José Leonaldo de Souza

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.

Determination of the factors of the universal soil loss equation in Sumé (Paraíba State, Brazil)

The Universal Soil Loss Equation (USLE) factors were determined in a Haplargs under natural rainfall conditions. Data concerning to the years of 1983 -1990 were obtained at the Sume Experimental Station (Paraiba State - Brazil) of the Federal University of Paraiba (UFPB). The treatments consisted of runoff plots with bare soil, native semiarid vegetation runoff plot, mulch runoff plot, palm leaf under downhill runoff plot and under contour palm leaf runoff plot. The annual average of the rainfall erosivity factors EI30 and PI30 were 4,928 MJ mm ha-1 h-1 and 19,734 mm-2 h-1, respectively. The calculated annual mean values of the erodibility parameters were calculated in 0.013 t h MJ-1 mm-1 and 0.003 t h ha-1 mm-2. The calculated values for the support practice factor cropping-management parameter were 0.0015, 0.0174, 0.0133, 0.0056, 0.5103 and 0.2355 for the native semiarid vegetation runoff plot, native semiarid vegetation (new) runoff plot, mulch runoff plots, downhill palm leaf runoff plot and contouring cropped palm leaf runoff plot treatments, respectively. The values of the support conservationist practice factor to downhill palm leaf runoff plot was 0.46.

Evapotranspiration and crop coefficient of Kaki tomato cultivated in greenhouse

The aerodynamic parameters of a crop cultivated in greenhouse can be considered dependent upon the level of global radiation, air temperature and relative humidity, based on exponential laws. Consequently, this work intends to estimate the evapotranspiration and the crop coefficient of Kaki tomato in greenhouse, under drip irrigation, using the Penman-Monteith model. The aerodynamic parameters were measured with sensors connected to the automatic station installed inside the greenhouse. The ETc was determined experimentally through drainage lysimeters and the soil water content was measured through sensors installed at a depth of 20 cm. The performance of the Penman-Monteith model was compared to decennial values of the water balance in the lysimeters, while the reference evapotranspiration was calculated with external data and used for calculation of crop Kc. The results indicated that the Penman-Monteith model underestimates the evapotranspiration values found by the water balance in the lysimeters.

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.

Ocorrência de períodos secos na região de Rio Largo, Alagoas

Water availability in a region is directly related to intensity and frequency of rain occurrence. Major occurrences of days with low amounts of precipitation can produce many losses, especially for agriculture. Thus, the objective of this study was to determine the probability of occurrence of dry periods in Rio Largo, Alagoas, Brazil, and to relate it to climate scale phenomena such as El Nino - Southern Oscillation (El Nino and La Nina). The dry periods were evaluated for three different time intervals with sequence of dry days (> 5 days, > 7 days and > 10 days). The sequence of days was defined as dry based on different thresholds of precipitation (< 0, 1, 2, 3, 4 and 5 mm). The end of each dry period was determined by the occurrence of a rainy day. Analyses were performed using the Instat Climatic application. The 5 days interval was the most frequent in the dry and rainy seasons. In the rainy season (April-August), this dry period had higher frequency of occurrence of 5-85%. While the occurrence of dry periods of 7 days (0 to 45%) and 10 days (0 to 5%) was lower. It was noted the strong influence of ENSO events (El Nino Southern Oscillation) in the occurrence of dry periods. In El Nino years, the occurrences were enhanced (10-60%), and reduced in years of La Nina events (0-45%).

Estação chuvosa e de cultivo para a região de Rio Largo, Alagoas baseada em métodos diretos e sua relação com o El Niño - Oscilação Sul

Rainfall is one of the main meteorological factors responsible for agricultural crops yield. Its irregularity observed more intensely in the Northeast causes the alternation of annual agricultural production. Thus, this study aimed to determine the characteristics of the wet and growing season based on daily rainfall data between 1973 and 2008 in Rio Largo, Alagoas. The beginning (potencial and success), ending and length of the cultivation and rainy season were determinate by direct methods using daily rainfall and reference evapotranspiration. Statistical analysis of cultivation and rainy season characteristics were done using the Instat Climatic software. The expected rainy season, at 80% probability, began on April 7th and finished on October 24th, with a duration of 221 days. The beginning of the rainy season was anticipated in La Nina years (ten days) and postponed in years of El Nino (nine days) and consequently, cause a decrease in the cultivation length season for El Nino years and increase in La Nina years.

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

Mudança no Regime Temporal da Temperatura do Ar e Precipitação Pluviométrica na Região de Rio Largo, Alagoas (Change in the Temporal Regime of Air Temperature and Rainfall in the Region of Rio Largo, Alagoas, Brazil)

Compreender como as alteracoes no clima tem modificado a temperatura do ar e a precipitacao pluvial de uma regiao e essencial, sobretudo para regioes como o Nordeste brasileiro, que apresentam vasto historico de secas e altas temperaturas. No entanto, estudos com esse fim sao escassos ou ate mesmo inexistentes para essa regiao. Deste modo, objetivou-se identificar mudancas ocorridas no regime temporal da temperatura diurna e noturna e na precipitacao na regiao de Rio Largo, Alagoas. Para isto, utilizaram-se dados de temperatura diurna (maxima) e noturna (minima) compreendidos entre 1973 e 2002, e de precipitacao dispostos entre 1973 e 2008. As series temporais foram submetidas ao teste estatistico SNHT (Standard Normal Homogeneity Test) para identificar possiveis pontos de mudanca na media. A analise de regressao linear simples foi utilizada para identificar alteracoes nas series temporais, testada por meio do teste t de Student, adotando-se nivel de significância estatistica de 0,05%, para ambos os testes estatisticos. A analise mostrou que as temperaturas demostraram pontos de mudancas significativos, no entanto, foi observada uma defasagem de quase dez anos entre os pontos. A tendencia identificada entre as temperaturas foram opostas entre si, sendo de aumento para a temperatura diurna e de reducao para a noturna. A precipitacao demostrou tendencia de reducao, no entanto, nao apresentou mudanca estatistica significativa. ABSTRACT Understanding how changes in climate have changed air temperature and rainfall in a region is essential, especially for regions such as the Brazilian Northeast, which have long history of drought and high temperatures. However, studies for this purpose are scarce or even nonexistent for this region. Thus, this study aimed to identify changes in the temporal regime of daytime and nighttime temperature and rainfall in the region of Rio Largo, Alagoas, Brazil. For this, it was used data of daytime temperature (maximum) and night (minimum) ranging from 1973 to 2002, and rainfall arranged between 1973 and 2008. Time series were submitted to SNHT (Standard Normal Homogeneity Test) statistical test to identify possible change point in average. A simple linear regression analysis was used to identify changes in time series, tested using the Student t test, adopting a significance level of 0.05%, for both statistical tests. The analysis showed that temperatures demonstrated significant change points , however, there was a gap of almost ten years between the points. The trend identified among the temperatures was opposed to each other, with increasing daytime temperature and reduction of nighttime temperature. Rainfall demonstrated trend of reducing, however, showed no statistically significant change. Keywords: daytime and nighttime temperature, SNHT, trend, change point .

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.