Jacinto de Assunção Carvalho

Effect of irrigation water salinity on american lettuce production

With the objective of verifying the effect of different concentrations of salts in the irrigation water on the production of the American lettuce, as well as its accumulation in the saturation extract during a cultivation cycle, one experiment was conducted under greenhouse conditions in the Department of Engineering of the Federal University of Lavras. The statistical design adapted was completely randomized, with 6 levels of water salinity (electric conductivity of 0.18, 1.0, 1.5, 3.0, 4.5 and 6.0 dS m-1) and 5 replications. The results obtained showed that the consumption of water for the plants during the production cycle decreased with increasing levels of salinity of irrigation water, and that the increase of the salinity caused a reduction in appraised vegetative variables. The maximum commercial production of the American lettuce was obtained when the electrical conductivity of the saturated extract reached 0.2 dS m-1. For each unit increase of conductivity beyond the limit cited, there was a reduction of 17% in commercial production.

Vegetative growth and yield of eggplant under different soil water tensions.

Os efeitos de diferentes tensoes de agua no solo aplicadas em dois estadios fenologicos da cultura da berinjela (Solanum melongena L.) foram avaliados por meio de dois experimentos, ambos conduzidos em um delineamento experimental inteiramente casualizado com 5 tratamentos e 6 repeticoes. Os tratamentos se constituiram de 5 diferentes tensoes de agua no solo: 15, 30, 45, 60 e 80 kPa. Os resultados permitiram concluir que efeitos significativos foram encontrados para todas as variaveis analisadas apenas quando os tratamentos foram aplicados na fase de formacao de frutos/colheita, demonstrando que esta fase e mais sensivel a escassez de agua no solo, prejudicando o desenvolvimento da cultura; obtiveram-se maiores producoes com irrigacao realizada sob a tensao de 15 kPa.

Viabilidade técnica e econômica da aplicação de água na cultura do feijoeiro comum (Phaseolus Vulgaris L.)

Este experimento foi conduzido no campus II do Centro Universitario de Patos de Minas (UNIPAM) em Patos de Minas, MG, durante o ano de 2005, e objetivou-se avaliar o rendimento do feijoeiro comum-cultivar Talisma submetida a diferentes niveis de reposicao da agua de irrigacao, determinar a lâmina otima economica e a epoca de suspensao da irrigacao para a cultura. Os tratamentos constaram de 5 niveis de reposicao de agua no solo (40%, 70%, 100%, 130% e 160%), em funcao da lâmina para eleva-lo diariamente a capacidade de campo e 3 epocas de suspensao da irrigacao (0, 7 e 14 dias apos atingir o estadio R9 do ciclo cultural - modificacao da cor das vagens, maturidade fisiologica das plantas). Utilizou-se para a irrigacao um sistema por microaspersao. O delineamento experimental foi um DBC (blocos casualizados) em esquema fatorial de 5x3 com 4 blocos. Foram avaliadas a produtividade da cultura e as lâminas otima fisica e economica. A produtividade da cultura foi afetada pelos niveis de reposicao de agua no solo (houve aumento da produtividade ate reposicao de 100% com posterior queda) e pelas epocas de suspensao da irrigacao exceto na reposicao de 100%. As lâminas e produtividades que proporcionaram a maxima eficiencia economica foram 589,97 mm e 3205,76 kg ha-1 (R9), 535,72 mm e 2874,26 kg ha-1 (R9+7) e 575,84 mm e 3242,73 kg ha-1 (R9+14).

Efeitos da salinidade da água de irrigação na brotação e desenvolvimento inicial da cana-de-açúcar (Saccharum spp) e em solos com diferentes níveis texturais

Foram avaliados os efeitos de diferentes concentracoes de sal na agua de irrigacao, no desenvolvimento inicial da cana-de-acucar, cultivar SP80-1842, cultivada em solos com diferentes niveis texturais. O experimento foi conduzido em casa-de-vegetacao do Departamento de Engenharia da Universidade Federal de Lavras, em Lavras, MG. A finalidade do cultivo em ambiente protegido foi de possibilitar os tratamentos de niveis de sal na agua de irrigacao, sem a interferencia das precipitacoes pluviometricas. Os tratamentos consistiram em quatro niveis de salinidade da agua de irrigacao (condutividade eletrica de 0,10; 2,0; 5,0 e 8,0 dS m-1), e tres classes texturais de solo (texturas arenosa, media e argilosa), totalizando doze tratamentos e caracterizando um delineamento inteiramente casualizado (DIC), em esquema fatorial de 4 X 3, com oito repeticoes. No inicio e apos experimentacao, foram coletadas amostras dos solos para obtencao da condutividade eletrica do extrato saturado, retratando o efeito da salinidade da agua de irrigacao sobre os tipos de solo. Aos 38 dias apos plantio das gemas, obteve-se a massa seca da raiz e da parte aerea, sendo que, durante a experimentacao foram contados, diariamente, o numero de gemas que brotavam em cada vaso. Os resultados mostraram que a cana-de-acucar, cultivar SP80-1842, e sensivel a salinidade da agua de irrigacao, durante sua fase inicial de cultivo. Todos os parâmetros vegetativos foram reduzidos com aumento da salinidade da agua de irrigacao. Houve um aumento da salinidade do solo em virtude do aumento da condutividade eletrica da agua de irrigacao. As maiores medias dessas variaveis foram obtidas no solo de textura media.

