Ricardo Araujo Ferreira Junior

Desenvolvimento vegetativo e produção de variedades de cana-de-açúcar em relação à disponibilidade hídrica e unidades térmicas

Objetivou-se, neste trabalho, avaliar padroes de crescimento e de producao de variedades de cana-de-acucar (Saccharum officinarum L.) com os graus-dias e disponibilidade hidrica, durante os cultivos de cana-planta e cana-soca, na regiao dos Tabuleiros Costeiros Alagoano. O trabalho foi desenvolvido na area experimental de Agrometeorologia da Universidade Federal de Alagoas, Rio Largo-AL, num solo classificado como Latossolo Amarelo coeso argissolico. Utilizou-se o delineamento experimental de blocos cazualizados com cinco repeticoes e quatro tratamentos: variedades RB92579, RB931530, RB93509 e SP79-1011. As variaveis da cultura utilizadas foram: perfilhamento, altura da planta, indice de area foliar (IAF), acumulo de materia seca no colmo e producao final. Foram encontradas diferencas significativas entre as medias de perfilhamento das variedades em todas as epocas amostradas, de forma geral o maior perfilhamento foi observado na variedade RB92579. O crescimento das plantas apresentou curvas de formato sigmoidal, com tres fases distintas. Na fase de estabelecimento da cultura, apesar de ter ocorrido otima disponibilidade hidrica, o crescimento foi lento. Na fase de crescimento vegetativo as plantas nao cresceram em potencial, porque houve deficiencias hidricas. A fase final ocorreu entre 1500 e 2015 GD na cana-planta e 950 e 1800 GD na cana-soca. A variedade RB92579 alcancou valores de IAF superiores a 3, logo aos 600 GD nos dois ciclos, permanecendo o restante dos ciclos acima desse valor, contribuindo para uma melhor eficiencia no uso da agua e para o maior acumulo de materia seca.

Crescimento e fotossíntese de cana-de-açúcar em função de variáveis biométricas e meteorológicas

Sugarcane growth can be obtained by biophysical models in which gross photosynthesis (GP) is obtained as a function of solar radiation. This work aims to evaluate sugarcane varieties under irrigation in relation to intercepted photosynthetic active radiation (PARint) and the estimated accumulative GP. To achieve that, a study was conducted at the Federal University of Alagoas during 2008 and 2009, with RB sugarcane varieties. Biometric measurements, production variables and meteorological elements were made. The intercepted photosynthetic irradiance (PAR) was obtained by the difference between PAR and transmitted PAR (PART), which was determined by Beers Law. The daily GP was estimated numerically by the trapezoidal approach. The production variables had correlations with accumulated PARint and accumulated GP during the crop cycle. The average global solar radiation in the region for rainy season (May-August) was 14.9 MJ m-2. The variety RB92579 had the highest production variables as well as higher intercepted PAR and accumulated GP in the cycle due to its greater capacity for regrowth and energy conversion in photoassimilate.

Componentes da radiação solar em cultivo de tomate sob condições de ambiente protegido

ABSTRACT The objective of this paper was to evaluate of net radiation, photosynthetic and solar irradiation ingreenhouse conditions cultivated with tomato crop and its relationship with the global solar irradiationof the external environment. The tomato was cultivated in greenhouse (not acclimatized), with coveringof polyethylene 0.12 mm of thickness. The global solar irradiation (Rgi), the net radiation (Rni) and theflux density of photosynthetic photons were obtained by radiometers connected to a datalogger installedinto the protected environment. The external data (global solar irradiation, Rg) were collected in theAgrometeorological Station of the Agricultural Science Center of Federal University of Alagoas. Theprotecting environment promoted reduction in the solar irradiation, expressed as the transmittance of thepolyethylene in 62%. The relationships between the components of radiation from internal and externalenvironment were expressed satisfactorily by linear regressions, with coefficients of determination (R

Eficiência do uso da radiação em cultivos de milho em Alagoas

Maize was cultivated under three management systems: i) mulching (grass cover); ii) plastic cover in the inter rows and iii) traditional cultivation (bare soil). The components of the incident and transmitted solar radiation in a maize canopy were measured in order to determine the radiation use efficiency (RUE). The photosynthetic irradiation (HF) was considered as 44% of the solar global irradiation. The transmitted HF (HFT) was estimated using Beers law applied to a plant canopy (HFT = HF exp (-k LAI)), with the light extinction coefficient (k) by fitting an exponential function, which related the fraction of HFT (HFT/HF) and leaf area index (LAI). The intercepted HF (HFI) was calculated by the difference (HFI = HF - HFT). The RUE was estimated using a linear regression (forced to pass through the origin) between the dry matter accumulation (DM) and HFI. The k was 0.628 with the determination coefficient of 0.88. The plants RUE in plots covered with plastic was 3.85 g DM MJ-1 of HFI, showing a higher efficiency compared to other treatments (bare soil 3.31 g MJ-1 and grass 3.58 g MJ -1). However, this promoted lower LAI and therefore had less accumulated HFI, resulting in lower production of DM.

Water vapour and carbon dioxide fluxes in sugarcane grown in megathermal humid climate in Northeastern Brazil

The understanding about biophysical processes taking place between the crop and the atmosphere is essential to define the appropriate management practices in order to increase crop yield. The aim of the present study is to analyze water vapour and carbon dioxide (CO2) fluxes in sugarcane crop between the development and the mid-season as an environmental variables function, as well as to assess the correction effects on fluxes. Latent heat flux (lambdaE) and net ecosystem CO2 exchange (NEE) micrometeorological measurements were performed through the eddy covariance technique (EC), between June7th and November 17th, 2013 in a sugarcane crop grown in Northeastern Brazil. Days were characterized according to cloudiness conditions through the clearness index (Kt). The lambdaE and NEE, set through the EC technique, needed correction due to heat and water vapour transfer, because CO2 and lambdaE raw fluxes tend to overestimate and underestimate the values, respectively. Both lambdaE and NEE followed the daily photosynthetic solar irradiance course, but maximum values were not recorded at the same time. Apparent quantum yield and water use efficiency were higher under partly cloudy skies; both variables can be applied to simulation models in order to improve management practices and increase yield.