) e quatro doses de Si (0, 50, 100 e 150 kg ha-1). No levantamento dos custos de produção foram considerados como custos fixos o capital da terra e a depreciação da estrutura, e como custos variáveis as sementes, os insumos, eletricidade, a operação de máquinas, os equipamentos, a mão-de-obra e o Si. O estudo considerou a área produtiva de 175 m². Para determinação do retorno econômico foi considerada a produção de massa fresca da inflorescência e o preço médio anual de venda no estado do Paraná. O retorno econômico variou entre R$185,46 e R$660,81. Os resultados econômicos indicam que a produção de couve-flor em ambiente protegido apresenta viabilidade econômica para região noroeste do Paraná. A aplicação de Si, com exceção da condição de reposição hídrica de 40% da ETc com aplicação de 150 kg ha-1 de Si, ocasionou incremento no retorno econômico para couve-flor cultivada em ambiente protegido. Palavras-chave: Brassica oleracea var. botrytis, custo produtivo, viabilidade. WENNECK, G. S.; SAATH, R.; REZENDE, R.; ANDREAN, A. F. B. A.; SANTI, D. C.; TERASSI, D. S. ECONOMIC ANALYSIS OF THE USE OF SILICON ON GREENHOUSE CAULIFLOWER IN THE NORTHWEST PARANÁ REGION 2 ABSTRACT The study aimed to analyze the economic viability of growing greenhouse cauliflower under different conditions of water availability and quantities of silicon (Si) in the northwestern region of Paraná. The study was conducted in a greenhouse, with three water replacement conditions (40, 70 and 100% of daily evapotranspiration) and four doses of Si (0, 50, 100 and 150 kg ha-1). In the survey of production costs, land capital and depreciation of the structure was considered fixed costs, and seeds, inputs, electricity, machinery operation, equipment, labor and Si were variable costs. The study considered the productive area of ​​175 m². To determine the economic return, the production of fresh mass from the inflorescence and the average annual sale price in the state of Paraná was considered. The economic return ranged between R$185.46 and R$660.81. The economic results indicate that the production of greenhouse cauliflower presents economic viability for the northwestern region of Paraná. The application of Si, except for the condition of 40% of ETc with application of 150 kg ha-1 of water replacement condition of 40% of ETc with application of 150 kg ha-1 of Si, increased the economic return for cauliflower grown on greenhouse. Keywords: Brassica oleracea var. botrytis, production cost, viability.

Assessing Daily Evapotranspiration Methodologies from One-Time-of-Day sUAS and EC Information in the GRAPEX Project

Daily evapotranspiration (ETd) plays a key role in irrigation water management and is particularly important in drought-stricken areas, such as California and high-value crops. Remote sensing allows for the cost-effective estimation of spatial evapotranspiration (ET), and the advent of small unmanned aerial systems (sUAS) technology has made it possible to estimate instantaneous high-resolution ET at the plant, row, and subfield scales. sUAS estimates ET using “instantaneous” remote sensing measurements with half-hourly/hourly forcing micrometeorological data, yielding hourly fluxes in W/m2 that are then translated to a daily scale (mm/day) under two assumptions: (a) relative rates, such as the ratios of ET-to-net radiation (Rn) or ET-to-solar radiation (Rs), are assumed to be constant rather than absolute, and (b) nighttime evaporation (E) and transpiration (T) contributions are negligible. While assumption (a) may be reasonable for unstressed, full cover crops (no exposed soil), the E and T rates may significantly vary over the course of the day for partially vegetated cover conditions due to diurnal variations of soil and crop temperatures and interactions between soil and vegetation elements in agricultural environments, such as vineyards and orchards. In this study, five existing extrapolation approaches that compute the daily ET from the “instantaneous” remotely sensed sUAS ET estimates and the eddy covariance (EC) flux tower measurements were evaluated under different weather, grapevine variety, and trellis designs. Per assumption (b), the nighttime ET contribution was ignored. Each extrapolation technique (evaporative fraction (EF), solar radiation (Rs), net radiation-to-solar radiation (Rn/Rs) ratio, Gaussian (GA), and Sine) makes use of clear skies and quasi-sinusoidal diurnal variations of hourly ET and other meteorological parameters. The sUAS ET estimates and EC ET measurements were collected over multiple years and times from different vineyard sites in California as part of the USDA Agricultural Research Service Grape Remote Sensing Atmospheric Profile and Evapotranspiration eXperiment (GRAPEX). Optical and thermal sUAS imagery data at 10 cm and 60 cm, respectively, were collected by the Utah State University AggieAir sUAS Program and used in the Two-Source Energy Balance (TSEB) model to estimate the instantaneous or hourly sUAS ET at overpass time. The hourly ET from the EC measurements was also used to validate the extrapolation techniques. Overall, the analysis using EC measurements indicates that the Rs, EF, and GA approaches presented the best goodness-of-fit statistics for a window of time between 1030 and 1330 PST (Pacific Standard Time), with the Rs approach yielding better agreement with the EC measurements. Similar results were found using TSEB and sUAS data. The 1030–1330 time window also provided the greatest agreement between the actual daily EC ET and the extrapolated TSEB daily ET, with the Rs approach again yielding better agreement with the ground measurements. The expected accuracy of the upscaled TSEB daily ET estimates across all vineyard sites in California is below 0.5 mm/day, (EC extrapolation accuracy was found to be 0.34 mm/day), making the daily scale results from TSEB reliable and suitable for day-to-day water management applications.