Iêdo Teodoro

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.

Gas exchange alteration caused by water deficit during the bean reproductive stage

Neste trabalho, se analisaram as trocas gasosas das folhas e parâmetros de produtividade de feijao (Phaseolus vulgaris, L.) submetido a dois periodos de deficiencia hidrica e se empregaram tres regimes hidricos, a saber: W1 (1,0 ETo durante todo o ciclo da cultura); W2 (1,0 ETo ate a floracao e suspensao da irrigacao do 37 ao 51o dia apos a semeadura (DAS), correspondendo a fase de floracao) e W3 (alem da fase reprodutiva tambem se aplicou um deficit hidrico durante a fase vegetativa). A fotossintese foi um dos principais fatores fisiologicos afetados pelo deficit hidrico devido nao so ao fechamento estomatico, mas, tambem, a reducao da eficiencia de carboxilacao, resultante de um dano metabolico; este efeito, contudo, foi neutralizado 24 h apos reidratacao. Durante a floracao o deficit hidrico causou reducao sensivel da produtividade da cultura, com reducao tambem do numero de vagens e numero de sementes por vagem, independentemente do deficit durante a fase vegetativa, porem a massa de 100 sementes nao se alterou em nenhum dos regimes; esses resultados sugerem que o deficit hidrico leva a uma reducao dos fotoassimilados prejudicando a producao final; no entanto, uma vez formada, a semente se desenvolve plenamente, sendo esta uma estrategia da planta em produzir poucas sementes, mas viaveis para perpetuar a especie, mesmo sob condicoes de estresse.

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.

Sugars levels of four sugarcane genotypes in different stem portions during the maturation phase

Maturation is a characteristic of sugarcane plant (Saccharum spp.) and even when grown under the same soil and climate conditions the varieties differ on the maturation curve. Thus, studies that allow establishing maturation curves of different sugarcane genotypes in the local soil and climate may indicate the proper harvesting period to ensure better quality of the raw material. This study aimed to analyze the levels of soluble sugars during the maturation phase and assess the technological and productivity indexes of four irrigated sugarcane genotypes in the region of Rio Largo, Alagoas. The experiment was conducted in randomized blocks in a 4 x 2 x 5 factorial: four genotypes (RB92579, RB98710, RB99395 and RB961003), two stem portions (internodes 1-4 and internodes 5-8) and five seasons (82, 49, 25, 13 and 3 days before harvesting), each treatment with three replications. Internodes 1-4 showed the highest levels of reducing sugars, while the largest accumulation of sucrose and total soluble solids occurred in internodes 5-8. RB99395 genotype showed more stability in the sugar levels during sugarcane maturation, which can indicate early maturation and high agricultural yield.

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.

Influência do sistema de irrigação na incidência e nas perdas ocasionadas pelo Mosaico Dourado do Feijoeiro

One of the most severe diseases in common bean (Phaseolus vulgaris L.) is golden mosaic caused by Bean golden mosaic virus (BGMV, genus Begomovirus, family Geminiviridae). This study aimed to evaluate the influence of different irrigation systems on the incidence and losses caused by BGMV in common bean. The experiment consisted of the evaluation of three irrigation systems (drip, sprinkler and micro sprinkler), installed as 225m2 strips in the experimental area of the Federal University of Alagoas, Rio Largo, AL. Each strip contained 12 plots of 1m2 each, with 20 plants per plot. The experiment was conducted over two seasons: October 2006 to January 2007 and October 2007 to January 2008. The incidence of golden mosaic was evaluated by visual inspection of symptomatic plants, and the asymptomatic plants were tested for the presence of begomoviruses by PCR. For yield evaluations, the weight of mature grains from all plants was quantified, and the average weight per plant in each plot was calculated. The results indicate that drip and sprinkler irrigation resulted in the highest (62.31%) and lowest (16.74%) incidence, respectively, of golden mosaic. There was no correlation between the incidence of golden mosaic and yield. However, healthy plants yielded three times more grain than diseased plants.

Observed and modelled solar radiation components in sugarcane crop grown under tropical conditions

Abstract The net radiation over vegetated surfaces is one of the major input variables in many models of soil evaporation, evapotranspiration as well as leaf wetness duration. In the literature there are relatively few studies on net radiation over sugarcane crop in tropical climates. The main objective of the present study was to assess the solar radiation components measured and modelled for two crop stages of a sugarcane crop in the region of Rio Largo, Alagoas, North-eastern Brazil. The measurements of the radiation components were made with a net radiometer during the dry and rainy seasons and two models were used to estimate net radiation: the Ortega-Farias model and the Monteith and Unsworth model. The highest values of net radiation were observed at the crop development stage, due mainly to the high indices of incoming solar radiation. The daily average albedos of sugarcane at the crop development and mid-season stages were 0.16 and 0.20, respectively. Both models showed a better fit for the crop development stage than for the mid-season stage. When they were inter-compared, Monteith and Unsworth model was more efficient than Ortega-Farias model, despite the dispersion of their simulated radiation components which was similar.

Crescimento e produtividade do milho, submetido a doses de nitrogênio nos Tabuleiros Costeiros de Alagoas

Maize growth and yield under nitrogen levels in Coastal Plains of Alagoas, Brazil The objective of this work was to evaluate the growth and yield of maize subjected to different nitrogen rates. The experiment was conducted with maize cultivar Pioneer 30F35 from 25/06 to 28/10/2009, in the region of Rio Largo-AL. The experiment was arranged in a randomized block design, with six nitrogen rates (0, 50, 100, 150, 200 and 250 kg ha 1 of N in the form of urea) and five repetitions per treatment. The models logistic and log normal peak showed statistically significant adjustments (p<0.05) and maximum coef ficient of determination of 0.994 and 0.990, respectively . The values observed and estimated by these models showed high association by the Willmot’s index of agreement, with values greater than 0.953. The plants showed statistically significant differences by the F teste (p<0.05) between the treatments for height (h) and leaf area index (LAI), with a maximum growth corresponding to the rate of 100 kg ha 1 N. The treatments showed significant differences (p<0.05) for yield, with the rate of 200 kg ha -1 providing the highest yield (5.45 t ha -1 ). The growth models can assist the growth analysis.