Emerson Galvani

EFEITOS DE DIFERENTES ESPAÇAMENTOS ENTRE SULCOS NA PRODUTIVIDADE AGRÍCOLA DA CANA-DE-AÇÚCAR (Saccharum spp.)

The final productivity of sugar cane, among other yield factors, is affected by the distance between the row of plants. The potential production is obtained, for each genotype considered, under ideal edapho-climatic condictions, being the plants placed in ideal spacings. Several experiments present increases of the agricultural productivity of sugar cane with the use of narrower spacings between rows of plants. The present survey was performed at experimental stations of five districts (Araras/SP, Pirassununga/SP, Pradopolis/SP, Rubiacia/SP and Cristalina/GO), presenting variations in climate, soil, spacing and genetic material studied, with the objective of analysing the behaviour of the species, in agricultural production terms, and to propose equations to estimative the potential production as a function of the spacing to be adopted.

Balanço de radiação e fluxo de calor no solo em ambiente natural e protegido cultivado com pepineiro

ABSTRACT NET RADIATION AND SOIL HEAT FLUX IN NATURAL AND PROTECTEDENVIRONMENTS CROPPED WITH CUCUMBER Net radiation, global solar radiation and heat flux from/to the soil both inside and outsidegreenhouses with polyethylene cover throughout the fall-winter and spring-summer seasons havebeen assessed at the research sta tion of the Universidade Estadual Pa ulista, Campus of Botucatu, Stateof Sao Paulo, Brazil. Throughout the cycles of the experiment, both environments scrutinized in thecurrent study were cultivated with cucumber crop - Aoday, Hokuroo - a variety of undeterminedgrowth habit. The results indicated that the greenhouse with polyethylene cover tended to decreasethe intensity of solar radiation incidence per unity of area throughout the diurnal period, as well aslosses from emission during the nighttime. The transmissivity of polyethylene was altered as a functionof the day of the year and exposition time of the material, changing from 70.8% at the winter to 74.9%at the summer seasons. The heat flux from/to the soil during the spring-summer cycle was dependentof the leaf area of the crop.

Estimativa da radiação solar global diária em função do potencial de energia solar na superfície do solo

The solar radiation received at the surface of the earth, apart from its relevance to several daily human activities, plays an important role in the growth and development of plants. The aim of the current work was to develop and gauge an estimation model for the evaluation of the global solar radiation flux density as a function of the solar energy potential at soil surface. Radiometric data were collected at Ponta Grossa, PR, Brazil (latitude 25o13 S, longitude 50o03 W, altitude 880 m). Estimated values of solar energy potential obtained as a function of only one measurement taken at solar noon time were confronted with those measured by a Robitzsch bimetalic actinograph, for days that presented insolation ratios higher than 0.85. This data set was submitted to a simple linear regression analysis, having been obtained a good adjustment between observed and calculated values. For the estimation of the coefficients a and b of Angstroms equation, the method based on the solar energy potential at soil surface was used for the site under study. The methodology was efficient to assess the coefficients, aiming at the determination of the global solar radiation flux density, whith quickness and simplicity, having also found out that the criterium for the estimation of the solar energy potential is equivalent to that of the classical methodology of Angstrom. Knowledge of the available solar energy potential and global solar radiation flux density is of great importance for the estimation of the maximum atmospheric evaporative demand, of water consumption by irrigated crops, and also for building solar engineering equipment, such as driers, heaters, solar ovens, refrigerators, etc.

Estimate of leaf area index and productivity of cucumber in greenhouse - winter and summer crops.

