Evapotranspiração da cultura da melancia irrigada com água de diferentes salinidades

Sabe-se que a determinação precisa da evapotranspiração da cultura (ETc) é de grande importância para o uso eficiente da água, principalmente em regiões áridas e semiáridas onde se faz necessária a utilização de água salina para irrigação. O objetivo deste trabalho foi determinar a evapotranspiração da melancia, cultivar Mickylee, com o uso de diferentes níveis de salinidade da água de irrigação. O experimento foi conduzido na Fazenda Experimental da Alagoinha, pertencente à Universidade Federal Rural do Semiárido, Mossoró - RN. Os níveis de salinidade da água de irrigação foram: S1 = 0,55; S2 = 1,65; S3 = 2,35; S4 = 3,5, e S5 = 4,5 dS m-1, sendo os tratamentos dispostos no delineamento de blocos ao acaso, com quatro repetições. A determinação da evapotranspiração de referência (ETo) foi realizada pelo método FAO-Penmam-Monteith, e a ETc, pelas leituras obtidas em lisímetros de pesagem, instalados nos tratamentos S1 e S5. Os resultados mostraram que a ETc da melancia diminui com o aumento da salinidade da água aplicada e que a evapotranspiração total durante o ciclo foi de 245 e 214 mm, respectivamente, para os tratamentos S1 e S5. Os valores médios de Kc obtidos para cada fase fenológica foram 0,23; 0,68; 1,12; 0,90 e 0,24; 0,61; 0,98 e 0,78, respectivamente, para as águas S1 e S5.The knowledge of crop evapotranspiration (ETc) is very important for efficient water use in irrigated crops, mainly in arid and semi-arid regions, where the use of saline water is common. The objective of this study was to determine watermelon crop evapotranspiration (cv. Mickylee) in plants submitted to different irrigation water salinity levels. The experiment was carried out at the Experimental field of the Semi-Arid Federal Rural University, Mossoró, RN, Brazil. The irrigation water salinity levels were of S1 = 0.55; S2 = 1.65; S3 = 2.35; S4 = 3.5 and S5 = 4.5 dS m-1, with the treatments set up in randomized blocks with four replications. The determination of reference evapotranspiration (ETo) was accomplished by FAO-Penmam-Monteith method, and ETc was determined by two weighting lysimeters installed in the treatments S1 and S5. The results showed that watermelon ETc decreases with the increase of salinity in the irrigation water. The total ETc during the evaluated period was 245 and 214 mm, respectively for S1 and S5. The Kc medium values obtained for growth stage were: 0.23, 0.68, 1.12 and 0.90 for water S1, and 0.24; 0.61; 0.98 and 0.78 for S5

RENDIMENTO E QUALIDADE DE FRUTOS DE MELANCIA EM DIFERENTES ÉPOCAS DE PLANTIO

Watermelon is a cucurbit, grown in almost all regions of the world, and it is enjoyed by most of the population. In Rio Grande do Norte the cultivation of watermelon has been increasing, because of the good climatic conditions in the region that provides adequate light and temperature throughout the year. In this con-text, the present study aimed at evaluating the yield and quality of watermelon cultivars in different planting dates in Mossoró-RN. The experiment was conducted in the garden didactic Department of Plant Sciences, Federal Rural University of the Semi-Arid in the period between June and December 2010. The experimental design was a randomized complete block in a split plot design with four 3 x 3 repetitions. The plots consisted of three cultivars of watermelon (Crimson Sweet, Olympia and Denver) and subplots were planting (June, Au-gust and October). It is concluded that the yield and fruit quality were influenced by planting dates. The water-melon sowing in August resulted in higher average fruit weight and commercial productivity, and the fruits of lower acidity and better palatability were collected in the June planting

COMPARAÇÃO DE DADOS METEOROLÓGICOS OBTIDOS POR ESTAÇÃO CONVENCIONAL E AUTOMÁTICA EM JABOTICABAL-SP

The objective of this study was to compare the weather data obtained from both conventional (CWS) and automatic (AWS) weather stations, in Jaboticabal, SP, Brazil (latitude: 21º14'05" S, longitude: 48º17'09" W and altitude: 613,68m), from July 1997 to June 2002. Daily data were collected and analyzed statistically by regression analysis. The results showed a good relationship between CWS and AWS, specially for air mean temperature, minimum temperature, maximum temperature and rainfall. Air humidity and atmospheric pressure showed the highest errors, respectively equal to 5,69% and 3,64 hPa. Wind velocity at 2m did not show good precision and accuracy because its estimation for CWS