Viabilidade técnica e econômica da produção de ervilha (Pisum sativum L.) cultivada sob diferentes lâminas de irrigação

This work had the aim to verify the technical and economic feasibility of pea (Pisum satiums L.) yield under different irrigation depth levels, cultivated in greenhouse. It was used a completely randomized design (CRD), with five levels of replacement of water irrigation (50%, 75%, 100%, 125% and 150% of field capacity) with four replications. The crop was drip irrigated when the average soil water tension obtained from the tensiometers installed in the treatment of 100% was equivalent to 15 kPa. The results were affected by drought and water excess for total production of the plant and for number of beans for plant. The maximum productivity obtained was equal to 4,197 kg ha-1 for a water depth of 188.4 mm and the economic great irrigation depth was 187.4 mm; the greatest water use efficiency was 27.23 kg ha1 mm-1 for a water depth of 86.25 mm.

Efeito do déficit hídrico em duas fases fenológicas sobre a produção do pepino-japonês cultivado em ambiente protegido

The experiment was performed in the experimental area of the Engineering Department Federal University of Lavras, Minas Gerais State, Brazil. It aimed at identifying the adequate irrigation management of the greenhouse-cultivated Japanese cucumber (Cucumis sativus L.). complete randomized design, with four levels of soil water potential (15; 30; 60 e 120 kPa) at two phenological phases (vegetative and reproductive), and 5 replications. Overall, the results showed decrease of yield according to increase of soil water potentials. During the reproductive stage, Japanese cucumber plants were more sensitive to water deficit, resulting in further decrease in yield compared to applied water deficit during the vegetative stage of the culture.

Níveis de déficit hídrico em diferentes estádios fenológicos da cultura da berinjela (Solanum melongena L.)

The effects of different levels of water deficit, applied in two fenological phases of eggplant crop, were measured in an experiment conducted in a green house of the Department of Engineering - UFLA, in Lavras - MG, Brazil. A complete randomized experimental design was used in a factorial array of 2 x 4, being two phenological phases (after-transplanting/opening of the floral bud and fruits formation/harvest) and four levels of water deficit (100; 80; 60, and 40% of the evapotranspiration), in eight treatments with six replications. The stem diameter, height of the plants and number of leaves were evaluated in different times, production and number of fruits. The results showed that the production and the number of fruits were more affected by the water deficit when it occurred during the phase of formation of the fruits, and that, the quality of the fruit was more affected than the total production. The increase of the water deficit resulted in smaller values of the height of the plant, diameter of the stem and number of leaves, independently of the application time.

Consumo relativo de água do feijoeiro no plantio direto em função da porcentagem de cobertura morta do solo

In Brazilian Savannas, large part of irrigated common bean is cultivated under no-tillage system. The ground mulch reduces water requirement of common bean, which affects the management of irrigation. The present study was conducted to determine relative crop coefficients (Kr) under no-tillage system, related to the percentage of soil covered by mulch. The experiment was conducted at Embrapa - Rice & Bean Experimental Station, located in the municipality of Santo Antonio de Goias, GO, in an Oxisol, in a randomized block design, with four replications. The treatments were five different percentages of soil cover with sorghum mulch: 0, 25, 50, 75, and 100%. Crop evapotranspiration (ETc) was determined using field water balance approach. Kr was determined by the relationship between ETc and reference evapotranspiration (ETo). ETo was determined based on Class A pan evaporation. The ETc decreased as the percentage of soil cover increased. The maximum Kr values were 1.25, 1.24, 1.15, 1.12 and 1.01 for the percentages of soil cover of 0, 25, 50, 75 and 100%, respectively.

Avaliação técnica e econômica da produção de duas cultivares de alface tipo crespa em função de lâminas de irrigação

Objetivou-se, com o presente trabalho, a avaliacao tecnica e economica da producao de duas cultivares de alface tipo crespa em funcao de lâminas de irrigacao, cultivadas sob ambiente protegido, na regiao de Lavras, MG. O experimento foi instalado em casa de vegetacao, com delineamento em blocos casualizados, em esquema fatorial 2 x 4, com quatro repeticoes. Os tratamentos constituiram-se de duas cultivares de alface, Veronica e Hortencia, e quatro lâminas de irrigacao, 75, 100, 125 e 150% de reposicao de agua, sendo a lâmina de 100% correspondente a tensao da agua no solo de 15 kPa. Os resultados permitiram concluir que as duas cultivares apresentaram a mesma tendencia com relacao ao consumo de agua, durante o ciclo de producao (eficiencia de uso de agua media de 152,27 kg ha-1 mm-1); maiores produtividades (total e comercial) foram obtidas com a aplicacao da lâmina de irrigacao de 240 mm (121,2% de reposicao de agua); a maxima produtividade comercial, 33.225 kg ha-1, foi estimada com a aplicacao da lâmina de 244,9 mm (123,7% de reposicao de agua); a lâmina economicamente otima foi estimada em 244,2 mm, resultando em uma produtividade comercial praticamente igual a maxima fisica.

Análise produtiva e econômica do pimentão-vermelho irrigado com diferentes lâminas, cultivado em ambiente protegido

The irrigation management is not only an important factor to supply plants water needs, but also to minimize problems with diseases, nutrient leaching as well as unnecessary expenses with water and energy. This study had the aim to verify the economic feasibility of red bell pepper (Capsicum annuum, L.) yield under different irrigation depths, cultivated in greenhouse. A completely randomized design (CRD) was used, with five levels of replacement of irrigation water (50, 75, 100, 125 and 150%) with four replications. Significant differences were found for number of fruits per plant and total production of the plant. The maximum productivity obtained was equal to 35,300 kg ha-1 for a water depth of 443.9 mm and the optimum economic irrigation water depth was 443.5 mm; higher economic returns are obtained by keeping the crop with a water content near field capacity, restoring the full amount of water consumed. The highest water use efficiency was 74.76 kg ha 1 mm-1 for a water depth of 334.1 mm.