Avaliou-se, semanalmente, ao longo do ciclo da cultura de pepino (variedade Hokuho), a area foliar (AF), o indice de area foliar (IAF) e a produtividade (P) em ciclos de outono-inverno e primavera-verao, dentro e fora de casa de vegetacao. Os modelos foram gerados atraves de equacoes polinomiais de 3a e 4a ordem, tendo como variavel dependente o numero de semanas apos o transplante (SAT) e o IAF; ja o ciclo de outono-inverno iniciou-se em 13/05/98, com duracao de 18 semanas, para o qual foram obtidos os seguintes modelos: IAFint= 0,869 - 0,73x + 0,18x2 - 0,008x3 (R2 = 0,964, SD = 0,403) e, IAFext= 0,974 - 1,015x + 0,288x2 - 0,024x3 + 0,000584x4 (R2 = 0,940, SD = 0,211) em que x representa o numero de semanas apos o transplante. O ciclo de verao, teve inicio em 10/11/98, com duracao de 14 semanas, para o qual foram obtidos os seguintes modelos: IAFint= 2,619 - 3,913x + 1,515x2 - 0,161x3 + 0,005x4 (R2 = 0,959, SD = 0,642); IAFext= 3,807 - 4,893x + 1,635x2 - 0,161x3 + 0,005x4 (R2 = 0,968, SD = 0,597). Relacionando-se IAF com produtividade, obtiveram-se os seguintes modelos: ciclo de inverno - Pint = 0,426 . e0,364.IAF e Pext = 0,133 . e0,887.IAF; ciclo de verao - Pint = 0,4297 . e0,360.IAF e Pext = 0,4597 . e0,322.IAF, podendo-se estimar, com boa precisao, o valor do IAF e da produtividade da cultura de pepino (variedade Hokuho) a partir do numero de semanas apos o transplante.

Balanço de energia na cultura de pepineiro em ambiente natural e protegido

ABSTRACT ENERGY BALANCE IN CUCUMBER CROP IN GREENHOUSEAND FIELD CONDITIONSThe net radiation balance (SR), the flow of heat in the soil (G), the flow of latent heat of evaporation(LE) and the flow of sensitive heat (H) were evaluated daily along the cycle of the cucumber cropcultivated inside and outside greenhouse in the autumn-winter and spring-summer cycles. SR and Gwere quantified and LE and H were estimated at two different levels by the method of Bowen ratio.The results showed that most of the availa ble energy was used in the flow of latent heat of evaporationand that the components of the energy balance were more consistent in levels close to the dossel of thecrop and in the greenhouse. Key words: energy balance, greenhouse, cucumber, evapotranspiration. 1. INTRODUCAO O conhecimento da evapotranspiracao, ou fluxode calor latente de evapotranspiracao (LE), contribuipara o planejamento racional da tecnica de irrigacaoe fornece, juntamente com outros elementos meteoro-logicos, subsidios basicos a regionalizacao das areasmais adequadas ao desenvolvimento de determi-nadas especies vegetais. Alem disso, a avaliacao daquantidade de agua exigida por determinada culturatorna-se ainda mais importante, sobretudo em regioesaridas ou com secas regulares, onde o crescimento eo desenvolvimento das plantas e, consequentemente,a produtividade sao limitados pelo fator hidrico.O metodo do balanco de energia (M.B.E.) possi-bilita determinar os valores da demanda atmosfericaem escala horaria e ate mesmo em escalas menores.Apesar da grande diversidade de metodos paradeterminacoes em escala horaria, somente as medidaslisimetricas e o metodo do balanco de energia forne-cem resultados com eficacia. Considerando que aconstrucao de um lisimetro de precisao e dificil eonerosa, e que seu campo de atuacao se restringe aolocal de instalacao, o M.B.E., pela sua versatilidade eprecisao oferecida, e ideal para tal finalidade.Inumera e a literatura que trata da particao dobalanco de energia sobre as mais diversas culturas;

Models to Estimate Daily Diffuse Irradiation Inside Polyethylene Greenhouses Lined East-West and North-South

Publisher Summary This chapter describes simple linear equations to estimate daily diffuse radiation inside and outside of two polyethylene tunnel greenhouses, oriented at East–West and North–South directions. Diffuse irradiances were measured using an Eppley-PSP piranometer, shaded by a ring. Irradiance values were integrated to find the daily values of irradiation. It was found that for relatively high values of diffuse outside the greenhouse, the corresponding inside values were always lower while the converse occurred when the outside values were relatively low. A simple linear equation can be used, with good accuracy in the estimation of daily diffuse radiation inside the greenhouse from measurements taken outside.